TOPICAL COMPOSITION

1 . A topical composition comprising: fipronil or a pharmaceutically acceptable salt thereof; at least one surfactant and at least one crystallization inhibitor, wherein the flashpoint of the composition is at least 40° C.

2 . A topical composition according to claim 1 , wherein the flash point of the composition ranges from about 45° C. to about 55° C.

3 . A topical composition according to claim 1 , wherein surfactant is present in an amount ranging from 1 to 20% by weight of the composition.

4 . A composition according to claim 1 , wherein crystallization inhibitor is present in an amount ranging from 1 to 20% by weight of the composition.

5 . A topical composition according to claim 1 , wherein the surfactant comprises a polyoxyethylenated ester of sorbitan, such as polysorbate 20, polysorbate 60 and/or polysorbate 80; a polyoxyethylene castor oil derivative a propylene glycol; a fatty acid ester of propylene glycol such as propylene glycol monocaprylate, propylene glycol monolaurate; an oleoyl macrogol glyceride; a caprylocaproyl macrogol glyceride; a polyethylene glycol; a copolymers of ethylene oxide & propylene oxide; or a combination thereof.

6 . A topical composition according to claim 1 , wherein the surfactant is a polyoxyethylene castor oil derivative.

7 . A topical composition according to claim 1 , wherein the surfactant is a polyethylene glycol hydrogenated castor oil.

8 . A topical composition according to claim 1 , wherein the crystallization inhibitor comprises polyvinylpyrrolidone, a polyvinyl alcohol, a copolymer of vinyl acetate and vinylpyrrolidone, a polyethylene glycol, benzyl alcohol, mannitol, glycerol, sorbitol, a polyoxyethylenated sorbitan ester; lecithin, sodium carboxymethylcellulose; an acrylic derivatives such as a methacrylate; an anionic, cationic or anionic surfactant; or a combination thereof.

9 . A topical composition according to claim 1 , wherein the crystallization inhibitor is polyethylene glycol.

10 . A topical composition according to claim 1 further comprises at least one organic solvent and at least one organic cosolvent.

11 . A topical composition according to claim 1 , wherein the organic cosolvent is a C 1 to C 6 linear or branched alcohol.

12 . A topical composition according to claim 1 , wherein the organic cosolvent is methanol, ethanol or isopropanol.

13 . A topical composition according to claim 1 , wherein the organic cosolvent is present in an amount ranging from 2% to 15% by weight of the composition.

14 . A topical composition according to claim 1 , wherein the organic solvent is not a C 1 to C 6 alcohol cosolvent.

15 . A topical composition according to claim 1 wherein the organic solvent is diethylene glycol monoethyl ether.

16 . A topical composition comprising fipronil, at least one antiparasitic agent other than fipronil, or pharmaceutically acceptable salt thereof; at least one surfactant and at least one crystallization inhibitor, wherein the flashpoint of the composition is at least 40° C.

17 . A topical composition according to claim 16 , wherein the additional anti-parasitic agent comprises pyriproxyfens, hydroprene, cyromazine, lufenuron and 1-(2,6-difluorobenzoyl)-3-(2-fluoro-4-(trifluoromethyl)phenylurea, azadirachtin, diofenolan, fenoxycarb, hydroprene, kinoprene, S-methoprene, pyriproxyfen, tetrahydroazadirachtin, and 4-chloro-2-(2-chloro-2-methyl-propyl)-5-(6-iodo-3-pyridylmethoxy)-pyridizine-3(2H)-one, chlorfluazuron, cyromazine, diflubenzuron, fluazuron, flucycloxuron, flufenoxuron, hexaflumuron, lufenuron, tebufenozide, teflubenzuron, triflumuron, 1-(2,6-difluorobenzoyl)-3-(2-fluoro-4-(trifluoromethyl)phenylurea, 1-(2,6-difluoro-benzoyl)-3-(2-fluoro-4-(1,1,2,2-tetrafluoroethoxy)-phenylurea and 1-(2,6-difluoro-benzoyl)-3-(2-fluoro-4-trifluoro-methyl)phenylurea.

18 . A topical composition according to claim 16 , wherein the antiparasitic agent is S-methoprene or pharmaceutically acceptable salt thereof.

19 . A topical parasiticidal composition comprising: Fipronil in an amount of about 9.7%; ethanol in an amount of about 5.0% to about 7.5%; butylated hydroxylanisole in an amount of about 0.02%; butylated hydroxyltoluene in an amount of about 0.01%; polyethylene glycol 1000 in an amount of about 5.0% or about 7.5%; polyethylene glycol 60 hydrogenated castor oil in an amount of about 5.0% by weight of the composition; and diethylene glycol monoethyl ether in an amount to make up the final volume of the composition.

20 . A topical parasiticidal composition comprising: Fipronil in an amount of about 9.8%; S-Methoprene in an amount of about 11.8%; ethanol in an amount of about 5.0% to about 7.5%; butylated hydroxylanisole in an amount of about 0.02%; butylated hydroxyltoluene in an amount of about 0.01%; polyethylene glycol 1000 in an amount of about 5.0% to about 7.5%; polyethylene glycol 60 hydrogenated castor oil in an amount of about 5.0% by weight of the composition; and diethylene glycol monoethyl ether in an amount to make up the final volume of the composition.

21 . A topical parasiticidal composition comprising: Fipronil in an amount of about 9.8%; S-Methoprene in an amount of about 8.8%; ethanol in an amount of about 5.0% to about 7.5%; butylated hydroxylanisole in an amount of about 0.02%; butylated hydroxyltoluene in an amount of about 0.01%; polyethylene glycol 1000 in an amount of about 5.0% to about 7.5%; polyethylene glycol 60 hydrogenated castor oil in an amount of about 5.0% by weight of the composition; and diethylene glycol monoethyl ether in an amount to make up the final volume of the composition.

22 . A topical composition according to claim 1 for use as a parasaticide.

23 . A method of treating a parasitic infestation in an animal comprising administering an effect amount of a topical composition according to claim 1 to an animal in need thereof.

24 . A method of improving the stability of a composition comprising fipronil, or a pharmaceutically acceptable salt thereof, comprising using an effective amount of a surfactant and a crystallization inhibitor.

25 . A method of raising the flashpoint of a topical composition comprising fipronil, or a pharmaceutically acceptable salt thereof, comprising using an effective amount of a surfactant, a crystallization inhibitor, an organic solvent and an organic cosolvent.

26 . A process of manufacturing the topical composition according to claim 1 .

27 . A topical composition substantially as herein described and illustrated with examples.