Method for Stabilizing Arylcarboxylic Acid, Stabilizer Thereof and Aqueous

Europäisches Patentamt *EP001389469B1* (19) European Patent Office

Office européen des brevets (11) EP 1 389 469 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.7: A61K 45/06, A61K 31/52, of the grant of the patent: A61K 31/495, A61K 31/60, 26.10.2005 Bulletin 2005/43 A61K 9/00, A61K 47/22 (21) Application number: 03025332.2 // (A61K31/495, 31:19)

(22) Date of filing: 03.02.1998

(54) Method for stabilizing arylcarboxylic acid, stabilizer thereof and aqueous solution containing stabilized arylcarboxylic acid Verfahren zum Stabilisieren von Arylcarbonsäuren, dafür verwendbarer Stabilisator und eine stabilisierte Carbonsäure enthaltende wässrige Lösung Méthode pour stabiliser d’acide arylcarboxylique, stabilisateur utilisable pour celle-ci et solution contenant une acide arylcarboxylique stabilisée

(84) Designated Contracting States: • PATENT ABSTRACTS OF JAPAN vol. 1997, no. AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC 04, 30 April 1997 (1997-04-30) & JP 08 333246 A NL PT SE (TAISHO PHARMACEUT CO LTD), 17 December 1996 (1996-12-17) (30) Priority: 04.02.1997 JP 2180597 • PATENT ABSTRACTS OF JAPAN vol. 1997, no. 04, 30 April 1997 (1997-04-30) & JP 08 333265 A (43) Date of publication of application: (TAISHO PHARMACEUT CO LTD), 17 December 18.02.2004 Bulletin 2004/08 1996 (1996-12-17) • CHEMICAL ABSTRACTS, vol. 122, no. 26, 26 (62) Document number(s) of the earlier application(s) in June 1995 (1995-06-26) Columbus, Ohio, US; accordance with Art. 76 EPC: abstract no. 322527, VAN WIE BERGAMINI ET 98101804.7 / 0 856 310 AL.: "OPHTHALMIC FORMULATION BASED ON A STEROIDAL OR NONSTEROIDAL (73) Proprietor: Senju Pharmaceutical Co., Ltd. ANTIINFLAMMATORY AGENT AND A DNA Osaka-shi, Osaka 541-0046 (JP) GYRASE-INHIBITING ANTIBIOTIC" XP002123861 & ES 2 065 846 A (LABORATORIOS (72) Inventor: Shirou, Sawa CUSI, S.A.) 16 February 1995 (1995-02-16) Kobe-shi Hyogo 651-2116 (JP) • PATENT ABSTRACTS OF JAPAN vol. 1997, no. 10, 31 October 1997 (1997-10-31) & JP 09 157162 (74) Representative: von Kreisler, Alek et al A (SATO SEIYAKU KK;R P SHIILA- KK), 17 June Patentanwälte, 1997 (1997-06-17) von Kreisler-Selting-Werner, • PATENT ABSTRACTS OF JAPAN vol. 1995, no. Bahnhofsvorplatz 1 (Deichmannhaus) 07, 31 August 1995 (1995-08-31) & JP 07 097325 50667 Köln (DE) A (TAKEDA CHEM IND LTD), 11 April 1995 (1995-04-11) (56) References cited: EP-A- 0 105 635 EP-A- 0 269 278 EP-A- 0 359 195 EP-A- 0 621 036 EP-A- 0 631 782 WO-A-93/17716 WO-A-95/07082 WO-A-96/29997 WO-A-97/49405 CA-A- 1 336 687 GB-A- 873 526 GB-A- 2 082 456 US-A- 4 794 117

Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 389 469 B1

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Description

[0001] The present invention relates to a method for stabilizing arylcarboxylic acid, which is an acidic compound and which has an antiinflammatory activity, or a pharmacologically acceptable salt thereof. 5 BACKGROUND OF THE INVENTION

[0002] Arylcarboxylic acid and pharmacologically acceptable salts thereof have been known to be extremely superior antiinflammatory agents. However, said arylcarboxylic acids, particularly pranoprofen, diclofenac and bromfenac, are 10 associated with a problem that they become unstable in an aqueous solution. [0003] Arylcarboxylic acid and pharmacologically acceptable salts thereof have been also known to be stabilized by adding an antioxidant, by adjusting the pH, concentration and ionic strength thereof, by shutting out the light, and the like. These methods, nevertheless, cannot provide sufficient stability at lower temperatures. [0004] Thus, an aqueous solution has not been provided which contains an arylcarboxylic acid or a pharmacologically 15 acceptable salt thereof, particularly pranoprofen, dicrofenac or bromfenac, and which has sufficient stability at lower temperatures. [0005] While WO9632941 A1 discloses pranoprofen combined with an organic amine, it does not disclose the heterocyclic base to be used in the present invention. [0006] JP 08333246 (PATENT ABSTRACTS OF JAPAN vol 1997, no. 04) discloses a method for stabilizing an aryl- 20 carboxylic acid, which comprises adding a purine base.

