Primaquine is an important
antimalarial agent because of its activity against exoerythrocytic forms of Plasmodium sp.
Methemoglobinemia and
hemolytic anemia, however, are dose-limiting side effects of primaquine therapy. These hemotoxic effects are believed to be mediated by metabolites, though the identity of the toxic specie(s) and the mechanism underlying hemotoxicity have remained unclear. Previous studies showed that an N-hydroxylated metabolite of primaquine, 6-methoxy-8-hydroxylaminoquinoline, was capable of mediating primaquine-induced hemotoxicity. The present studies were undertaken to investigate the hemolytic mechanism of 5-hydroxyprimaquine (5-HPQ), a phenolic metabolite that