Kinetic studies on the combination rifampicin-trimethoprim in man

Abstract

The existence of kinetic interactions between rifampicin and trimethoprim in man was investigated in two studies. In the first, the two compounds were administered to the same subjects singly and in combination. In the second, the combination was administered for seven consecutive days. In both, the daily dose of rifampicin was 600 mg, that of trimethoprim 160 mg. The serum levels and urinary excretion of each compound given alone did not differ from those observed when the other drug was associated. In both studies the ratios of the rifampicin-trimethoprim serum concentrations were found to be similar to those associated with in vitro synergy.