SUMMARY OF THE INVENTION

[0007] It is therefore an object of the present invention to provide a method for stabilizing an arylcarboxylic acid and 25 a pharmacologically acceptable salt thereof. [0008] According to the present invention, it has now been found that the addition of a pyridonecarboxylic acid to an arylcarboxylic acid or a pharmacologically acceptable salt thereof leads to successful stabilization thereof, particularly pranoprofen, at every temperature range, particularly at low temperatures. [0009] Thus, the present invention provides the following. 30 [0010] A method for stabilizing an arylcarboxylic acid or a pharmacologically acceptable salt thereof in an aqueous solution, which comprises adding

(a) a pyridonecarboxylic acid of the formula (IV):

45 wherein.

X is a carbon atom or a nitrogen atom; and R12, R13, R14 and R15 are the same or different and each is a hydrogen atom; a halogen; a carboxyl group, an optionally substituted C1-C6 alkyl group; an optionally substituted C3-C9 cycloalkyl group; 50 an acyl group selected from the group consisting of formyl, acetyl, propionyl, butyryl, isobutyryl, valeryl, benzoyl, naphthoyl, toluoyl and salicyloyl, which may be substituted by C1-C3 alkyl, C1-C3 alkoxy, C1-C2 alkylthio, C1-C3 alkylamino, cyclo(C3-C6)alkyl, cyclo (C3-C6)alkenyl, halogen, amino, amino protecting group, hydroxy, protected hydroxy cyano, nitro, carboxy, protected carboxy, sulfo, sulfamoyl, imino, oxo, amino(C1-C2)alkyl, 55 carbamoyloxy or hydroxy(C1-C3)alkyl; an optionally substituted aryl group or an optionally substituted heterocyclic group;

wherein R12 and R13 optionally form a 4- to 6-membered heterocyclic group with the adjacent nitrogen atom

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and X, and R14 and R15 optionally form a 4- to 6-membered heterocyclic group with the adjacent carbon atom, provided that when X is a nitrogen atom, R13 is void, or (b) cinoxacin or sparfloxacin, 5 or a pharmacologically acceptable salt thereof, to an arylearboxylic acid of the formula (I)

1 1 L -R COOH (I) 10 wherein

DETAILED DESCRIPTION OF THE INVENTION

20 [0011] The stabilizing method of the present invention comprises the addition of a stabilizer containing a pyridonecarboxylic acid as an active ingredient to an arylcarboxylic acid, which is an acidic compound and which has an antiinflammatory activity, or a pharmacologically acceptable salt thereof. For example, a pyridonecarboxylic acid is added to an arylcarboxylic acid or a pharmacologically acceptable salt thereof. [0012] To be specific, an arylcarboxylic acid and a pyridonecarboxylic acid are dissolved in water and the pH thereof 25 is adjusted with boric acid, acetic acid, phosphoric acid, which is followed by lyophilization where necessary. [0013] While the pH varies depending on the kind of arylcarboxylic acid, it is generally 5-9, preferably about 6-8. [0014] Said pyridonecarboxylic acid may be any as long as it has the formula (IV) as defined above. [0015] The alkyl of the "optionally substituted C1-C6 alkyl group" may be a linear or branched one, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, isohexyl, and neohexyl. 30 [0016] The cycloalkyl of the "optionally substituted C3-C9 cycloalkyl group" is exemplified by cyclopropyl, cyclobutyl, cyalopentyl, cyclohexyl, and cycloheptyl. [0017] The substituents of the above-mentioned C1-C6 alkyl group and C3-C9 cycloalkyl group include C1-C3 alkyl group, and halogen. [0018] The lower acyl of the "optionally substituted lower acyl group" may be, for example, formyl group, acetyl group, 35 propionyl group, butyryl group, isobutyryl group, valeryl group, benzoyl group, naphthoyl group, toluoyl group, and salicyloyl group. [0019] The above-mentioned acyl may be substituted by suitable substituents which may be the same or different, such as lower alkyl (e.g., methyl, ethyl, propyl); 40 lower alkoxy (e.g., methoxy, ethoxy, propoxy); lower alkylthio (e.g., methylthio, ethylthio); lower alkylamino (e.g., methylamino, ethylamino, and propylamino); cyclo(lower)alkyl such as cyclo(C3-C6)alkyl (e.g., cyclopentyl, and cyclohexyl); cyclo(lower)alkenyl such as cyclo(C3-C6)alkenyl (e.g., cycloxenyl, and cyclohexadienyl); 45 halogen (e.g., fluorine, chlorine, bromine and iodine); amino; amino protecting group; hydroxy; protected hydroxy; cyano; nitro; carboxy; protected carboxy; sulfo; sulfamoyl; imino; oxo; amino(lower)alkyl (e.g., aminomethyl, aminoethyl), carbamoyloxy, hydroxy(lower)alkyl (e.g., hydroxymethyl, 1- or 2-hy- droxyethyl, 1- or 2- or 3-hydroxypropyl). 50 [0020] The aryl of the "optionally substituted aryl group" is exemplified by phenyl, and naphthyl, with preference given to naphthyl. [0021] The heterocyclic group of the optionally substituted heterocyclic group may contain, besides the carbon atom, at least one hetero atom selected from the group consisting of a nitrogen atom, sulfur atom and oxygen atom, as the atom constituting the ring, and may be a saturated or unsaturated, heteromonocyclic or heteropolycyclic group. 55 [0022] The preferable heterocyclic groups are the following:

