Pharmacokinetics of sulfadoxine-pyrimethamine in HIV-infected and uninfected pregnant women in Western Kenya.

Background: Sulfadoxine-pyrimethamine (SP) is among the most commonly used antimalarial drugs during pregnancy, yet the pharmacokinetics of SP are unknown in pregnant women. HIV-infected (HIV(+)) women require more frequent doses of intermittent preventive therapy with SP than do HIV-uninfected (HIV(-)) women. We investigated whether this reflects their impaired immunity or an HIV-associated alteration in the disposition of SP.

Methods: Seventeen pregnant HIV(-) women and 16 pregnant HIV(+) women received a dose of 1500 mg of sulfadoxine and 75 mg of pyrimethamine. Five HIV(-) and 6 HIV(+) postpartum women returned 2-3 months after delivery for another dose. The pharmacokinetics of sulfadoxine and pyrimethamine were compared between these groups.

Results: HIV status did not affect the area under the curve (AUC(0-->infinity)) or the half-lives of sulfadoxine or pyrimethamine in prepartum or postpartum women, although partum status did have a significant affect on sulfadoxine pharmacokinetics. Among prepartum women, the median half-life for sulfadoxine was significantly shorter than that observed in postpartum women (148 vs 256 h; P<.001), and the median AUC(0-->infinity) was ~40% lower (22,816 vs 40,106 microg/mL/h, P<.001). HIV status and partum status did not show any significant influence on pyrimethamine pharmacokinetics.

Conclusion: Pregnancy significantly modifies the disposition of SP, whereas HIV status has little influence on pharmacokinetic parameters in pregnant women.