Getting Started in Therapeutics

CET Continuing education

Getting started in therapeutics Part 8a – What drugs will I prescribe and supply? Continuing our series on therapeutics in practice, Lucy Titcomb and Professor John Lawrenson review the range of ophthalmic drugs currently available to optometrists at all levels and those that may be used by future independent prescribers. C7749, two CET points suitable for optometrists, additional supply optometrists and supplementary prescribers

ata from the recent therapeu- Antibacterials tic practice survey carried out This monthly series is designed to provide optometrists This group, covered in section 11.3.1 of by City University showed with a practical, step-by-step guide to getting started the British National Formulary (BNF), that community optometrists in therapeutic practice and will seek to answer the contains the following drugs: routinely managed a range of following questions: ● Aminoglycosides (gentamicin and Dcommon non-sight-threatening ocular neomycin) conditions using therapeutic agents ● How should I plan my strategy? ● Bacitracin available through the Medicines Act ● What training will I need? ● Chloramphenicol exemptions (Optician, July 27, 2007). ● What equipment will I need? ● Fluoroquinolones (ciprofloxacin, Recent changes to medicines legis- ● What conditions should I manage and treat initially? levofloxacin and ofloxacin) lation have provided opportunities ● What conditions can I manage and treat with training? ● Fusidic acid for optometrists to train for extended ● How do therapeutics fit in to contact lens practice? ● Gramicidin prescribing roles. For example, ● What drugs will I prescribe and treat? ● Polymyxin B additional supply (AS) optometrists ● What are the legal and ethical considerations? ● Propamidine and are able to use and supply further ● How should I market my therapeutics business? Dibrompropamidine. prescription-only medicines (POMs) from an ‘additional supply’ list that The series is compiled by Alison Ewbank with input from Aminoglycosides includes the antimicrobial mixture, Bill Harvey, John Lawrenson and Nick Rumney. The aminoglycosides are bactericidal Polyfax (polymyxin B and bacitracin), antibiotics derived from fungal isolates. anti-allergy drugs, a mucolytic and the They inhibit bacterial protein synthesis non-steroidal anti-inflammatory drug anti-inflammatories. by binding to the 30S ribosomal subunit. (NSAID) diclofenac sodium. Emphasis will be placed on those Their antibacterial spectrum varies, with Optometrist supplementary prescrib- drugs currently available to optom- gentamicin possessing a wide spectrum ers are theoretically able to prescribe any etrists (entry level and AS) as well as of activity being effective against both licensed medicine, provided that the drugs that can be appropriately used Gram-positive and Gram-negative drug is listed in the patient’s clinical by supplementary prescribers or future organisms, including Peudomonas aerugi- management plan. independent prescribers. nosa, while neomycin is active against While this prescribing model works Gram-negative bacteria but not P aerugi- for practitioners working in a hospi- nosa. Neomycin, therefore, is rarely used tal environment, it has limited scope ● Antimicrobials alone but is found in combination with in community optometric practice agents active against Gram-positive as a diagnosis has to be made by an Antimicrobials include agents active bacteria such as gramicidin and those independent prescriber and a clinical against bacteria, fungi, viruses, protozoa with activity against P aeruginosa such management plan has to be drawn up and other parasites. as polymyxin B. before treatment can begin. The aim of antimicrobial therapy Neomycin is widely used as the This limitation has been recognised is to kill (for a microbicidal agent) antibiotic in antibiotic-corticosteroid by the Department of Health which or stop the growth of (for a microbi- combinations employed post-opera- recently announced that optometrists static agent) the pathogen, known as tively in products such as betametha- will soon be able to train as independ- the prokaryote, with minimal adverse sone and neomycin and prednisolone ent prescribers of any licensed medicine effects on the host, the eukaryote. and neomycin and with polymyxin B for ocular conditions affecting the eye Choice of a drug delivery system to in Maxitrol, although there is a reported and the surrounding tissues, within administer the drug is dependent upon allergy rate of about 4 per cent. their recognised area of expertise and the concentration of the antimicro- Two other aminoglycoside antibiot- competence. bial required at the site of the infec- ics, framycetin and tobramycin, are not Before prescribing any medication it tion. Thus eye drops are suitable for used alone in the UK but are available is important that the prescriber is aware the treatment of conjunctivitis, while in the antibiotic-steroid combinations of the licensed indications of the partic- intravitreal injections are necessary Sofradex and Tobradex respectively. ular drug, its contraindications, dosage for endophthalmitis and systemically Although gentamicin eye drops are and potential side-effects. administered agents for the treatment licensed for the treatment and prophy- This article provides an overview of of ocular toxoplasmosis. laxis of bacterial infections, with the the major classes of therapeutic agent This article will concentrate on wide range of antibacterial prepara- used in ophthalmic practice: commercially available topical antimi- tions now available, this antibiotic ● Antimicrobials crobials (Table 1) with special reference is no longer the drug of choice for ● Corticosteroids and other to those available to the optometrist. patients intolerant of, or unresponsive

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Table 1

CommerciallyPANTONE 543 availableBLACK topical ophthalmic preparations containing antimicrobials Antibacterials Antibacterial Formulation(s) Trade name(s) Combination Other combinations antibiotic preparations POM P Bacitracin Polyfax eye ointment** Chloramphenicol Eye drops 0.5% * ^ Chloromycetin Brochlor Eye ointment 1% *^ Chloromycetin Optrex Infected Unit dose eye drops Minims Eyes 0.5% * Chloramphenicol Galpharm Chloramphenicol Boots Pharmacy Antibiotic Eye Drops Ciprofloxacin Eye drops 0.3% Ciloxan Eye ointment 0.3% Dibrompropamidine Eye ointment Brolene isetionate 0.15 % ^ Golden eye Framycetin Sofradex eye drops Fusidic acid Eye drops 1% * Fucithalmic Gentamicin Eye drops 0.3% Genticin Unit dose eye drops Minims 0.3% Gentamicin Sulphate Gramicidin Neosporin eye drops Levofloxacin Eye drops 0.5% Oftaquix Neomycin Eye drops 0.5% Neosporin eye drops Betnesol-N eye drops (3500 units/ml) Vistamethasone-N Eye ointment 0.5% eye drops (3500 units/g) Maxitrol eye drops and ointment Neo-Cortef eye ointment Predsol-N eye drops Ofloxacin Eye drops 0.3% Exocin Polymyxin B Neosporin eye drops Maxitrol eye drops and Polyfax eye ointment ointment ** Propamidine Eye drops 0.1% ^ Brolene isetionate Golden eye Tobramycin Tobradex eye drops Antivirals Antiviral Formulation(s) Trade name(s) Combination Other combinations antiviral preparations POM P Aciclovir Eye ointment 3% Zovirax