3- to 6-membered unsaturated heteromonocyclic group having 1 to 4 nitrogen atoms, such as pyrrolyl, pyrrolinyl,

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imidazolyl, pyrazolyl, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazolyl (e.g., 4H-1,2,4-triazolyl, 1H-1,2,3-triazolyl, and 2H-1,2,3-triazolyl), tetrazolyl (e.g., 1H-tetrazolyl, and 2H-tetrazolyl), triazinyl (e.g., 1,2,4-triazinyl); 3- to 7-membered saturated heteromonocyclic group having 1 to 4 nitrogen atoms, such as pyrrolidinyl, imidazo- lidinyl, piperidinyl, piperazinyl, homopiperazinyl; 5 saturated heteropolycyclic group having 1 to 4 nitrogen atoms, such as quinuclidinyl; unsaturated heteropolycyclic group having 1 to 5 nitrogen atoms, such as indolyl, isoindolyl, 3H-indolyl, indolizinyl, benzoimidazolyl, quinolyl, isoquinolyl, indazolyl, phthalazinyl, naphthyridinyl, quinoxalinyl, quinazolinyl, cinnolinyl, benzotriazolyl, tetrazolopyridazinyl (e.g., tetrazolo[1,5-b]pyridazinyl), pteridinyl, carbazolyl, phenanthrinidyl, acrid- inyl, and perimidyl; 10 3- to 6-membered unsaturated heteromonocyclic group having 1 to 3 nitrogen atoms and 1 or 2 oxygen atoms, such as oxazolyl, isooxazolyl, oxadiazolyl (e.g., 1,2,4-oxadiazolyl, 1,3,4-oxadiazolyl, 1,2,5-oxadiazolyl); 3- to 6-membered saturated heteromonocyclic group having 1 to 3 nitrogen atoms and 1 or 2 oxygen atoms, such as morpholinyl, and sydnolyl; unsaturated condensed heterocyclic group having 1 to 3 nitrogen atoms and 1 or 2 oxygen atoms, such as ben- 15 zofurazanyl, benzoxazolyl, benzoxazinyl, and benzoxadiazolyl; 3- to 6-membered unsaturated condensed heterocyclic group having 1 to 3 nitrogen atoms and 1 or 2 sulfur atoms, such as thiazolyl, isothiazolyl, thiadiazolyl (e.g., 1,2,4-thiadiazolyl, 1,3,4-thiadiazolyl, and 1,2,5-thiadiazolyl). 3- to 6-membered saturated heteromonocyclic group having 1 to 3 nitrogen atoms and 1 or 2 sulfur atoms, such as thiazolidinyl; 20 unsaturated condensed heterocyclic group having 1 to 3 nitrogen atoms and 1 or 2 sulfur atoms, such as benzo- thiazolyl, and benzothiadiazolyl; 3- to 6-membered unsaturated heteromonocyclic group having 1 oxygen atom, such as furyl, and pyranyl; 3- to 6-membered unsaturated heteromonocyclic group having 1 or 2 sulfur atoms, such as thienyl, and dihydro- thienyl; 25 unsaturated condensed heterocyclic group having 1 or 2 sulfur atoms, such as benzothienyl.

