Primaquine
An 8-aminoquinoline that kills dormant liver forms of vivax and ovale malaria to stop relapse; G6PD is tested first.
Drug card
- Class
- 8-aminoquinoline
- How it works
- Killing dormant liver forms (hypnozoites) through oxidizing metabolites
- Used for
- Preventing relapse of vivax and ovale malaria (radical cure)
- Blocking falciparum transmission (single low dose)
- Malaria prevention for travel to vivax areas
- Known for
- Hemolytic anemia in G6PD deficiency
- Methemoglobinemia
- Its name
- -quine means a quinoline drug, often an antimalarial
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does primaquine work?
Primaquine is thought to act through hydroxylated metabolites made by liver CYP2D6, which create oxidative stress and impair the parasite's mitochondria; the exact mechanism is not established. It kills liver-stage schizonts and hypnozoites, and a single low dose cuts the infectiousness of P. falciparum gametocytes.
Uses
What is primaquine used for?
- Preventing relapse of vivax and ovale malaria (radical cure)
- Blocking falciparum transmission (single low dose)
- Malaria prevention for travel to vivax areas
Side effects
Side effects of primaquine
- Hemolytic anemia in G6PD deficiencyKnown forSerious
- MethemoglobinemiaKnown forSerious
- Nausea and vomiting
- Abdominal cramps and epigastric pain
- Low white cell count
- Long QT and arrhythmiasSerious
- Dizziness
- Rash and itching
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Test G6PD first: contraindicated in severe deficiency; in milder deficiency, check hemoglobin closely.
- Contraindicated in pregnancy, and when breastfeeding an infant whose G6PD is deficient or unknown.
- Avoid quinacrine and other hemolytic or methemoglobin-forming drugs; monitor the ECG with QT-prolonging drugs.
- Strong CYP2D6 inhibitors may cut the making of its active metabolites, and so its effect.
Good to know: The usual drug for radical cure of vivax and ovale malaria, given alongside chloroquine or an ACT, which clear only the blood stages.
Remember it
A way to remember it
Primaquine prevents the relapse, but test G6PD first.
It kills the dormant liver forms (hypnozoites) of P. vivax and P. ovale that cause relapses. In G6PD deficiency it can break down red cells, so G6PD is checked before it is given.
Written for biofideX
Its name
-quine means quinoline drug, often an antimalarial
Chloroquine, hydroxychloroquine, primaquine and mefloquine are antimalarials, but debrisoquine and oxamniquine, also quinolines, are not.
- Every drug name stem
Its class
8-aminoquinolines
8-aminoquinolines kill the liver stages of malaria, including the dormant hypnozoites of P. vivax and P. ovale that cause relapse, and the gametocytes that infect mosquitoes. Their mechanism is not settled: liver CYP2D6 makes hydroxylated metabolites thought to create oxidative stress and disrupt parasite mitochondria. In G6PD deficiency they can cause serious hemolysis. Tafenoquine is a newer member.
Easily mixed up with 4-aminoquinolines and artemisinins.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Primaquine phosphate tablets: label (DailyMed)
- Primaquine (NCI Thesaurus)
- WHO guidelines for malaria (WHO)
- Malaria (CDC Yellow Book)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Antifungals and antiparasitics
Primaquine is one of 14 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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