Randomized dose-ranging study of the safety and efficacy of WR 238605 (tafenoquine) in the prevention of relapse of Plasmodium vivax malaria in Thailand

WR 238605 is an 8-aminoquinoline developed for the radical cure of Plasmodi um vivax. Forty-four P. vivax-infected patients were randomly assigned to 1 of 4 treatment regimens: 3 groups received a blood schizonticidal dose of chloroquine followed by WR 238605: group A (n = 15) received 300 mg daily f or 7 days; group B (n = 11), 500 mg daily for 3 days, repeated 1 week after the initial dose; group C (n = 9), 1 dose of 500 mg, A fourth group (D; n = 9) received chloroquine only. Among patients who completed 2-6 months of follow-up (n = 23), there was I relapse in group B (day 120) and 1 in group C (day 112), Among patients treated with chloroquine only, there were 4 re lapses (days 40, 43, 49, and 84), WR 238605 was safe, well tolerated, and e ffective in preventing P. vivax relapse.