[0023] The aryl group and heterocyclic group are optionally substituted by one or more substituents selected from the group consisting of hydroxyl group, halogen atom, aliphatic alkyl group, aromatic alkyl group, aliphatic carboxylic acid group, aromatic carboxylic acid group, aliphatic carboxylate group, aromatic carboxylate group, aliphatic ether 30 group, aromatic ether group, aliphatic alcohol group, aromatic alcohol group, aliphatic aldehyde group, aromatic aldehyde group, aliphatic amino group, aromatic amino group, which are optionally substituted by halogen atom. [0024] The 4- to 6-membered ring formed by R12 and R13 with the adjacent nitrogen atom and X, and the 4- to 6-membered heterocyclic ring formed by R14 and R15 with the adjacent carbon atom may be, for example, thienyl group, furyl group, pyrrolyl group, imidazolyl group, pyrazolyl group, thiazolyl group, isothiazolyl group, oxazolyl group, 35 isooxazolyl group, oxadiazolyl group, thiadiazolyl group, triazolyl group, pyridyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, triazinyl group, dithiazolyl group, dioxolanyl group (e.g., 1,3-dioxolanyl group), dithiolyl group, pyrrolidinyl group, thiaziadinyl group, dithiaziadinyl group, morpholinyl group, oxazinyl group, thiazinyl group, piperazinyl group, piperidinyl group, pyranyl group, and thiopyranyl group. [0025] Examples of the pyridonecarboxylic acid include norfloxacin: [1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piper- 40 azinyl)-3-quinolinecarboxylic acid], ofloxacin: [(±)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo- 7H-[1,2,3-de]-1,4-benzoxazine-6-carboxylic acid], enoxacin: [1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)- 1,8-naphthyridine-3-carboxylic acid], cinoxacin: [1-ethyl-1,4-dihydro-4-oxo-[1,3]-dioxolo[4,5-g]cinnoline-3-carboxylic acid], ciprofloxacin: [1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid], sparfloxacin: [5-amino-1-cyclopropyl-7-(cis-3,5-dimethyl-1-piperazinyl)-6,8-difluoro-1,4-dihydro-4-oxoquinoline-3-carbox- 45 ylic acid], tosufloxacin: [(±)-7-(3-amino-1-pyrrolidinyl)-1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-1-naphthyridine-3-carboxylic acid], fleroxacin: [6,8-difluoro-1-(2-fluoroethyl)-1,4-dihydro-7-(4-methyl-1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid], levofloxacin: [(-)-(S)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H-pyrido [1,2,3-de][1,4]benzoxazine-6-carboxylic acid], lomefloxacin: [1-ethyl-6,8-difluoro-1,4-dihydro-7-(3-methyl-1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid], 5,8-dihydro-8-ethyl-2-(1-piperazinyl)-5-oxopyrido[2,3-d]pyrimidinecarboxylic 50 acid, 7-(3-amino-1-pyrrolidinyl)-1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid, 7-(3-amino- 1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid, 1-cyclopropyl-6-fluoro- 7-(3-methylamino-1-pyrrolidinyl)-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid, and 7-(3-amino-3-methyl- 1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid, and salts thereof. [0026] The pharmacologically acceptable salts of pyridonecarboxylic acid include, for example, acid addition salts 55 with inorganic acid such as hydrochloric acid, sulfuric acid, and phosphoric acid, organic acid such as acetic acid, lactic acid, succinic acid, methanesulfonic acid, maleic acid, malonic acid, and gluconic acid, or amino acid such as aspartic acid, and glutamic acid; metal salts such as sodium salt, and potassium salt. [0027] The arylcarboxylic acid to be used for the stabilization of the present invention may be any compound as long

4 EP 1 389 469 B1

as it has the following formula (I):

