Evaluation of the safety and tolerability of a short higher-dose primaquine regimen for presumptive anti-relapse therapy in healthy subjects.

The safety and tolerability of primaquine (PQ) administered as a short higher-dose (30mg twice daily for 7 days) regimen in 203 Australian Defence Force personnel was evaluated in an open-label presumptive anti-relapse therapy study. No clinically significant differences were measured in the subjects' haematological and biochemical indices before and after PQ treatment. The most common adverse events were nausea, abdominal pain, headache and insomnia, many of which were mild in severity (30%; 60/203) and transient; 19% of subjects (39/203) experienced moderate (with some interference with daily duties requiring no or minimal medical therapy) adverse events. Two subjects (1%) had severe gastrointestinal adverse events requiring cessation of medication, but neither was seriously ill. Ten subjects (5%) had peripheral cyanosis (blueness of the lips), but none reported any respiratory compromise. These findings suggest that the short higher-dose PQ regimen is safe and well tolerated, which could improve PQ compliance and effectiveness.