NZ192352A - Injectable flukicidal compositions containing tetramisole derivatives - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number 1 92352 192352 Priorfiy Dfitefs): . ■. IP-'-1?. '■ 7.8 Compf&'io Specification Filed: Publication Bste: . .0.5. i«k IrSr*...

S5 /"* P- --- 1 Pi - rr'» • SvsU.

NEW ZEALAND PATENTS ACT, 1953 1. _■• * lc^'c®7$ No.: Date: COMPLETE SPECIFICATION "COMPOSITION AND PROCESS" We, ICI AUSTRALIA LIMITED, of 1 Nicholson Street, Melbourne, Victoria, Australia, a Company organised and existing under the laws of the State of Victoria, Commonwealth of Australia. hereby declare the invention for which Jc/ we pray that a patent may be granted to P5t«g/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - I00?r0 1 S t-J JC.

This invention relates to pharmaceutical compositions for the treatment of internal parasites in warm-blooded animals, to methods for the preparation of the compositions and to processes for the treatment of _ .5.. warm-blooded animals excluding humans using the compositions.

The:imidazo^S, l-b7thiazole a tetramisole acid'addition - salt and its laevorotatory optical isomer, hereinafter referred to "--as levamisole, is a well known anthelmintic which has found considerable commercial success because of its 10 efficacy in the control of intestinal nematodes and lungworm in warm-blooded animals. Part of the commercial success of levamisole is undoubtedly due to the development of formulations suitable for administration by injection resulting in a considerable improve-15 ment in the ease of administration of the drug to animals and in particular to large animals such as cattle.

Many anthelmintics effective in the control of trematodes and in particular the liver fluke Fasciola 20 hepatica also have been developed. However, the majority of these compounds, and in particular the more efficacious compounds which have been developed commercially, are substantially water insoluble and as a result are administered orally, usually in the form of 25 a drench.

It is evident that a composition suitable for parenteral administration and comprising levamisole in combination with an effective flukicide would result in a considerable improvement in the economics of treat-30 ment of animals to control helminths by providing a means for the treatment to be carried out in one simple operation.

As levamisol is a base of pKa 7.9 and forms salts with both inorganic and organic acids and many of the 35 commercially available flukicides are weak acids of the 16FE6;-,t« i-sf if 3 3 phenol type it might be expected that a water soluble combination of levamisole with an acidic flukicide might be obtained by the preparation of the acidic flukicide acid addition salt of levamisole. However, such salts 5 are neutral to basic in character and it is known that for satisfactory shelf-life aqueous solutions of levamisole need to have an acid pH,. preferably in the range from pH 3 to pH 3.5, to minimize hydrolysis of the levamisole. Solutions of levamisole acid addition salts 10 at this pH are only formed with relatively strong acids and can not be formed with the commercially available acidic flukicides of the weak acid type. cides suitable for parenteral administration have been 15 reported, for example for the formulation of rafoxanide with polyvinylpyrrolidone and an alkali metal hydroxide described in British Patent Specification 1,472,385. However, these formulations have either a neutral or, more often, a basic pH and as such are incompatible with 20 aqueous levamisole formulations. water-insoluble flukicide and levamisole in an aqueous composition suitable for administration by injection. pharmaceutical composition in the form of a clear, transparent solution suitable for parenteral administration comprising micelles of an organic liquid containing a substantially water insoluble flukicide in an aqueous solution containing racemic tetramisole or laevorotatory 30 levamisole in the form of a pharmaceutically acceptable acid addition salt. tion of the invention are those pharmaceutically acceptable liquids which are solvents for the substan-35 tially water insoluble flukicide and which form a clear, Certain aqueous formulations of specific fluki- We have now found a novel means of combining a Accordingly the invention provides an aqueous Organic liquids suitable for use in the composi- 1 ,T-» transparent micellar solution or microemulsion of the organic liquid in an aqueous solution of a tetramisole or laevorotatory tetramisole salt. The organic liquids preferred for use in the compositions of the invention 5 are suitable organic surface active agents including those emulsifying agents commonly used for the preparation of oil-in-water emulsions and having a hydrophile -lipophile balance (HLB) approximately in the range from 8 to 18, and mixtures of such surface active agents. 10 Particularly preferred organic liquids for use in the compositions of the invention are the products of ethoxylation of castor oil and hydrogenated castor oil including those products commercially available under the Trade Marks"Teric" C12, "Cremophor" RH40, "Cremophor" 15 RH60, "Cremophor" 410, "Cremophor" EL, "Arlatone" 285, "Arlatone" 287, "Arlatone" 983, "Emulsogen" EL, and "Sinnopal" EL33.