1 1 L -R COOH (I) 5 wherein

L1 is an optionally substituted heterocyclic group or aryl group having not more than 14 carbon atoms; and R1 is an optionally substituted alkyl group having not more than 4 carbon atoms or a single bond. 10 [0028] The heterocyclic group in the optionally substituted heterocyclic group having not more than 14 carbon atoms may be exemplified by those mentioned above, and the substituents of said heterocyclic group are also exemplified by those mentioned above. [0029] The aryl of the "optionally substituted aryl group having not more than 14 carbon atoms" may be exemplified 15 by those mentioned above, and the substituents of said aryl group are also exemplified by those mentioned above. [0030] The alkyl of the "optionally substituted alkyl group having not more than 4 carbon atoms" may be, for example, a linear or branched one such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl. [0031] Examples of the arylcarboxylic acid include naphthoic acid-related compounds, salicylic acid-related compounds, phenylacetic acid-related compounds, pyrazolone-related compounds, anthranilic acid-related compounds, 20 indoleacetic acid-related compounds, fenclozic acid-related compounds and salts thereof. [0032] Examples of the naphthoic acid-related compounds include 2-naphthoic acid, 2-naphthylacetic acid, and 2-naphthoxyacetic acid. [0033] Examples of the salicylic acid-related compounds include salicylic acid, aspirin, flufenisal, ethenzamide, and benorylate. 25 [0034] Examples of the phenylacetic acid-related compounds include ibufenac, alclofenac, flurbiprofen, ketoprofen, naproxen, ibuprofen, bromfenac, pranoprofen, namoxylate, and fenoprofen. [0035] Examples of the pyrazolone-related compounds include aminopyrine phenylbutazone, azapropazone, and cinopentazone. [0036] Examples of the anthranilic acid-related compounds include mefenamic acid, niflumic acid, diclofenac, me- 30 tiazihic acid, protizinic acid, clonixin, flufenamic acid, and ketoprofen. [0037] Examples of the indoleacetic acid-related compounds include indomethacin, and intrazole. [0038] The amount of the heterocyclic base to be added to the arylcarboxylic acid or a pharmacologically acceptable salt thereof is preferably 0.001-5 parts by weight per 100 parts by weight of the arylcarboxylic acid or pharmacologically acceptable salt thereof. 35 [0039] The stabilizer of the arylcarboxylic acid and a pharmacologically acceptable salt thereof contains a heterocyclic base as an active ingredient, and the amount thereof is about the same as the amount mentioned above. [0040] The solvent to be used for the aqueous solution of the present invention may be, for example, purified water, particularly distilled water for injection. The concentration of the active ingredient of the aqueous solution, i.e. arylcarboxylic acid, can be markedly increased by a heterocyclic base, preferably to 0.1-10 (w/v)%. 40 [0041] The heterocyclic base to be used for the aqueous solution of the present invention may be those mentioned above. [0042] Said aqueous solution may contain various additives as appropriate, such as buffer, isotonizing agent, solubilizer, antiseptic, thickener, chelating agent, and aromatic. [0043] Examples of the buffer include phosphate buffer, borate buffer, citrate buffer, tartrate buffer, acetate buffer, 45 and amino acid. [0044] Examples of the isotonizing agent include sugars such as sorbitol, glucose, and mannitol, polyhydric alcohols such as glycerol, and propylene glycol, salts such as sodium chloride. [0045] Examples of the solubilizer include non-ionic surfactants such as polyoxyethylenesorbitan monoolate, poly- oxyethyleneoxystearic acid triglyceride, polyethylene glycol, and polyoxyethylene hydrogenated castor oil. 50 [0046] Examples of the antiseptic include quaternary ammonium salts such as benzalkonium chloride, benzethonium chloride, and cetylpyridinium chloride, p-hydroxybenzoates such as methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, and butyl p-hydroxybenzoate, benzyl alcohol, phenethyl alcohol, sorbic acid, salts thereof, thimerosal, chlorobutanol, and sodium dehydroacetate. [0047] Examples of the thickener include polyvinylpyrrolidone, hydroxyethylcellulose, hydroxypropylcellulose, meth- 55 ylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, and salts thereof. [0048] Examples of the chelating agent include sodium edetate, and citric acid. [0049] Examples of the aromatic include 1-menthol, borneol, camphor, and eucalyptus oil.

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[0050] The aqueous solution of the present invention is used as an eye drop, nasal drop or ear drop. When it is used as an eye drop, its pH is generally adjusted to 3.5-8.5, preferably 6-7, when it is used as a nasal drop, its pH is generally adjusted to 3.5-8.5, preferably about 6-7, and when it is used as an ear drop, its pH is generally adjusted to 3.5-8.5, preferably 6-7. 5 [0051] While the method for producing the aqueous solution of the present invention varies depending on the kind of a desired solution, a known method can be used to produce such aqueous solution. [0052] When the aqueous solution of the present invention is used as an eye drop, for example, the dose thereof need only be sufficient to effectively suppress an inflammation in the eye, and may vary according to symptoms, the kind of inflammation, the patients (human or animal) in need of said solution. A typical dose is 20-200 µL, preferably 10 50-100 µL, which may be administered 1 to 12 times a day. [0053] The present invention is described in more detail by way of Examples and Experimental Examples.

