Efficacy and safety of artemisinin-based combination therapy and chloroquine with concomitant primaquine to treat Plasmodium vivax malaria in Brazil: an open label randomized clinical trial

André Daher, Dhelio Pereira, Marcus V. G. Lacerda, Márcia A. A. Alexandre, Cristiana T. Nascimento, Júlio Castro Alves de Lima e Silva, Mauro Tada, Rosilene Ruffato, Ivan Maia, Tereza Cristina dos Santos, Paola Marchesini, Ana Carolina Santelli, David G. Lalloo

There is general international agreement that the importance of vivax malaria has been neglected, and there is a need for new treatment approaches in an effort to progress towards control and elimination in Latin America. This open label randomized clinical trial evaluated the efficacy and safety of three treatment regimens using either one of two fixed dose artemisinin-based combinations or chloroquine in combination with a short course of primaquine (7-9 days: total dose 3-4.2 mg/kg) in Brazil. The primary objective was establishing whether cure rates above 90% could be achieved in each arm. A total of 264 patients were followed up to day 63. The cure rate of all three treatment arms was greater than 90% at 28 and 42 days. Cure rates were below 90% in all three treatment groups at day 63, although the 95% confidence interval included 90% for all three treatments. Most of the adverse events were mild in all treatment arms. Only one of the three serious adverse events was related to the treatment and significant drops in haemoglobin were rare. This study demonstrated the efficacy and safety of all three regimens that were tested with 42-day cure rates that meet World Health Organization criteria. The efficacy and safety of artemisinin-based combination therapy regimens in this population offers the opportunity to treat all species of malaria with the same regimen, simplifying protocols for malaria control programmes and potentially contributing to elimination of both vivax and falciparum malaria. Trial registration RBR-79s56s.