What is the recommended dose of Chloroquine (Chloroquine phosphate) for uncomplicated malaria?

Chloroquine Dosing for Uncomplicated Malaria

For uncomplicated malaria caused by chloroquine-sensitive species, administer chloroquine phosphate 1000 mg salt (600 mg base) initially, followed by 500 mg salt (300 mg base) at 6,24, and 48 hours, for a total dose of 2500 mg salt (1500 mg base) or 25 mg/kg over 3 days. 1, 2

Species-Specific Dosing

P. vivax, P. ovale, P. malariae, and P. knowlesi

Adult dosing:

• Initial dose: 1000 mg salt (600 mg base) at hour 0
• Second dose: 500 mg salt (300 mg base) at 6 hours
• Third dose: 500 mg salt (300 mg base) at 24 hours
• Fourth dose: 500 mg salt (300 mg base) at 48 hours
• Total cumulative dose: 2500 mg salt (1500 mg base) or 25 mg/kg 1, 3, 2

Pediatric dosing:

• Initial dose: 10 mg base/kg at hour 0 (maximum 600 mg base)
• Second dose: 5 mg base/kg at 6 hours (maximum 300 mg base)
• Third dose: 5 mg base/kg at 24 hours
• Fourth dose: 5 mg base/kg at 36 hours
• Total cumulative dose: 25 mg base/kg 3, 4, 2

P. falciparum

Chloroquine is NOT recommended as first-line treatment for P. falciparum in most regions due to widespread resistance. 1 However, in the rare chloroquine-sensitive areas, use the same dosing regimen as above. 1

Critical Considerations

Formulation Differences

• Chloroquine phosphate tablets contain 500 mg salt = 300 mg base
• Chloroquine sulfate tablets contain 200 mg salt = 150 mg base, requiring 6 tablets initially, then 3 tablets at 6,24, and 48 hours 1
• Always verify which formulation you are prescribing to avoid underdosing

Geographic Resistance Patterns

• Chloroquine-resistant P. vivax occurs in Papua New Guinea and Indonesia; use artemisinin-based combinations instead 1
• P. falciparum in Southeast Asia and most of sub-Saharan Africa is chloroquine-resistant 1, 5

Special Populations

Pregnancy:

• Use standard adult chloroquine dosing—chloroquine is safe in all trimesters 1, 4, 5
• Do not withhold treatment due to pregnancy 4

Renal failure:

• No dose adjustment needed, even in dialysis patients, as chloroquine is primarily hepatically metabolized 5

Radical Cure for P. vivax and P. ovale

• Must add primaquine 30 mg base daily for 14 days (adults) or 0.3 mg/kg/day for 14 days (children) to eradicate hypnozoites 1, 3
• Check G6PD status before primaquine—contraindicated in severe G6PD deficiency due to hemolysis risk 1, 3

Monitoring and Follow-up

• Directly observe all doses when possible to ensure adherence 3, 4
• Repeat thick blood smear if symptoms persist beyond 3 days 3, 4
• Switch to alternative therapy if parasitemia has not decreased markedly by day 3 3, 4

Common Pitfalls

Underdosing in children: Age-based dosing regimens commonly used in endemic areas (dispensing in plastic bags) lead to suboptimal dosing in 30-64% of children, particularly younger patients. 6 Always calculate dose by weight, not age.

Assuming malaria is the only cause of fever: The presence of Plasmodium on blood smear does not exclude other causes such as pneumonia, meningitis, or acute respiratory infections—evaluate and treat accordingly. 3, 4

Using chloroquine in resistance areas: This leads to treatment failure and potentially fatal outcomes. 5 Verify local resistance patterns before prescribing.

Adverse Effects

• Common: Nausea, vomiting, pruritus, postural hypotension 1
• Cardiovascular: QTc prolongation can occur but is generally well-tolerated at standard doses 7
• Higher doses (50-70 mg/kg) are well-tolerated in children but show similar QTc prolongation to standard dosing 7