Experimental Example 1: Stabilization of pranoprofen - 1

15 [0054] Solutions (Examples 1-3 below) of 0.5 w/v% pranoprofen were respectively charged in 5 ml colorless glass ampoules, and allowed to stand at 80°C for 1 week and 2 weeks, at 60°C for 1 week and 2 weeks, and at 4°C for 1 week. The percentage of residual pranoprofen in the ampoules after standing was determined by high performance liquid chromatography. The results are shown in Table 1. The values in the Table are relative to the amount of pranoprofen when it was prepared, which was taken as 100. 20 Table 1 temperature-period residual pranoprofen (%) w/o addition norfloxacin ofloxacin enoxacin 25 80°C -1W 95.4 91.0 99.5 96.7 80°C - 2W 93.0 85.0 100.4 95.9 60°C -1W 98.7 98.0 99.8 99.2 60°C - 2W 98.5 93.8 98.8 98.4 30 4°C -1W 87.5 99.8 99.9 99.2

[0055] As is evident from the results shown in Table 1, pranoprofen was markedly stabilized against heat by the addition of of loxacin, and enoxacin. The decomposition of pranoprofen which occurs at low temperatures was signif- 35 icantly suppressed by norfloxacin, of loxacin, and enoxacin.

Example 1

[0056] An eye drop having the following formulation was prepared. 40 pranoprofen 1.0 g norfloxacin 0.6 g boric acid 3.2 g sodium hydroxide appropriate amount 45 sterile purified water appropriate amount total amount 200 ml (pH 7)

Example 2 50 [0057] An ear drop having the following formulation was prepared.

pranoprofen 1.0 g ofloxacin 0.6 g 55 boric acid 3.2 g sodium hydroxide appropriate amount

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(continued) sterile purified water appropriate amount total amount 200 ml (pH 7) 5

Example 3

[0058] A nasal drop having the following formulation was prepared.

10 pranoprofen 1.0 g enoxacin 0.6 g phosphoric acid 0.1 g sodium hydroxide appropriate amount 15 sterile purified water appropriate amount total amount 200 ml (pH 7)

Example 4

20 [0059] An eye drop having the following formulation was prepared.

pranoprofen 0.1 g ofloxacin 0.3 g 25 boric acid 1.8 g sorbic acid 0.1 g sterile purified water appropriate amount total amount 100 ml (pH 7)

30 Example 5

[0060] An eye drop having the following formulation was prepared.

35 pranoprofen 0.1 g enoxacin 0.3 g boric acid 1.8 g benzalkonium chloride 0.002 g sodium citrate 0.1 g 40 sterile purified water appropriate amount total amount 100 ml (pH 7)

Example 6 45 [0061] An ear drop having the following formulation was prepared.

pranoprofen 1.0 g of loxacin 0.6 g 50 phosphoric acid 0.1 g sodium hydroxide appropriate amount sterile purified water appropriate amount total amount 200 ml (pH 7) 55 [0062] According to the stabilization method of the present invention, arylcarboxylic acid and pharmacologically acceptable salts thereof, particularly pranoprofen, can be stabilized at every temperature range, particularly at lower

7 EP 1 389 469 B1

temperatures, thereby making the production of an aqueous solution to be used as an eye drop, nasal drop, and ear drop possible.

5 Claims

1. A method for stabilizing an arylcarboxylic acid or a pharmacologically acceptable salt thereof in an aqueous solution, which comprises adding

10 (a) a pyridonecarboxylic acid of the formula (IV):

wherein

X is a carbon atom or a nitrogen atom; and 25 R12, R13, R14 and R15 are the same or different and each is a hydrogen atom; a halogen; a carboxyl group, an optionally substituted C1-C6 alkyl group; an optionally substituted C3-C9 cycloalkyl group; an acyl group selected from the group consisting of formyl, acetyl, propionyl, butyryl, isobutyryl, valeryl, benzoyl, naphthoyl, toluoyl and salicyloyl, which may be substituted by C1-C3 alkyl, C1-C3 alkoxy, C1-C2 alkylthio, C1-C3 alkylamino, cyclo 30 (C3-C6)alkyl, cyclo(C3-C6)alkenyl, halogen, amino, amino protecting group, hydroxy, protected hydroxy cyano, nitro, carboxy, protected carboxy, sulfo, sulfamoyl, imino, oxo, amino(C1-C2)alkyl, carbamoyloxy or hydroxy(C1-C3)alkyl; an optionally substituted aryl group or an optionally substituted heterocyclic group;

