Synergistically Active Veterinary Compositions and Process for Preparing Same

The invention relates to synergistically active veterinary compositions, useful particularly for the treatment of mastitis and metritis. The invention further relates to a process for preparing these compositions.

The mastitis and metritis of various animal species can cause severe economical losses. This inflammation process, induced by various bacteria, is accompanied by e.g. a significant decrease in the milk production and number of progeny of cattle.

At present, various antibacterial agents are employed for the treatment of mastitis and metritis, which is usually carried out topically. Although the infection in itself is caused by bacteria, a fungal infection frequently occurs during the treatment, therefore a really favourable result can be ensured only by a veterinary composition equally effective against gram-positive and gram-negative bacteria as well as against fungi.

In the practice, the treatment is carried out in the most cases by using antibiotics.

A suspension of 6,9,18-tris(2-aminoethyl)-15-benzyl-21-[2,8-bis(2-aminoethyl)-5-(1-hydroxy ethyl)-15-methyl-4,7,10-trioxo-3,6,9-triazaheptadecanamido]-3-(1-hydroxyeth yl)-12-isobutyl-1,4,7,10,13,16,19-heptaazacyclotricosane-2,5,8,11,14,17,20- heptaone (polymyxin B) and 4-dimethylamino-3,5,6,10,12,12a-hexahydroxy-6-methyl-1,11-dioxo-1,4,4a,5,5 a,6,11,12a-octahydronaphthacene-2carboxamide (oxytetracycline) is used for the treatment of both mastitis and metritis; however, this composition exerts a very weak effect on several bacterial species (e.g. Staphylococcus aureus or Streptococcus zooepidermicus).

A combination of 2,4-diamino-5-(2,6-diamino-2,6-dideoxy-.beta.-D-glucosyloxy)-6-[3-0-(2,6-d iamino-2,6-dideoxy-.beta.-L-idosyl)-.alpha.-D-ribosyloxy]-(1R, 2S, 4R, 5S, 6S)-1-cyclohexanol (neomycin) with oxytetracycline is used in a form of an uterine rod or udder infusion. However, these known compositions exert a very weak action on gram-negative bacteria.

A disadvantage of an uterine rod containing 3-[(5-nitrofurfurylidene)amino]-2-oxazolidinone (furazolidone) used for the treatment of metritis consists in that the active ingredient is toxic.

D-(-)-threo-2,2-dichloro-N-[2-hydroxy-1-hydroxymethyl-2-(4-nitrophenyl)ethy l]acetamide (chloramphenicol) alone or together with N.sup.1 -(4,6-dimethylpyrimidinyl)sulfanylamide (sulfadimidine) is also used for the treatment of metritis in the form of a foam or uterine capsule. However, these compositions are not favourable because they have practically no action on gram-negative bacteria.

6-[4-Dimethylamino-3-hydroxy-6-methyl-2-tetrahydropyranyloxy]-14-ethyl-7,12 ,13-trihydroxy-4-(5-hydroxy-4-methoxy-4,6-dimethyl-2-tetrahydropyranyloxy)- 3,5,7,9,11,13-hexamethyl-1-oxa-2,10-tetradecanedione (erythromycin) is used as udder infusion for the treatment of mastitis. This known composition does not exert any effect on gram-negative bacteria, either.

An udder infusion containing 6-phenylacetylamino-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2 -carboxylic acid (benzylpenicillin) together with 3,5-diguanidino-6-[2-0-(2-methylamino-2-deoxy-.alpha.-N-glucosyl)-.alpha.- L-streptosyloxy]-1,2,4-cyclohexanetriol sulfate (streptomycin sulfate) is also used which, however, acts only on some bacteria (such as Streptococcus and Staphylococcus) [Proceedings of Symposium on Mastitis Control, Espoo, Finland, June 1986, pages 10 to 12, Ed. Markus Sandholm; Belak-Tuboly and Varga: Allatorvosi mikrobiologia ("Veterinary Microbiology"; in Hungarian), Budapest, Mezogazdasagi Konyvkiado, 1983; Meszaros and Szent-Ivanyi: Haziallatok fertozo betegsegei ("Infective Diseases of Domestic Animals"; in Hungarian), Mezogazdasagi Kiado, 1985; Goodman-Gilman's: The Pharmacological Basis of Therapeutics, 7th Edition, MacMillan Publishing Co. Inc., New York, 1985; M. Jones, H. Nicholas Booth and L. E. McDonald: Veterinary Pharmacology and Therapeutics, 4th Edition, Iowa State University Press, USA].