Other preferred organic liquids are the pluronics which are based on polypropylene oxide ethoxy-20 lated to varying degrees. Suitable pluronics in the HLB range of 8 to 18 are those available commercially under the Trade Marks "Teric" PE62 and "Teric" PE64.

Other pluronics outside this HLB range, for example "Teric" PE6 8 with an HLB of 29, may be used in combina-25 tion with the preferred organic liquids such that the HLB of the combination is within the range of 8 to 18.

The choice of organic liquid for use in a composition of the invention depends to a large extent on the specific flukicide to be used in the composition 30 and in particular on the solubility properties of that flukicide. Following the teaching of the invention suitable organic liquids may be chosen without undue experimentation by those skilled in the art.

The organic liquid used in the composition of the 35 invention optionally may comprise pharmaceutically 1 C *? "T 3, ^ i-irj acceptable suitable cosolvents to facilitate the preparation of the composition by, for example, improving the solubility of the flukicide or prolonging the storage life of the composition, or to improve the efficacy 5 of the composition or its suitability for parenteral administration.

The choice of suitable cosolvent(s) for use in a composition of the invention depends to a large extent on the specific flukicide to be used in the composition. 10 Suitable cosolvents may include, for example, pharmaceutically acceptable cosolvents chosen from: polyvinylpyrrolidone) ; glycols such as hexylene glycol; polyalkylene glycols such as polyethylene glycols, polypropylene glycols, and mixed polyethylene - polypropylene 15 glycols; long chain alcohols such as the Cg to C2Q alcohols; alcohol alkoxylates; sorbitan fatty acid esters and their ethoxylateS such as those sold under the Trade Marks "Span" and "Tween"; glycerol; aliphatic esters such as fatty acid esters; aromatic esters such 20 as benzyl benzoate; urea, biuret; and camphor.

Flukicides which may be used in the compositions of the invention are those therapeutically effective flukicides which are substantially water insoluble.

Such flukicides include flukicides of the salicylanilide 25 family, flukicides of the phenol family and other miscellaneous flukicides.

Suitable salicylanilide "type" flukicides include, for example, those described in the patents and patent applications listed below. (i) United States Patent 3,798,258 and including 3,5-diiodo-3'-chloro^41 -(p-chlorophenoxy)-salicylanilide (rafoxanide); (ii) United States Patent 3,34 9, 090 and including 3,3 ' ,5,5',6-pentachloro-2'-hydroxysalicylanilide 35 (oxyclozanide or zanil); 1 (iii) Australian Patent 471,872 and including 3,5-diiodo-3',51-dichlorosalicylanilide; (iv) Australian Patent 418,861 and including 3,4'-dibromo-5-chlorothiosalicylanilide acetate (dirian); and (v) Australian Patent Application No 84,517/75 and including 21-bromo-3-tertbutyl-4',5-dicyano-6-methylsalicylanilide.

Suitable phenol "type" flukicides include, for 10 example, the specific compounds listed below together with the compounds described in the cited patents and patent applications.

