European Medicines Agency Veterinary Medicines and Inspections
Doc. Ref.: EMEA/CVMP/342257/2007 2 August 2007
REFUSAL CVMP ASSESSMENT REPORT for VERAFLOX
International Non-proprietary Name: pradofloxacin
Procedure No. EMEA/V/C/099
Assessment Report as adopted by the CVMP with all information of a commercially confidential nature deleted.
7 Westferry Circus, Canary Wharf, London, E14 4HB, UK Tel. (44-20) 74 18 84 00 Fax (44-20) 74 18 84 47 E-mail: [email protected] http://www.emea.europa.eu © EMEA 2008 Reproduction and/or distribution of this document is authorised for non-commercial and commercial purposes, provided the EMEA is acknowledged. PRODUCT INFORMATION
Invented Name: Veraflox
Applicant: Bayer HealthCare AG, D-51368 Leverkusen, Germany
Active substance (INN): pradofloxacin
Target species: Dogs and Cats
Withdrawal periods: Not applicable
Pharmaco-therapeutic group Antibacterials for systemic use, fluoroquinolones (ATCvet Code): QJ01MA
Proposed therapeutic Veraflox Tablets: indications: Dogs: • For the treatment of wound infections caused by susceptible strains of Staphylococcus intermedius, superficial and deep pyoderma caused by susceptible strains of Staphylococcus intermedius, and acute urinary tract infections caused by susceptible strains of Escherichia coli and Staphylococcus intermedius. • As adjunctive treatment to mechanical or surgical periodontal therapy in the treatment of infections of the gingiva and periodontal tissues caused by susceptible strains of anaerobic organisms, for example Porphyromonas spp. and Prevotella spp.
Cats: • For the treatment of acute infections of the upper respiratory tract caused by susceptible strains of Pasteurella multocida, Escherichia coli and Staphylococcus intermedius.
Veraflox Oral Suspension:
Cats: • For the treatment of acute infections of the upper respiratory tract caused by susceptible strains of Pasteurella multocida, Escherichia coli and Staphylococcus intermedius. • For the treatment of wound infections and abscesses caused by susceptible strains of Pasteurella multocida and Staphylococcus intermedius.
Pharmaceutical forms & Tablets: 15 mg, 60 mg, 120 mg. Strengths: Oral suspension: 2.5%
Route of administration: Oral use
Packaging: Tablets: Blister (Alu/Alu) Oral suspension: Bottle (HDPE)
Package sizes: Tablets: 7, 21, 70 & 140 tablets Oral suspension: 15ml; 30ml
EMEA/CVMP/342257/2007 © EMEA 2008 2/37 STEPS TAKEN FOR THE ASSESSMENT OF THE PRODUCT
• Further to the submission of a letter of intent by Bayer HealthCare AG on 25 February 2004, the CVMP accepted during its meeting of 16-18 March 2004 that Veraflox would be eligible for the submission of a dossier for granting of a Community marketing authorisation via the centralised system as provided for under Part B of the Annex to Council Regulation (EEC) 2309/93.
• During its meeting of 16-18 March 2004, the Committee for Veterinary Medicinal Products appointed Prof. R. Kroker from Germany as Rapporteur and Dr T. Høy from Norway as Co- Rapporteur for the assessment of the application.
• The application was received by the EMEA on 29 June 2004.
• The procedure started on 14 July 2004.
• The Rapporteur’s Assessment Report was circulated to all CVMP Members on 21 September 2004. The Co-Rapporteur’s critique was circulated to all CVMP Members on 6 October 2004.
• The CVMP requested that their Scientific Advisory Group on Antimicrobials (SAGAM) consider the risk of antimicrobial resistance for this product, which the SAGAM did, by written procedure, between October and November 2004. Their conclusions and recommendations were forwarded to the CVMP for consideration during their plenary meeting held in November 2004, prior to the adoption of the List of Questions.
• During its meeting in November 2004 the CVMP agreed on the consolidated List of Questions and this was sent to the Applicant on 11 November 2004.
• At the November 2004 meeting of the CVMP it was confirmed that an inspection of the manufacturing site was not required.
• The Applicant submitted the responses to the CVMP consolidated List of Questions on 8 September 2005.
• The Rapporteurs circulated their joint Assessment Report on the company’s responses to the List of Questions to all CVMP Members on 7 October 2005. This was also forwarded to the SAGAM, for their consideration of the resistance issues and their comments.
• During their plenary meeting held from 8-10 November 2005 the CVMP decided that an Oral Explanation was required and agreed the List of Outstanding Issues.
• The Applicant submitted written responses to the List of Outstanding Issues on 14 December 2005.
• An Oral Explanation was provided by the Applicant to the CVMP on 19 April 2006.
• The Applicant submitted a Letter of Commitment regarding the Follow-Up Measures on 16 May 2006.
• During its meeting in May 2006, the CVMP, having considered the overall data submitted and the scientific discussion within the Committee, recommended the refusal of the granting of a marketing authorisation for Veraflox on 17 May 2006.
EMEA/CVMP/342257/2007 © EMEA 2008 3/37 STEPS TAKEN FOR THE RE-EXAMINATION PROCEDURE
• The applicant submitted written notice to the EMEA on 2 June 2006 requesting a re- examination of the Veraflox CVMP opinion of 17 May 2006.
• Via a Written Procedure, on 30 June 2006 the CVMP appointed Ms Lesley Johnson as Rapporteur and Mr Rory Breathnach as Co-Rapporteur for the re-examination procedure.
• The detailed grounds for the re-examination request were submitted by the applicant on 17 July 2006. The re-examination procedure started on 18 July 2006.
• The joint Rapporteur/CoRapporteur preliminary Assessment Report was circulated to all CVMP members on 25 August 2006.
• An Ad Hoc Expert Group meeting for Veraflox was held on 6 September 2006 at the EMEA. During this meeting the applicant presented an oral explanation. The report from this meeting was forwarded to all CVMP members and the applicant on 8 September 2006.
• During the September 2006 CVMP meeting, the applicant presented an oral explanation before the CVMP on 12 September 2006.
• During their meeting of 12-14 September 2006, in the light of the overall data submitted and the scientific discussion within the Committee, the CVMP was asked to consider whether its initial opinion dated 17 May 2006 should be revised, to recommend the granting of a Marketing Authorisation for Veraflox. The CVMP concluded that its initial opinion should not be revised and issued a final Opinion, recommending the refusal of the granting of the Marketing Authorisation for Veraflox.
EMEA/CVMP/342257/2007 © EMEA 2008 4/37 SCIENTIFIC DISCUSSION
INTRODUCTION
Veraflox contains pradofloxacin, a fluoroquinolone antibiotic, and is intended for use in dogs and cats. Pradofloxacin is a member of the class of 8-cyano-fluoroquinolone compounds with a broad spectrum of antimicrobial activity. Veraflox is presented in two different pharmaceutical forms.
Veraflox 15 mg, 60 mg and 120 mg Tablets are presented in packs of 7, 21, 70, and 140 tablets each. Veraflox 15 mg tablets are indicated for use in dogs for the treatment of infections of the skin and soft tissues; urinary tract; gingival and periodontal tissues, and in cats for the treatment of acute infections of the respiratory tract. Veraflox 60 and 120 mg tablets are indicated for use in dogs for the treatment of infections of the skin and soft tissues; urinary tract; gingival and periodontal tissues.
Veraflox 2.5% Oral Suspension is presented in bottles of 15 ml and 30 ml. Veraflox 2.5% oral suspension is indicated for use in cats for the treatment of infections of the respiratory tract and soft tissues.
For both pharmaceutical forms the route of administration is oral.
PART 2 – QUALITY ASPECTS
In this report the quality aspects of the tablets are presented first in each section (“1. Tablets”), followed by the equivalent information for the oral suspension (“2. Oral Suspension”).
Composition
1. Tablets
Veraflox Tablets are unremarkable in terms of their composition and include, in addition to the active substance, pradofloxacin, conventional tablet excipients: lactose (filler); microcrystalline cellulose (filler/dry binder); povidone (wet binder); colloidal anhydrous silica (glidant); croscarmellose sodium (disintegrant); magnesium stearate (lubricant); and, an artificial beef flavour (to improve palatability to the target species, cats and dogs). The formulation is defined for each tablet strength. All dosage strengths are compressed from a common strength granulate, the tablets differing only in their weight and size. Their relative composition is identical.
2. Oral Suspension
The composition of Veraflox 2.5% Oral Suspension is also unremarkable, and includes, in addition to the active substance, pradofloxacin, excipients commonly used in oral suspensions: an Amberlite ion exchange resin (taste masking); xanthan gum (thickener); propylene glycol (humectant); ascorbic acid (antioxidant); sorbic acid (preservative); purified water (vehicle); and, a vanilla flavour (to improve palatability to the target species, cats).
Containers
1. Tablets
Veraflox Tablets will be packed into blister strips formed from a polyamide/aluminium/polypropylene composite material sealed with a coated aluminium film (Alu/Alu blister). Each blister strip contains 7 tablets. 1, 3, 10 or 20 blister strips are packaged in an outer cardboard box giving pack sizes of 7, 21, 70 or 140 tablets respectively.
EMEA/CVMP/342257/2007 © EMEA 2008 5/37 2. Oral Suspension
15 ml Veraflox 2.5% Oral Suspension will be filled into white, polyethylene bottles closed with a child resistant screw cap containing a polyethylene adapter. This bottle size will be supplied with a polypropylene oral syringe which is graduated up to 2.0 ml, in 0.1 ml steps.
30 ml Veraflox 2.5% Oral Suspension will be filled into white, polyethylene bottles closed with a child resistant screw cap containing a polyethylene adapter.
Clinical Trial Formula
1. Tablets
The formulation of the tablets used in the clinical trial batches was identical to that of the tablet formulation proposed for marketing. The clinical samples were packed into glass bottles, closed with a PE-press-in-stopper (15 tablets/60ml bottle). The analysis certificates for the clinical trial batches show that all batches fulfil the stated quality requirements.
2. Oral Suspension
The formulation of the oral suspension used in the clinical batches was that of the proposed marketed formulation. Full batch details were provided.
Development Pharmaceutics
1. Tablets
Based on a desired dose of 3 mg pradofloxacin/kg bodyweight, three different tablet strengths were developed, 15, 60 and 120 mg. Divisible tablets (with score marks on both sides) were chosen to facilitate the administration of an accurate dose to small animals. Capsule shaped tablets were chosen to facilitate their ingestion and swallowing by the target species. A flavour (artificial beef) is incorporated to mask the bitter taste of the active ingredient and to improve the palatability of the tablets.
Pradofloxacin can exist in several crystal forms. The choice of the selected polymorph was justified. The particle size of the active substance was well controlled. Pradofloxacin is soluble in water, so micronisation was not necessary to achieve immediate release tablets.
An optimal content of the artificial beef flavour was determined. Irradiated artificial beef flavour is used in many other veterinary medicinal products (mainly tablets for dogs and cats) and is widely accepted in Europe. All the other excipients are well established and widely used in both human and veterinary medicinal products. Results of compatibility studies and stability studies have demonstrated that the excipients chosen have no significant impact on pradofloxacin or on other ingredients of the formulation.
The quantity of each excipient and the manufacturing process have been optimised to produce tablets of optimal hardness, disintegration and dissolution.
Homogeneity of the granulate has been demonstrated on 3 production scale batches and tablets were compressed from these batches and tested. The tablets met all the relevant requirements of their specifications and also the relevant monographs of the Ph.Eur.
The choice of primary packaging for the tablets (aluminium/aluminium blisters) was justified.
EMEA/CVMP/342257/2007 © EMEA 2008 6/37 2. Oral Suspension
The aim of the development pharmaceutics was to manufacture a palatable, liquid formulation for oral administration to cats. Based on the desired dose of 5 mg/kg bodyweight and considering a potential weight range of 0.25 kg to 10 kg as well as an application volume of 1 ml for a 5 kg animal, a formulation containing 25 mg/ml was developed. An ion exchange resin and a flavouring agent (vanilla) are included in the formulation to mask the bitter taste of the active ingredient and to improve the palatability of the suspension.
Pradofloxacin can exist in several crystal forms. The choice of the selected polymorph for this pharmaceutical form was justified. The particle size of the active substance was well controlled. Pradofloxacin is soluble in water, so micronisation was not necessary. Consistency of pradofloxacin particle size in the suspension from batch to batch and on scale-up has been demonstrated, as has the stability of active substance particle size on storage over the claimed shelf-life (24 months) over challenging storage conditions, including short periods of freeze-thaw cycling.
