What is the dosage and frequency of chloroquine (Chloroquine phosphate) for treating uncomplicated malaria?

Chloroquine Dosage and Frequency for Uncomplicated Malaria

For uncomplicated malaria treatment, chloroquine phosphate should be administered at a total dose of 25 mg/kg body weight (calculated as base) over 3 days, with specific dosing of 10 mg/kg initially, followed by 5 mg/kg at 6,24, and 36 hours. 1

Adult Dosing Regimen

• Initial dose: 600 mg base (1000 mg salt/phosphate)
• Second dose: 300 mg base (500 mg salt/phosphate) at 6 hours after first dose
• Third dose: 300 mg base (500 mg salt/phosphate) at 24 hours after first dose
• Fourth dose: 300 mg base (500 mg salt/phosphate) at 36 hours after first dose
• Total dose: 1500 mg base (2500 mg salt/phosphate) 2, 1

This can alternatively be expressed as:

• Day 1: 600 mg base, followed by 300 mg base after 6-8 hours
• Day 2: 300 mg base
• Day 3: 300 mg base 1

Pediatric Dosing Regimen

• Initial dose: 10 mg base/kg (not exceeding 600 mg base)
• Second dose: 5 mg base/kg (not exceeding 300 mg base) at 6 hours after first dose
• Third dose: 5 mg base/kg (not exceeding 300 mg base) at 24 hours after first dose
• Fourth dose: 5 mg base/kg (not exceeding 300 mg base) at 36 hours after first dose
• Total dose: 25 mg base/kg over 3 days 2, 1

Important Clinical Considerations

Chloroquine Resistance

• In areas with known chloroquine resistance, alternative first-line treatments should be used such as artemether/lumefantrine or dihydroartemisinin-piperaquine 2
• For P. vivax or P. ovale infections, primaquine should be added to eradicate hypnozoites and prevent relapse 1

Special Populations

• Pregnant women: Chloroquine is safe during pregnancy and should follow the adult dosing regimen 2
• Children: Dosage should be calculated based on body weight, never exceeding the adult dose regardless of weight 1

Monitoring

• Patients who remain symptomatic longer than 3 days into therapy should have a repeat thick blood smear examined 2
• Alternative therapy should be instituted if parasitemia has not diminished markedly by this time 2

Administration Tips

• The first dose of chloroquine should be administered when the blood smear is taken 2
• If supervised therapy during the 3-day period is not possible, the first dose should be given under supervision and additional doses may be given to the patient with appropriate instructions 2

Potential Adverse Effects

• Common: Nausea, vomiting, pruritus, postural hypotension 2
• Cardiac: QTc interval prolongation (dose-dependent) 3
• Higher doses (50-70 mg/kg) have been studied and appear well-tolerated, but standard dosing is recommended for chloroquine-sensitive malaria 3, 4

Remember that chloroquine dosage is often expressed in terms of equivalent chloroquine base, with each 500 mg tablet of chloroquine phosphate containing the equivalent of 300 mg chloroquine base 1.