35 wherein R12 and R13 optionally form a 4- to 6-membered heterocyclic group with the adjacent nitrogen atom and X, and R14 and R15 optionally form a 4- to 6-membered heterocyclic group with the adjacent carbon atom, provided that when X is a nitrogen atom, R13 is void, or (b) cinoxacin or sparfloxacin, 40 or a pharmacologically acceptable salt thereof, to an arylcarboxylic acid of the formula (I):

1 1 L -R COOH (I) 45 wherein

2. The method of claim 1, wherein the pyridonecarboxylic acid is at least one compound selected from the group consisting of lomefloxacin, norfloxacin, ofloxacin, enoxacin, ciprofloxacin, tosufloxacin, fleroxacin and levofloxacin. 55 3. The method of claim 1, wherein the arylcarboxylic acid is at least one compound selected from the group consisting of ibuprofen, diclofenac, 2-naphthoic acid, 2-naphthylacetic acid, bromfenac, pranoprofen, salicylic acid, aspirin,

8 EP 1 389 469 B1

flufenisal, ibufenac, alclofenac, flurbiprofen, ketoprofen, naproxen, mefenamic acid, niflumic acid, metiazinic acid, protizinic acid, clonixin, indomethacin and fenclozic acid.

4. The method of claim 1, wherein the pyridonecarboxylic acid is added in a proportion of 0.001-5 parts by weight 5 per 100 parts by weight of the arylcarboxylic acid.

Patentansprüche

10 1. Verfahren zum Stabilisieren einer Arylcarbonsäure oder eines pharmakologisch annehmbaren Salzes davon in einer wäßrigen Lösung, das das Zufügen

(a) einer Pyridoncarbonsäure der Formel (IV):

25 worin

X ein Kohlenstoffatom oder ein Stickstoffatom ist und R12, R13, R14 und R15 gleich oder verschieden sind und jeweils ein Wasserstoffatom, ein Halogen, eine 30 Carboxygruppe, eine gegebenenfalls substituierte C1-C6-Alkylgruppe, eine gegebenenfalls substituierte C3-C9-Cycloalkylgruppe, eine aus der aus Formyl, Acetyl, Pro- pionyl, Butyryl, Isobutyryl, Valeryl, Benzoyl, Naphthoyl, Toluoyl und Salicyloyl bestehenden Gruppe ausgewählte Acylgruppe, die durch C1-C3-Alkyl, C1-C3-Alkoxy, C1-C2-Alkylthio, C1-C3-Alkylamino, Cyclo(C3-C6)alkyl, Cyclo(C3-C6)alkenyl, Halo- 35 gen, Amino, eine Aminoschutzgruppe, Hydroxy, geschütztes Hydroxy, Cyan, Nitro, Carboxy, geschütztes Carboxy, Sulfo, Sulfamoyl, Imino, Oxo, Amino(C1-C2)alkyl, Carbamoyloxy oder Hydroxy(C1-C3)alkyl substituiert sein kann, eine gegebenenfalls substituierte Arylgruppe oder eine gegebenenfalls substituierte heterocyclische Gruppe sind, 40 worin R12 und R13 gegebenenfalls mit dem benachbarten Stickstoffatom und X eine 4- bis 6gliedrige heterocyclische Gruppe bilden und R14 und R15 gegebenenfalls mit dem benachbarten Kohlenstoffatom eine 4- bis 6gliedrige heterocyclische Gruppe bilden, vorausgesetzt, daß wenn X ein Stickstoffatom ist, R13 abwesend ist oder 45 (b) von Cinoxacin oder Sparfloxacin oder eines pharmakologisch annehmbaren Salzes davon zu einer Aryl- carbonsäure der Formel (I):

1 1 L -R COOH (I) 50 worin

L1 eine gegebenenfalls substituierte heterocyclische Gruppe oder Arylgruppe mit nicht mehr als 14 Kohlen- stoffatomen ist und 55 R1 eine gegebenenfalls substituierte Alkylgruppe mit nicht mehr als 4 Kohlenstoffatomen oder eine Einfachbin- dung ist,

9 EP 1 389 469 B1

oder einem pharmakologisch annehmbaren Salz davon umfaßt.