As the oral suspension will be supplied in multidose containers and the formulation would not be self preserving, the inclusion of a suitable preservative was necessary. Sorbic acid was chosen and the preservative effectiveness of the chosen preservative and its content in the final formulation has been demonstrated according to the Ph.Eur. Sorbic acid is a widely used preservative in human and veterinary medicinal products and also in foods. A small amount of ascorbic acid is included in the formulation in order to stabilise the sorbic acid.
Xanthan gum was chosen to stabilise the suspension for its pseudoplastic properties. Propylene glycol is included to improve the solubility of sorbic acid but also acts as an humectant.
The Amberlite ion exchange resin is included in the oral suspension for taste-masking the active substance, in conjunction with an artificial vanilla flavour. Amberlite IRP 64 is the commercial name for polacrilex or polacrilin resin. The potassium form is the subject of a USP monograph and has been used in human medicinal products. The pradofloxacin/Amberlite IRP 64 ratio for the maximum binding capacity of the active substance to the ion exchange resin (IER) was optimised. The pradofloxacin/Amberlite IRP 64 complex is insoluble in water and has, therefore, virtually no taste. In contact with the gastrointestinal fluids the complex breaks down, releasing the pradofloxacin for absorption. The artificial vanilla flavour is widely used in the food industry, complies with Council Directive 88/388/EEC for flavours and is included in the formulation to improve both its smell and taste in order to improve compliance in the cat.
Veraflox 2.5% Oral Suspension has shown a very high dissolution rate at both release and at all time points during the stability studies, independent of test conditions.
No incompatibilities between the active substance and the excipients, or between any of the excipients in the formulation have been found, in any of the stability studies. Particular attention was paid to ensuring there is no interaction between the preservative and the ion exchange resin over time which might affect the antimicrobial action of the preservative and no such interaction was found.
A standard polyethylene bottle was chosen for this oral suspension. Filling overages are included to ensure that the stated volume can be withdrawn from the bottles and these have been justified.
The 15 ml container is supplied with a syringe (graduated up to 2.0 ml in 0.1 ml steps). A dose reproducibility study demonstrated the accuracy and precision of withdrawing both 0.2 ml and 1.0 ml doses. The results fulfilled the requirements of Ph.Eur. monograph 2.9.27 “Uniformity of mass of delivered doses from multidose containers”. For administration of the intended lowest dose of 0.1 ml (for small kittens only) the use of a small volume graduated 1 ml syringe (insulin-type, with graduations from 0.01 to 1.0 ml) is recommended.
EMEA/CVMP/342257/2007 © EMEA 2008 7/37 Method of Manufacture
1. Tablets
The manufacturing formula is given for a typical production batch size. The manufacturing process is typical for conventional tablets, is described in detail and is carried out with adequate in-process controls. Appropriate validation studies have been performed, the results of which demonstrate that the product is produced consistently and in accordance with the agreed specifications, using the defined process.
2. Oral Suspension
The manufacturing formula is given for a typical production batch size. The oral suspension manufacturing process is unremarkable, described in detail and is carried out with adequate in-process controls. Appropriate validation studies have been performed, the results of which demonstrate that the oral suspension is produced consistently and in accordance with the agreed specifications, using the defined process.
Control of Starting Materials
Pradofloxacin, a fluoroquinolonecarboxylic acid, is a brownish light yellow to yellow, fine crystalline substance. Its chemical name is 8-Cyano-1-cyclopropyl-7-(1S,6S)-2,8-diazabicyclo-(4,3,0)nonan-8- yl)-6-fluoro-1,4-dihydro-4-oxo-3-quinoline carboxylic acid. Due to the two chiral carbon atoms of the pyrrolopiperidine group, four enantiomeric forms (two pairs of enantiomers) can exist. The S,S-isomer has been chosen because of its high antimicrobial potency.
The anhydrous substance (the chosen polymorph) is easily dissolved in water but the resultant solution is unstable and, with time, pradofloxacin precipitates as an hydrated form. Pradofloxacin crystallises from water-free solvents in one anhydrous crystal polymorph. Three other anhydrous forms and the amorphous solid state are known, having different thermograms, spectra and x-ray diffraction patterns. The anhydrous substance is stable under the following conditions: up to 120°C and below 95% relative humidity. In the presence of water or high humidity (>97%), hydrates are formed.
The active substance specification includes tests for appearance, identity (IR & HPLC), presence of the desired enantiomeric form (optical rotation in CHCl3); appearance of solution (clarity and colour) (Ph.Eur.), pH (Ph.Eur.), assay (HPLC), chemical purity (HPLC and GC), chloride (potentiometric titration) residual solvents content (GC), sulphated ash (Ph Eur), heavy metals (USP method II, although it was noted that the product would meet the requirements of the Ph.Eur. if tested by that method), water content (Ph.Eur.) and microbial purity (Ph.Eur.). The absence of a test and limits for particle size in the active substance specification has been justified as the manufacturing process has been demonstrated to produce pradofloxacin of a consistently small particle size. The specification reflects all the relevant quality attributes of the active substance. The analytical methods used in the routine controls are suitably described and validation studies are in accordance with the relevant VICH and EU Guidelines. Impurity limits in the specifications are justified by batch history and toxicology studies.
Pradofloxacin is manufactured, tested and released by Bayer Healthcare AG, Friedrich-Ebert-Straße 217-333, 42096 Wuppertal, Germany. The manufacturing process is described in detail and is carried out with adequate in-process controls. Comprehensive specifications and control methods for the starting materials, reagents, solvents and auxiliary materials used during synthesis have been presented. All methods have been described and validated where necessary.
Special attention has been paid to the control of the enantiomeric and diastereomeric purity of the pivotal starting material. The content of residual solvents in this starting material are higher than would normally be allowed in active substances for pharmaceutical use, but residual solvents are controlled to the VICH limit in the active substance specification for pradofloxacin. Batch analysis data demonstrate the levels of residual solvents in pradofloxacin are consistently low.
EMEA/CVMP/342257/2007 © EMEA 2008 8/37
Excipients and Packaging Materials
1. Tablets
The VICH guideline on impurities in new veterinary drug substances has been applied to pradofloxacin and the impurities have been specified and justified. Batch analysis results show that the active substance can be manufactured in sufficient quantity and in a reproducible and consistent manner to the desired quality.
Excipients described in a Pharmacopoeia
Lactose monohydrate, microcrystalline cellulose, Povidone K25, magnesium stearate, colloidal anhydrous silica and croscarmellose sodium all meet the requirements of the appropriate Ph.Eur. monographs. Satisfactory certificates of analysis have been provided for all excipients, demonstrating their compliance with the stated specifications.
Excipients not described in a Pharmacopoeia
The artificial beef flavour consists of three components: hydrolysed vegetable protein; hydrogenated vegetable oil; and natural flavouring. The hydrolysed vegetable protein and the hydrogenated vegetable oil are produced from human-grade soybeans. The natural flavour is sourced from human- grade pork livers. The manufacture of each of the three components and the flavour itself is adequately described.
The in-house specification for the artificial beef flavour contains the following quality characteristics: appearance, odour, protein content, particle size, fat content, moisture and microbiological purity. The test methods are all described. Batch analysis data are in agreement with the quality specifications.
The artificial beef flavour is gamma-irradiated to inactivate potential viruses and micro-organisms. Full details of the process and its validation are provided. An expert assessment of viral safety has also been provided. The viral safety considering the origin of the raw material, the manufacturing process and the intended use has been discussed. The CVMP concluded that the risk of viral contamination is negligible.
Packaging Material (Immediate Packaging)
The tablets will be packed into blister strips consisting of a polyamide/aluminium/polypropylene bottom foil and an aluminium foil with a heat-seal coating (top foil). Polypropylene, the inside layer of the bottom foil, and the heat-seal lacquer, the inside layer of the top foil, are melted together to form the seal. The heat-seal lacquer is also fully described. The polypropylene used is in agreement with the requirements of the European Pharmacopoeia and the heat-seal lacquer and polypropylene used in the bottom foil both meet appropriate specifications. For both of the foils, specifications for routine tests are provided. Likewise for the pure aluminium foil. Batch analysis data for the top and bottom foils are in agreement with the stated specifications.
2. Oral Suspension
Excipients described in a Pharmacopoeia
Sorbic acid, ascorbic acid, xanthan gum, propylene glycol and purified water correspond to their relevant Ph.Eur. requirements. For all excipients certificates of analysis have been provided.
Excipients not described in a Pharmacopoeia
The artificial vanilla flavour is composed of nature identical flavouring substances, natural flavouring substances and flavouring extracts. Propylene glycol is used as a carrier (solvent). The qualitative
EMEA/CVMP/342257/2007 © EMEA 2008 9/37 composition of the artificial vanilla flavour and the quality specifications for propylene glycol carrier, have both been provided and are acceptable to control the quality of this flavouring. The in-house specification for it includes the following quality characteristics: odour, taste, identity (IR), clarity, colour and relative density, and is suitable to control this excipient. The test methods are described. Batch analysis data are in agreement with the stated quality specifications. Additionally the manufacturer has confirmed that vanilla flavour complies with the requirements of the EEC Council Directive 88/388 as amended.
Amberlite IRP 64 is an unifunctional linked carboxylic cation exchange resin prepared from methacrylic acid and divinylbenzene which is not described in any pharmacopoeia, although the potassium form is the subject of a USP monograph. Therefore, an in-house specification is used which is suitable and contains the following quality characteristics: appearance, colour, identity (IR), sodium content (AAS), methacrylic acid content (GC), water extractable content, loss on drying, particle distribution (sieve analysis) and assay (exchange capacity). The test methods are described. Batch analysis data are in agreement with the stated quality specifications.
Packaging Material (Immediate Packaging)
15 ml Veraflox 2.5% Oral Suspension will be filled into white, polyethylene bottles of 20 ml capacity closed by a polypropylene child-resistant screw cap with tamper-evident ring and with a polyethylene adapter (injection moulding plug). This bottle size will be supplied with a 3.0 ml polypropylene syringe graduated up to 2.0 ml in 0.1 ml steps.
30 ml Veraflox 2.5% Oral Suspension will be filled into white, polyethylene bottles of 50 ml capacity closed by a polypropylene child-resistant screw cap with tamper-evident ring. No administration syringe is included with this pack size.
The containers, closures and syringes all comply with the requirements of the European Pharmacopoeia monograph 3.1.3 “Polyolefines” and the monograph 3.2.2 “Plastic containers and closures for pharmaceutical use”. Declarations are presented which demonstrate that all materials used, including the raw material used for the production of the silicone ring of the syringe, are in compliance with the relevant European and FDA requirements. Specifications for routine tests are also provided for the bottle, the screw cap and the syringe. Batch analysis data demonstrate compliance with the stated specifications. The graduations on the printed scale of the syringe are checked and the results comply with the requirements of the Ph.Eur. monograph 2.9.27 “Uniformity of mass of delivered doses from multidose containers”.
Specific measures concerning prevention of transmission of animal spongiform encephalopathies
1. Tablets
Lactose monohydrate is derived from milk sourced from healthy animals in the same conditions as milk collected for human consumption. It is prepared without the use of ruminant materials other than calf rennet which meets the requirements stated in the Public Statement “Lactose Prepared Using Calf Rennet: Risk Assessment in Relationship to Bovine Spongiform Encephalopathitis” of February 27, 2002 (EMEA/CPMP/571/02). According to this Public Statement the Public Report “Risk and Regulatory Assessment of Lactose and Other Products Prepared using Calf Rennet” of May 22, 2002 (EMEA/CPMP/BWP/337/02) the TSE risk in pharmaceutical grade lactose is negligible and pharmaceutical grade lactose can be excluded from the scope of the TSE Guideline (EMEA/410/01- Rev.2).
Artificial beef flavour is obtained from human grade pork liver and contains no beef or bovine products.
Veraflox tablets are in compliance with the Ph.Eur. monograph 5.2.8. “Minimising the risk of transmitting animal spongiform encephalopathy agents via medicinal products”. There is no risk of
EMEA/CVMP/342257/2007 © EMEA 2008 10/37 transmission of spongiform encephalopathy in connection with the use of this veterinary medicinal product.
2. Oral Suspension
The active substance and all excipients used in the manufacture of Veraflox 2.5% Oral Suspension are in accordance with the Ph.Eur. monograph 5.2.8. “Minimising the risk of transmitting animal spongiform encephalopathy agents via human and veterinary medicinal products”. The raw materials of the containers and closures (polypropylene, polyethylene) can contain additives of animal origins (tallow derivatives). Considering the several steps in the manufacturing process of plastic materials and the additionally forming process of the containers and the screw caps the TSE risk is negligible. There is, therefore, no risk of transmission of spongiform encephalopathy in connection with the use of this veterinary medicinal product.