*Available to optometrists at registration **Available only to additional supply optometrists ^Available as pharmacy medicine to chloramphenicol. Neomycin has activity against treatment of ophthalmic infection, their However, fortified preparations Acanthamoeba but being a poor cysticide use has declined with the introduction of gentamicin eye drops, containing is used in combination with a diamidine of newer agents. All aminoglycoside- five times the concentration of the although Acanthamoeba infections are containing preparations are POMs and aminoglycoside in the commercially generally treated with chlorhexidine or none are available to optometrists. available product and available from polyhexamethylbiguanide which have special order manufacturers, still have been shown to be more effective. Bacitracin a place in the treatment of bacterial It can be seen that while there is still Bacitracin is an antibiotic derived from keratitis. a place for the aminoglycosides in the Bacillus subtilis which interferes with opticianonline.net 26.10.07 | Optician | 23 Continuing education CET

Table 2 Commercially available topical ocular corticosteroids Corticosteroid Formulation(s) Trade name(s) Combination Formulation of combination products products Betamethasone 10ml eye drops 0.1%, Betnesol Betnesol N 10ml eye drops containing betamethasone 3g eye ointment 0.1% 0.1% and neomycin 0.5% 10ml eye drops 0.1% Vista-Methasone Vista-Methasone 5ml and 10ml eye drops containing betametha- N sone 0.1% and neomycin 0.5% Dexamethasone 5ml eye drops 0.1% Maxidex Maxitrol 5ml eye drops containing dexamethasone 0.1%, hypromellose 0.5%, neomycin 0.35% and polymyxin B 6,000 units/ml 3.5g eye ointment containing dexamethasone 0.1%, neomycin 0.35% and polymyxin B 6,000 units/g Tobradex 5ml eye drops containing dexamethasone 0.1% and tobramycin 0.3% Dexamethasone sodium Single dose eye drops Minims phosphate 0.1% Dexamethasone Dexamethasone sodium Sofradex 10ml eye/ear drops containing dexamethasone metasulphobenzoate sodium metasulphobenzoate 0.05%, framycetin 0.5% and gramicidin 0.005%

Fluorometholone 5ml and 10ml eye drops FML 0.1% Hydrocortisone acetate 10ml eye drops 1% Neo-cortef 3.9g eye ointment containing hydrocortisone 3g eye ointment 0.5%, acetate 1.5% and neomycin 0.5% 1%, 2.5% Prednisolone acetate 5ml and 10ml eye drops Pred-Forte 1% Prednisolone sodium 10ml eye drops Predsol Minims Predsol N 10ml eye drops containing prednisolone phosphate Single dose eye drops Prednisolone sodium phosphate 0.5% and neomycin 0.5% 0.5% sodium phosphate Rimexolone 5ml eye drops 1% Vexol bacterial cell wall synthesis and is prima- other antibacterials for this condition are Fluoroquinolones rily active against Gram-positive bacte- compared. It is well tolerated, exhibits The three fluoroquinolones − cipro- ria. It is not, therefore, used alone but in good ocular penetration and is available floxacin, levofloxacin and ofloxacin combination with antibacterials active in a range of formulations. − while licensed for the treatment of against Gram-negative bacteria such as The eye drop form of chlorampheni- conjunctivitis, are generally reserved for polymyxin B in Polyfax. col (0.5 per cent) and the eye ointment more serious bacterial infections such as Polyfax eye ointment, which is (1 per cent) classed as POMs have been bacterial keratitis. In countries where licensed for the treatment and preven- available for sale or supply by all regis- they are widely used, there are concerns tion of bacterial infection of the eye, is tered optometrists, provided this is in about fluoroquinolone resistance. a suitable alternative to chlorampheni- the course of their professional practice The fluoroquinolones inhibit DNA col eye ointment for patients intolerant and in an emergency, since 1989. gyrase, an enzyme needed by the bacte- of or unresponsive to chloramphenicol However, in June 2005 the eye drops, rium for the synthesis of DNA. Thus, and is available to AS optometrists. and in June 2007 the eye ointment, were vital information from the bacterial granted pharmacy (P) licences for the chromosomes cannot be transcribed, Chloramphenicol treatment of acute bacterial conjunc- which causes a breakdown of bacte- Chloramphenicol is an antibiotic which tivitis in patients older than two years rial metabolism. They are active against is mainly bacteriostatic in action, but and may now be sold or supplied by almost all Gram-negative microorgan- exerts a bactericidal effect against some optometrists without the ‘emergency’ isms including P aeruginosa but less strains of Gram-positive cocci and against restriction. active against Gram-positive bacteria Haemophilus influenzae and neisseria. It The BNF describes the recom- and are not the drugs of choice for strep- has a broad spectrum of action against mendation that chloramphenicol eye tococcal infections. both Gram-positive and Gram-negative drops should be avoided because of Each fluoroquinolone has its bacteria (excluding P aeruginosa), rickett- an increased risk of aplastic anaemia own advantages and disadvantages. siae and chlamydia. Chloramphenicol as ‘not well founded’ although topical Ciprofloxacin is available in drop and is the drug of choice for the treatment chloramphenicol should be avoided in ointment forms and has greater in vitro of bacterial conjunctivitis and is the those with a known personal or family antibacterial activity than ofloxacin. gold standard treatment against which history of blood dyscrasias. However, it does not penetrate the eye

