Pharmacokinetics of Rifampicin and Desacetylrifampicin in Tuberculous Patients After Different Rates of Infusion

Four rates of rifampicin infusion ranging from 3.3 to 15 mg/min in 12 tuberculous patients were studied. Blood samples (n = 10) were drawn during infusion and 8 h later. Urine samples were collected in six fractions during a 24-h period. Rifampicin and desacetylrifampicin were measured by high-pressure liquid chromatography. Results show that the maximum plasma concentrations increase linearly for each dose with the rate of infusion, and that the amounts excreted in the urines are highly dependent on the administered dose. Simulation of plasma concentrations after different dosage regimens shows that a double rate of infusion--20 mg min-1 during 1 h and then 200 mg h-1--allows plasma concentrations to be quickly reached and maintained at a 20 mg L-1 level, far higher than the minimum inhibitory concentrations of most germs.