The
artemisinin antimalarials cause
embryo death and malformations in animals by killing embryonic erythroblasts. Groups of pregnant rats (N = 4) were administered 35 and 48 µmol/kg
artesunate and 17.2, 28.7, 48, 96, and 191 µmol/kg
artelinic acid as a single oral dose on gestational day (GD) 12. Litters were examined on GD21. The ED(50) for
embryo death with
artelinic acid (23.4 µmol/kg) was just slightly lower than that for decreased reticulocyte count at 24 hr postdose (33.5 µmol/kg) and both had similarly steep dose responses (maximal effects of total litter loss and ∼60% decreases in reticulocyte count at 48 µmol/kg). Results with
artesunate were similar. The correlation coefficient between
embryo death and decreased reticulocyte count was 0.82 (p<0.01). The close relationship between embryotoxicity and reticulocytopenia is suggestive of a common mechanism-
artemisinin-induced mitochondrial damage leading to cell death. At 9 days postdose, treatment with
artesunate and
artelinic acid also caused increases in counts of reticulocytes, lymphocytes, basophils, and monocytes (up to 3.7 ×, 1.7 ×, 4.7 ×, and 1.7 × control, respectively). This stimulation of hematopoiesis may have been mediated by the direct oxidative conversion of
artesunate or
artelinic acid to the artemisininyl
hydroperoxide within the bone marrow cells or by an indirect increase in
reactive oxygen species. The high correlation between embryotoxicity and reticulocytopenia further supports the assertion that therapeutic dosage regimens of
artemisinins that cause decreases in reticulocyte count in pregnant women during the putative critical period (approximately postconception wk 3 to 9) are at risk of also causing adverse effects on the embryo.