Pharmacokinetics of sulphamethoxazole and trimethoprim administered intravenously and orally to Japanese quails

Abstract

The pharmacokinetic behaviour of sulphamethoxazole and trimethoprim was studied after combined intravenous (i.v.) administration at doses of 20 mg/kg and 4 mg/kg, respectively, and after oral administration at doses of 50 mg/kg and 10 mg/kg. The serum concentration versus time data after i.v. administration were best described by the biexponential equations C = 34.77.e-2.655.t + 39.03.e-0.241.t for sulphamethoxazole and C = 3.29.e-3.878.t + 0.83.e-0.306.t for trimethoprim. Mean biological half-lives of the drugs were 2.89 +/- 0.11 and 2.38 +/- 0.33 h, respectively. The distribution volumes (V area) were 0.475 +/- 0.026 l/kg (sulphamethoxazole) and 3.89 +/- 0.61 l/kg (trimethoprim). Orally administered sulphamethoxazole and trimethoprim were rapidly absorbed. The maximum serum concentrations were reached 0.5-1 h after administration. The bioavailability was 81% for sulphamethoxazole and 41% for trimethoprim.