Control Tests on the Finished Product
1. Tablets
Veraflox Tablets (15 mg / 60 mg / 120 mg) are tested to specifications which include tests, by suitable and validated methods, for appearance, identification of the active substance (HPLC, UV), uniformity of mass (Ph.Eur.), microbial quality (Ph.Eur.), assay (HPLC), degradation products (HPLC), dissolution (USP) and moisture content (Ph.Eur.). Testing of dissolution according to the USP method is acceptable, because this method is nearly identical to the method of the European Pharmacopoeia. The flavour is hygroscopic and can absorb moisture, leading to softening of the tablets. Therefore, the water content is limited.
Degradation products are controlled. Their limits are justified by reference to stability studies and toxicology studies and in accordance with the relevant VICH guideline (‘Impurities in new veterinary medicinal products’) and are considered justified.
It has been demonstrated that the manufacturing process and storage have no influence on enantiomeric/diastereomeric purity. No routine test at release is, therefore, necessary.
The tests and limits of the specifications for the finished product are appropriate to control the quality of the finished product for its intended purpose.
Batch analysis data on pilot-scale and production batches of each tablet strength confirm satisfactory uniformity of the product at release.
2. Oral Suspension
Veraflox 2.5% Oral Suspension is tested to a specification which include tests, by suitable and validated methods, for appearance, identification of the active substance (HPLC, TLC) and sorbic acid (HPLC), relative density (USP), viscosity, pH (Ph.Eur.), microbial quality (Ph.Eur.), assay of pradofloxacin (HPLC), assay of sorbic acid (HPLC), degradation products (HPLC), dissolution (USP), and moisture content (Ph.Eur.). The specified tolerance ranges for pradofloxacin assay and sorbic acid assay at release are in line with the relevant guidelines. Testing of relative density and dissolution according to the USP method is acceptable because these methods are nearly identical to those of the European Pharmacopoeia. The content of free pradofloxacin is always 0.1%. The specified upper limit for any unspecified degradation product ensured that no degradation product exceeds the qualification limit of ≤1.0% stated in the VICH guideline. The results for the largest unspecified degradation product and for the sum of unspecified degradation products have never exceeded the amount of 0.1% at release. The proposed limits are justified.
The absence of a test and limits for resuspendability are justified as the product has never shown any sedimentation, even after 12 months storage at room temperature.
EMEA/CVMP/342257/2007 © EMEA 2008 11/37 The test methods have all been fully described and appropriately validated.
Analysis certificates are presented for three pilot batches. All results are in accordance with the specifications and show batch to batch uniformity.
Stability
Active substance:
Data from three batches of pradofloxacin produced at the proposed final site of production are available for up to 12 months. The batches have been stored in polyethylene bags, packed in sealed containers, at 25°C/60% RH and 40°C/75% RH. Additional data from six batches of an earlier development stage are available for up to 24 months and support the findings. Testing methods were identical to those described for the active substance.
Pradofloxacin was found to be very stable to heat and acidic hydrolysis. 7-hydroxy-8-cyano-FCS was found to be the main degradation product under alkaline conditions. In the presence of organic peroxides (which can be present in organic solvents like N-methylpyrrolidone) 3-decarboxy-3- hydroxy-pradofloxacin was found to be the main degradation product.
When exposed to light (1.2 million lux hours and >200 Watt / square meter according to the VICH- guideline), in the solid state, only surface coloration takes place. But, when exposed to light in solution (0.1% in water), considerable degradation takes place making it difficult to identify the cascade of products formed.
Pradofloxacin has been found to be a stable substance in bulk when packed in polyethylene bags (inside of metal or fibre drums). No special storage conditions are required, but it should be stored in a dry place protected from light, especially if the container has been opened. The proposed retest period of 24 months is justified.
Finished Product:
1. Tablets
The shelf life specifications are the same as the release specifications except for the upper limit for water content, which was widened slightly at end of shelf life. Testing methods for stability studies are the same as those described for release.
Stability studies demonstrated that Veraflox tablets are stable in Alu/Alu blisters for up to 24 months at 25°C/60%RH and at accelerated conditions of up to 30°C/80%RH, and for up to 6 months at 40°C/75%RH. The specifications are fulfilled for all parameters tested. The content of the degradation product 7-hydroxy-8-cyano-FCS remained at about 0.1%. Very slight increases in the levels of single unspecified degradation products and the sum of unspecified degradation products were observed under all conditions. These results are in accordance with the stated specifications.
Stability of tablets in the proposed bulk containers up to the claimed storage period was demonstrated.
Pradofloxacin is sensitive to light (discoloration on the surface, but no degradation). In a mixture with the tablet excipients this effect is reduced, but still observable. As the tablets are packaged in light protecting Alu/Alu blisters, the absence of photostability studies on the finished product was justified.
With the stability data provided, the proposed shelf-life of 3 years with no restrictions on storage is justified when tablets are stored in the commercial packaging (Alu/Alu blisters).
The tablets can be divided into halves if required. The half tablet not immediately administered would then remain in the opened blister at ambient temperature and humidity. To investigate the stability of Veraflox tablets outside their sealed blister packs, water uptake was measured in Veraflox 15 mg
EMEA/CVMP/342257/2007 © EMEA 2008 12/37 tablets. The results show that at 25°C/60% RH, an equilibrium of 9% water was reached only after 10 days. It was concluded that storage of tablet halves will not be problematic for short periods of time, such as from one dose to the next (24 hours). However, any half tablets remaining at the end of a course of treatment should be disposed of (in accordance with local requirements for the disposal of medicinal products).
2. Oral Suspension
The stability of the bulk suspension has been demonstrated and a maximum standing time of 12 months for the bulk suspension is justified.
Quality specifications for the oral suspension at end of shelf life are the same as for the release specification, except for the limits for pradofloxacin and sorbic acid which were widened for shelf-life purposes. Testing methods for stability studies are identical to those described for release.
In addition to the specified parameters, preservative efficacy (Ph.Eur.), viscosity and loss of mass were determined during stability studies.
Stability studies on 3 batches of Veraflox 2.5% Oral Suspension demonstrated the product to be stable for 24 months in the proposed packaging at both 25°C/60%RH and under accelerated conditions of up to 30°C/70%RH, and for 6 months at 40°C/75%RH. The specifications are fulfilled for all parameters tested.
Photostability was tested on two batches according to the current VICH guideline. The unprotected samples in the original bottles have shown no significant changes in colour or pradofloxacin assay. The level of degradation products increased but remained within the limits. Therefore, no special protection from light and no special labelling are necessary.
With the stability data provided, the proposed shelf-life of 3 years is justified. Considering the stability results at long term and accelerated conditions, no restriction for storage conditions is necessary.
In-use stability data were provided from two batches stored at 25°C/60%RH for 3 months and the results justify the proposed in-use shelf-life.
OVERALL CONCLUSION ON QUALITY
Veraflox is presented as 15 mg, 60 mg and 120 mg tablets for use in dogs and cats and also as a 2.5% oral suspension for use in cats.
Pradofloxacin, a fluoroquinolonecarboxylic acid, has been developed as an antibacterial for use in veterinary medicine. Out of four possible isomeric forms the S,S-configuration has been chosen because of its high antibacterial activity. Pradofloxacin crystallises from water-free solvents in one anhydrous crystal polymorph. This form is stable under normal storage conditions and has been found to be most suitable for both the tablets and the oral suspension.
The flavour used in the tablets originates from pig livers and is irradiated to ensure the inactivation of any potential contaminant viruses and microorganisms. However, given the specified source and processing details of the pig livers used and the subsequent heat treatment of the pork liver powder during the manufacture of this flavour, the risk of viral contamination is concluded to be negligible.
The control tests for both of the finished products cover the relevant quality criteria and are suited to confirm adequate and consistent product quality.
Stability data for the active substance, pradofloxacin, are available for up to 12 months stored at 25°C/60% RH and 40°C/75% RH. Additional data from batches of an earlier development stage are
EMEA/CVMP/342257/2007 © EMEA 2008 13/37 available for up to 24 months and support the findings. A retest period of 24 months has been claimed and is justified.
Tablets: Batches of Veraflox tablets have been stored at 25°C/60% RH and at accelerated conditions (30°C/70% RH and 40°C/75% RH) for up to 24 months. It has been demonstrated necessary to use Alu /Alu blisters as the primary packaging material to prevent moisture uptake by the tablets. A shelf life for the tablets of 3 years, with no restrictions on storage conditions, is justified when stored in the proposed Alu/Alu blisters.
Oral suspension: 24 months data at 25°C/60% RH are available from 3 pilot batches of each container size of the oral suspension stored in the proposed packaging. The batches were also stored under accelerated conditions of up 30°C/70% RH for 24 months and at 40°C/75% RH for 6 months. A shelf- life of 36 months has been claimed and is justified. The proposed in-use shelf-life of 3 months is also justified.
In conclusion, information on the development, manufacture and control of the drug substance and drug products (tablets and oral suspension) have been presented in a satisfactory manner. The results of tests carried out indicate satisfactory consistency and uniformity of important product quality characteristics, and these in turn lead to the conclusion that the product should have a satisfactory and uniform performance.
EMEA/CVMP/342257/2007 © EMEA 2008 14/37 PART 3 - SAFETY ASSESSMENT
PHARMACODYNAMICS
General pharmacological effects
In rats, diuretic effects were seen after the oral administration of 10 and 30 mg pradofloxacin/kg bodyweight. In a mechanistic model using extracellular recordings from rat hippocampus slices, pradofloxacin exhibited a moderate excitatory potential comparable to that of moxifloxacin. Central nervous system effects represent a common side effect of fluoroquinolones, with dizziness and headache being commonly reported side effects with fluoroquinolones. In very rare cases, convulsions may occur.
In anaesthetised dogs, intravenous doses of 10 and 30 mg/kg bw led to changes of heart rate, peripheral resistance at the two higher doses, and, at 30 mg/kg bw to increased inspiratory pressure and pulmonary resistance, which were interpreted as a consequence of a pseudoallergic reaction. A slight prolongation of QTc-interval and an increase of T-wave height was seen in this study at both of the higher cumulative doses. The CVMP considered that pseudoallergic reactions, including histamine release in anaesthetized dogs, are a common reaction to the bolus administration of most fluoroquinolones and concluded that this reaction would have no relevance for the oral administration of pradofloxacin.
Antibacterial activity
Mode of action
Pradofloxacin is a third generation fluoroquinolone. Its primary mode of action involves interaction with enzymes essential for major DNA functions like replication, transcription and recombination. The primary targets for pradofloxacin are the bacterial DNA gyrase and topoisomerase IV enzymes where reversible association between them and pradofloxacin results in inhibition of these enzymes and death of the bacterial cell. Its bactericidal effect is rapid.
Antimicrobial activity
A number of studies were presented demonstrating the activity of pradofloxacin in pathogens isolated between 1996 and 2004 from studies on an earlier product, and also from canine and feline wound infections, canine pyoderma, canine urinary tract infections and feline upper respiratory tract infections from the clinical pradofloxacin studies. The strains examined came from a number of different European countries and were considered to be representative for the European region.
Studies on the antimicrobial spectrum of activity and Minimum Inhibitory Concentrations (MICs) demonstrate the broad spectrum activity of pradofloxacin and its concentration dependence. Kill rates for Gram-negative organisms were greater than for Gram-positive organisms. Clear post-antibiotic effects (growth suppression) were demonstrated in vitro for the majority of bacteria investigated. Results of studies on the possible influence of environmental factors on the antimicrobial activity of pradofloxacin indicate that it is most likely that disease dependent changes of the animal’s physiological system do not affect its activity.
Minimum Inhibitory Concentrations (MIC) for the bacteria species relevant for the proposed indications are given in the following tables. The bacteria were isolated between 2001 and 2005 from clinical cases in Belgium, France, Germany, Hungary, Poland and Sweden.
EMEA/CVMP/342257/2007 © EMEA 2008 15/37 Dogs:
Bacterial species Number MIC50 MIC90 MIC90s MIC range of strains (µg/ml) (µg/ml) (µg/ml) (µg/ml) Staphylococcus intermedius 593 0.031 0.125 0.125 ≤ 0.016 – 2 Escherichia coli 204 ≤ 0.016 0.125 0.062 ≤ 0.016 – 8 Porphyromonas spp. 75 0.062 0.25 0.25 ≤ 0.016 – 4 Prevotella spp. 69 0.062 1 1 ≤ 0.016 – 4 MIC90 = MIC90 of the susceptible population
Cats:
Bacterial species Number MIC50 MIC90 MIC90s MIC range of strains (µg/ml) (µg/ml) (µg/ml) (µg/ml) Pasturella multocida 240 ≤ 0.016 ≤ 0.016 ≤ 0.016 ≤ 0.016 – 0.062 Escherichia coli 150 ≤ 0.016 4 0.031 ≤ 0.016 – 8 Staphylococcus intermedius 116 0.031 0.125 0.25 ≤ 0.016 – 4 MIC90 = MIC90 of the susceptible population
Minimum Inhibitory Concentration, (PK-PD) Based on MIC-data (number of strains tested, in vitro sensitivity) in connection with PK-PD analysis the following organisms are justified for the respective indications.