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as well as ofloxacin and has an unfor- spectrum and is recommended in the of polymyxin B and trimethoprim tunate side-effect of precipitation of the BNF for staphylococcal infections. The (Polytrim) which is included in the drug on the cornea in a small percentage eye drops are licensed for the treatment 2005 legislation, allowing the use of of patients. of bacterial conjunctivitis where the topical ocular polymyxin B prepara- Levofloxacin, the most expensive organism is known to be sensitive to tions by AS optometrists, was discon- topical quinolone, penetrates the eye the antibiotic and this is unlikely for tinued before the legislation reached better than ciprofloxacin or ofloxacin infections caused by Streptococcus or the statute book. However, Polyfax, but this has not yet been shown to result Haemophilus species. One advantage the combination of polymyxin B and in an increase in clinical efficacy. While of fusidic acid eye drops over other bacitracin, an antibiotic active against it is more active against Gram-positive commercially available eye drops is that Gram-positive bacteria, is available to organisms than ciprofloxacin, it is less the preparation is not contraindicated in AS optometrists. active against certain Gram-negatives pregnancy or lactation. including P aeruginosa. A marketing Propamidine isetionate and authorisation has been granted for unit- Gramicidin dibrompropamidine isetionate dose (preservative-free) levofloxacin Gramicidin is a polypeptide antibiotic These bacteriostatic antimicrobi- eye drops 0.5 per cent but at the time produced by the growth of Bacillus als, present in eye drop and eye of writing these were not commercially brevis. It is effective against many Gram- ointment formulations respectively, available in the UK. Neither cipro- positive organisms and is therefore used are aromatic diamidines active against floxacin nor levofloxacin are licensed in combination with antibacterials with Gram-positive bacteria, particularly for use in children under one year-old. activity against Gram-negative bacteria. staphylococci, but less active against Ofloxacin is the least expensive topical Gramicidin increases the permeability Gram-negative bacteria. quinolone and is not contraindicated of cell membranes and uncouples oxida- They also have antifungal activity. in babies, although its duration of use tive phosphorylation in the bacterial cell They are licensed for the treatment of is restricted to 10 days. All the topical wall with a temporary stimulation of minor eye infections such as conjunc- fluoroquinolones are POMs and none oxygen consumption. It is an ingredi- tivitis and blepharitis at a dose of four are available to optometrists. ent of neosporin eye drops which also times a day for the eye drops and once contains neomycin and polymyxin B. or twice daily for the eye ointment. The Fusidic acid Neosporin is a POM and is not avail- activity of the diamidines is retained in This antibiotic, which was first isolated able to optometrists. the presence of organic matter such as in 1962 from the fungus Fusidium tissue fluids, pus and serum. coccineum, exerts its bacteriostatic activ- Polymyxin B Ophthalmic preparations of these ity by inhibition of protein synthesis. Polymyxin B is one of a family of drugs are classified as P medicines and Fusidic acid eye drops are presented as polypeptide antibiotics produced by so are available to all registered optom- a carbomer-containing gel which has various Bacillus polymyxa strains. etrists. One advantage of the diamidines a long ocular retention time (tear fluid It is bactericidal for a variety of Gram- over chloramphenicol is that there is concentrations of fusidic acid exceed 10 negative bacteria, including P aerugi- no restriction on the age of the patient micrograms/ml six hours after instilla- nosa, Enterobacter and Escherichia coli, by in whom the P medicine can be used. tion) allowing twice daily dosage. Since disrupting the integrity of the bacterial Although these drugs are also active April 2005 it has been available to all cell membrane and increasing bacterial against Acanthamoeba species, this is not registered optometrists for sale and cell permeability. However, as it is not a licensed use of these preparations. supply, provided this is in the course active against Gram-positive bacteria it of their professional practice and in an is used in combination with antibiotics Oral antibiotics emergency. with activity against these organisms. Although optometrists are not permitted TLC_eyeclinic_188_78Fusidic acid has a limited 6/8/07 bacterial 1:35 pm Page 1Unfortunately, the combination to sell or supply oral preparations, the

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Table 3 Pharmacy and general sales list oral and nasal preparations for allergic rhinitis Class Drug Products available Restrictions on dose and pack size Restrictions on age POM P GSL P GSL Antihistamine Azelastine 140 Rhinolast nasal spray Rhinolast Hayfever N/A Maximum dose 140 micrograms per N/A Adults and children nasal spray micrograms/spray (22ml) (36 doses) nostril, maximum daily dose 280 over 5 years micrograms per nostril, package contains not more than 5.04mg azelastine (36 doses)

Antihistamine Cetirizine Benadryl Allergy Oral Syrup; Galpharm hayfever and Galpharm hayfever and allergy relief Maximum daily dose = 10mg Maximum daily dose = 10mg, Adults and children tablets allergy relief tablets (30); Piriteze Allergy tablets (30); tablets (7)and syrup; maximum strength 10mg, not > over 6 years Pollenshield Hayfever(30); Zirtek Allergy tablets; Zirtek Benadryl One A Day Relief; Benadryl 14 tablets in pack or maximum Allergy Solution for Children Allergy Solution; Piriteze strength 1mg/ml, not > 70ml in pack Allergy tablets (7); Pollenshield Hayfever (7); Zirtek Allergy relief (7); Zirtek Allergy relief for children (70ml)

Loratadine Clarityn Allergy tablets (30), Clarityn Allergy Syrup Clarityn Allergy tablets (7) Maximum daily dose = 10mg Maximum daily dose = 10mg, Adults and children maximum strength 10mg, not > 7 over 2 years and tablets in pack weighing 30Kg or more Corticosteroid Beclometasone dipropionate Beconase nasal spray (aqueous) Beconase allergy nasal spray (100, 180 doses) Beconase Hayfever Relief for Adults Maximum dose 100 micrograms per nostril, maximum daily dose 200 micro- Adults, 18 years and nasal spray 50 micrograms/spray Nasobec aqueous spray Hayfever relief nasal spray (200 doses) Nasobec Hayfever 0.05% Nasal Spray (100 doses) grams per nostril, maximum period of 3 months, package contains not more over (200 doses) than 20mg beclometasone (200 doses) Fluticasone propionate 50 Flixonase aqueous nasal spray (150 Flixonase Allergy Nasal Spray (60 doses) N/A Maximum dose 100 micrograms per N/A POM - adults and micrograms/spray doses), Nasofan aqueous nasal nostril, maximum daily dose 200 children over 12 sparay (150 doses) micrograms per nostril, maximum years, P - adults, 18 period of 3 months and pack size of years and over 3mg fluticasone Triamcinolone acetonide 55 Nasacort (120 doses) Maximum dose and daily dose 110 Adults, 18 years and micrograms/ spray micrograms per nostril, maximum over period of 3 months and pack size of 3.575mg triamcinolone Decongestant Ephedrine 0.5%, 1% Ephedrine nasal drops 0.5%, 1% Maximum strength 2% 0.5% child over 3 nasal drops months and spray Oxymetazoline 0.05% Afrazine nasal spray, Boots nasal spray, Non-oily nasal spray, maximum Adults and children Vicks Sinex decongestant strength 0.05% over 5/6 years (product dependent) Phenylephrine 0.5% Fenox nasal drops, Fenox nasal spray Nasal drops, nasal sprays and nasal All preparations except nasal drops, Adults and children inhalations nasal sprays and nasal inhalations over 5 years equivalent to maximum dose 10mg Xylometazoline 0.05% Otrivine child nasal drops, Otradrops Non-oily nasal spray or drops Child over 3 months child formula maximum strength 0.1%, maximum period 7 days Xylometazoline 0.1% Otrivine adult nasal spray and drops, Adults and children Otradrops, Otraspray over 12 years treatment of blepharitis, and particularly Aciclovir viral DNA synthesis without affecting that associated with acne rosacea, may Aciclovir is an antiviral agent which normal cellular processes. Aciclovir is involve the use of a tetracycline antibiotic is highly active in vitro against herpes rapidly absorbed from the ophthalmic such as oxytetracycline or doxycycline or simplex (HSV) types I and II, but its ointment through the corneal epithe- erythromycin. A referral to the patient’s toxicity to mammalian cells is low. This lium and superficial ocular tissues, general practitioner recommending a is because the drug is phosphorylated to achieving antiviral concentrations in three-month course of one of these treat- the active compound aciclovir triphos- the aqueous humour. Aciclovir 3 per ments may be appropriate. phate after entry into cells infected by cent eye ointment (Zovirax) is used at a the herpes virus. The first step in this frequency of five times a day at approxi- Antivirals process requires the presence of the mately four hourly intervals. Treatment The only topical ophthalmic antivi- HSV-coded enzyme thymidine kinase. should continue for at least three days ral commercially available in the UK, Aciclovir triphosphate acts as an inhibi- after healing is complete. Aciclovir eye covered in section 11.3.3 of the BNF is tor of, and substrate for, herpes-specified ointment is a POM and is not available aciclovir. DNA polymerase, preventing further to optometrists.

