Chloroquine Tablets: Indications, Dosing, and Contraindications
Chloroquine tablets are indicated for treatment of uncomplicated malaria caused by susceptible strains of P. falciparum, P. malariae, P. ovale, and P. vivax, malaria prophylaxis in chloroquine-sensitive areas, and extraintestinal amebiasis, but are contraindicated in patients with retinal/visual field changes and known hypersensitivity to 4-aminoquinoline compounds. 1
Primary Indications
Treatment of Uncomplicated Malaria (Chloroquine-Sensitive Areas Only)
Adults:
- Total dose: 1,500 mg chloroquine base over 3 days
- Regimen: 600 mg at 0 hours, 600 mg at 24 hours, 300 mg at 48 hours 2
Children:
- Total dose: 25 mg/kg body weight over 3 days
- Regimen: 10 mg/kg at 0 hours, 10 mg/kg at 24 hours, 5 mg/kg at 48 hours 2
Pregnant Women:
- Use adult dosing regimen
- Chloroquine is safe during pregnancy 2
Malaria Prophylaxis (Chloroquine-Sensitive Areas)
Standard Prophylaxis:
- 300 mg chloroquine base weekly
- Start 1-2 weeks before travel
- Continue weekly during exposure
- Continue for 4 weeks after leaving endemic area 2, 3
Alternative Loading Dose Regimen:
- 620 mg chloroquine base 48 hours before departure
- Then 310 mg base weekly throughout visit
- This provides prophylactic concentrations immediately and is better tolerated 4
Treatment of Extraintestinal Amebiasis
- Per FDA labeling, chloroquine is indicated for this condition 1
Critical Limitations and Warnings
Do NOT Use Chloroquine For:
Complicated/Severe Malaria - High-grade parasitemia, cerebral malaria, acute renal failure require IV artesunate or quinine 1
Chloroquine-Resistant Areas - Resistance is widespread in P. falciparum and reported in P. vivax 1. If symptoms persist 48-72 hours after starting chloroquine, switch to second-line drugs (sulfadoxine-pyrimethamine, mefloquine, quinine, or tetracycline) 2
P. vivax/P. ovale Liver Stages - Chloroquine does not prevent relapses; concomitant primaquine (15 mg daily for 14 days in adults, 0.3 mg/kg/day in children) is necessary for radical cure 2, 1. Critical caveat: In populations with severe G6PD deficiency (especially Asians), primaquine should not exceed 5 days to avoid life-threatening hemolysis 2
Absolute Contraindications
Per FDA labeling 1:
- Retinal or visual field changes of any etiology - For chronic use beyond acute malaria treatment
- Known hypersensitivity to 4-aminoquinoline compounds
Important Safety Considerations
Adverse Effects
Minor (common, usually do not require discontinuation):
- Gastrointestinal disturbance, headache, dizziness, blurred vision, pruritus 3
Serious (rare at prophylactic doses):
- Retinopathy - Associated with high doses (rheumatoid arthritis treatment), not routine weekly prophylaxis. However, periodic ophthalmologic exams recommended for >6 years cumulative weekly prophylaxis 3
- QT prolongation - Monitor ECG, especially with concurrent medications
- Psoriasis exacerbation 3
Drug Interactions
- May interfere with antibody response to intradermal human diploid cell rabies vaccine 3
- Avoid concurrent use with other QT-prolonging drugs
Special Populations
Elderly: High risk for toxicity; dose reduction should be considered 5
Renal Dysfunction: One-third of clearance is renal; monitor closely 6
Children: Extremely dangerous in overdose - 1-2 tablets can be fatal. Chloroquine has a narrow safety margin; three times the therapeutic dose can be lethal in adults 6, 7
Clinical Pearls
- Compliance is essential - Most malaria deaths occur in those who do not comply fully with prophylaxis 8
- Supervised first dose recommended when possible 2
- If patient vomits within 30 minutes of oral dose, repeat the dose 2
- For patients unable to swallow, chloroquine can be given via nasogastric tube and is well absorbed even in comatose children 7
- Resistance monitoring: If symptoms persist >3 days, repeat thick blood smear and switch to alternative therapy if parasitemia has not diminished markedly 2