Ci) United States Patent 2,849,4 94 and including bis-(2-hydroxy-3,5-dichlorophenyl)sulfide (bithional); 15 (ii) United States Patent 3,082,151 and including ,5'-dichloro-2,2'-dihydroxy-3,3?-dinitrobiphenyl (niclofolan); (iii) United States Patent 3,331,738 and including 4-hydroxy-3-iodo-5-benzonitrile (nitroxynil) ; 20 (iv) United States Patent 4,064,266 and including 3 - i o do - 5 -1-bu ty 1-4-hydroxybenzylidenema 3ononi trile; (v) Australian Patent 488,458 and including 2-chloro-4-fluoro-6-nitrophenol; (vi) Australian Patent Application No 26,215/77 and 25 including 2,6-bis(3-bromo-5-chloro-2-hydroxy- benzyl)-4-fluorophenol; (vii) Australian Patent Application No 41,016/78 and including 1,1-bis(5-chloro-2-hydroxy^3-nitro-phenyl)-2,2-dichloroethylene; and (viii) 2-iodo-4-nitro-6-trifluorovinylphenol, Other flukicides suitable for use in the compositions of the invention include, for example, the phenoxybispyridylamines such as 3,3',5,5'-tetrachloro-2,2',6-trifluoro-6-(4-chlorophenoxy)-4,4'-bis-35 pyridylamine disclosed in Belgium Patent 858,810; the 1 923 7 4,5-dicyano-2-phenylimidazoles such as 2-(4-biphenylyl)-4,5-dicyanoimidazole disclosed in Australian Patent Application 28,734/77; emetine, the principal alkaloid of ipecac; and hexachlorophene. solution preferably contains L-tetramisole in the form of a pharmaceutically acceptable acid addition salt. Our Australian Patents No 440,746 and 450,036 teach aqueous formulations of tetramisole suitable for administration 10 by injection and such formulations are suitable for use as the aqueous component of the compositions of the present invention. vention the tetramisole is preferably present as the L-15 isomer in the form of the hydrochloride, citrate, tartrate or more preferably the dihydrogen phosphate salt. In the compositions of the invention the aqueous L-tetramisole solution preferably also comprises water soluble therapeutically acceptable salts, particularly 20 the sodium or potassium salts of citric, tartaric or phosphoric acid, to prevent or reduce the incidence of tissue reaction at the site of the injection. As tetramisole undergoes base catalysed hydrolysis to an inactive derivative in the compositions of the invention 25 the aqueous L-tetramisole solution is preferably adjusted to an acid pH to prevent the loss of the active ingredient. Preferably the pH is adjusted to a pH in the range from 2.0 to 4.0 by the addition of an acid having a therapeutically acceptable anion such as, for example, 30 hydrochloric, tartaric, citric or, preferably, phosphoric acid. vention little or no change has been observed in the efficacy of the tetramisole. Therefore, in the com-35 positions of the invention tetramisole may be administer- In the composition of the invention the aqueous Thus, in the compositions of the present in- When formulated into a composition of the in- 92352 8 - ed at the same dose rate usually employed for the particular animal when the tetramisole is parenterally administered as a single therapeutic agent.

Surprisingly when formulated into a composition 5 of the invention an improvement in the efficacy of the flukicides has been observed in comparison to their efficacy when administered by oral drenching, the normal mode for the administration of water-insoluble flukicides. The improved efficacy of the flukicides when 10 administered in a composition of the invention means that the dose rate at which the flukicides are administered may be reduced without loss of therapeutic activity.

The compositions of the invention represent a 15 significant advance in the art as they provide a means of combining proven, effective water-insoluble flukicides and the proven, effective anthelmintic tetramisole in a single aqueous injectable composition which may be used for the treatment of warm-blooded animals to con-20 trol trematodes and lungworm. Such a composition has the obvious advantage of being able to be administered by a single injection in contrast to prior art processes in which a water insoluble flukicide is adminstered in one operation and an anthelmintic is administered in 25 a separate operation.

The injectable compositions of the invention are conveniently prepared by dissolving a water-insoluble flukicide in an organic liquid, optionally in the presence of a cosolvent, with the application of heat as 30 necessary and slowly adding to this solution with stirring, an aqueous solution of a tetramisole salt or an L-tetramisole salt. Preferably the ratio of water-insoluble flukicide to organic liquid is in the range from about 1:2 to 1:40 w/w. Preferably the aqueous 35 solution comprises an acid addition salt of L- 192352 tetramisole, pharmaceutically acceptable salts and is buffered to an acid pH preferably in the range from 2 to 4.

In a further embodiment the invention provides 5 a process for killing internal parasites of warm-blooded animals excluding humans which process comprises treatment of the infected animal by parenteral administration of a therapeutically effective dose of a composition of the invention as hereinbefore defined.

When formulated into a composition of the in vention little or no change has been observed in the efficacy of the tetramisole. Thus in the process of treatment using a composition of the invention the tetramisole is preferably administered at the same dose 15 rate as that normally employed for the particular animal when the tetramisole is administered as a single therapeutic agent.

When formulated into a composition of the invention the flukicide component in general shows in im-20 provement in efficacy over that observed when the same flukicide is administered by oral drenching in the form of a suspension. Thus in the process of treatment using a composition of the invention the flukicide is preferably administered either at a lower or the same dose 25 rate as that employed fpr the particular animal when the flukicide is administered as a single therapeutic agent.

