Patients' adherence and clinical effectiveness of a 14-day course of primaquine when given with a 3-day chloroquine in patients with Plasmodium vivax at the Thai-Myanmar border.

Primaquine is the only antimalarial drug available for eradicating the hypnozoite stage of Plasmodium vivax to prevent the disease from recurring. However, one limitation of its clinical use is the long treatment course of 14 days, which may result in poor patients' adherence and low treatment efficacy. The aim of the current study was to assess patients' adherence and the clinical effectiveness of the unsupervised standard 14-day primaquine regimen (daily dose of 15mg base/kg body weight daily for 14 days) when given together with 3-day chloroquine (25mg base/kg body weight over 3 days). The study was conducted in 85 patients with P. vivax malaria in a malaria endemic area along the Thai-Myanmar border. Patients' adherence to primaquine therapy was assessed based on primaquine concentrations in finger-prick dried blood spot (DBS) samples alongside patients' self-reporting on drug administration and pill counting methods. Results suggest high rate of patients' adherence to this 14-day primaquine regimen (95-98% based on primaquine concentrations in DBS on days 3, 7, and 14 of treatment, and 100% based on patients' self-reporting and pill counting methods. Clinical effectiveness was 100% during the 42-day follow-up.