Summing up, it can be stated that about 30 to 50% of the pathogens inducing the inflammation are only sensitive to the known compositions used for treating mastitis and metritis of cattle and these compositions do not possess any fungicidal effect at all. The majority of the known compositions is being used for decades whereby a resistance rapidly develops.

The aim of the present invention is to provide a novel broad-spectrum veterinary composition which is effective also in low doses and acts on both bacteria and fungi.

It has been found that the above aim can entirely be achieved by using polymyxin B or a pharmaceutically acceptable acid addition salt such as the sulfate or chloride thereof together with 1-(2-chlorophenyl)-diphenylmethyl-1H-imidazole (clotrimazole) or with 2-methyl-5,7-dichloro-8-hydroxyquinoline (chlorquinaldol), respectively.

The invention is based on the recognition that polymyxin B and clotrimazole or polymyxin B and chlorquinaldol, respectively are capable to significantly potentiate the antibacterial and fungicidal effect of each other.

Thus, the present invention relates to a novel, synergistically active veterinary composition, useful particularly for the treatment of mastitis and metritis, which comprises, based on 1 part by weight of polymyxin B or a pharmaceutically acceptable acid addition salt thereof, 1 to 1000 parts by weight of 1-(2-chlorophenyl)-diphenylmethyl-1H-imidazole (clotrimazole) or 1 to 400 parts by weight of 2-methyl-5,7-dichloro-8-hydroxyquinoline (chlorquinaldol), respectively optionally in admixture with carriers and/or additives commonly used in the pharmaceutical industry.

The effect of the compositions of the invention is supported by the following in vitro results.

The minimum inhibitory concentrations (MIC values) of the above compounds and their two-component combinations of 1:1 ratio by weight against the following microorganisms arising from mastitis and metritis processes of cattle were tested by using the serial dilution method in a phenol red-glucose broth medium (manufactured by DIFCO) or, by using a Sabouraud's broth medium, respectively in the cases of fungal strains.

A--Staphylococcus aureus

B--Streptococcus zooepidemicus

C--Escherichia coli 494

D--Escherichia coli 17

E--Klebsiella pneumoniae

F--Pseudomonas aeruginosa

G--Candida albicans

H--Streptococcus agalactiae

I--Streptococcus dysgalactiae

J--Streptococcus uberis

K--Streptococcus faecalis

L--Listeria monocytogenes

M--Corynebacterium pyogenes

N--Salmonella typhimurium

O--Campylobacter fetus

P--Campylobacter jejuni

R--Bacteroides fragilis

S--Fusobacterium necrophorum

T--Mycoplasma bovis

U--Mycoplasma bovirhinis

V--Mycoplasma canadense

Z--Aspergillus fumigatus.

Campylobacter strains were tested in a semiliquid thiol culture medium (manufactured by DIFCO). Bacteroides fragilis and Fusobacterium necrophorum strains were examined by using the agar dilution method on bloody agar containing also tryptose.

Bacterial strains were cultivated at 37.degree. C. whilst the fungal strain (Candida albicans) was propagated at 26.degree. C. The minimum inhibitory concentrations (MIC values) showing a bactericidal effect, i.e. complete inhibition of the growth of microorganisms whereby the media inoculated remained sterile, are summarized in Table 1.

It is obvious from the data of Table 1 that e.g. Staphylococcus aureus is inhibited only by a high concentration (50 .mu.g/ml) of polymyxin B but the common presence of 0.1 .mu.g/ml of polymyxin B together with 0.1 .mu.g/ml of clotrimazole is sufficient to ensure the bactericidal effect. Escherichia coli strains are inhibited by a low concentration (0.5 .mu.g/ml) of polymyxin B alone, however, a lower concentration of 0.15 or 0.1 .mu.g/ml of polymyxin B is also sufficient in the presence of clotrimazole. Clotrimazole alone has a very weak effect on these bacterial strains. The same observations can be registered in the common presence of polymyxin B and chlorquinaldol.

It bears a great importance that poymyxin B has practically no fungicidal action but the common presence of 0.25 .mu.g/ml of polymyxin B together with 0.25 .mu.g/ml of clotrimazole or chlorquinaldol, respectively is sufficient to kill the Candida albicans strain tested.

It can unequivocally be concluded from Table 1 that all tested microorganisms are inhibited even by a very low concentration of polymyxin B combined with clotrimazole or chlorquinaldol, respectively thus the danger of development of a resistance is also lowered.