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Other antimicrobials ● Corticosteroids combination with antibacterials allows A number of other antimicrobials are This group, covered in section 11.4.1 of use when prophylactic antibiotic treat- used in secondary care for the treat- the BNF, contains the following drugs: ment is also required. ment of resistant infections or in ● Betamethasone The choice of steroid (Table 2) is cases where there are no commer- ● Dexamethasone dependent on the potency of anti-inflam- cially available preparations or those ● Fluorometholone matory action required, the susceptibility that are available are not suitable or ● Hydrocortisone of the patient to a corticosteroid-induced not tolerated. ● Prednisolone rise in intraocular pressure (IOP) and the Such ‘special’ eye drops include the ● Rimexolone. drug delivery system best suited to the antibacterials amikacin, benzylpenicil- When used alone, they are licensed patient’s needs. lin, cefuroxime and ceftazidime, the for the short-term treatment of steroid- antifungals clotrimazole, econazole, responsive inflammatory conditions of Hydrocortisone, prednisolone sodium miconazole and natamycin, and the the eye, after clinical exclusion of bacte- phosphate and betamethasone antiviral trifluorothymidine. rial, viral and fungal infections, while These corticosteroids are used where

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Table 4 Commercially available topical antihistamines Drug and Drug Trade name and Licensed indications Age restrictions and dosages Comments formulation properties volume Antazoline 0.5% Antihistamine Otrivine-Antistin Temporary relief of redness Adults and children over five Available as a P with xylometazoline with sympatho- 10ml and itching of the eye due years old. One drop in each eye medicine there- 0.05% eye drops mimetic to seasonal and perennial two to three times daily fore available to allergies such as hay fever optometrists at or house dust allergy registration

Azelastine 0.05% Antihistamine Optilast Treatment and preven- Adults and children over 4 POM but eye drops and mast cell 8ml tion of the symptoms years old. available to stabiliser of seasonal allergic One drop in each eye twice a additional supply (Aller-eze eye conjunctivitis day. optometrists drops, the P This may be increased to four version of azelas- times a day tine, have been Treatment of the symptoms Adults and children over 12 discontinued) of non-seasonal (perennial) years old. allergic conjunctivitis One drop in each eye twice a day increased if necessary to four times a day. It is licensed for a period of up to 6 weeks as longer periods have not been studied Emedastine 0.05% Antihistamine Emadine Symptomatic treatment Age 3-65 years old. POM but eye drops 5ml of seasonal allergic One drop in the affected eyes available to conjunctivitis twice a day. additional supply Due to lack of data they optometrists are only licensed for 6 weeks’continuous use

Epinastine 0.05% Antihistamine Relestat Treatment of the symptoms Adults and children over 12. POM eye drops and mast cell 5ml of seasonal allergic One drop in the affected eye/s stabiliser conjunctivitis twice daily. Not available to Due to lack of data it is only optometrists licensed for 8 weeks’ continuous use Ketotifen 0.025% Antihistamine Zaditen Symptomatic treatment Adults and children over 3 POM but eye drops and mast cell 5ml of seasonal allergic years. available to stabiliser conjunctivitis One drop in affected eye/s additional supply twice a day optometrists

Olopatadine 0.1% Antihistamine Opatanol Treatment of ocular signs Adults and children over 3 POM but eye drops and mast cell 5ml and symptoms of seasonal years. available to stabiliser allergic conjunctivitis One drop in the affected eye/s additional supply twice a day. optometrists Treatment may be continued for up to 4 months a mild to medium anti-inflammatory by special order manufacturers for use betamethasone and are generally potency drug is required with hydro- by ophthalmologists in conditions reserved for patients who have experi- cortisone being at the lower end of the where there is a contraindication to enced an increase in IOP with other potency scale and betamethasone being use of the full-strength preparation, topical corticosteroids as both fluorome- more potent than prednisolone sodium for example in viral infection of the thalone and rimexolone have a lower phosphate. However, the potency of an eye. Severe cases of allergic or vernal propensity to cause this adverse effect. individual product is also dependent on conjunctivitis may also necessitate use However, increased intraocular concentration of the active ingredient of one of the less potent corticosteroids. pressure with these drugs does still and hydrocortisone 2.5 per cent eye All these drugs are available in combina- occur in certain individuals and patients ointment is seen as a suitable alterna- tion with neomycin in either eye drop should be regularly monitored while on tive to betamethasone 0.1 per cent eye or eye ointment form. these treatments. While both drugs are ointment. Strengths of prednisolone licensed for the treatment of anterior sodium phosphate lower than that Fluoromethalone and rimexolone uveitis, and for the treatment of corti- commercially available (for example, These drugs are more expensive than costeroid responsive inflammation of 0.05 per cent, 0.1 per cent) are produced prednisolone sodium phosphate and the palpebral and bulbar conjunctiva,

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Table 5 Commercially available topical mast cell stabilisers Drug and Trade name(s) Licensed indications Dosages Available to formulation optometrists?