The compositions of the invention are preferably administered parenterally and are therefore particularly suitable for the treatment of large farm animals such as 30 sheep and cattle. However, the process may also be used to treat other domestic and farm animals including pigs, dogs, cats, horses and goats and laboratory animals such as rats, mice and guinea pigs.

The term "parenterally", as used herein, includes 35 intravenous, intramuscular and subcutaneous injection. 1 923 The compositions of the invention may comprise, in addition to the components hereinbefore defined, other pharmaceutically therapeutic agents, additives to improve the shelf life of the composition, buffering agents, preservatives and/or additives to prevent or reduce adverse tissue reaction at the site of the injection. 1 9235 The invention is now illustrated by, but by no means limited to, the following Examples.

Example 1 A solution of 2,6-bxs(3-bromo-5~chloro-2-5 hydroxybenzyl)~4-fluorophenol in "Teric" C12 ("Teric" is a registered Trade Mark and "Teric" C12, a product of ethoxylation of castor oil, is available from ICI Australia Limited) was prepared by dissolving 30 g of the phenol in 300 g of the solvent. An aqueous solution of 10 L-tetramisole dihydrogen phosphate, sodium citrate and sodium metabisulfite was prepared (ref. Australian Patent 440,746) containing the equivalent of 90 g of L-tetramisole as the free base in 600 ml of water and the pH was adjusted to 3.5 by the addition of phosphoric acid. 15 The aqueous L-tetramisole solution was added slowly, with stirring, to the solution of the phenol in "Teric" C12 to give a clear almost colourless composition comprising a microemulsion of "Teric" C12 micelles in an aqueous solution of L-tetramisole phosphate. The volume 20 of the composition was adjusted to 1500 ml by the addition of distilled water to give a composition comprising 2% w/v flukicide and 6% w/v (as the free base) of L-tetramisole dihydrogen phosphate.

On storage the composition showed no signs of 25 instability.

Example 2 A solution of 3, 5-diiodo-3 ■ , 5 T-dichloro-i salicylanilide was prepared by dissolving 2 g of the salicylanilide in 30 g of "Teric" C12. An aqueous solu-30 tion of L-tetramisole dihydrogen phosphate, sodium citrate, and sodium metabisulfite was prepared (ref. Australian Patent 440,746) containing the equivalent of 6 g of L-tetramisole as the free base in 50 ml of water and the pH was adjusted to 3.5 by the addition of 35 phosphoric acid. - 11. - 1 9235 The aqueous L-tetramisole solution was added slowly with stirring to the solution of the salicylanilide in "Teric" C12 to give a clear almost colourless composition. The volume of the composition was adjusted to a volume of 5 100 ml by the addition of distilled water to give a composition comprising 2% w/v flukicide and 6% w/v (as the free base) of L-tetramisole phosphate.

The composition having the appearance of a clear, almost colourless solution showed no signs of instability 10 on storage.

Example 3 An aqueous stock solution comprising L-tetramisole dihydrogen phosphate (12% w/v as the free base) sodium citrate and sodium metabisulfite was prepared and adjusted 15 to a pH of 3-5 by the addition of phosphoric acid (ref. Australian Patent 440,746).

A solution of 2,6-bis(3-bromo-5-chloro-2-hydroxybenzyl)-4-fluorophenol (1.5 g) in "Teric11 C12 (15 g) was prepared and to this was added, with stirring, 20 25 ml of the L-tetramisole stock solution. The resulting composition was adjusted to a volume of 50 ml by the addition of distilled water to give a composition comprising 3% w/v flukicide and 6% w/v (as the free base) of L-tetramisole dihydrogen phosphate. 25 The composition^having the appearance of a clear, almost colourless solution^showed no signs of instability on storage.

Example 4 A solution of 2, 6-bis( 3-bromo~5-chloro-2-> 30 hydroxybenzyl)-4-fluorophenol (2.0 g) in "Teric" C12 (20 g) was prepared and to this was added, with stirring, 25 ml of an L-tetramisole stock solution prepared as described in Example 3- The resulting composition was adjusted to a volume of 50 ml by the addition of distilled water to 35 give a composition comprising 4-% w/v flukicide and 6% w/v 1 9 23 5 (as the free base) of L-tetramisole dihydrogen phosphate.

The composition,having the appearance of a clear, almost colourless, solution^showed no signs of instability on storage.

