Disposition of Trimethoprim — Sulphamethoxazole Combination Following Intrauterine Administration in Buffaloes

Abstract

Plasma and uterine tissue concentrations of trimethoprim (TMP) and sulphamethoxazole (SMZ) were estimated following their intrauterine administration during the follicular and h e a l phases of the oestrous cycle in apparently healthy, non-lactating, Murrah buffaloes (4-8 years of age). Both TMP and SMZ were found to be absorbed quickly from the uterine lumen and excreted quite rapidly from the blood circulation. Uterine tissue levels of the drugs were several times higher than the corresponding plasma levels. The drugs were also detectable for longer durations in uterine tissue than in plasma.Both TMP and SMZ were found in effective concentrations in uterine tissue for about 12 hours at the lower dose (0.4 g TMP plus 2 g SMZ) and for about 24 hours at the higher dose (0.8 g TMP plus 4g SMZ), indicating that the drug combination should be repeated at 12-24hours interval, depending upon the dose, for intrauterine therapy in buffaloes. Since the levels of the drugs were higher during the h e a l phase, it is suggested that the drug combination be preferably administered during this phase of the oestrous cycle.