Canine acute urinary tract infections Escherichia coli, Staphylococcus intermedius Canine wound and soft tissue infections Staphylococcus intermedius Canine superficial and deep pyoderma Staphylococcus intermedius Canine periodontal disease Porphyromonas spp., Prevotella spp. Feline acute upper respiratory tract infections E. coli, Staphylococcus intermedius, Pasteurella multocida Feline wound and soft tissue infections Staphylococcus intermedius, Pasteurella multocida
Break-points
Based on the MIC90 data and susceptibility profiles provided, the CVMP agreed the following microbiological breakpoints for pradofloxacin: • Susceptible: ≤ 1 µg/ml • Resistant: ≥ 2µg/ml
Cross-resistance
Cross-resistance was confirmed to other fluoroquinolones. A considerable high number of multi- resistant strains were found, however due to the small data base, a clear pattern of co-resistance could not be demonstrated. Data on cross-resistance data for anaerobic bacteria were not provided.
Resistance / Mutant Prevention Concentration
Three studies were provided on Mutant Prevention Concentration (MPC), which is used to define the capacity of an antimicrobial to minimise or limit development of resistant organisms. No standard method is currently available describing the determination of MPCs. Moreover, it is unknown how to integrate MPCs in pharmacodynamic models for specific clinical indications and, hence, how to apply the concept in the design of optimal dosing schemes. In the documented MPC studies, pradofloxacin resistance is postulated to be most commonly acquired stepwise and via a chromosomal mechanism. Pradofloxacin exhibited the most favourable characteristics of the fluoroquinolones tested.
EMEA/CVMP/342257/2007 © EMEA 2008 16/37 PHARMACOKINETICS
A number of GLP compliant studies were presented to evaluate the pharmacokinetics of pradofloxacin, including the metabolism of radiolabelled pradofloxacin in rats. In dogs and cats, the pharmacokinetics of pradofloxacin (in form of the final formulations, that is, tablets and oral suspension) has been sufficiently characterised. No gender-related differences in the pharmacokinetic behaviour of pradofloxacin have been reported.
Absorption
Pharmacokinetic investigations in rats showed that pradofloxacin was rapidly absorbed and distributed throughout all compartments.
After oral administration to dogs, pradofloxacin is rapidly (Tmax of 2 hours) absorbed reaching peak concentrations of 1.6 mg/l. A single oral administration of pradofloxacin showed high bioavailability (close to 100%) irrespective of the tablet strength or dose administered. Systemic drug availability is high (AUC = 13 mg*h/l).
In cats, the absorption of pradofloxacin from orally administered tablets is rapid, reaching peak concentrations of 1.2 mg/l within 0.5 hours. The systemic drug availability (AUC) is 6 mg*h/l. After oral administration of the oral suspension to cats, absorption of pradofloxacin rapidly reaches peak concentrations of 2.1 mg/l within 1 hour with a systemic drug availability of 9 mg*h/l. The administration of a single oral dose demonstrated that the bioavailability of pradofloxacin was close to 70% for the tablets and 60% for the oral suspension.
In both dogs and cats, pradofloxacin plasma concentrations increase linearly with dose.
The bioavailability of pradofloxacin was reduced in fed dogs and cats compared to fasted animals.
Distribution
In dogs, pradofloxacin concentrations increased linearly with dose in skin and serum without accumulation. Pradofloxacin concentrations in skin homogenates of dogs exceed those in serum up to seven times.
The volume of distribution (Vd) is high in dogs (>2 l/kg bodyweight) and cats (>4 l/kg bodyweight), indicating good tissue penetration. Repeated dosing showed no impact on the pharmacokinetic profile. In vitro plasma protein binding is moderate in dogs (35%) and cats (30%). This is within the range known for other fluoroquinolones.
Metabolism
In vitro studies on canine and feline hepatocytes indicate that pradofloxacin is conjugated to glucuronic acid in significant amounts in cats (up to 50%). In canine hepatocytes, in addition to glucuronides, negligible amounts of mono- and bishydroxylation products could be detected.
Excretion
In rats, the excretion of pradofloxacin occurred by biliary and extrabiliary routes into the stomach and the intestine. Pradofloxacin was mainly excreted as the parent compound. The sulfate was the only metabolite of pradofloxacin found in rats.
In dogs, approximately 40% of the pradofloxacin administered orally or intravenously is excreted via urine, independent of the dose and route of administration. Renal excretion is rapid, with approximately 85% of the fraction of pradofloxacin recovered in urine being excreted within 24 hours after administration. Pradofloxacin is cleared from the body at 0.24 l/h/kg. Unchanged pradofloxacin
EMEA/CVMP/342257/2007 © EMEA 2008 17/37 and glucuronide are the main excretion products. The plasma elimination half-life in dogs averages 7 hours.
In cats, approximately 10% of the administered drug is excreted via the kidneys. Renal excretion is rapid with approximately 70% of the fraction recovered in urine being excreted within 24 hours after administration. Pradofloxacin is cleared from the body at 0.28 l/h/kg. Unchanged pradofloxacin and glucuronide are the major excretion products. The plasma elimination half-life in cats averages more than 8 hours with the tablets and 7 hours with the oral suspension.
TOXICOLOGICAL STUDIES
Single dose toxicity
Acute toxicity studies of pradofloxacin were carried out on male and female rats and mice. Pradofloxacin is of low to moderate acute toxicity. The active substance was administered orally or intraperitoneally. The studies were conducted in compliance with GLP and according to the OECD guidelines for acute oral toxicity (No 401 and 423). The LD50 in rats and mice after single oral application was > 2500 mg/kg bodyweight and 500-1000 mg/kg bodyweight (bw), respectively. In rats, reversible effects on the kidney were seen with 100 and 500 mg pradofloxacin/kg bodyweight. Cytotoxic effects have been observed in the testes and epididymides, which were reversible at 500 mg/kg body weight and irreversible at 1000 mg/kg body weight. The haematopoietic and lymphoid systems were also affected, but recovered after withdrawal of pradofloxacin. Although pradofloxacin showed cytotoxic effects on the kidney, testes, haematopoietic and lymphoid systems and the liver in sublethal doses, the doses used were far above the relevant therapeutic doses. The approximate LD50 after a single intraperitoneal application in rats was > 50 mg/kg body weight. Clinical signs and various macroscopic findings on liver, kidney, gastrointestinal tract, spleen, testes and inflammation in the abdominal cavity were seen at 100 mg/kg bodyweight. An acute dermal toxicity study in the rats showed an LD50 of > 2000 mg/kg bodyweight.
Various toxicity studies (acute oral and dermal toxicity, dermal and eye irritation and dermal sensitisation studies) were performed in laboratory animals. Administration of the final oral suspension formulation at an oral dose of 2 ml (corresponding to approximately 50 mg /kg bodyweight) and at dermal dose of 4 ml (corresponding to approximately 100 mg /kg bodyweight) was not acutely toxic to rats. Veraflox 2.5 % oral suspension for cats had no eye or skin irritating potential and was not sensitizing.
In young cats, pradofloxacin proved to be well tolerated after a single oral dose of 100 mg/kg bw.
In dogs, one oral single dose of 100 mg pradofloxacin /kg bw did not adversely affect renal function. However, in one individual animal there was evidence of transient overloading of its renal excretory capacity.
Repeated dose toxicity
In rats and mice, repeated dose studies were performed in the form of feeding studies, with up to 7000 to 7500 ppm (corresponding to <999 mg/kg bw in rats and <2675 mg/kg bw in mice) being administered for up to 4 and 13-14 weeks, with or without following recovery periods. Several special tests were included in individual rat studies as measurements of liver tissue enzyme activity, immunotoxicity and kidney cell proliferation. Toxicokinetic investigations in rat feeding studies showed stable and dose proportional plasma levels and no indication of either accumulation or increased metabolism and elimination.
Prominent features of drug effects at low doses in these studies were diarrhoea, partly leading to dehydration of the animal, increased water intake, haematological alterations as decreased neutrophil and macrophage counts, changes in antibody titres, urinary volume and density, decreased liver enzyme activities, changes in thymus weights and enlarged caeca. At higher doses, degenerative and inflammatory effects in the intestinal tract were seen, as well as changes in the cartilage of knee joints
EMEA/CVMP/342257/2007 © EMEA 2008 18/37 in individual animals. While in the subacute studies NOELs could be allocated to 500 ppm in rats and 2000 ppm in mice, corresponding to about 45-54 and 547-869 mg/kg bw, respectively, the subchronic toxicity studies did not reveal reliable NOELs and the lowest doses in rats (approximately 25 mg/kg bw) at best could be, designated as LOEL. In mice the lowest dose of approximately 150 mg/kg bw was a clear effect level, at which caecal distension, increased water and feed intake could be observed.
In young adult or growing dogs of less than 6 months, a 2-week oral repeat dose toxicity study (up to 44 mg/kg bw) and a 13-week oral repeat dose toxicity study (up to 15 mg/kg bw) were performed. In young growing dogs, the administration of pradofloxacin at 4 mg/kg bw per day and above induced articular cartilage lesions, but these are well known effects for quinolones. No other toxic effects were observed. In particular, no changes in potential target organs and tissues including cardiac function, blood pressure, liver, kidneys, bone marrow, male reproductive organs and eyes were observed. Increased absolute and relative liver weights were found at daily doses of 19 mg/kg bw, and above, but no histopathological correlates or changes in liver tissue enzyme activities were found. Thus, from a toxicological point of view, a NOEL of 4 mg/kg bw was derived. From a pathological point of view, a NOEL of 1.9 mg/kg bw could be established. The risk of quinolone-induced chondropathy in growing dogs could have been addressed (had the product evaluation resulted in a positive opinion) in the SPC, point 5.3, contraindications, where it would have been recommended to contraindicate the use of pradofloxacin in animals with persisting joint lesions, as lesions may worsen during therapy.
In young cats, pradofloxacin proved to be well tolerated after repeated daily doses up to 30 mg/kg bw administered in food for 14 consecutive days. In particular, no adverse effects on articular cartilage, liver, kidneys, bone marrow, male reproductive organs and eyes were observed. However, absorption of the test compound from the intestinal tract was not controlled, the content and stability of pradofloxacin in food was not examined and the actual daily doses were not calculated based on food consumption. The potential of pradofloxacin to induce chondropathy in developing articular cartilage was also investigated in 6 weeks old cats. A NOEL of 25 mg/kg related to a treatment duration of 3 weeks was derived. Although there was no evidence of articular cartilage toxicity in growing cats in the therapeutic dose range, it would have been recommended (if the product evaluation had resulted in a positive opinion) to contraindicate the use of pradofloxacin in animals with persisting joint lesions, as lesions may worsen during therapy.
Tolerance in the target species of animal
The design of the target animal safety study in healthy Beagle dogs aged 8 to 11 months was appropriate to examine the tolerance of the product at the recommended repeated treatment dose and at elevated doses over a period of 3 months. No significant adverse effects attributed to treatment were observed, either with the recommended treatment dose or with the 3X and 5X doses. While the target animal tolerance study did not provide evidence for treatment related cartilage damage, even at overdoses, toxicity studies in Beagle dogs revealed toxic effects in 5 – 6 months old animals already at the therapeutic dose. The clinical studies did not reveal any treatment related adverse effects beyond those already acknowledged for fluoroquinolones.
The tolerance of Veraflox 15 mg tablets in cats was investigated in a GLP compliant study following daily doses of 0, 1X, 3X and 5X the recommended dose, administered for 21 consecutive days. Occasional vomiting, which might have been treatment related, was the only abnormal clinical finding. The assessment of blood parameters, which were sometimes outside the reference range, remained inconclusive as the reference ranges were not based on historical control data, but on data obtained from another experimental study. With respect to the cartilage damaging potential of pradofloxacin, the cats used in this study (11 months old) did not present the subgroup of growing cats primarily exposed to this effect. This potential has, therefore, been addressed in a 3 week oral toxicity study in 6 weeks old kittens and a NOEL of 25 mg/kg was derived for the articular cartilage toxicity of pradofloxacin. The safety of the oral suspension formulation of Veraflox (2.5% oral suspension) in 8 to 9 month old kittens was investigated in a GLP compliant study administering oral doses of 0, 1X, 3X and 5X the recommended dose once daily for 21 consecutive days. Occasional vomiting, soft
EMEA/CVMP/342257/2007 © EMEA 2008 19/37 faeces and salivation post dosing, which seem to result from high volumes and the formulation of the administered product, were the only abnormal clinical observations.