Example 5 A solution of 2-chloro-4-fluoro-6-nitrophenol (1.5 g) in "Teric" C12 (20 g) was prepared and to this was added, with stirring, 25 ml of an L-tetramisole stock solution prepared as described in Example 3. The result-10 ing composition was adjusted to a volume of 50 ml by the addition of distilled water to give a composition comprising 2% w/v flukicide and 6% w/v (as the free base) of L-tetramisole dihydrogen phosphate.

The composition,having the appearance of a clear, 15 almost colourless, solution, showed no signs of instability on storage.

Example 6 A solution of 3,5-diiodo-3'-chloro-4T-(£-chlorophenoxy)salicylanilide (rafoxanide; 28 parts) in 20 "Teric" C12 (250 parts) was prepared and to this was added, with stirring, 350 parts by volume of an L-tetramisole stock solution prepared as described in Example 3» The resulting composition was adjusted to 700 parts by volume by the addition of distilled water to give a composition 25 comprising 4% w/v flukicide and 6% w/v (as the free base) of L-tetramiSole dihydrogen phosphate.

The composition,, having the appearance of a clear almost colourless solution,showed no signs of instability on storage.

Example 7 A solution of 3,3r,5,5T,6-pentachloro-2T-hydroxy-salicylanilide (oxyclozanide, 3 parts) in "Teric" C12 (33 parts) was prepared and to this was added, with stirring, 50 parts of an L-tetramisole stock solution 35 prepared as described in Example 3- The resulting com- 1 9 23 5 2 position was adjusted to 100 parts by volume by the addition of distilled water to give a composition comprising 3% w/v flukicide and 6% w/v (as the free base) of L-tetramisole dihydrogen phosphate. 5 The composition,having the appearance of a clear, almost colourless, solution,showed no signs of instability on storage.

Example 8 A solution of 1,l-bis(5-chloro-2-hydroxy-3-10 nitrophenyl)-2,2,2-trifluoroethylene (20 parts) in "Cremophor" RH-60 (280 parts; "Cremophor" is a Trade Mark and "Cremophor" RH 60, a product of ethoxylation of hydrogenated castor oil is available from BASF Aktiengesellschaf) and benzyl benzoate (20 parts) was 15 prepared. To this solution was added, with stirring, 500 parts by volume of an L-tetramisole stock solution prepared as described in Example 3* The resulting composition was adjusted to 1,000 parts by volume by the addition of distilled water to give a solution comprising 2% w/v 20 flukicide and 6% w/v (as the free base) of L-tetramisole dihydrogen phosphate.

The composition was filtered and the filtrate, having the appearance of a clear almost colourless solution showed no signs of instability on storage.

Example 9 A solution of 3, 3 1 > 5, 5'-tetrachloro-2, 2 ' , 6-trifluoro-6'-(4-chlorophenoxy)-4, 4'-bispyridylamine (10 parts) in "Teric" C12 (150 parts) was prepared and to this was added, with stirring, 250 parts of an L-30 tetramisole stock solution prepared as described in Example 3' The resulting composition was adjusted to 500 parts by volume by the addition of distilled water to give a composition comprising 2% w/v flukicide and 6% w/v (as the free base) of L-tetramisole dihydrogen phosphate. 35 The composition^having the appearance of a clear, 1 9 23 if2 solution#showed no signs of instability on storage.

Example 10 A solution of 2,6-bis(3-bromo-5-chloro-2-hydroxy-benzyl)-4-fluorophenol in "Teric" C12 was prepared by 5 dissolving 30 parts of the phenol in 300 parts of the solvent. An aqueous solution of L-tetramisole hydrochloride was prepared containing the equivalent of 75 parts of L-tetramisole as the free base in 500 parts of water and the pH was adjusted to 3.5 by the addition of hydrochloric 10 acid.

The aqueous L-tetramisole solution was added slowly, with stirring to the solution of the phenol in "Teric" C12. The resulting composition was ajusted to 1000 parts by volume by the addition of distilled water to 15 give a solution comprising 2>% w/v flukicide and 7.5% w/v (as the free base) of L-tetramisole hydrochloride.

The composition, having the appearance of a clear solution, showed no signs of instability on storage. Example 11 The composition prepared as described in Example was tested in vivo for efficacy against liver fluke and nematodes.

