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8-aminoquinoline antimalarial Pregnancy: Contraindicated in pregnant women (US label).

Primaquine

Primaquine is an 8-aminoquinoline antimalarial used to achieve radical cure of Plasmodium vivax and Plasmodium ovale malaria by eradicating dormant liver stages, and as a single-dose transmission-blocking agent in falciparum malaria.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 1 tablet (equivalent to 15 mg base) once daily for 14 days, for radical cure/prevention of relapse of vivax malaria
Route: Oral
Frequency: Once daily for 14 days
Recommended only for radical cure of vivax malaria, prevention of relapse in vivax malaria, or following termination of chloroquine phosphate suppressive therapy in an area where vivax malaria is endemic. Administered concurrently with a course of chloroquine phosphate (which destroys erythrocytic parasites) to eradicate exoerythrocytic parasites. May be taken with or without food; taking with food may reduce gastrointestinal symptoms. Elderly: start at low end of dosing range.

Dose auto-extracted from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Known hypersensitivity to primaquine, other 8-aminoquinolines, or any component
  • Severe glucose-6-phosphate dehydrogenase (G6PD) deficiency
  • Pregnancy
  • Breastfeeding when the infant is G6PD deficient or G6PD status unknown
  • Recent or concurrent use of quinacrine (increased toxicity)

Side effects

  • Nausea, vomiting, epigastric distress, abdominal cramps
  • Hemolytic anemia (common in G6PD deficiency; may be severe/fatal in severe deficiency)
  • Leukopenia, decreased hemoglobin, methemoglobinemia
  • Cardiac arrhythmia and QT interval prolongation
  • Dizziness; rash, pruritus

Interactions

  • Quinacrine (mepacrine) - concurrent use contraindicated (increased toxicity)
  • Hemolytic agents and methemoglobinemia-inducing drugs - avoid concurrent use; close blood monitoring if unavoidable
  • QT-prolonging drugs - close/frequent ECG monitoring advised
  • Potent CYP2D6 inhibitors may reduce active metabolite formation and antimalarial efficacy - consider alternatives / increase monitoring for relapse

Clinical monograph

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.

Reference: UKHSA; WHO; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways