Prevention of Plasmodium vivax malaria recurrence: Efficacy of the standard total dose of primaquine administered over 3 days

Background: The standard total dose (STD) of primaquine to prevent Plasmodium vivax recurrence is 0.25 mg/kg day administered over 14 days (STD-14). We evaluated, in an endemic zone of Colombia, the anti-recurrence efficacy of the STD dose administered over 3 and 14 days, and of sub-STD dose administered over 3 days (71%STD-3, 50%STD-3). Methods: A controlled clinical trial was carried out with 188 subjects allocated into one of four treatment groups: STD-14, STD-3, 71%STD-3, 50%STD-3. Results: Recurrences during the 120 days of follow-up were 15% in STD-14, and 57% in STD-3. Treatment with 71%STD-3 and 50%STD-3 resulted in recurrence in >48% subjects within 120 days after the primary episode. High daily doses (1.17 mg/kg day) were well tolerated. Conclusions: (a) The standard dose and regimen (STD-14) of primaquine to prevent P. vivax relapse is recommended. The administration of the same dose over 3 days (STD-3) should be avoided; (b) doses lower than the STD doses administered over 3 days are ineffective in preventing relapse. (C) 2009 Elsevier B.V. All rights reserved.