Each beast in a group of six cattle was infected on day 0 with 500 metacercariae and on day 77 with 30,000 25 Cooperia oncophora. On day 98 two of the beasts were injected with the test composition (Dose rate: 7.5 mg/kg L-tetramisole hydrochloride and 3 mg/kg of 2,6-bis/3-bromo-5-chloro -2-hydroxybenzyl7-4-fluorophenol),0n days 105 and 106 the cattle were slaughtered and the faeces 30 were counted for adult worms and total liver counts of fluke were made. The results are detailed in Table 1 t 923 below.

TABLE 1 Treatment Liver Fluke Count Cooperia Count Control 63 7,520 i» 78 13,430 it 23 ,350 ii 43 ,100 Treated 0 0 ii 0 0 Example 12 Sheep infected with adult Fasciola hepatica (liver 5 fluke) were injected subcutaneously with the composition prepared as described in Example 1 at a dose rate of 1 ml per 10 kilogram body weight (equivalent to 2 mg/kg flukicide and 6 mg/kg L-tetramisole calculated as the free base). Faecal samples taken before and after dosing 10 were examined microscopically and the fluke eggs were counted by a standard technique. At day 14 the animals were slaughtered and their livers were closely examined for adult fluke. The results are detailed in Table 2 below TABLE 2 Animal Faecal Egg Count (eggs/g faeces) Number of Adult Fluke at Post Mortem No Day 0 Day 7 Day 14 1 860 40 0 0 2 400 0 0 0 192352 Example 13 Sheep with an adult Fasciola hepatica and a mixed helminth infection were injected subcutaneously with the composition prepared as described in Example 2 at a dose rate of 1 ml per 10 kilogram body weight (equivalent to 2 mg/kg flukicide and 6 mg/kg L-tetramisole calculated as the free base). Faecal eggs samples taken before and after dosing were examined microscopically and the nematode and fluke eggs were counted by standard techniques. The results are detailed in Table 3 below.

TABLE 3 Day Faecal Egg Count (eggs/g faeces) Fluke Eggs Nematode Eggs 0 2 7 14 1000 0 0 0 3000 140 0 Example 14 This Example demonstrates the improved efficacy of water—insoluble flukicides when formulated into a composition of the invention.

Sheep infected with adult Fasciola hepatica were injected subcutaneously with the composition prepared as described in Example 7 at a dose rate of 2 ml per 10 kilogram body weight (equivalent to 6 mg/kg flukicide and 12 mg/kg L-tetramisole calculated as the free base), Faecal samples taken before and after dosing were examined microscopically and the fluke eggs were counted by a standard technique. The results are detailed in Table 4 below (Note: In current commercial 25 applications the recommended dose for oral 1 9235 drenching with 3,3 *,5,5',6-pentachloro-2'-hydroxy-salicylanilide or oxyclozanide is 15 mg/kg body weight).

TABLE 4 Flukicide Dose Rate (mg/kg) Faecal Egg Count (egg/g faeces) Day 0 Day 7 Day 14 6 660 0 0 Example 15 This Example demonstrates the improved efficacy of water-insoluble flukicides when formulated into a composition of the invention.

Rats infected with adult Fasciola hepatica were injected subcutaneously with the composition prepared as 10 described in Example 7- The composition was administered to two groups of rats at dose rates equivalent to 15 and 10 mg/kg body weight of flukicide. Six days after treatment the rats in the two treatment groups were sacrificed and their livers were examined for fluke. No 15 fluke were found in the bile ducts of the rats of either treatment group. Xn contrast the same flukicide administered to rats orally in the form of a milled suspension, while active at a dose rate of 15 mg/kg body weight was not active at a dose rate of 12.5 mg/kg body 20 weight.

Examples 16-23 A series of microemulsions based on the pluronics "Teric" PE62, "Teric" PE64, and "Teric" PE68 were prepared having the compositions shown in Table 5. The 25 proportions of these pluronics were chosen to give the range of HLB values shown in the table.

In each case the flukicide (2-iodo-4-nitro-6-trichlorovinylphenol) was dissolved in the pluronic •• 1923 mixture with gentle warming and the solution cooled before adding the required volume of L-tetramisole dihydrogen phosphate solution (12% w/v as free base) slowly with stirring. After this addition water was added to 5 bring the mixture to 100 volumes. All of these solutions were clear and could be diluted further with 0.9% aqueous sodium chloride solution before turbidity occurs. The composition of Example 22 with the highest HLB of the series could be particularly highly diluted.

