| Abstract: | A RP-HPLC method was used for the determination of eprinomectin concentration in sheepplasma following i.v. and s.c. administration at a single dose of 0. 2 mg kg-1. Eprinomectin in plasma within2.5 - 200 ng mi-1 ranges had a good linear relationship(R=0. 9968). The average recovery of the method was99.65±3.84%. The RSD% of within-day and between-day assays were less than 10 and 12%, respectively.The extract of plasma samples were loaded onto a C18 catridge. After solvent exchange, the methanol eluatewas derivatized via the addition of 1-methylimidazole and trifluoroacetic anhydride in acetonitrile. The fluo-rescent derivative was analyzed. The main pharmacokinetic parameters were as follows, for i.v. administra-tion: T1/2β =12. 66± 2. 05 h, AUC0-t = 1.02 ± 0.3 mg h L-1 , fc =0. 13+0.05; for s.c. administration:T1/2sa = 4.42 ±l. 04 h, Cmax =0. 02±0.01 μg mi-1 , Tmax = 15.36 ± 2.91 h, t1/2K=26. 22±9.04 h, AUC0-t= 1.19±0.37 mg h L-1. The results showed that eprinomectin was distributed widely and taken long time toeliminate in sheep after i. v. adminstration. When given subcutaneously, eprinomectin had better absorptionand longer residue time in sheep. Eprinomectin was eliminated much slowly after s. c. adminstration comparedwith i.v. administration. |