REPRODUCTIVE TOXICITY, INCLUDING TERATOGENICITY
Studies of the effects on reproduction
A one generation study was conducted. Dosages of 0, 100, 500 and 2500 ppm were administered to male and female rats in their diet. No effects were observed on reproduction and pup parameters up to a dose of 2500 ppm (NOEL).
Regarding the safety evaluation for breeding animals, a 1-generation study in rats was provided which meets all the requirements stated in Annex I of Directive 2001/82/EC. In this study no effects on fertility and reproduction were seen, before and during, mating and pregnancy. Therefore, the CVMP concluded that treatment with pradofloxacin is without any risk for breeding animals.
Some negative effects on body weight gain were seen from postnatal day 14 in female pups of the high dose group. These were explained as a consequence of maternal toxicity and decreased nursing, but might also reflect a direct effect of pradofloxacin due to lactational exposure. Thus, as there are no additional data on the possible excretion of pradofloxacin in milk, a warning against its use during lactation would have been included in the SPC (if the product evaluation had resulted in a positive opinion).
Embryotoxicity/foetotoxicity, including teratogenicity
Not applicable.
MUTAGENICITY
Data from a comprehensive battery of genotoxicity assays were provided, including tests for gene mutations and chromosomal aberrations in vitro and in vivo. A Salmonella microsome test was performed with pradofloxacin resulting in increased mutation rates in one (TA102) but not in four other strains of Salmonella typhimurium. However, due to the bactericidal properties of pradofloxacin the test is not valuable.
Pradofloxacin was positive in two independent HPRT-tests and two chromosome aberration tests in vitro, both with and without metabolic activation, indicating a mutagenic and clastogenic potential in vitro. The mouse bone marrow micronucleus test revealed clear positive results in vivo, with a dose- dependent increase in the number of micronucleated polychromatic erythrocytes. The positive effects were reproduced in three independently conducted experiments. At dose levels of 320 mg/kg bodyweight and above, clastogenic effects could be observed. As a consequence, pradofloxacin has to be evaluated as an in vivo clastogen at exposure levels close to therapeutic exposure.
According to the applicant, the genotoxic effects of pradofloxacin are related to its topoisomerase II inhibitory activity. However, pradofloxacin is a moderate inhibitor of topoisomerase II, and the mutagenicity studies have revealed a discrepancy between the genotoxic potency seen with pradofloxacin compared to other fluoroquinolones with similar moderate level of enzyme inhibition. These discrepancies indicate that pradofloxacin may have a second mechanism for genotoxicity, unrelated to the topoisomerase inhibition.
The applicant performed postlabelling studies in vitro and in vivo to elucidate a potentially direct effect on the DNA. However, due to equivocal results and major methodological deficiencies in the in vitro, study the results are considered inconclusive. However, in the following postlabelling study in mice it could be demonstrated that a direct action on the DNA could be excluded.
To assess the photo-genotoxic potential of pradofloxacin two chromosome aberration tests were performed in vitro under conditions of UV-irradiation. These resulted in increased clastogenicity of
EMEA/CVMP/342257/2007 © EMEA 2008 20/37 pradofloxacin. Compared to the aberration frequency without irradiation, cytotoxicity and genotoxicity were also increased. However, in vivo no DNA strand breaking potential of pradofloxacin was detected in a Comet assay in the epidermal cells of hairless mice after oral application and subsequent UV irradiation and the CVMP concluded that pradofloxacin is not photo-genotoxic in vivo at doses up to 200 mg/kg bodyweight.
CARCINOGENICITY
No carcinogenicity studies have been performed. The argumentation presented by the applicant in support for this was partly that pradofloxacin has a topoisomerase II-inhibiting effect, and also its lack of structural alerts. However, these arguments did not satisfy the CVMP because pradofloxacin displays a clear mutagenic potential in vitro (HPRT test) and a strong clastogenic potential in vivo (micronucleus test in mice) which could not be demonstrated with the majority of fluoroquinolones, which possess a probable comparable topoisomerase II activity.
Although the maximum intended treatment period is 35 days, prolonged and/or repeated treatments within the animal’s lifespan cannot be excluded for the agreed indications. Furthermore, the proposed dosage regimen implies routine dosing of many animals with doses of up to 2 X the recommended dose. Consequently, the Committee concluded that pradofloxacin might have a carcinogenic potential and, therefore, the carcinogenic risk to target animals could not be evaluated.
STUDIES OF OTHER EFFECTS
Some additional studies investigating other effects, which are relevant to the safety evaluation of pradofloxacin were presented. These studies provided further information concerning the CNS-, as well as the photo-, chondro- and immunotoxicity of the compound.
Cytotoxicity/Phototoxicity
Some fluoroquinolones are known to be phototoxic, photoallergic or photomutagenic, therefore, the phototoxic and photoallergic effects of pradofloxacin were tested. The cytotoxicity of various fluoroquinolones, including pradofloxacin, was tested in three cell lines: human lymphoblastoma cells from bone marrow (IM9), mouse macrophage cells (J774.A1) and rat hepatoma cells (H4-II-E-C3). Pradofloxacin was shown to possess a pronounced cytotoxic potential in vitro in comparison to other fluoroquinolones.
The phototoxic potential of pradofloxacin was determined in a 3T3 cell line. Pradofloxacin was classified as moderately phototoxic in vitro.
The photoallergic potential of pradofloxacin after oral administration was tested in the local lymph node assay of mice and guinea pigs. Pradofloxacin has a moderate photoreactive potential in guinea pigs and a low photoreactive potency in mice.
Skin/eye irritation
Dermal or ocular irritant properties were studied with the final formulation in rabbits, in compliance with GLP and according to OECD principles. It was concluded that pradofloxacin has no skin or eye irritation or sensitisation potential.
Immunotoxicity
No conspicuous immunotoxic reactions were seen at pradofloxacin levels comparable to the intended therapeutic doses.
EMEA/CVMP/342257/2007 © EMEA 2008 21/37 Chondrotoxicity
Pradofloxacin showed strong chondrotoxic effects in vitro on canine chondrocytes. At repeat oral doses of 4 mg/kg and above, the typical quinolone-induced joint lesions were evident (as shown in the repeat dose toxicity studies on young Beagle dogs at the age of up to six months). The risk of quinolone-induced chondropathy would have been addressed in the SPC under “Contraindications” (had the product evaluation resulted in a positive opinion).
Studies on other substances in the formulations
Various studies assessing the toxicological properties of Propylene glycol, Amberlite IRP 64, Ascorbic acid (E 300) Sorbic acid (E200) Xanthan gum and Vanillin flavour (artificial) were submitted. The CVMP agreed that the use of these substances in Veraflox would be safe for dogs and cats and for users.
USER SAFETY
Veraflox is a veterinary medicinal product containing pradofloxacin indicated for use in dogs and cats and is available as tablets or as an oral suspension. The acute oral toxicity of the product is very low and pradofloxacin was considered non-irritating to the eyes or on the skin. The proposed SPC included a warning that people with a known hypersensitivity to quinolones should avoid any contact with the product. In order to avoid accidental ingestion by children, the oral solution is presented in a bottle with a child resistant closure. The product is to be administered by the veterinarian or by the animal owner.
The most likely accidental exposure for humans with the product would be via the oral or dermal routes. Repeated exposure to the skin of the administrator would be expected, especially when using the oral solution.
In view of the low acute toxicity of the product, the CVMP considered that the use of Veraflox in accordance with its recommendations would cause no immediate risk for the user, or for other humans in the environment of treated animals. However, the genotoxic profile and the lack of carcinogenicity data lead to serious reservations in terms of the long term user safety for this product. At present, the mechanism for the genotoxic potential is unknown, and, therefore, a threshold can not be determined. Thus, although the maximal exposure dose for users is estimated to be as low as 0.033 mg/kg, safety margins cannot be determined.
Conclusion on user safety, including risk management proposals, as appropriate:
The product literature would have included a warning (if the product evaluation had resulted in a positive opinion) that people with known hypersensitivity to quinolones should avoid any contact with the product.
ENVIRONMENTAL RISK ASSESSMENT
Extent of exposure of the product, its active substances or relevant metabolites to the environment (Phase I assessment)
A short Expert Report for Environmental Risk Assessment (Phase I) is provided which is in accordance with the relevant guideline (CVMP/VICH/592/98/Final). Considering that Veraflox is indicated for the individual treatment of companion animals only, the CVMP agreed that both the pharmaceutical formulations of Veraflox do not present an unacceptable risk to the environment, and therefore that no further environmental risk assessment is required (Phase 1 decision tree, CVMP/VICH/592/98-Final).
EMEA/CVMP/342257/2007 © EMEA 2008 22/37 OVERALL CONCLUSIONS ON SAFETY
Pradofloxacin is of moderate acute oral and parenteral toxicity. Results from repeat dose toxicity studies in mice and rats revealed that the gastrointestinal tract, the kidneys, liver, thymus and testes are the target organs. In dogs of less than 6 months of age, pradofloxacin induced dose-dependent lesions in the chondral parts of multiple joints, which is typical for fluoroquinolones. Apart from these effects pradofloxacin was well tolerated in dogs at all doses tested. Appropriate information on the potential of pradofloxacin to induce chondropathy in young growing dogs was included in the proposed product literature. Pradofloxacin proved to be well tolerated in cats at all doses tested.
Since the safety of the product has not been established in the target species during pregnancy and lactation, warnings were included in the proposed product literature.
The potential secondary pharmacodynamic and toxic effects of pradofloxacin have been investigated in a series of pre-clinical safety studies including acute pharmacological in vitro and in vivo studies, acute, subacute and subchronic toxicity studies in rats (oral, intravenous and subcutaneous) and dogs (oral, intravenous and subcutaneous); hazard assessment studies in rats, mice, and guinea pigs; and mutagenicity studies. Carcinogenicity studies were not provided.
Pradofloxacin proved to be non-photogenotoxic. It is, therefore, very unlikely, that the compound is photocarcinogenic.
Pradofloxacin showed a low to moderate photoreactive potential in mice and guinea pigs.
No conspicuous immunotoxic reactions were seen at pradofloxacin levels comparable to the intended therapeutic doses.
Pradofloxacin has shown genotoxic properties in vitro and in vivo, in the latter case at exposure levels close to therapeutic levels. In contrast to other fluoroquinolones with established uses in veterinary medicine (difloxacin, sarafloxacin, danofloxacin, flumequine, marbofloxacin, oxolinic acid, enrofloxacin), pradofloxacin induced dose-dependently and reproducibly the formation of micronuclei in the bone marrow of mice at doses of 320 mg/kg bw and above, despite a topoisomerase inhibition potential comparable to other fluoroquinolones. In general, fluoroquinolones do show clastogenic effects in vitro and some also show mutagenic effects. However, the mutagenicity studies with pradofloxacin have revealed a different genotoxic profile when compared to other fluoroquinolones with similar moderate level of enzyme inhibition, indicating that pradofloxacin may have a second mechanism for genotoxicity, unrelated to its topoisomerase inhibition. At present, the mechanism for the genotoxic potential is unknown, and may involve a mechanism without a threshold. Therefore, a threshold calculation for safety margins cannot be performed.
Based on the genotoxic properties of pradofloxacin, a carcinogenic potential of pradofloxacin is possible and without any threshold concept. Although the maximum intended treatment period is 35 days, prolonged and/or repeated treatments within the dog’s and cat’s lifespan cannot be excluded for the agreed indications. Furthermore, the proposed dosage regimen implies routine dosing of many animals with doses of up to 2 X the recommended dose. Consequently, pradofloxacin may pose a carcinogenic risk to the target animals.
The mutagenic profile and the lack of carcinogenicity data lead to reservations in terms of the user safety for this product. Although the maximal exposure dose for users is estimated to be as low as 0.033 mg/kg, safety margins cannot be determined when the mechanism of actions may not involve a threshold level. Even if a threshold mechanism had been unequivocally established, the margin between exposure levels in the target species at the dose levels proposed in the draft product literature and at the NOEL dose level for clastogenicity do not provide an adequate safety margin.
EMEA/CVMP/342257/2007 © EMEA 2008 23/37 PART 4 – EFFICACY DOCUMENTATION
PRE-CLINICAL STUDIES:
Pharmacodynamics - See Safety Assessment
Pharmacokinetics - See Safety Assessment
Target Species Tolerance - See Safety Assessment
Resistance - See Safety Assessment
CLINICAL STUDIES:
LABORATORY TRIALS
Claim I - Dogs
Taking into account all relevant information derived from PK/PD aspects, pharmacokinetic calculations, available dose determination and dose confirmation studies and the clinical field studies the following indications in dogs are supported: • Treatment of wound infections caused by susceptible strains of Staphylococcus intermedius • Treatment of superficial and deep pyoderma caused by susceptible strains of Staphylococcus intermedius • Treatment of acute urinary tract infections caused by susceptible strains of Escherichia coli and Staphylococcus intermedius • As adjunctive treatment to mechanical or surgical periodontal therapy in the treatment of infections of the gingiva and periodontal tissues caused by susceptible strains of anaerobic organisms, for example Porphyromonas spp. and Prevotella spp.
