PHARMACOKINETICS OF TETROXOPRIM AND SULFADIAZINE IN HUMAN VOLUNTEERS

The pharmacokinetics of tetroxoprim (TXP) and sulphadiazine (SDZ) were studied in healthy volunteers. In a single dose study TXP and SDZ were given alone and in combination. No interaction could be detected as a result of combined administration. The data was fitted for both drugs by computer analysis to a one-compartment model. After a dose of 80 mg orally. TXP was observed to have a mean plasma half-life of 5 1 h. The mean peak concentration was 1 7 mg/1 at 2 5 h. The half-life of renal excretion of unchanged TXP was 6'7 h, with a recovery of 40 to 60%. Urine concentrations ranged 30 to 70 mg/1 in the first 4 h after the dose. The mean plasma half-life of SDZ was 12 6 h, with a mean peak concentration of 16 mg/1 at 3 5 h. Urinary recovery of unchanged SDZ was 65 to 70% of the dose, giving concentrations of 100 to 200 mg/1. Total recovery of unchanged plus metabolised drug was 94 to 102%. After repeated doses of TXP 160 mg 12-hourly, a steady-state was reached in 24 h giving peak concentrations of 4-4 mg/1 and nadir concentrations of 1 2 mg/1. © 1979 Oxford University Press.