Coated particles releasing acid in the gastrointestinal tract - for reaction with xanthates to release larvicidal carbon disulphide

摘要

Auxiliary for releasing an acid substance (I), which is dispersible or soluble in the gastro-intestinal (G-I) tract of horses, and which react with a xanthate (II) in the G-I tract to release CS2, consists of particles of (I) provided with a water- or base- soluble coating. Pref. (I) is fumaric acid (Ia) or glutamic acid hydrochloride (Ib) as spherical particles of dia, 0.5-15 mm coated with cellulose for (Ia) or a methyl methacrylate - methacrylic acid copolymer for (Ib). The released CS2 eliminates gadfly (Gastrophilus spp) larvae from the G-I tract. Use of (I) accelerates and improves the activity of (II); thus the optimum dose of choline xanthate alone is 132 mg/kg (giving 90-100% removal of larvae in 24 hr) but is only 66 mg/kg. (giving 90-100% removal in 0.5-3 hr) when used together with = a stoichiometric amt. of acid. The coated acid particles and (II) can be stored together for a long time without reaction.