Pharmacokinetics of Clorsulon in Sheep Following Intravenous and Subcutaneous Administration

The study established a method to analyze clorsulon concentration in sheep plasma byreverse phase-high performance liquid chromatography (RP-HPLC) with an internal-standard.In plasma, clorsulon concentration within 0.01-1.0gmL-1 and 1.0-20gmL-1 ranges had agood linear relationship (R=0.9991, 0.9958). The average recovery of the method was 98.11±3.52%. The relative standard deviation (RSD)s% of within-day and between-day assayswere less than 7 and 8% respectively. After giving clorsulon to sheep by intravenous (i.v.)or subcutaneous (s.c.) routes at a single dose of 4mgkg-1, drug concentration-time datain plasma were both fitted to a two-compartment open model. The main pharmacokineticparameters were: 1) i.v. administration: T1/2β=10.040.819h, area under the concentrationversus time curve (AUC)=81.8514.24mghL-1; 2) s.c. administration: T1/2ka=1.360.75h,T=71.0314.15%. The results indicated that clorsulon in sheep following a single s.c.administration was absorbed rapidly and eliminated slower than that following a single i.v.administration, and showed a better bioavailability.