TABLE 5 Components Flukicide "Teric" PE62 "Teric" PE64 "Teric" PE68 L-tetrami sole Water to HLB value EXAMPLES 16 %~~ w/v 6 .5 19.5 17 w/v 6 7.5 22.5 18 |— w/v 6 3.9 26.1 19 K o w/v 6 %~ w/v 6 24.3 2.7 21 % w/v 22.4 4.3 22 % w/v .8 6.2 23 w Jv 3.5 .8 6.2 50% v/v (dihydrogen phosphate solution; 12% w/v as free base) 100 volumes 12 13 14 16 17 18 18 Example 24 The compositions of Examples 22 and 23 were each injected into sheep infested with Fasciola hepatica at dose rates of 3.5 and 6.0 mg/kg respectively of 2-iodo-4-nitro-6-trichlorovinylphenol, and 6 mg/kg (free base) L-tetramisole dihydrogen phosphate in both cases. The sheep faeces were examined for eggs of F. hepatica and these were counted by standard techniques just before 1 923 dosing and at day 7 and day 14 after dosing. The egg count is expressed as the number of eggs/gram faeces. On the fourteenth day the sheep were slaughtered and the bile ducts were examined for adult fluke. The results are given in Table 6.

TABLE 6 Dose Eggs per gram faeces (mg/kg body-weight) Day 0 Day 7 Day 14 . No of fluke Post Mortem 3.5 170 0 0 4 6.0 210 0 0 0 These results show high flukicidal activity at both 3.5 and 6 mg/kg.

Example 25 Microemulsions of oxyclozanide were prepared having the compositions below: (A) (B) Oxyclozanide 5.8 6 % w/v "Teric" C12 30 30 " " 2-methyl-2,4-pentanediol 18.2 18.0 11 " ("hexylene glycol") L-tetramisole dihydrogen 50 50 " v/v solution (12% w/v as free base) Water to 100% 100% Portions of each of these compositions were injected subcutaneously into sheep infested with adult Fasciola hepatica at dose rates of 5.8 and 6.8 mg/kg 1 923 of oxyclozanide. The activity of the compositions was assessed as described in Experiment 24 and the results are given in Table 7.

TABLE 7 Dose Oxyclozanide (mg/kg bodyweight) Eggs/gram faeces No fluke Post Mortem Day 0 Day 7 Day 14 .8 6.0 150 2 80 20 0 0 0 0 These results indicate that oxyclozanide is highly active in this form by subcutaneous injection at 5.8 and 6.0 mg/kg. The recommended dose for oral administration of aqueous suspensions of oxyclozanide is 15 mg/kg bodyweight.

Example 26 A microemulsion of hexachlorophene having the composition below was prepared by the general procedure of Example 1.

Hexachlorophene "Teric" C12 L-tetramisole dihydrogen phosphate salt (12% w/v as Free Base) Water 2% w/v 20% w/v 50% v/v to 100% On administration subcutaneously at a dose rate of 2 mg/kg to a sheep infected with Fasciola hepatica, the faecal egg count fell from 110 before dosing to 10 by the fourteenth day after dosing. This indicates a high level of activity. 192352

Claims (36)

WHAT WE CLAIM IS:

1. An injectable composition comprising micelles of an organic liquid containing a substantially water-insoluble flukicide in an aqueous solution containing a tetramisole or a laevorotatpry tetramisole acid addition salt, said organic liquid being a solvent for the substantially water insoluble flukicide.

2. A composition according to claim 1 wherein acid addition salt is selected from the group consisting of the hydrochloride, citrate, tartrate, and phosphate salts of laevorotatory tetramisole.

3. A composition according to claim 2 wherein the v said salt is the hydrochloride salt of laevorotatory tetramisole.

4. A composition according to claim 2 wherein the said salt is the dihydrogen phosphate salt of laevorotatory tetramisole.

5. A composition according to any one of claims 1 to 4 wherein the pH of said composition is in the range from 2.0 to 4.0.

6. A composition according to any one of claims 1 to 5 wherein the weight ratio of flukicide to organic liquid is in the range from 1:2 to 1:40.