Claim II - Cats
Taking into account all relevant information derived from PK/PD aspects, pharmacokinetic calculations, available dose determination and dose confirmation studies and the clinical field studies the following indications in cats are supported: Veraflox 15 mg tablets: • Treatment of acute infections of the upper respiratory tract caused by susceptible strains of Escherichia coli, Staphylococcus intermedius, and Pasteurella multocida Veraflox 25 mg/ml oral suspension: • Treatment of acute infections of the upper respiratory tract caused by susceptible strains of Escherichia coli, Staphylococcus intermedius and Pasteurella multocida • Treatment of wound infections and abscesses caused by susceptible strains of Pasteurella multocida and Staphylococcus intermedius
FIELD TRIALS
Claim I - Dogs
Pyoderma (superficial and deep):
Three laboratory studies employing a canine superficial pyoderma model were reported for dose finding. The infection model for superficial pyoderma is considered predictive also for deep pyoderma because the pathogens and mechanisms involved in superficial and deep pyoderma are the same, although deep pyoderma requires a longer treatment period.
EMEA/CVMP/342257/2007 © EMEA 2008 24/37
Two of the studies were suitable to indicate that 3 mg/kg bodyweight (bw) was the lowest effective dose and this dose was therefore selected for the pivotal field studies.
It was noted that a controlled multicentre randomised clinical field trial was conducted in dogs suffering from superficial pyoderma as an exploratory dose confirmation study without blinding. This study was inappropriate due to serious shortcomings.
A multicentre, controlled, randomised and blinded clinical field study was carried out comparing 2 parallel treatment groups of dogs displaying clinical signs of superficial or deep pyoderma to confirm the clinical efficacy of pradofloxacin tablets. Dogs were orally treated with 3 mg/kg bw pradofloxacin once daily or with a control product (containing 10 mg/kg amoxicillin with 2.5 mg/kg clavulanic acid) twice daily for 14 - 63 days. The cure rate in superficial pyoderma was 86.36% for pradofloxacin and 81.58% for the potentiated amoxicillin (amoxicillin with clavulanic acid) with no significant difference between the groups. The prevalence of bacterial strains isolated from superficial and deep pyoderma was too low to prove their causal relationship with the disease except for Staphylococcus intermedius. Whilst the efficacy in superficial pyoderma was considered proven by the trial, the efficacy for deep pyoderma was not supported based on these data.
The applicant conducted a second clinical field study in dogs suffering from deep pyoderma, according to the same protocol as the previous study. 86% of the dogs treated with pradofloxacin and 72% of the dogs treated with the control product were cured. The pathogen involved in a sufficient number of clinical cases was Staphylococcus intermedius. Based on these data, pradofloxacin was considered efficacious in the treatment of canine deep pyoderma caused by Staphylococcus intermedius.
As regards the treatment duration for superficial pyoderma, a sufficient number of animals suffering from superficial pyoderma were cured after 14 days treatment and only 25% of the dogs needed treatment for longer than 21 days. Thus a treatment duration of 14 – 21 days was recommended for superficial pyoderma.
As regards the treatment duration for deep pyoderma, a sufficient number of animals suffering from deep pyoderma were cured after 14 days treatment and 68% of the dogs needed a treatment period of up to 35 days. Thus a treatment duration of 14 – 35 days was recommended for deep pyoderma.
The treatment duration should not be longer than necessary, and the effect of treatment should be regularly assessed during the treatment course. If the product evaluation had resulted in a positive opinion the product literature would have included a warning in section 4.9 of the SPC to this effect.
Wound infections:
A laboratory dose determination study was reported employing an established model of canine surgical wound infection. From this study a minimum effective dose of 3 mg/kg bw was justified.
A multicentre, multiregional, controlled, randomised and blinded clinical field study was carried out comparing 2 parallel treatment groups to confirm the clinical efficacy of pradofloxacin tablets in dogs that had wounds from bites or another trauma. Dogs were orally treated with 3 mg pradofloxacin/kg bw once daily or with a control product, 10 mg/kg amoxicillin and 2.5 mg/kg clavulanic acid (= potentiated amoxicillin) twice daily for 7 days. All dogs treated with pradofloxacin were cured at the end of the study and pradofloxacin was therapeutically non-inferior to the control product (potentiated amoxicillin). The prevalence of isolated bacterial strains was too low to prove their causal relationship with the disease except for Staphylococcus intermedius. Thus, pradofloxacin was considered efficacious for the treatment of wound infections caused by susceptible strains of Staphylococcus intermedius, using a treatment duration of 7 days.
EMEA/CVMP/342257/2007 © EMEA 2008 25/37 Urinary tract infections:
Two laboratory dose determination studies were reported employing a urinary tract infection model in dogs. However, a therapeutic dose could not properly be derived because of the variable infection rates in the treatment groups, therefore, the selected therapeutic dose of 3 mg/kg bw is solely based on the favourable results of a prospective PK-PD analysis and the high concentrations of pradofloxacin in urine following administration at the recommended dose level.
A controlled, randomised, multicentre, blinded field trial was conducted comparing 2 parallel treatment groups to confirm the clinical efficacy of pradofloxacin tablets in dogs suffering from clinical signs of acute urinary tract infections (UTIs), i.e., cystitis or prostatitis. Dogs were orally treated with 3 mg/kg pradofloxacin once daily or with the control product which contained 10 mg/kg amoxicillin combined with 2.5 mg/kg clavulanic acid, twice daily for 7 - 21 days. It was agreed to consider “bacteriological recovery” (BR) and “clinical recovery” (CR) separately to assess the efficacy of pradofloxacin in canine UTIs. BR and CR are comparable with rates reported from other fluoroquinolones, and were significantly higher than those achieved with the control product. The pathogen involved in a sufficient number of clinical cases was E. coli. Staphylococcus spp. was identified in only 18.6% of cases. However, taking into account the favourable pre-clinical data for that pathogen, the claim against Staphylococcus intermedius was considered supported. CVMP concluded that the number of dogs infected with Proteus spp. was too low for a causal relationship with the disease or a claim for efficacy to be substantiated. Therefore, based on the data submitted, pradofloxacin was considered by the Committee to be efficacious after a treatment duration of 7 – 21 days in acute urinary tract infections caused by susceptible strains of Escherichia coli and Staphylococcus intermedius.
Periodontal disease:
Two studies were conducted employing a “dirty tooth model” which provided a practical method of determining the actual effect of antimicrobial treatment. A relatively short-term effect on gingival flora and a small reduction in pocket depth were reported which is the best that could be expected using such a model without further mechanical periodontal therapy.
Firstly, a controlled exploratory dose-confirmation study was conducted, under laboratory conditions, in Beagle dogs to investigate periodontal loss of attachment and the natural sub-gingival flora in cases of periodontal disease. A dose of 3 mg pradofloxacin/kg bw was administered over 6 days. A combination product (tablets) containing metronidazole combined with spiramycin served as the positive control and was administered at 12.5 mg/kg bw metronidazole and 7500 IU/kg bw spiramycin twice a day for the same period. The flora which are currently accepted to be pathogenic for the periodontium consist of a variety of Gram-negative anaerobic bacteria. In addition to spirochetes, the organisms found inter alia in the study, that is, Porphyromonas spp. and Prevotella spp. are primarily involved. The study results demonstrate that pradofloxacin and the positive control were not significantly different in their activity on periodontal loss of attachment and sub-gingival flora. The buccal ecosystem was positively changed in both treatment groups.
Secondly, a controlled, randomised, multicentre, blinded field trial comparing 2 parallel treatment groups of dogs suffering from periodontal disease was conducted to confirm the efficacy of pradofloxacin tablets (3 mg/kg bw once daily for 7 days) in the alleviation of clinical signs associated with periodontal disease in dogs. Efficacy was compared to that of a control product: clindamycin capsules (clindamycin hydrochloride: 5.5 mg/kg bw twice daily, 7 days). Both antimicrobial treatments (pradofloxacin or clindamycin) induced a significant reduction of pocket depth over the study period at both target teeth. The reduction of pocket depth induced by treatment with either pradofloxacin or clindamycin was similar for all probing sites. No statistically significant difference was detected between the groups for mean bleeding on probing (BOP) score. The BOP score decreased significantly in both groups over the study period. No statistically significant difference was detected between the groups for general condition score. No bacterial strain could be isolated from most of the samples, but from the positive samples Porphyromonas gingivalis and Prevotella intermedia were the predominant organisms. It was concluded that pradofloxacin was effective in the
EMEA/CVMP/342257/2007 © EMEA 2008 26/37 alleviation of clinical signs associated with periodontal disease in dogs and that it was non-inferior to clindamycin.
By providing expert reports from recognised specialists in veterinary dentistry, the complexity of periodontal diseases in dogs was illustrated. According to these, inconsistent bacteriological findings are commonly observed in dogs due to the mixed character of the periodontal flora, but in general periodontal diseases are associated with a prevalence of Gram-negative anaerobic bacteria. This corresponds with the findings of the clinical field study. Periodontal treatment consists primarily of mechanical teeth cleaning. However, antibiotic treatment is justified in order to achieve a reduction of pathogens and physiological bacterial flora, and by this detoxification of the peridontium from detrimental bacterial toxins, as this cannot solely be reached by scaling, and for the prevention of local and systemic secondary infections. The latter have been shown to be significantly correlated with periodontal diseases by literature references supplied. By its broad spectrum of antimicrobial activity, pradofloxacin is considered suitable for these purposes.
Based on these data, the Committee considered the indication “As an adjunct (to mechanical or surgical periodontal therapy) in the treatment of infections of the gingiva and periodontal tissues caused by susceptible strains of anaerobic organisms, for example Porphyromonas spp. and Prevotella spp.” proven, after a treatment period of 7 days.
Claim II - Cats
In the clinical field studies Escherichia coli, Pasteurella multocida, and Staphylococcus intermedius (feline upper respiratory tract infections) and Staphylococcus intermedius and Pasteurella multocida (feline wound infections) were the only pathogens whose prevalence was significant enough to prove their causal relationship with their respective diseases.
Veraflox 15 mg tablets:
No dose determination studies were submitted for the indication claimed. Thus the recommended dose for Veraflox tablets was based solely on PK-PD aspects. A GCP compliant, blinded multicentre field study was carried out comparing two treatment groups to demonstrate the efficacy of pradofloxacin 15 mg tablets in the treatment of feline subacute or acute upper respiratory infections. Chronic diseases or infections of the lower respiratory tract including pneumonia were not included. Cats were orally treated with 3 mg/kg bw pradofloxacin once daily or with a reference product containing potentiated amoxicillin as tablets (12.5 mg/kg bw) twice daily for 5 consecutive days. The treatment results with pradofloxacin were comparable to those obtained with the reference product. The prevalence of isolated bacterial strains was too low to prove their causal relationship with the disease except for Escherichia coli and Staphylococcus intermedius.
Although MIC data and clinical efficacy were not demonstrated for Pasteurella multocida from the tablet studies, the claim is supported. Pasteurella multocida is one of the predominant causative pathogens in feline respiratory infection as demonstrated in the studies using the oral suspension formulation. MIC data have shown a high susceptibility to pradofloxacin without indicating resistant isolates, superior results were reached in PK/PD-analysis and good clinical results were presented in the studies with the suspension.
Veraflox 2.5% oral suspension:
Acute infections of the upper respiratory tract:
A controlled, blinded, randomised challenge dose determination study in close compliance to GCP was conducted which provided sufficient evidence that 5 mg/kg bw pradofloxacin oral suspension is efficacious in the treatment of bacterial secondary infections. Furthermore, a controlled, blinded, randomised, GCP compliant dose confirmation study was conducted under field conditions, which provided sufficient evidence that a dose of 5 mg/kg bw was non-inferior to a dose of 10 mg/kg bw.
