1998, Number 1
Vet Mex 1998; 29 (1)
Sumano LH, Ocampo CL, Abascal TG
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ABSTRACTIn order to evaluate the pharmacokinetics of three mixtures of sulfonamide-trimethoprim 21 mix-bred pigs, weighing 20 kg approximately, were randomly divided in three groups of 7 animals each. Each of the seven animals per group were dosed with 100 mg/kg of the following mixtures: sulfachlorpyridazine-trimethoprim (SCP-TMP); sulfamonomethoxine-trimethoprim (SMM-TMP) and sulfamethoxazole-trimethoprim (SMX-TMP) initially iv, respectively, and 15 days later orally as a bolus. Blood samples were collected by venipuncture of the auricular veins at increasing intervals, and the serum was separated by clotting and centrifugation. Serum samples were stored at -4°C, until analysis. Determination of serum concentrations of the mixture were carried out by the bacteriological agar-diffusion test, using pig serum as the vehicle and a sensitive strain of Escherichia coli as the test organism, with an intra-assay variation coefficient of 8%. Computer assisted compartmental pharmacokinetics was carried out. Results indicate greater bioavailability, higher peak serum concentrations and better apparent volumes of distribution for SCP-TMP. Although elimination half life values were slightly longer for SMM-TMP and SMX-TMP, clearance did not vary substantially among the three mixtures. It is concluded that there are important pharmacokinetic variations among these three apparently bioequivalent sulfonamide-trimethoprim mixtures. Information on the impact of these variations in clinical settings are discussed.