tafenoquine

Tafenoquine is an antimalarial medication in the 8-aminoquinoline class, related to primaquine. It is active against liver-stage parasites and is used for both malaria prophylaxis and radical cure of Plasmodium vivax infection. Tafenoquine is marketed under the brand names Arakoda for prophylaxis and Krintafel for radical cure, and was approved by the U.S. Food and Drug Administration in 2018.

Mechanism and pharmacology: The exact mechanism is not fully understood, but tafenoquine is believed to disrupt parasite mitochondria and redox processes, producing reactive metabolites that kill hypnozoites and other parasite stages. It has a long half-life, which supports weekly dosing for prophylaxis and a single-dose regimen for radical cure. It is absorbed orally and is metabolized in the liver, with slow elimination.

Medical use: For prophylaxis, tafenoquine is taken as a weekly dose starting before travel to malaria-endemic areas and continuing during exposure and for a period after departure. For radical cure, a single-dose regimen is used to eradicate dormant liver forms after treating the blood stages with a schizonticide such as chloroquine. In both uses, a confirmed normal G6PD status is required before prescription due to the risk of hemolytic anemia in G6PD-deficient individuals; tafenoquine is contraindicated in G6PD deficiency, pregnancy, and lactation.

Safety and adverse effects: Common adverse effects include headache, nausea, diarrhea, and dizziness. Hemolysis can occur in G6PD-deficient individuals, and methemoglobinemia has been reported in rare cases. Patients with hepatic impairment or those taking interacting medications should be evaluated by a clinician before use.