What is the recommended dosage of primaquine (Phosphogluconic acid dehydrogenase, G6PD) for malaria treatment?

Primaquine Dosage for Malaria Treatment

The recommended dosage of primaquine for radical cure of Plasmodium vivax malaria is 15 mg base (1 tablet) daily for 14 days, administered concurrently with chloroquine or other blood schizonticide therapy. 1

Dosage Recommendations by Malaria Species

For P. vivax or P. ovale (Anti-relapse treatment)

• Standard dosage: 30 mg base (2 tablets) per day for 14 days 2
• Alternative for G6PD intermediate deficiency: Weekly dosing of 0.75 mg base/kg (maximum 45 mg) for 8 weeks with close monitoring for hemolysis 2

For P. falciparum (Gametocytocidal effect)

• Single low dose: 0.25 mg/kg as a single dose to reduce transmission 3
• This replaces the previous higher dose of 0.75 mg/kg to reduce hemolysis risk in G6PD-deficient individuals

Critical Safety Considerations

G6PD Testing

• Mandatory requirement: G6PD status must be verified before administering primaquine 2
• Life-threatening hemolysis can occur in G6PD-deficient individuals, particularly with the Mediterranean variant 2
• In areas where G6PD testing is unavailable, the weekly regimen (0.75 mg/kg weekly for 8 weeks) may be safer for those with mild G6PD deficiency 4

Special Populations

• Pregnancy: Primaquine is contraindicated during pregnancy 2, 5
• Breastfeeding: Not recommended for breastfeeding women 2
• Children: Dosing for children:
  • 0.3 mg/kg/day for 14 days 2
  • In populations with severe G6PD deficiency (notably Asians), primaquine should not be administered for more than 5 days 2

Administration Guidelines

Timing and Co-administration

• Primaquine should be administered concurrently with blood schizonticide therapy (e.g., chloroquine) 1
• For P. vivax/P. ovale, chloroquine is typically given first to clear blood parasites, followed by primaquine to prevent relapse 2

Monitoring Requirements

• Monitor for signs of hemolysis, especially in the first 7 days 5
• Baseline and follow-up hemoglobin measurements are recommended 5
• Patients who remain symptomatic longer than 3 days should have repeat thick blood smears examined 2

Alternative Dosing Regimens

Shorter Course Options

• 0.5 mg/kg/day for 7 days (same total dose as standard regimen) may be as effective as the 14-day course with similar safety profile 6
• 1.0 mg/kg/day for 7 days compared to 0.5 mg/kg/day for 14 days shows similar efficacy but may have more serious adverse events 6

Common Pitfalls to Avoid

1. Failure to test for G6PD deficiency before administering primaquine, which can lead to severe hemolysis
2. Inadequate duration of therapy for radical cure, resulting in relapse
3. Inappropriate use in pregnant women where primaquine is contraindicated
4. Confusion between dosing for radical cure (P. vivax/P. ovale) versus gametocytocidal effect (P. falciparum)
5. Overlooking the need for concurrent blood schizonticide therapy (e.g., chloroquine)

Remember that primaquine is the only available antimalarial that kills dormant liver stages (hypnozoites) of P. vivax and P. ovale, making it essential for preventing relapse despite the need for careful administration due to hemolysis risk in G6PD-deficient individuals.