POM P POM P POM P POM P

Lodoxamide Alomide Alomide Allergy The treatment The treatment Adult and child Adult and child Available to P 0.1% eye (10ml) (5ml) of allergic-atopic of ocular signs over 4 years over 4 years additional medicine drops conjunctivitis, and symptoms – one drop in – one drop in supply available vernal conjunctivi- of allergic each eye four each eye four optometrists to optom- tis and giant papil- conjunctivitis times a day times a day etrists at lary conjunctivitis registration Nedocromil Rapitil Rapitil Allergy Prevention, relief Prevention, Allergic Adult and child Available to P 2% eye (5ml) (3ml) and treatment of relief and conjunctivitis, over 6 years additional medicine drops P medicine allergic conjunc- treatment adult and child – One drop supply available marketing author- tivitis, including of seasonal over 6 years into each eye optometrists to optom- isation granted to seasonal allergic and peren- and vernal twice daily, etrists at Aventis Pharma conjunctivitis, nial allergic keratoconjunc- increasing if registra- Ltd (now Sanofi allergic conjunc- conjunctivitis tivitis in adults necessary to tion Aventis) in tivitis and vernal one drop in four times when P 2004 but no P keratoconjunc- each eye twice daily. Maximum medicine product currently tivitis a day, increased period of use becomes available if necessary 12 weeks available to four times without a day consulting doctor

Sodium Hay-Crom Clariteyes, Allergic conjunc- Acute seasonal Adult and child Adult and child Available to P cromoglicate Aqueous, Galpharm Allergy, tivitis, vernal and peren- – one drop in – one drop in additional medicine 2% eye Opticrom Numark Allergy, keratoconjunctivitis nial allergic each eye four each eye four supply available drops Aqueous, Opticrom Allergy, conjunctivitis times a day times a day optometrists to optom- Vividrin Optrex Allergy etrists at (13.5ml) Eyes, Pollenase , registra- Vivicrom tion (10ml)

cornea, and anterior segment of the potent end of the anti-inflammatory used postoperatively in cases in which globe, rimexolone is also licensed for spectrum with prednisolone acetate betamethasone is considered to have the treatment of postoperative inflam- being the most and dexamethasone insufficient anti-inflammatory activ- mation following ocular surgery. sodium phosphate the least potent. ity, for example in diabetic patients or They are used in the treatment of those with pre-existing inflammatory Dexamethasone, dexamethasone conditions such as anterior uveitis, iritis, disease. sodium phosphate and prednisolone cyclitis, herpes zoster keratitis, superfi- All topical corticosteroids can cause acetate cial punctate keratitis and non-specific a secondary glaucoma with optic nerve These corticosteroids are at the most superficial keratitis. They are also damage, visual acuity or field defects,

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secondary ocular infection from patho- the optometrist should recommend because of the occurrence of rebound gens liberated from ocular tissues, one of the antihistamine or corticoster- hyperaemia when the eye drops are exacerbation of viral and fungal infec- oid nasal sprays available as P and as stopped.Emedastine is a potent selec- tions, and perforation of the globe, General Sale List (GSL) medicines (see tive and topically effective histamine particularly in diseases which cause BNF, section 12.2.1) for intermittent H1 antagonist. In vitro examinations thinning of the cornea or sclera. or continual symptoms respectively. of emedastine’s affinity for histamine Intensive or prolonged use of topical Several topical nasal decongestants are receptors (H1, H2, and H3) demon- corticosteroids may lead to the forma- also available as P and GSL medicines strate 10,000-fold selectivity for the tion of posterior subcapsular cataract. but should only be recommended for H1 receptor. Local side-effects of steroid therapy, such short-term use because of the danger of In vivo topical ocular adminis- as skin atrophy, striae and telangiecta- rebound vasodilatation. tration of emedastine produces a sia, may affect facial skin. The systemic Oral antihistamines are an alterna- concentration-dependent inhibition effects of corticosteroids are possi- tive therapy for those who prefer this of histamine-stimulated conjunctival ble with excessive use of steroid eye route and the optometrist can recom- vascular permeability. Studies with drops, particularly when administered mend cetirizine or loratadine tablets, emedastine have not shown effects on concomitantly with other forms of the non-sedating antihistamines which are adrenergic, dopaminergic or serotonin drugs. All these corticosteroid-contain- also available as P and GSL medicines receptors. ing preparations are POMs and none (Table 3). However, for the control of The overall incidence of ocular are available to optometrists. ocular symptoms, oral therapy is not the adverse events in the clinical trials was preferred route because oral antihista- 14-18 per cent. ● Other anti-inflammatory mines, even the non-sedating ones, can preparations cause drowsiness in certain individuals; Antihistamines with mast cell- they are not as fast-acting as topically stabilising activity These groups of drugs which are used administered drugs and may give rise Azelastine is a well tolerated dual-action in the treatment of allergic eye disorders to anticholinergic side-effects such as antihistamine which may give rise to are covered in section 11.4.1 of the BNF blurred vision and a reduction in tear a bitter taste in some patients. The P and include topical antihistamines and secretion. The latter is particularly medicine form of the product, Aller- mast cell stabilisers. Diclofenac, which unwanted in allergic conjunctivitis eze eye drops, was discontinued by the is licensed for the treatment of allergic where the effect of tears washing out manufacturer in 2006. conjunctivitis in addition to a number of the allergen is protective. The preferred Epinastine, while not as specific for other indications, is included in section route of administration of an antihis- H1 receptors as emedastine, having 11.8.2 with the other topical NSAIDs. tamine for allergic conjunctivitis is affinity for adrenergic and serotonin There are three commercially avail- topical. receptors and affinity for cholinergic and able eye preparations of non-steroidal dopaminergic receptors, is well toler- anti-inflammatory drugs (NSAIDs), Topical antihistamines ated and has an adverse drug reaction diclofenac (Voltarol Ophtha), flurbipro- This group of drugs includes: rate less than 10 per cent. Epinastine fen (Ocufen) and ketorolac (Acular). ● Antazoline ameliorates ocular symptoms follow- Flurbiprofen is available in a single dose ● Azelastine ing ocular antigen challenge for at form, ketorolac in a multidose form and ● Emedastine least eight hours allowing a twice daily diclofenac, the only one of these prepa- ● Epinastine dosage. Epinastine was not commer- rations available to additional supply ● Ketotifen cially available while the 2005 legisla- optometrists, is available in both forms. ● Olopatadine. tion was being considered and is not These drugs have anti-inflammatory The group may be subdivided into therefore available to optometrists. It is and analgesic properties due to their pure antihistamines and those with the most expensive preparation in this inhibition of the biosynthesis of prostag- antihistamine and mast cell-stabilising class. landins, chemical mediators which play activity (Table 4). Ketotifen is another well tolerated, a major role in the causation of inflam- twice daily, dual-action antihistamine mation and pain. Prostaglandins in the Pure antihistamines shown to be as effective as but faster eye cause vasodilation, increased vascu- Antazoline is not available alone but acting than emedastine in allergic lar permeability, disruption of ocular in combination with the sympathomi- conjunctivitis and superior to olopata- blood barriers and miosis so these drugs metic vasoconstrictor xylometazoline. It dine in vernal keratoconjunctivitis. It is are used to control pain and inflamma- has been available for many years as a P faster acting than the mast cell stabiliser tion post laser and postoperatively, for medicine and is therefore available to all nedocromil and superior to a two-week, allergic conjunctivitis and to prevent registered optometrists. four times daily regimen of sodium miosis during cataract surgery. The inclusion of a sympathomi- cromoglicate in alleviating symptoms Non-steroidal anti-inflammatory metic in the formulation means that it of allergic conjunctivitis in the conjunc- drugs have no intrinsic mydriatic is contraindicated in patients receiving tival allergen-challenge model. properties and are used preoperatively monoamine oxidase inhibitors, or who Olopatadine is the least expensive in conjunction with mydriatic and have stopped such treatment in the previ- of the topical antihistamines (exclud- mydriatic-cycloplegic drugs. Diclofenac ous 14 days, and in those with narrow ing Otrivine-Antistin) and its use is eye drops, in addition to being available angle-glaucoma, and with caution in supported by a very large number of in more than one topical ocular presen- patients susceptible to angle-closure clinical trials as the drug was available tation have the widest range of indica- glaucoma. for many years as Patanol in the US tions. None of these drugs are licensed The preparation is not recommended before the launch of Opatanol in the for use in children. for long-term use because of the poten- UK. If nasal symptoms predominate in tial for systemic side-effects from the Olopatadine has been shown to be a case of allergic rhinoconjunctivitis, sympathomimetic component and more effective than the antihistamines

