Controlled-release compositions for administration of therapeutic agents to ruminants

Claim 1

WHAT WE CLAIM IS:- 1 A controlled release composition for administering active agents to 50 ruminants, the composition comprising a therapeutic agent and a solid surfactant having an HLB value of 8 5 or less wherein the composition has a melting point in excess of 390 C and wherein the composition, when inserted as a solid into the rumen of a ruminant, is capable of slowly disintegrating at the interface between the composition and ruminal fluid present in the rumen 55 2 A controlled release composition according to claim 1, wherein the composition is capable of disintegrating at a rate in the range from 0 01 cm/day to 0.3 cm/day. 1,603,970 R 3 A controlled release composition according to claim I or claim 2, wherein the composition is capable of imbibing moisture from the ruminal fluid to cause the composition to swell at the interface thereby rendering it susceptible to disintegration. 4 A controlled release composition according to any of claims I to 3, wherein 5 the solid surfactant is selected from the group consisting of stearylamine ethoxylated with 2 moles of ethylene oxide, cetyl alcohol ethoxylated with 2 moles of ethylene oxide, stearyl alcohol ethoxylated with 2 moles of ethylene oxide and polyoxyethylene sorbitol hexastearate. 5 A controlled release composition according to any one of claims I to 4, 10 wherein the composition comprises at least two surfactants having an HLB value of 8.5 or less, the HLB value of the surfactants differing by no more than 2 units. 6 A controlled release composition according to claim 5, wherein the surfactants are selected from sorbitan monostearate, sorbitan mono-oleate and stearyl alcohol ethoxylated with 2 moles of ethylene oxide 15 7 A controlled release composition according to claim 6, wherein the surfactant comprises about 80 % by weight of sorbitan monostearate and about 20 % by weight of stearyl alcohol ethoxylated with 2 moles of ethylene oxide. 8 A controlled release composition according to any of claims I to 7, wherein the composition contains no more than 50 % by weight of the therapeutic agent 20 9 A controlled release composition comprising layers of a composition according to any of claims I to 8 interposed between layers of the solid surfactant having an HLB value of 8 5 or less as defined in claim 1. A controlled release composition according to any of claims I to 9, wherein the therapeutic agent is oxfendazole 25 11 A method of treating a ruminant with a controlled release composition according to any one of claims 1 to 10 which method comprises administering the composition to a ruminant in such a manner that the composition passes into the rumen of the ruminant. 12 A method according to claim 11, wherein the composition is administered 30 to a ruminant by means of a variable geometry capsule as described in the complete specification of Australian Patent No 449,029. 13 A method according to claim 11, wherein the composition is administered to a ruminant by means of thel apparatus as described with reference to Figure 1 of the accompanying drawings 35 14 A controlled release composition for administration to ruminants substantially as hereinbefore described with reference to the Examples. ELKINGTON AND FIFE, Chartered Patent Agents, High Holborn House, 52-54 High Holborn, London W C IV 65 H Agents for the Applicants. Printed for Her Majesty's Stationery Office, by the Courier Press, Leamington Spa, 1981 Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained. 1,603,970