Primaquine Double Dose for Radical Cure of Plasmodium Vivax in Colombia

Primaquine (PQ) is the only widely available treatment to prevent P. vivax relapses. World Health Organization recommends increased PQ doses in East Asia and Oceania, frequently relapsing strains. In 2005, the Centers for Diseases Control and Prevention began also recommending higher dose PQ to treat infections from all parts of the world. In Latin America, PQ for a radical cure has been largely implemented as 3.5 mg/kg over 14 days (standard dose, long-course, PQsd14) or 3.5 mg/kg over 7 days (short-course, or PQsd7) in combination with chloroquine (CQ). A recent randomized controlled trial in Brazil showed that a 7 mg/kg double dose regimen over 14 days (PQdd14) was superior in preventing relapses compared to the standard of care regimen in Brazil of 3.5 mg/kg over 7 PQsd7 Direct Observed Therapy (DOT) and PQsd7 without DOT and with or 14 days PQsd14 with DOT (92% versus 66% were relapse-free in the 6-month follow-up in adjusted analyses). These data were presented at the 2019 PAHO Malaria Technical Advisory Group (TAG) meeting. To inform whether there should be a policy change by Panamerican Health Organization, the Malaria TAG recommended more evidence from the results of another trial to confirm the efficacy of high versus low-dose PQ. This project aims to generate the necessary evidence to inform a policy decision regarding high-dose PQ. Impact Malaria (IM) proposes to conduct another trial, per the PAHO Malaria TAG's recommendation, assessing the efficacy of high-dose PQ compared to low-dose PQ. The objective is to compare a standard regimen, which in Colombia is PQsd14 (3,5mg/kg divided in 14 days), to a double dose alternative PQ 7 mg/kg double dose regimen over 14 days (PQdd14).