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A GCP compliant, multicentre, controlled, randomised and blinded field study was carried out comparing two treatment groups to demonstrate the efficacy of pradofloxacin 2.5% oral suspension in the treatment of feline acute upper respiratory infections. Chronic diseases or infections of the lower respiratory tract including pneumonia were not included. Cats were treated orally for 5 consecutive days with 5 mg/kg bw pradofloxacin once daily or with a reference product (10 mg/kg bw amoxicillin combined with 2.5 mg/kg bw clavulanic acid) twice daily. Non-inferiority of pradofloxacin to the reference product was shown for the primary efficacy criterion, complete cure. Only claims against Escherichia coli, Pasteurella multocida and Staphylococcus intermedius were supported. The Committee concluded that the prevalence of other isolated bacterial strains (which included Pseudomonas oryzihabitans, Klebsiella oxytoca, Staphylococcus hyicus, Streptococcus canis and Enterobacter cloacae) was too low to prove their causal relationship with the disease or to prove clinical efficacy.
Wound infections and abscesses:
A GCP compliant, multicentre, controlled, randomised and blinded field study was carried out comparing two treatment groups to demonstrate the efficacy of pradofloxacin 2.5% oral suspension in the treatment of wound infections and abscesses from bites and traumas in cats. Cats were treated orally for 7 consecutive days with 5 mg/kg bw pradofloxacin once daily or with a reference product (10 mg/kg bw amoxicillin combined with 2.5 mg/kg bw clavulanic acid) twice daily. Non-inferiority between the two treatment groups was shown. Only claims against Pasteurella multocida and Staphylococcus intermedius were supported. The Committee concluded that the prevalence of other isolated bacterial strains (which included Escherichia coli, Streptococcus canis and Staphylococcus spp.) was too low to prove their causal relationship with the disease or to prove clinical efficacy.
OVERALL CONCLUSIONS ON EFFICACY
Dogs: The submitted studies demonstrate the efficacy of Veraflox tablets administered at doses of 3 mg/kg bw in the treatment of infected wounds, superficial and deep pyoderma, acute urinary tract infections, and as adjunctive treatment to mechanical or surgical periodontal therapy in the treatment of infections of the gingiva and periodontal tissues caused by susceptible strains of pathogens. Treatment durations vary considerably depending on each indication.
Target animal safety was demonstrated for a treatment duration of 90 days. Measures for the safe use of the product would have been necessary and appropriate warnings would have been included in the product literature accordingly, had the product evaluation had resulted in a positive opinion.
Cats: The tolerance of cats aged 6 weeks and older to the recommended treatment dose of Veraflox 15 mg tablets and Veraflox 25 mg/ml oral suspension and to the recommended treatment duration has been demonstrated. The available studies demonstrate the efficacy of pradofloxacin tablets administered at doses of 3 mg/kg bw in the treatment of acute infections of the upper respiratory tract, and the efficacy of pradofloxacin 2.5% oral suspension administered at doses of 5 mg/kg bw in the treatment of acute infections of the upper respiratory tract and infected wounds and abscesses.
The following indications for use were justified for Veraflox Tablets:
Dogs: • For the treatment of wound infections caused by susceptible strains of Staphylococcus intermedius, superficial and deep pyoderma caused by susceptible strains of Staphylococcus intermedius, and acute urinary tract infections caused by susceptible strains of Escherichia coli and Staphylococcus intermedius.
EMEA/CVMP/342257/2007 © EMEA 2008 28/37 • As adjunctive treatment to mechanical or surgical periodontal therapy in the treatment of infections of the gingiva and periodontal tissues caused by susceptible strains of anaerobic organisms, for example Porphyromonas spp. and Prevotella spp.
Cats: • For the treatment of acute infections of the upper respiratory tract caused by susceptible strains of Pasteurella multocida, Escherichia coli and Staphylococcus intermedius.
The following indications for use were justified for Veraflox Oral Suspension:
Cats: • For the treatment of acute infections of the upper respiratory tract caused by susceptible strains of Pasteurella multocida, Escherichia coli and Staphylococcus intermedius. • For the treatment of wound infections and abscesses caused by susceptible strains of Pasteurella multocida and Staphylococcus intermedius.
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PART V - RISK BENEFIT ASSESSMENT
Veraflox contains pradofloxacin, a fluoroquinolone antibiotic, and is indicated for use in for cats and dogs. Pradofloxacin is a member of the class of 8-cyano-fluoroquinolone compounds with a broad spectrum of antimicrobial activity.
In general the quality aspects of the product have been well documented. The active substance and finished product are manufactured and controlled in the appropriate manner, in compliance with current EU and VICH guidelines. Satisfactory information has been provided to demonstrate that the manufacture and control processes routinely and consistently generate a product of uniform quality. There were a few minor unresolved quality issues at time of opinion, but the CVMP considered these to have no impact on the benefit:risk balance of the product when used according to the proposed product literature and it was agreed that they could have been resolved as follow-up measures (if the application had led to an authorisation).
The starting materials of animal origin used in the production of the final product have all been declared in compliance with the current regulatory texts related to the TSE Note for Guidance (EMEA/410/01-Rev.2) and Commission Directive 2001/82/EC as amended.
The potential secondary pharmacodynamic and toxic effects of pradofloxacin have been investigated in a series of pre-clinical safety studies including acute pharmacological in vitro and in vivo studies, acute, subacute and subchronic toxicity studies in rats (oral, intravenous and subcutaneous) and dogs (oral, intravenous and subcutaneous); hazard assessment studies in rats, mice, and guinea pigs; and mutagenicity studies. Carcinogenicity studies were not provided.
Pradofloxacin was positive in two independent HPRT-tests and two chromosome aberration tests in vitro, and in three independent mouse bone marrow micronucleus tests in vivo. These findings indicate that pradofloxacin is clastogenic and potentially mutagenic in vivo.
Pradofloxacin is a moderate inhibitor of topoisomerase II. In general, fluoroquinolones do show some clastogenic effects in vitro. However, the mutagenicity studies with pradofloxacin (at non-cytotoxic doses) have revealed a pronounced discrepancy between the genotoxic potency seen with pradofloxacin compared to other fluoroquinolones with similar moderate levels of enzyme inhibition (negative micronucleus tests in vivo) at exposure levels close to therapeutic levels. These discrepancies indicate that pradofloxacin may have a second mechanism for genotoxicity, unrelated to its topoisomerase inhibition. At present, the mechanism for the genotoxic potential is unknown, and a direct action on DNA cannot be excluded. A direct action on DNA would imply a mechanism of action without a threshold and without safety margins.
Two supplementary postlabelling studies (in vitro and in vivo) were provided to address the potentially direct effect of pradofloxacin on DNA. However, due to some equivocal results and major methodological deficiencies, the results from these studies cannot be regarded as conclusive. As a consequence, the underlying mechanism for the mutagenic and clastogenic effects of pradofloxacin remains unclear, and a direct action on DNA in vivo cannot be excluded.
Based on the genotoxic properties of pradofloxacin, a carcinogenic potential of pradofloxacin must be assumed, without any threshold concept. Although the maximum intended treatment period is 35 days, prolonged and/or repeated treatments within the dog’s and cat’s lifespan cannot be excluded for the agreed indications. Furthermore, the proposed dosage regimen implies routine dosing of many animals with doses of up to 2 X the recommended dose. Consequently, pradofloxacin is considered to be a carcinogenic risk to the target animals.
The mutagenic profile and the lack of carcinogenicity data led to reservations in terms of the long term user safety for this product. Although the maximal exposure dose for users is estimated to as low as
EMEA/CVMP/342257/2007 © EMEA 2008 30/37 0.033 mg/kg, safety margins cannot be determined for mechanisms of actions potentially without a threshold level.
Notwithstanding the fact that a threshold concept is not applicable (for the reasons stated above) for pradofloxacin, the margin between exposure levels in the target species at the dose levels prescribed in the product literature and at the NOEL dose level for clastogenicity do not provide an adequate safety margin.
The CVMP considered that Veraflox was not approvable based on the evaluation of the safety data.
From the clinical point of view, the CVMP considered that the submitted studies demonstrate the short term target animal safety and the efficacy of Veraflox tablets administered to dogs at doses of 3 mg/kg bw in the treatment of infected wounds, superficial and deep pyoderma, acute urinary tract infections and as adjunctive treatment to mechanical or surgical periodontal therapy in the treatment of infections of the gingiva and periodontal tissues caused by susceptible strains of pathogens. Treatment durations vary considerably depending on each indication.
The tolerance of cats aged 6 weeks and older to the recommended treatment dose of Veraflox 15 mg tablets and Veraflox 25 mg/ml oral suspension and to the recommended treatment duration has been demonstrated. The available studies demonstrate the efficacy of pradofloxacin tablets administered at doses of 3 mg/kg bw in treatment of acute infections of the upper respiratory tract of cats and the efficacy of pradofloxacin 2.5% oral suspension administered at doses of 5 mg/kg bw in treatment of acute infections of the upper respiratory tract and infected wounds and abscesses in cats.
Overall conclusions
The CVMP concluded that based on the submitted documentation it cannot be excluded that pradofloxacin is a carcinogenic risk to the target animals and to the user, and that a favourable benefit- risk profile for Veraflox had not been established due to the safety profile of the product.
Based on the original and complementary data presented, the Committee for Medicinal Products for Veterinary Use (CVMP) concluded that the quality and efficacy of Veraflox were considered to be in accordance with the requirements of Directive 2001/82/EC of the European Parliament and of the Council, as amended. However, the safety of the product is considered not to be in accordance with the requirements of Directive 2001/82/EC of the European Parliament and of the Council, as amended.
The CVMP, therefore, did not recommend the granting of a marketing authorisation at its May 2006 meeting.
RE-EXAMINATION OF THE CVMP OPINION OF 17 MAY 2006 FOR VERAFLOX
At the May 2006 CVMP meeting following discussion of the Marketing Authorisation Application for Veraflox, the CVMP concluded that the overall benefit/risk for Veraflox was negative.
The grounds for refusal stated in the negative opinion for Veraflox were:
• The CVMP concluded that a direct effect of pradofloxacin on DNA in vivo cannot be excluded.
• Even if a threshold effect had been accepted, an adequate margin of safety regarding clastogenicity would not be ensured at the proposed dosage rates.
EMEA/CVMP/342257/2007 © EMEA 2008 31/37 • No carcinogenicity studies have been performed.
• In the absence of unequivocally proven safety, the clastogenic, potentially mutagenic and potentially carcinogenic profile of pradofloxacin constitutes a concern for both the target species and also users.
The applicant submitted written notice requesting a re-examination on 2 June 2006, and the detailed grounds for the re-examination request were submitted on the 17 July 2006. An Ad Hoc Expert Group meeting was held on 6 September 2006 in preparation of the CVMP meeting on 12-14 September 2006.
The applicant gave further oral explanations at both the Ad Hoc Expert Group meeting (6 September 2006) and at the CVMP meeting (12 September 2006).
Grounds for refusal 1: The CVMP concluded that a direct effect of pradofloxacin on DNA in vivo cannot be excluded.
Applicants position:
The applicant argued that a DNA reactive mode of action for pradofloxacin was not supported as: • Structural analysis suggest no ability for DNA binding (formation of an electrophile) • The only biotransformation is conjugation (which leads to excretion) • There was no effect on DNA damage (comet assay), repair (UDS) or dominant lethal test in vivo • The positive micronucleus test was attributable to pradofloxacin’s in vitro clastogenicity due to inhibition of topoisomerase II. • 33P postlabelling test in vitro in V79 cells – the one positive result was obtained at highly toxic concentrations which are not achievable in vivo • 32P postlabelling test in mouse bone marrow and liver – no DNA modifications were shown even with doses exceeding the lowest positive dose that induced micronuclei.
The Applicant did agree (with the Ad Hoc Expert Group) that: • there are only a few publications on the DNA reactivity of fluoroquinolones and therefore the results with pradofloxacin cannot easily be put into context • the in vitro study in V79 cells really did not contribute at all to an understanding of the genotoxicity (for the reasons given above) and that this was not a helpful study
CVMP position:
The studies with pradofloxacin and adenosine suggest pradofloxacin is not a strong electrophile but Members could not preclude some interaction with DNA in other ways.
The CVMP agreed that the original data set does not give a strong indication for direct DNA reactivity of pradofloxacin (as is also the case with other gyrase and topoisomerase inhibitors) and acknowledged that there are few published data on adduct formation with other fluoroquinolones (FQs) and topoisomerase inhibitors. The submitted 33P-postlabelling data in vitro were not considered to make a helpful contribution to the assessment of the genotoxicity of pradofloxacin. This is mainly due to: - lack of adduct data on other FQs and topoisomerase II inhibitors - non-standard techniques (in particular PAGE instead of 4-dimensional TLC) used in the in vitro study - equivocal results not being tested for reproducibility - qualitative rather than quantitative method.
EMEA/CVMP/342257/2007 © EMEA 2008 32/37 The 32P-postlabelling data in vivo do not suffer the same technical deficiencies as the in vitro study, but the lack of other published adduct data with FQs means that these data do not help in positioning this FQ in relation to other FQs and mammalian topoisomerase inhibitors.
