Primaquine
Primaquine phosphate
Brand names:Primaquine
An 8-aminoquinoline antimalarial used for terminal prophylaxis and radical cure of Plasmodium vivax and P. ovale malaria. Primaquine targets the dormant hypnozoite liver stage that other antimalarials do not address, preventing relapsing malaria after deployment to regions where these species are endemic. Requires G6PD screening before administration due to hemolytic anemia risk.
Pharmacology and Actions
Primaquine's exact antimalarial mechanism is incompletely understood but appears to involve metabolites that disrupt parasite mitochondrial function and generate reactive oxygen species. The drug is uniquely active against hypnozoites (dormant liver-stage parasites) of P. vivax and P. ovale, which is why it provides radical cure and terminal prophylaxis where other antimalarials provide only blood-stage suppression. The reactive oxygen species production also explains the hemolytic anemia in G6PD-deficient patients.
Indications
- Terminal prophylaxis against P. vivax and P. ovale after departure from endemic regions
- Radical cure of acute P. vivax or P. ovale malaria (after blood-stage treatment)
- Prevention of malaria relapse from dormant liver stages
- Pneumocystis jirovecii pneumonia (in combination with clindamycin, alternative regimen)
Absolute Contraindications
- Glucose-6-phosphate dehydrogenase (G6PD) deficiency
- Known primaquine allergy
- Pregnancy (G6PD status of fetus unknown)
- Breastfeeding when infant G6PD status unknown
- Severe granulocytopenia
- Active rheumatoid arthritis or systemic lupus erythematosus (relative)
Precautions and Side Effects
G6PD-mediated hemolytic anemia is the major safety concern and can be severe. G6PD testing must be performed before administration. Methemoglobinemia can occur, particularly at higher doses. Gastrointestinal upset is common; take with food to reduce nausea. Abdominal cramps, diarrhea, and headache are common. Hematologic monitoring during treatment courses is advisable. Avoid in patients with NADH methemoglobin reductase deficiency.
Adult Dosing
Pediatric Dosing
Pediatric dosing: 0.5 mg base/kg/day PO for 14 days for terminal prophylaxis or radical cure (maximum 30 mg/day). Pediatric G6PD testing is required before administration. Use is generally limited to clinical settings rather than tactical environments.
Pharmacokinetics
Peak Effect: PO: 1 to 2 hours after dose
Duration: Half-life 4 to 8 hours; once-daily dosing supported by tissue effect on hypnozoites
Storage and Handling
Store tablets at controlled room temperature (15 to 30 degrees Celsius). Protect from moisture and light.
Reconstitution:
Tablets require no reconstitution. Dosing is expressed as primaquine base; verify formulation labeling before calculating dose.
TCCC and TECC Role
Primaquine is not a wound or trauma management agent but is critical to deployment medicine anti-malarial doctrine for operations in regions where P. vivax or P. ovale are endemic. The drug is taken as terminal prophylaxis upon departure from the endemic region to eliminate dormant hypnozoites that other antimalarials do not address. Failure to complete primaquine terminal prophylaxis can result in malaria relapse months to years after deployment. G6PD screening before deployment is essential for any team operating in vivax-endemic regions.
Primaquine is the drug that prevents the deployed-medic phone call from a team member months after redeployment, presenting with malaria they thought they had escaped. The 14-day terminal prophylaxis course addresses dormant liver-stage parasites that survive the standard prophylactic regimens. The G6PD screening requirement is non-negotiable; severe hemolysis in G6PD-deficient personnel can be life-threatening. Pre-deployment G6PD testing should be standard for any operation in regions with P. vivax or P. ovale, which includes much of South America, sub-Saharan Africa, the Mediterranean basin, the Middle East, South Asia, and Oceania.
Administering primaquine without confirming G6PD status. G6PD deficiency is more common than many providers realize, with prevalence around 10 to 25 percent in some populations (Mediterranean, African, Asian descent). Hemolytic anemia from primaquine in a G6PD-deficient patient can require transfusion and rarely cause death. The other common error is incomplete terminal prophylaxis courses; the full 14 days is required for hypnozoite elimination.
This drug profile is provided as educational reference material for trained medical providers. It is not medical advice, not a substitute for formal training, and not a substitute for current published guidelines or medical direction.
Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances are subject to additional handling, accountability, and documentation requirements per DEA and state law. Always verify dosing, indications, contraindications, and route of administration against current published guidelines and your local protocols before administration.
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Penn Tactical Solutions publishes this reference for educational purposes. PTS does not provide medical direction and does not assume responsibility for clinical decisions made in the field. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Educational reference for trained medical providers. Not medical advice. Not a substitute for formal training, current published guidelines, or medical direction. Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances require additional storage, accountability, and documentation per DEA and state law.
In a medical emergency, call 911. This reference is not a substitute for emergency medical services.
Verify dosing, indications, and contraindications against current published guidelines and your local protocols before administration. Confirm content currency against the source citation. Penn Tactical Solutions does not provide medical direction. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Primaquine
| PO | Terminal prophylaxis: 30 mg base PO daily for 14 days starting upon departure from endemic region. Radical cure of P. vivax/ovale: 30 mg base PO daily for 14 days (after blood-stage treatment with chloroquine or other agent). PJP treatment alternative: 30 mg base PO daily combined with clindamycin for 21 days. (1 to 2 hours (rapid absorption)) |