Plasma concentrations in pyrimethamine and sulfadoxine and evaluation of pharmacokinetic data by computerized curve...

For the determination of the plasma concentration profiles of pyrimethamine and sulfadoxine after the administration of 1 tablet of Fansidar, highly specific analytical methods are needed as the pyrimethamine concentration is low (0.2 - 0.02 mg/litre) and the concentration ratio of the two components in the plasma is high (> 1: 500). The microbiological method described in this paper fulfils these requirements for high specificity and sensitivity (the sensitivity limit for sulfadoxine is 1 mg/litre and for pyrimethamine is 0.013 mg/litre).Pharmacokinetic data were evaluated for 14 volunteers after administration of 1 tablet of Fansidar, and a computer simulation of multiple dosing (1 tablet per week) was performed.