CVMP did not consider that the UDS and comet assays contributed to the genotoxicity assessment as: - the Comet assay in the absence of UV irradiation was sampled very early (compared to the recommended 2 to 4 hours and 12 to 16 hours), which is considered adequate when used as a control for the UV-irradiated animals but which is too early to be used in a standard test - the UDS test is generally accepted not to be sensitive to clastogens because large scale DNA damage is expected to be repaired via other processes (e.g., recombinational repair) and not predominantly by excision repair.
The CVMP was of the opinion that it does appear that pradofloxacin does not exert its genotoxic effects via a direct interaction with DNA. However, the CVMP remained concerned that whatever the non-DNA target(s) is/are, the consequences are a range of DNA lesions that result in a spectrum of genotoxic changes from gene mutations to structural chromosomal aberrations.
Compounds that damage DNA as a secondary effect still pose a genotoxic risk if tissue exposures are achieved that will exert that effect.
Pradofloxacin is genotoxic in vivo at plasma exposures that are less than 10-fold higher than expected therapeutic exposures. Given the variability that exists between species, the CHMP feels that genotoxic effects in the target species cannot therefore be excluded.
Grounds for refusal 2: Even if a threshold effect had been accepted, an adequate margin of safety regarding clastogenicity would not be ensured at the proposed dosage rates.
Applicants position:
Pradofloxacin was not considered by the applicant to pose a relevant genotoxic/carcinogenic hazard as: • Its mode of action is topoisomerase II inhibition and this is accountable for all genotoxicity • Its mode of action allows the determination of a threshold • The exposure at the bench mark dose at lower limit of 95% confidence interval for micronucleus test was in the same range as the exposure in the target animal safety studies with 5X therapeutic dose for 3 months in dogs and 3 weeks in cats • No cytotoxic effects in bone marrow or testis in target animal safety studies • No preneoplastic changes after 3 months in mice, rats and dogs • No carcinogenic potential of concern for other EU marketed fluoroquinolones • Dose ratios (high dose in carcinogenicity studies/therapeutic dose) based on a mg/m2 comparison from 0.4 – 48 • Short term use for the product
CVMP position:
The CVMP accepted that the mechanism(s) of enhanced genotoxicity for pradofloxacin probably involved inhibition of topoisomerase(s), and therefore probably exhibited a threshold, but it is not clear whether one or several topoisomerases are inhibited or whether all have the same threshold.
However, the group was concerned that, because of the positive in vivo MN response, the margin of safety (MOS) levels for pradofloxacin are as low as 3 to 6, even without the additional safety factors for inter- and intra-species variability. Even though treatment periods in target animal species will be short, recommended doses may be exceeded (e.g. in smaller animals) and treatments may be repeated. Thus the possibility to achieve DNA–damaging exposures in target animal species cannot be excluded.
EMEA/CVMP/342257/2007 © EMEA 2008 33/37 The margins of safety had been derived based on the mouse MN test. Whilst qualitative differences between species are unlikely, there could be quantitative differences as it is not known whether the mouse is the most sensitive species for the determination of genotoxicity in vivo (so other species, e.g., rat, may have produced positive MN responses at lower exposures. Also, pradofloxacin induces gene mutations in vitro and this has not been investigated in vivo. Thus, even if there are thresholds for other genotoxic endpoints in vivo it is not known how these compare with target animal exposures. The inadequacy of the Comet assay and lack of relevance of the UDS test do not help in this regard.
As the profile of genotoxicity for pradofloxacin is different from other marketed FQs, and its genotoxic profile may not be completely explained by topoisomerase II inhibition, this lack of understanding of mechanism suggests that genotoxic effects in target animal species cannot be excluded.
In conclusion the CVMP had concerns that as pradofloxacin could be considered to be positioned amongst the more potent FQs in terms of genotoxicity, and is positive in vivo at doses that do not induce bone marrow toxicity, then the margins of safety of 3 to 6 are considered too small, to exclude possible genotoxic effects in target animal species.
Based on the above, the potential implications for target animals could include genetic defects resulting in carcinogenicity, germ cell defects and other mutations.
Grounds for refusal 3: No carcinogenicity studies have been performed.
Applicants position:
The applicant considered that pradofloxacin had shown no risk for tumour induction at therapeutic concentrations in dogs and cats.
The applicant argued that there are no known carcinogens amongst marketed FQs. Some short-term initiator/promotor studies had been performed and these had also not led to tumour development, but it was acknowledged that some mammalian topoisomerase inhibitors, such as amsacrine and genistein do induce tumours. Therefore, the lack of carcinogenicity data do not permit an understanding as to whether pradofloxacin is more like a conventional gyrase inhibitor or more like a mammalian topoisomerase II inhibitor is important.
CVMP position:
The absence of carcinogenicity data contributed to gaps in the toxicological profile of pradofloxacin, however, it was agreed by the CVMP that the toxic effects of FQs might make it difficult to conduct a rigorous carcinogenicity study and to therefore provide data from exposures high enough to derive acceptable safety margins.
Regarding the applicant’s argument that there are no known carcinogens amongst marketed FQs, this did not mean that positive results had never been obtained for fluoroquinolones that were not subsequently marketed. It is possible that positive results may well have prevented the submission of such a marketing application.
Members noted that the 90-day toxicity data in the rat and mouse, and 90-day target animal safety study in the dog, did not reveal any signs of pre-neoplastic lesions, but it was agreed that this period of exposure was too early for all but the most potent carcinogens, especially in the dog, and that the small animal group sizes would preclude detection of all but the most potent effects.
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Grounds for refusal 4: In the absence of unequivocally proven safety, the clastogenic, potentially mutagenic and potentially carcinogenic profile of pradofloxacin constitutes a concern for both the target species and also users.
Applicants position:
The Applicant stated that there are no known marketed veterinary FQs that are genotoxic in vivo. The Applicant used gemifloxacin (not marketed in the EU, but was positive in vivo) for comparison of MN-inducing effect, and comparison of plasma exposure levels. The Applicant also presented data from in-house studies that trovafloxacin and clinafloxacin induce MN in vivo at similar plasma exposures to Pradofloxacin.
MN were claimed to be only induced at doses that were cytotoxic to the bone marrow.
In respect to the CVMP question to the Applicant on the HPRT mutation data, the Applicant stated that most FQs are positive for HPRT mutation.
An important point raised by the Applicant (agreed by the AHEG and the CVMP) is that there are very few comparative data on FQs tested side by side in the same animals or the same cell culture systems.
Regarding user safety, the applicants view was that since the genotoxicity of pradofloxacin is linked to topoisomerase II inhibition there is no concern with human exposures, no concern for carcinogenicity in the target animal and the threshold level (NOEL in MNT) was estimated to be more than 4000-fold higher than the worst case human exposure (according to the Rapporteurs calculation in the List of Outstanding Issues).
CVMP position:
It was accepted that most or all FQs induced mutations in Ames strain TA102, and that data from this strain do not permit any distinction in terms of overall risk.
Given the concerns for genotoxicity, there were no additional concerns for photogenotoxicity raised by effects seen in the presence of UVA irradiation. CVMP considered the warnings in the proposed SPC were sufficient.
With respect to FQs with a known genotoxic profile (including those that failed during drug development or during a product authorisation process) pradofloxacin clearly belongs to the potent end of the genotoxicity spectrum. However, compared to FQs that are currently on the market in the EU there are none that are positive in vivo* – in this sense pradofloxacin is different. In many ways (HPRT mutations, clastogenicity in vitro at relatively low concentrations, positive for micronuclei in vivo) pradofloxacin shows a genotoxicity profile which is more comparable to that of an anticancer topoisomerase II inhibitor than to any currently EU-authorised FQ antibiotic and is thus positioned at the end of the more potent FQs. [*NB It was felt that the Mukherjee paper showing ciprofloxacin positive for micronuclei (MN) is not robust, and that in rigorous studies ciprofloxacin has been negative for MN at high exposures.]
It was also noted that there are no obvious correlations between available data on topoisomerase inhibition, clastogenicity in vitro and MN-induction in vivo for a wide variety of FQs. Although Pradofloxacin has been shown to inhibit mammalian topoisomerase II in acellular in vitro tests, it is not known whether it inhibits other topoisomerases and whether this contributes to its enhanced genotoxic profile.
Regarding structural analysis, CVMP was concerned at the markedly different genotoxicity profiles in mammalian systems for moxifloxacin and pradofloxacin, considering their structural similarities and similar inhibition of bacterial DNA gyrase and mammalian topoisomerase II. No explanation for these differences was apparent. If genotoxicity is related closely to inhibition of topoisomerase II then
EMEA/CVMP/342257/2007 © EMEA 2008 35/37 similar genotoxicity profiles would have been expected for moxifloxacin and pradofloxacin. Differences in bone marrow exposure as claimed by the Applicant to explain the differences in MN induction in vivo could not be supported by data. In fact, data with other FQs have shown that strong clastogenic compounds in vitro were negative for MN in vivo even at significant exposure levels (clearly exceeding the lowest observed effective concentration (LOEC) for clastogenicity in vitro).
Regarding the micronuclei test, Members considered there was no overt toxicity at 320 and 640 mg/kg and yet there were significant increases in MN frequency. This decision was based on (i) the lack of concurrent control data at 16 and 48 hr sampling times, (ii) the fact that the Applicant’s own historical control PCE/NCE ratios for the 24 hr sampling time ranged from around 0.75 to 1.5, and this encompassed the PCE/NCE ratios seen at 24 hr at 320 and 640 mg/kg pradofloxacin.
The CVMP agreed that pradofloxacin induced micronuclei in vivo at doses that were not cytotoxic to the bone marrow. In this sense pradofloxacin is different from other FQs, including gemifloxacin (not marketed in EU) which induces MN at doses that are cytotoxic to the bone marrow. It was also noted that gemifloxacin is not marketed in the EU and that the AHEG had been informed by the Applicant (during the oral explanation) that the margin of safety for the human use of gemifloxacin in the USA is as low as 3.
Regarding the HPRT mutation data, the CVMP believed that in their analysis, most EU marketed FQs do not induce HPRT mutations.
Benefit/risk:
Applicants position:
Pradofloxacin was claimed by the applicant to have a very favourable safety profile in comparison to other fluoroquinolones in: • safety pharmacology – no convulsive potency/no induction of hypo- or hyperglycaemia/no effects on QT-prolongation • subchronic toxicity studies (2 rodent species & fairly high doses) – did not induce signs of cyto- organotoxicity/no pre-neoplastic changes after 3 months of treatment
In target animal safety studies, pradofloxacin was shown to have no clinical signs or organ toxicity at 5-fold overdose and 3-fold treatment duration, no signs of retina toxicity in cats, and no signs of chrondrotoxicity in cats.
Veraflox has a sufficient margin of safety in regard to exposure (5-fold overdose and 3-fold treatment duration in the target animals does not show any toxicity). All target animal safety studies showed no risk of overdosing.
CVMP position:
The CVMP acknowledged that pradofloxacin is an efficacious antibiotic and has some benefits, but that the totality of its genotoxicity profile is unfavourable compared to other EU marketed fluoroquinolones, in particular as: • pradofloxacin is not typical of other marketed FQs and shows a genotoxicity profile more comparable with mammalian topoisomerase inhibitors used as anticancer treatments than with marketed fluoroquinolone antibiotics • the mechanism of this enhanced genotoxicity, in particular in comparison with the structural analogue moxifloxacin, is not known, but may be due to effects on other isoforms of topoisomerase II or on other topoisomerase enzymes, but it was not considered to be due to a potential to induce DNA adducts • the positive in vivo MN results at exposures that were considered not to be toxic to the bone marrow distinguishes pradofloxacin from all other marketed fluoroquinolones, even including gemifloxacin (which is not marketed in the EU)
EMEA/CVMP/342257/2007 © EMEA 2008 36/37 • given the above, the possibility that the mouse may not be the most sensitive species for induction of genotoxicity in vivo, and that MN-induction may not be the most sensitive endpoint in vivo the margins of safety relative to veterinary use are considered too small to exclude the possibility of genotoxic effects in target animal species.
CVMP’s CONCLUSION ON BENEFIT/RISK AND RECOMMENDATION:
Considering the available data submitted in the marketing authorisation application, the applicant’s detailed grounds for the re-examination, the applicant’s responses to the CVMP’s List of Questions to the Applicant, the report to the CVMP from the Ad Hoc Expert Group meeting, and the oral explanations provided by the applicant, the CVMP conclusions at the end of the re-examination were that the benefit/risk for Veraflox for the claimed indication remains negative, and therefore that it could not recommend the granting of a marketing authorisation for Veraflox.
References:
• Mukherjee A., Sens S. and Agarwal K. (1993) Mutation Research 301 (1993), 87-92. ID 29274
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