34 | Optician | 26.10.07 opticianonline.net CET Continuing education

azelastine and epinastine, the mast cell- stabilisers sodium cromoglicate and Multiple-choice questions – take part at opticianonline.net nedocromil, the corticosteroid lotepre- dnol and the non-steroidal anti-inflam- The antibiotic chloramphenicol: Which of the following drugs is an matory drug ketorolac in the treatment 1 7antihistamine with mast cell-stabilising of seasonal allergic conjunctivitis. A May be used by all registered optometrists activity? However, nedocromil has been B Is available in eye drop and eye ointment form A Emedastine shown to be superior in the treatment as a P medicine B Azelastine of perennial allergic conjunctivitis and C Is available as preservative-free eye drops C Nedocromil ketotifen in vernal keratoconjunctivi- D All of the above D Antazoline tis. Although ketotifen and olopatadine appear to be equally efficacious in the Which of the following statements Which of the following anti-inflammatory treatment of seasonal allergic conjunc- 2relating to fusidic acid eye drops is false? 8preparations may be used in children tivitis, olopatadine seems to be better A It is available to all registered optometrists under three years of age? tolerated and preferred by patients. B It is a prescription-only medicine A Ketotifen eye drops C It is a broad-spectrum antibacterial B Olopatadine eye drops Mast cell stabilisers D It requires twice daily instillation C Lodoxamide eye drops Topical mast cell stabilisers prevent the D Sodium cromoglicate eye drops release of histamine and other inflam- Which of the following antimicrobial matory mediators from mast cells. They 3agents are available as eye drops as a P Which of the following statements on have been proven to be more effective medicine? 9aminoglycosides is false? than placebo in several randomised A Ciprofloxacin A They are derived from fungi controlled trials but may take up to 14 B Propamidine isetionate B They bind to the 30S ribosomal subunit days to relieve symptoms if used alone. C Gentamicin C They all have a wide spectrum of antibacterial All three mast cell stabilisers (Table D Polymyxin B activity 5) are available to AS optometrists and, D They include neomycin and gentamicin where a P medicine product is available, Which of the following drugs requires to all registered optometrists. 4phosphorylation before it can exert its Which of the following is an Sodium cromoglicate is the original antimicrobial activity? 10antihistamine? topical ocular mast cell-stabiliser. It is A Aciclovir A Xylometazoline inexpensive, widely available and there B Bacitracin B Oxymetazoline are no restrictions on the age of the C Polymyxin B C Antazoline patients. A preservative-free prepara- D Neomycin D Phenylephrine tion is available on a named patient basis. However, sodium cromoglicate needs Which of the following corticosteroids Which of the following is unavailable to be used four times a day which is a 5would be preferred in a patient with a 11to entry level optometrists? disadvantage. history of a steroid-induced rise in IOP? A Diclofenac Lodoxamide and nedocromil are A Betamethasone 0.1% B Fusidic acid newer, more expensive topical agents B Dexamethasone 0.1% C Chloramphenicol available as alternatives to sodium C Prednisolone 1% D Propamidine isetionate cromoglicate. Nedocromil has the D Rimexolone 1% advantage of a twice daily dosage Against which of the following will and could be sold as a P medicine if Which of the following corticosteroid eye 12polymixin B be ineffective? such a preparation becomes available. 6drops may be prescribed by an additional A Pseudomonas aeruginosa Although lodoxamide must be admin- supply optometrist? B Staphylococcus aureus istered four times a day, it is available as A Hydrocortisone 1% C Enterobacter a P medicine. B Fluoromethalone 0.1% D Escherichia coli C Prednisolone 0.5% Diclofenac D None of the above The other topical preparation licensed for the treatment of seasonal allergic Successful participation counts as two credits towards the GOC CET scheme and one towards conjunctivitis is diclofenac 0.1 per cent the Association of Optometrists Ireland’s scheme. Deadline for response is November 22 (Voltarol Ophtha) eye drops for which it has been shown to be superior to ketoro- ● Part 8b will cover anti-glaucoma 4 Doughty MJ, Dutton GN. Fusidic acid lac, another NSAID, but not antihista- medication and artificial tears/ lubricants. viscous eyedrops – an evaluation of mines or mast cell-stabilisers. pharmacodynamics, pharmacokinetics and It is a POM but available to AS Bibliography clinical use for UK optometrists Ophthalmic optometrists in multidose and unit-dose 1 British National Formulary (September Physiol Opt, 2006;26:4 343-61. (preservative-free) forms, an advan- 2007) (available at: www.bnf.org.uk/bnf/). 5 The electronic medicines compendium tage over other treatments. It is used 2 Competency Framework for Prescribing (available at http://emc.medicines.org.uk ) at a frequency of four times a day for Optometrists (can be downloaded from: as long as required. Diclofenac is also www.assoc-optometrists.org/uploaded_ ● Lucy Titcomb is lead ophthalmic licensed for the control of ocular pain files/pdf/optometrist_document_final.pdf). pharmacist at the Birmingham and and discomfort associated with corneal 3 Clinical Knowledge Summaries (available Midland Eye Centre. John Lawrenson is epithelial defects after excimer PRK at: www.cks.library.nhs.uk/clinical_ professor of clinical visual science in the surgery or accidental non-penetrating knowledge/clinical_topics/by_clinical_ Department of Optometry and Visual trauma. ● specialty/eyes). Science, City University, London opticianonline.net 26.10.07 | Optician | 35 Continuing education CET

