Primaquine

How it works

Its metabolites generate reactive oxygen species that are toxic to hypnozoites and other parasite stages, eliminating the liver forms responsible for relapse.

Prescribing in practice

• It causes acute haemolysis in glucose-6-phosphate dehydrogenase (G6PD) deficiency, so G6PD status must be checked before treatment and the drug avoided or used with caution accordingly.
• It is contraindicated in pregnancy because the G6PD status of the foetus cannot be assured.
• It is used together with a blood schizonticide such as chloroquine to clear the erythrocytic infection while primaquine targets the liver stages.

Monitoring

Check G6PD activity before starting and monitor for signs of haemolysis such as dark urine, pallor and breathlessness during treatment.

Counselling the patient

• A blood test for G6PD deficiency is needed before you start this medicine.
• Stop and seek advice if your urine turns dark or you feel unusually tired or short of breath.
• Take the full prescribed course to prevent the malaria from returning.

Evidence & guidelines

Primaquine is the established agent for radical cure of vivax and ovale malaria, with G6PD testing emphasised in WHO and UK malaria guidance.