Lack of inhibition of the anti-malarial action of sulfadoxine-pyrimethamine by folic acid supplementation when used for intermittent preventive treatment in Gambian primigravidae.
Folic acid is frequently given to pregnant women at the same time as intermittent preventive treatment (IPTp) with sulfadoxine/pyrimethamine (SP), but it is not known if it interferes with the anti-malarial activity of SP. To investigate this concern, 1,035 Gambian primigravidae were randomized to receive either folic acid (500-1,500 microg/day) together with oral iron (522) or oral iron alone (513) for 14 days at the same time as they received IPTp with SP. On presentation, 261 women (25%) had Plasmodium falciparum asexual parasitemia. Prevalences of parasitemia on day 14 after treatment were similar in both groups: 5.7% (26 of 458) in the iron plus folic acid group and 4.9% (22 of 446) in the iron alone group (risk difference = 0.74%, 95% confidence interval [CI] = -2.2% to 3.7%). Parasitologic cure was observed in 116 (91%) of 128 of women who were parasitemic on presentation and who received iron and folic acid and in 122 (92%) of 133 women who received iron alone (difference = 1.1%, 95% CI = -5.6% to 8.0%). Women who received folic acid and iron had a slightly higher mean hemoglobin concentration at day 14 than women who had received iron alone (difference = 0.14 g/dL, 95% CI = 0.01-0.27 g/dL). The results of this study suggest that in an area of low SP resistance, administration of folic acid to pregnant women in a dose of 500-1,500 mug/day will not interfere with the protective effect of SP when used for IPTp.