Table 6 Drug Bimatoprost Latanoprost Travoprost Drug class Prostamide Prostaglandin analogue Prostaglandin analogue Manufacturer Allergan Pharmacia Alcon Trade name Lumigan Xalatan Travatan Strength 300 micrograms/ml (0.03%) 50 micrograms/ml (0.005%) 40 micrograms/ml (0.004%) Preservative Benzalkonium chloride 0.005% Benzalkonium chloride 0.02% Benzalkonium chloride 0.01% Combination product Ganfort Xalacom Duotrav (with 0.5% timolol ) Dose One drop at night (Lumigan) One drop at night (Xalatan) Once drop at night (Travatan) One drop in the morning (Ganfort) One drop in the morning (Xalacom) One drop in the morning or night (Duotrav)

Table 7 Drug Betaxolol Carteolol Levobunolol Metipranolol Timolol Maleate Hydrochloride Hydrochloride

Drug class Selective beta Non-selective beta Non-selective beta Non-selective beta Non-selective beta blocker blocker blocker blocker blocker

Trade names Betoptic Tetoptic Betagan Minims Metipranolol Timoptol®

Long-acting Nyogel® Timolol LA® For combination products see Tables 6, 8 and 9 Available 0.5% eyedrops 1% eyedrops 0.5% eyedrops 0.1% SDU 0.25% eyedrops formulations 0.25% suspension 2% eyedrops 0.5% SDU 0.25% SDU 0.25% SDU 0.1% gel (Nyogel) 0.25% gel forming solution (Timolol LA)

Dose One drop twice a One drop twice a One drop once or One drop twice a day One drop twice a day day day twice a day Nyogel and Timolol LA ( once a day)

Table 8 Drug Brand name Available as Dose Acetazolamide Diamox® Tablets 250mg 250mg to 1 gram daily in divided doses Diamox sodium® parenteral Injection 500mg 250mg to 1 gram daily in divided doses Diamox SR® Modified-release capsules 250mg 250 – 500mg daily Brinzolamide Azopt® Eye drop suspension 1% As monotherapy or as adjunctive therapy with an ophthalmic beta-blocker twice a day., some patients may have a better response with a three times a day. dosage Dorzolamide Trusopt® Eye drop solution 2% As monotherapy, three times per day; as adjunctive Trusopt preservative-free 2% SDU therapy with an ophthalmic beta-blocker, twice a day. Cosopt® Combination product with timolol 0.5% Twice a day Cosopt preservative-free Eye drop solution Unit dose eye drops

36 | Optician | 26.10.07 opticianonline.net CET Continuing education

Table 9

Drug Trade Preparations Dosage Therapeutic indication name available

Apraclonidine Iopidine Eye drops One drop tds Short-term adjunctive therapy of chronic glaucoma in patients on 0.5% maximally tolerated medical therapy who require additional intraocular pressure (IOP) reduction to delay laser treatment or glaucoma surgery

Unit dose eye One drop one hour Control or prevention of postsurgical elevations in intraocular pressure drops 1% before and one drop on that occur in patients after anterior segment laser surgery completion of procedure

Brimonidine Alphagan Eye drops One drop bd Reduction of elevated intraocular pressure in patients with open 0.2% angle glaucoma or ocular hypertension. ● As monotherapy in patients in whom topical beta-blocker therapy is contraindicated. ● As adjunctive therapy to other intraocular pressure lowering medications when the target IOP is not achieved with a single agent

Combigan Eye drops One drop bd Chronic open-angle glaucoma or ocular hypertension in patients who containing are insufficiently responsive to topical beta-blockers Brimonidine 0.2% Timolol 0.5%

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Table 10 Generic name Trade name Formulation Dosage Therapeutic indication Acetylcysteine Ilube 5% acetylcysteine, 0.35% Adults & children (1 month Relief of dry eye syndromes hypromellose and over). Instill 1 or 2 drops associated with deficient tear into the affected eye three or secretion and impaired or four times daily. abnormal mucus production. Carbomers GelTears 0.2% carbomer 980 Adults & children (12 years Carbomers are synthetic high and over, except GelTears and molecular weight polymers of Liposic 0.2% carbomer 980 Liposic which are licensed acrylic acid used for the treat- Liquivisc 0.25% carbomer 974P from 1 month). Apply 1or 2 ment of dry eye or an unstable drops 3-4 times per day or as tear film. Viscotear 0.2% carbomer 980 required. Viscotears (SDU) 0.2% carbomer 980

Hydroxyethycellulose Minims Artifiical 0.44% hydroxyethylcellulose Adults & children (1 month Tear substitute for the treat- Tears (SDU) and over). Apply 1 or 2 drops ment of dry eye 3-4 times per day or as required. Hypromellose Artelac (SDU) 0.32% hypromellose Adults & children (1 month Tear substitute for the treat- and over). Apply 1 or 2 drops ment of dry eye. Isopto Alkaline 1% hypromellose 3-4 times per day or as required. Isopto Plain 0.5% hypromellose Tears Naturale 0.3% hypromellose with dextran 70 0.1% Liquid paraffin Lacrilube 57.3% white soft paraffin, Adults & children (1 month Lubrication and protection of 42.5% liquid paraffin, 0.2% and over). Apply a small the eye in conditions such as wool alcohols amount to the affected eye(s) exposure keratitis, decreased as required. corneal sensitivity, recurrent Lubritears 60% white soft paraffin, 30% corneal erosions and keratocon- liquid paraffin, 10% wool fat junctivitis sicca. Polyvinyl Alcohol Liquifilm Tears 1.4% polyvinyl alcohol Adults & children (1 month Treatment of dry eye or an and over). Apply 1 or 2 drops unstable tear film 3-4 times per day or as Liquifilm Tears required. (SDU)

