Excretion, distribution, and metabolism of primaquine in rats.

The metabolism of the 8-aminoquinoline antimalarial drug, primaquine (I) was studied using rats. The drug was administered intravenously, intraperitoneally, and orally, and blood samples were collected at various time intervals. Primaquine was metabolized by oxidative deamination to give 8-(3-carboxy-l- methylpropylamino )-6- methoxyquinoline (III). The plasma levels of both primaquine and its metabolite were determined by HPLC. The tissue distributions of radioactive primaquine after intravenous, intraperitoneal, and oral administrations were also determined. Significant concentrations of radioactivity were found in the lungs, adrenal glands, and liver. In addition, a significant portion of the dose was found to be excreted in the feces within 24 h after administration of the drug by either of the three routes.