Pharmacokinetics of Sulfadoxine and Pyrimethamine for Intermittent Preventive Treatment of Malaria During Pregnancy and After Delivery.

CPT Pharmacometrics Syst Pharmacol, 2017; 6(7): 430-438
de Kock M1, 2, Tarning J3, 4, Workman L1, Nyunt MM5, Adam I6, Barnes KI1, Denti P1, 2
Doi: 10.1002/psp4.12181  PMID: 28597978

Sulfadoxine/pyrimethamine is recommended for intermittent preventative treatment of malaria during pregnancy. Data from 98 women during pregnancy and 77 after delivery in four African countries were analyzed using nonlinear mixed-effects modeling to characterize the effects of pregnancy, postpartum duration, and other covariates such as body weight and hematocrit on sulfadoxine/pyrimethamine pharmacokinetic properties. During pregnancy, clearance increased 3-fold for sulfadoxine but decreased by 18% for pyrimethamine. Postpartum sulfadoxine clearance decreased gradually over 13 weeks. This finding, together with hematocrit-based scaling of plasma to whole-blood concentrations and allometric scaling of pharmacokinetics parameters with body weight, enabled site-specific differences in the pharmacokinetic profiles to be reduced significantly but not eliminated. Further research is necessary to explain residual site-specific differences and elucidate whether dose-optimization, to address the 3-fold increase in clearance of sulfadoxine in pregnant women, is necessary, viable, and safe with the current fixed dose combination of sulfadoxine/pyrimethamine.