Distribution of Trimethoprim-Sulfamethoxazole in Tissues of Rhesus Monkeys

Abstract

The distributions of trimethoprim (TMP) and nonacetylated sulfamethoxazole (SMZ) were studied in tissues of rhesus monkeys at equilibrium after establishment of serum levels comparable to those in man. Concentrations of nonacetylated SMZ in tissue were always lower than those in serum, with the highest concentrations in kidney, lung, and heart. In contrast, concentrations of TMP in tissue were greater than those in serum, except in brain, skin, and fat. The greatest uptake of TMP by tissues was observed in kidney and liver. The ratio of SMZ to TMP was significantly less in tissue than in serum and was lower than the optimal 20:1 ratio for antibacterial synergy. The rate of disappearance of both drugs from tissues was identical to their rate of elimination from serum.