2. Verfahren des Anspruchs 1, wobei die Pyridoncarbonsäure wenigstens eine aus der aus Lomefloxacin, Norfloxa- cin, Oxofloxacin, Enoxacin, Ciprofloxacin, Tosufloxacin, Fleroxacin und Levofloxacin bestehenden Gruppe ausge- 5 wählte Verbindung ist.

3. Verfahren des Anspruchs 1, wobei die Arylcarbonsäure wenigstens eine aus der aus Ibuprofen, Diclofenac, 2-Naph- thoesäure, 2-Naphthylessigsäure, Bromfenac, Pranoprofen, Salicylsäure, Aspirin, Flufenisal, Ibufenac, Alclofenac, Flurbiprofen, Ketoprofen, Naproxen, Mefenamsäure, Nifluminsäure, Metiazinsäure, Protizinsäure, Clonixin, Indo- 10 methacin und Fenclozinsäure bestehenden Gruppe ausgewählte Verbindung ist.

4. Verfahren des Anspruchs 1, wobei die Pyridoncarbonsäure in einem Anteil von 0,001-5 Gewichtsteilen je 100 Gewichtsteile Arylcarbonsäure zugefügt wird.

15 Revendications

1. Procédé de stabilisation d'un acide arylcarboxylique ou d'un sel pharmacologiquement acceptable de celui-ci dans une solution aqueuse, qui comprend l'addition 20 (a) d'un acide pyridonecarboxylique de la formule (IV)

dans laquelle 35 X est un atome de carbone ou un atome d'azote ; et R12,R13,R14 et R15 sont identiques ou différents et chacun est un atome d'hydrogène ; un halogène ; un groupe carboxyle, un groupe alkyle en C1-C6 éventuellement substitué ; un groupe cycloalkyle en C3-C9 éven- tuellement substitué ; un groupe acyle choisi dans le groupe consistant en formyle, acétyle, propionyle, buty- ryle, isobutyryle, valéryle, benzoyle, naphthoyle, toluoyle et salicyloyle, qui peut être substitué par un alkyle 40 en C1-C3, un alcoxy en C1-C3, un alkylthio en C1-C2, un alkylamino en C1-C3, un cyclo-alkyle en. (C3-C6), un cyclo-alcényle en (C3-C6), un halogène, un amino, un groupe protecteur amino, un hydroxy, un groupe cyano hydroxy protégé, un groupe nitro, carboxy, carboxy protégé, sulfo, sulfamoyle, imino, oxo, amino-alkyle en (C1-C2), un carbamoyloxy ou hydroxy-alkyle en (C1-C3) ; un groupe aryle éventuellement substitué ou un groupe hétérocyclique éventuellement substitué ; 45 dans lequel R12 et R13 forment éventuellement un groupe hétérocyclique à 4 à 6 éléments avec l'atome d'azote adjacent et X, et R14 et R15 forment éventuellement un groupe hétérocyclique à 4 à 6 éléments avec l'atome de carbone adjacent, à condition que lorsque X est un atome d'azote, R13 soit vide ou (b) de cinoxacine ou de sparfloxacine, 50 ou d'un sel pharmacologiquement acceptable de ceux-ci, à un acide arylcarboxylique de la formule (I)

1 1 L -R COOH (I) 55 dans laquelle L1 est un groupe hétérocyclique éventuellement substitué ou un groupe aryle ayant au plus 14 atomes de

10 EP 1 389 469 B1

carbone ; et R1 est un groupe alkyle éventuellement substitué ayant au plus 4 atomes de carbone ou une liaison simple, ou un sel pharmacologiquement acceptable de celui-ci.

5 2. Procédé selon la revendication 1, dans lequel l'acide pyridonecarboxylique est au moins un composé choisi dans le groupe consistant en loméfloxacine, norfloxacine, ofloxacine, énoxacine, ciprofloxacine, tosufloxacine, fléroxa- cine et lévofloxacine.

3. Procédé selon la revendication 1, dans lequel l'acide arylcarboxylique est au moins un composé choisi dans le 10 groupe consistant en ibuprofène, diclofénac, acide 2-naphtoïque, acide 2-naphtylacétique, bromfénac, pranopro- fène, acide salicylique, aspirine, flufénisal, ibufénac, alclofénac, flurbiprofène, kétoprofène, naproxène, acide mé- fénamique, acide niflumique, acide métiazinique, acide protizinique, clonixine, indométhacine et acide fenclozique.

4. Procédé selon la revendication 1, dans lequel l'acide pyridonecarboxylique est ajouté selon une proportion de 15 0,001-5 parties en poids pour 100 parties en poids d'acide arylcarboxylique.