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Analysis of data from more than 6,800 patients located across 16 countries has supported the need to increase the dose of the antimalarial drug, primaquine, in Plasmodium vivax malaria endemic countries.

Women sitting together in Nepal © Simone D. McCourtie, World Bank

This is detailed in two studies recently published in The Lancet Infectious Diseases, which reviewed the efficacy and safety of primaquine doses used to prevent recurrence of Plasmodium vivax (P. vivax) malaria.

Led by Menzies School of Health Research (Menzies) Senior Research Fellow Dr Rob Commons, and The University of Melbourne Biostatistician Dr Megha Rajasekhar, this research is part of an international collaboration of malaria experts from the WorldWide Antimalarial Resistance Network (WWARN).

The study measuring efficacy found that increasing the dose of primaquine from 3.5mg/kg to 7mg/kg halved malaria relapses, with limited impact on gastrointestinal symptoms. The second study examined the safety of this dosing, with similar risks found between different primaquine dose regimens.

Primaquine is a medication used for more than 60 years to target malaria parasites in the liver and prevents infection from continuing. The results of the combined studies significantly increase understanding of the best primaquine dose to prevent malaria relapses.

P. vivax malaria affects more than 7 million people each year, mainly throughout the Americas, Africa and the Asia-Pacific. It puts 40% of the world’s population at risk of the infection. Once infected, P. vivax can hide in the liver for long periods of time before reappearing and causing a malaria relapse. The findings around the safety of the higher primaquine regimen have the potential to pave the way for the widespread implementation of effective malaria treatment. Increasing the dose of primaquine could have a significant impact on reducing P. vivax malaria relapses, as well as deaths and malaria transmission.

The full story is available on the WWARN website.

Read the publications:

'Effect of primaquine dose on the risk of recurrence in patients with uncomplicated Plasmodium vivax: a systematic review and individual patient data meta-analysis' on The Lancet Infectious Diseases website

'Primaquine dose and the risk of haemolysis in patients with uncomplicated Plasmodium vivax malaria: a systematic review and individual patient data meta-analysis' on The Lancet Infectious Diseases website