According to the process of the invention, 1 part by weight of polymyxin B or its pharmaceutically acceptable acid addition salt is mixed with 1 to 1000 parts by weight of clotrimazole or 1 to 400 parts by weight of chlorquinaldol, respectively and with carriers and/or additives commonly used in the pharmaceutical industry and the mixture thus-obtained is converted into a pharmaceutical composition by a method known per se.

According to a preferred embodiment of the invention, the composition comprises, based on 1 part by weight of polymyxin B, 5 to 50 parts by weight of clotrimazole or chlorquinaldol, respectively in admixture with carriers and/or additives commonly used in the pharmaceutical industry.

The active ingredients are preferably converted into veterinary compositions that are suitable to treat mastitis and metritis such as suspensions, aerosols, uterine tablets (uterine rods), uterine capsules, foams and the like. These compositions usually contain the active ingredients in a total amount of 0.01 to 90% by weight, preferably 0.1 to 10% by weight, suitably 0.1 to 2.0% by weight.

The veterinary compositions can be prepared by the means of carriers and auxiliary agents commonly used in the pharmaceutical industry, by employing pharmaceutical formulating processes known per se (see e.g.: Remington's Pharmaceutical Sciences, 16th Edition, Mack Publishing Co., Easton, USA, 1980). Suitable carriers and additives are fatty acid esters and ethers of fatty alcohols; emulsifying agents; colloidal silicon dioxide; tabletting auxiliary materials such as lactose, polyvinylpyrrolidone, talc, magnesium stearate and the like; stabilizing agents and the like; as stabilizing agent 1,1,1-trichloro-2-methylpropan-2-ol is preferably used in an amount of 0.1 to 10% by weight, suitably 0.5 to 2% by weight.

The veterinary compositions according to the invention are useful for the efficient treatment of mastitis and metritis as well as for combatting the simultaneously frequently occurring fungal infections.

The invention is illustrated in detail by the aid of the following non-limiting Examples.

After dissolving Softigen 701 in Mygliol 812, the other components are dispersed therein. (Before dispersing, the solid particles are crushed e.g. in an air jet mill to less than 10 .mu.m size.) The suspension obtained is filled into a plastic udder syringe and used for the treatment of mastitis.

The process described in Example 1 is followed to obtain a composition which is useful for the treatment of mastitis.

Glyceryl monostearate and the Cremophor emulsifying agents are dissolved in the mixture of isopropyl myristate and cetyl stearyl 2-ethylhexanoate, then the solid particles are dispersed in the solution. The suspension thus obtained is used for the treatment of mastitis.

Polyethylene glycol, nonylphenol polyethylene glycol ether and Mygliol 812 are added to the mixture of propylene glycol and glyceryl caprylate and the solid particles previously crushed to less than 10 .mu.m size are suspended in the solution. The suspension obtained is filled into a plastic bottle and used for the treatment of metritis, e.g. by introducing it to the uterus through an uterine catheter.

The anhydrous citric acid having a particle size less than 200 .mu.m, sodium hydrogen carbonate and polyvinylpyrrolidone are stirred while adding water in a vortex-flow granulating device for 6 minutes. The wet granulate is dried at 70.degree. to 80.degree. C., then the dry granulate is broken through a sieve of 1.0 mm thread-distance. The other components are added and the mixture obtained is transformed to uterine rods weighing 7.0 g each by using a press die of 60 mm in length and 10 mm in width in an eccentric tabletting machine. The uterine rod obtained is used for the treatment of metritis.

The process described in Example 5 is followed, except that 2.00 g of clotrimazole and 1.10 g of lactose are used.

The process described in Example 5 is followed, except that 0.01 g of clotrimazole and 3.0 g of lactose are used.

The process described in Example 5 is followed, except that 0.01 g of chlorquinaldol instead of clotrimazole and 3.09 of lactose are used.

The solution of polyvinylpyrrolidone and sodium dioctyl sulfosuccinate in 100 ml of ethanol is added to the mixture of adipic acid having a particle size less than 200 .mu.m, sodium hydrogen carbonate and lactose while stirring in a vortex-flow apparatus. After granulating for 6 minutes the granulate is dried, then broken through a sieve of 1.0 mm thread-distance, the other components are added and the mixture obtained is transformed to uterine rods as described in Example 5.

The process described in Example 9 is followed, except that chlorquinaldol is used instead of clotrimazole.