Sno Tears Povidone Oculotect (SDU) 5% povidone Adults & children (1 month Treatment of dry eye or an and over). Apply 1or 2 drops 4 unstable tear film times per day or as required. Carmellose Sodium Celluvisc 0.5%, 1% carmellose sodium Adults & children (1 month Tear substitute for the treat- and over). Apply 1 or 2 drops ment of dry eye. 3-4 times per day or as required. Polyethylene glycol Systane (Alcon) 0.4% polyethylene glycol 400 Adults & children (from 1 Treatment of dry eye or an 400 and 0.3% propylene glycol month). Apply 1or 2 drops 3-4 unstable tear film. Systane (SDU) demulcents with HP-Guar times per day or as required. (Alcon) (hydroxypropylguar) as a gelling agent

SDU= Single dose unit (preservative-free)

38 | Optician | 26.10.07 opticianonline.net CET Continuing education

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patients taking travoprost (35 per cent than PGAs and beta-blockers but can be of patients in clinical trials), although used as adjunctive therapy or first line second part it rarely leads to a discontinuation of in those unresponsive to other agents. therapy. PGAs may also cause darken- The most common side-effects of topical ing of the iris and lengthening of the CAI include a foreign-body sensation, eyelashes. conjunctival hyperaemia and a bitter Bimatoprost (Lumigan) is a prosta- taste in the mouth. mide, a synthetic structural analogue of prostaglandin with ocular hypotensive Selective alpha-2 agonists ● Anti-glaucoma activity. It selectively mimics the effects Selective alpha-2 agonists lower IOP medication of naturally occurring substances, prosta- by reducing aqueous formation as well mides. Bimatoprost is believed to lower as a possible increase in uveoscleral The principal aim of glaucoma therapy IOP in humans by increasing outflow outflow. Apraclonidine (Iodipine) is is to reduce IOP to a level that prevents of aqueous humour through both the indicated for short-term use in patients further visual loss. Modern glaucoma trabecular meshwork and uveoscleral on maximum drug therapy or peri- management advocates the use of ‘target routes. Side-effects of bimatoprost are operatively who require further IOP pressures’. similar to PGAs. lowering. Brimonidine (Alphagan) Target pressures will vary depend- can be used long-term as monotherapy ing on risk factors and disease severity, Beta-blockers where beta-blockers are contraindicated but typically involve an IOP reduc- Beta-blockers reduce IOP principally by or as adjunctive therapy in primary open tion of between 20-40 per cent from reducing the rate of aqueous secretion. angle glaucoma (POAG) and ocular the pressure at which damage first The non-selective beta-blocker timolol hypertension (Table 9). occurred. This is usually achieved by remains the gold standard against which topical agents that decrease aqueous all new therapies are compared and Combination products secretion or increase outflow (achieved topical beta-blockers remain an effec- The effect of different drugs used either by improving flow through the tive therapy for selected patients. For together is not necessarily additive. conventional (trabecular) pathway or example, beta-blockers are the drug of Some drugs work synergistically and the increasing uveoscleral drainage). choice in pregnant women and children overall effect is greater than the sum of Drugs used in the treatment of and several members of this class of their individual responses. This is partic- glaucoma are covered in section 11.6 drugs are available in preservative-free ularly true where the drugs reduce IOP of the BNF and include: formulations (Table 7). by different mechanisms. ● Prostaglandin analogues/prostamide Particular caution needs to be exercised Several combination products are ● Beta-blockers when prescribing topical beta-block- available commercially, such as timolol ● Carbonic anhydrase inhibitors ers as there have been several reports with prostaglandin/prostamide ● Sympathomimetics/alpha2-agonists of serious systemic adverse reactions, analogues, and timolol combined with ● Cholinergic agonists/miotics. particularly with non-selective recep- the carbonic anhydrase inhibitor dorzola- Systemic therapy is sometimes used tor blockers (beta-1 and beta-2). At least mide. Combined preparations can poten- for short-term treatment of acutely 80 per cent of the administered drop tially improve compliance and reduce elevated IOP, consisting of oral or intra- drains through the nasolacrimal canal exposure to preservatives (compared to venous (IV) acetazolamide (Diamox) from where it can be absorbed across two separate preparations). or the osmotic diuretics IV mannitol or the nasal mucosa. Since the systemi- oral glycerol. This section will deal with cally-absorbed drug bypasses hepatic Other medications the most commonly prescribed first-line first-pass metabolism, the drug behaves Miotics, such as pilocarpine, have been and second-line anti-glaucoma drugs like an intravenous dose, increasing used for many years for the treatment of (Tables 6-9). Initial glaucoma therapy the propensity to cause prolonged and chronic glaucoma. They reduce IOP by is almost always with a single agent severe side-effects. Several cardiovas- improving outflow through the conven- (monotherapy) which may be substi- cular adverse events that have been tional drainage pathway. Miotics are no tuted if unresponsive or a second drug reported, including arrhythmias, longer prescribed as first line therapy in added as adjunctive therapy. hypotension, angina pectoris, myocar- POAG, although they still have a role in dial infarction, heart failure, and the treatment of angle closure. Prostaglandin analogues syncope (fainting). Topical beta-block- Prostaglandin analogues (PGAs) are ers can also exacerbate bronchospasm ● Artificial tears and thought to reduce IOP by increasing in asthmatics and patients with chronic ocular lubricants the rate of uveoscleral aqueous outflow. obstructive pulmonary disease. There is evidence that PGAs reduce IOP A distinction is often made between more effectively than the beta-blockers Carbonic anhydrase inhibitors products that are marketed as ‘artificial and they are commonly the first drug of Carbonic anhydrase is a key enzyme tears’ or ‘tear substitutes’ and lubricant choice (Table 6). Latanoprost (Xalatan) involved in aqueous production. ointments and gels. is preferred since it has a better safety Carbonic anhydrase inhibitors (CAIs) Artificial tears are characterised by profile than other members of the class; include both oral and topical agents hypotonic or isotonic buffered solutions although there is some evidence that (Table 8). Acetazolamide (Diamox) that are formulated at a neutral or travoprost (Travatan) is more effective can be given by mouth or intravenous slightly alkaline pH. They are the in patients of African origin. (IV) injection and is typically used in mainstay of treatment for dry eye or The most common side-effect of PGAs the treatment of angle closure (500mg an unstable tear film. However, since is conjunctival hyperaemia, particular IV stat dose followed by 250mg orally most products also contain viscosity- during the early weeks of treatment. four times daily). Topical CAIs, dorzola- enhancing agents that help to facilitate Hyperaemia is most pronounced in mide and brinzolamide, are less potent the movement of the eyelid across the opticianonline.net 26.10.07 | Optician | 40