7. A composition according to any one of claims 1 to 6 wherein the flukicide is a salicylanilide.

8. A composition according to any one of claims 1 to 6 wherein the flukicide is a phenol.

9. A composition according to any one of claims 1 1^ to 6 wherein the flukicide is a phenoxybispyridylamine.

10. A composition according to any one of claims 1 to 6 wherein the flukicide is a 4,5-dicyano-2-^^°'*J w phenylimidazole.;- 23 -;1 Q 0 7 C 0 I / ljjl;

11. A composition according to any one of claims 1 to 6 wherein the flukicide is rafoxanide.;

12. A composition according to any one of claims 1 to 6 wherein the flukicide is oxyclozanide.;

13. A composition according to any one of claims;1 to 6 wherein the flukicide is 3,5-diiodo-3',51-dichloro-salicylanilide.;

14. A composition according to any one of claims 1 to 6 wherein the flukicide is 3, 4'-dibromo-5-chlorothio-salicylanilide acetate.;

15. A composition according to any one of claims;1 to 6 wherein the flukicide is 2'-bromo-3-t-butyl-4',-51-dicyano-6-methyisalicylanilide.;

16. A composition according to any one of claims 1 to 6 wherein the flukicide is bithional.;

17. A composition according to any one of claims 1 to 6 wherein the flukicide is niclofolan.;

18. A composition according to any one of claims to 6 wherein the flukicide is nitroxynil.;

19. A composition according to any one of claims 1 to 6 wherein the flukicide is 3-iodo-5-t-butyl-4-hydroxybenzylidenemalononitrile.;

20. A composition according to any one of claims 1 to 6 wherein the flukicide is 2-chloro-4-fluoro-6-nitrophenol.;

21. A composition according to any one of claims 1 to 6 wherein the flukicide is 2,6-bis(3-bromo-5-chloro-2-hydroxybenzyl)-4-fluorophenol.;

22. A composition according to any one of claims;192352;- 24 -;1 to 6 wherein the flukicide is 1,1-bis(5-chloro-2-hydroxy-3-nitrophenyl)-2,2-dichloroethylene.;

23. A composition according to any one of claims 1 to 6 wherein the flukicide is 2-iodo-4-nitro-6-trifluoro-vinylphenol.;

24. A composition according to any one of claims 1 to 6 wherein the flukicide is 3,3',5,5'-tetrachloro-2,2',6-trifluoro-6-(4-chlorophenoxy)-4,4*-bispyridylamine.

25. A composition according to any one of claims 1 to 6 wherein the flukicide is 2-(4-biphenylyl)-4,5-dicyanoimidazole.

26. A composition according to any one of claims 1 to 6 wherein the flukicide is emetine.

27. A composition according to any one of claims 1 to 6 wherein the flukicide is hexachlorophene.

28. A composition according to any one of claims 1 to 27 wherein the organic liquid comprises a surface active agent having a hydrophile-lipophile balance in the range from 8 to 18.

29. A composition according to claim 28 wherein the surface active agent is selected from the group consisting of ethoxylated castor oil, ethoxylated hydrogenated castor oil, and ethoxylated polypropylene oxide.

30. A composition according to any one of claims 1 to 29 wherein the composition comprises additionally a pharmaceutically acceptable cosolvent selected from the group consisting of poly(vinylpyrrolidone), hexylene glycol,polyethylene and polypropylene glycol, Cg to C2Q aliphatic alcohols, alcohol alkoxylates, sorbitan fatty acid esters and ethoxylates thereof, glycerol, fatty acidfS _ t esters, benzyl benzoate and camphor. f/w

31. A process for combatting helminthiasis in warmblooded animals excluding humans which process comprises the parenteral administration of a therapeutically effective amount of a composition comprising a tetramisole acid addition salt or a laevorotatory tetramisole acid addition, salt and a substantially water-insoluble flukicide as defined according to any one of claims 1 to 30.

32. A process according to claim 31 wherein said warm-blooded animals are sheep.

33. A process according to claim 31 wherein said warm-blooded animals are cattle.

34. A process according to any one of claims 31 to 33 wherein said composition is administered by subcutaneous injection.

35. A composition according to any one of claims 1 to 30 substantially as described with reference to any one of Examples 1 to 10, 16 to 23, '25, and 26.

36. A process according to any one of claims 31 to 34 substantially as described with reference to any one of Examples 11 to 15 and 24 to 26. dated this I day of. d A. J. PAFrK &~S;0N FOR THE APPl-tGAN agents fo^THEX?pucants