Chloroquine Prophylaxis Dosing for Malaria Prevention
For malaria prophylaxis in chloroquine-sensitive regions, adults should take 300 mg base (500 mg chloroquine phosphate) once weekly, and children should receive 5 mg base/kg once weekly, not to exceed the adult dose, starting 1-2 weeks before travel and continuing for 8 weeks after leaving the endemic area. 1
Adult Dosing
- Standard prophylactic dose: 300 mg base (500 mg chloroquine phosphate) once weekly on the same day each week 1
- Begin suppressive therapy 2 weeks prior to exposure when circumstances permit 1
- If unable to start 2 weeks early, give an initial loading dose of 600 mg base (1 g chloroquine phosphate) in two divided doses, 6 hours apart 1
- Continue weekly dosing for 8 weeks after leaving the malarious area 1
- Expatriates working in endemic areas should follow this same 300 mg base weekly regimen during entire exposure period plus 6 weeks post-departure 2
Pediatric Dosing
- Standard prophylactic dose: 5 mg base/kg body weight once weekly 2, 1
- The pediatric dose must never exceed the adult dose of 300 mg base regardless of the child's weight 1
- If starting prophylaxis late, children may receive a loading dose of 10 mg base/kg divided into two doses, 6 hours apart 1
- Continue for 8 weeks after leaving the endemic area 1
Critical Dosing Distinction
Important: The dose is expressed as chloroquine base, not chloroquine phosphate salt. Each 500 mg tablet of chloroquine phosphate contains 300 mg of chloroquine base 1. This distinction is essential to avoid underdosing or overdosing.
Geographic Considerations
- Chloroquine prophylaxis is only appropriate for chloroquine-sensitive regions 2
- In areas with documented chloroquine resistance, mefloquine 250 mg weekly is recommended instead 2
- North Africa, parts of the Middle East, and limited areas may still have chloroquine-sensitive malaria 2
- Sub-Saharan Africa has widespread chloroquine-resistant P. falciparum, making chloroquine monotherapy inadequate 2
Special Populations
Pregnant women: Chloroquine is safe during pregnancy and should not be withheld; use the standard adult prophylactic regimen 3
Renal failure: Chloroquine may be used as it is largely metabolized and excreted through the liver; dose remains unchanged even in dialysis patients 2
Common Pitfalls
- Failing to continue prophylaxis for 8 weeks post-exposure is a frequent error that leaves patients vulnerable to delayed parasitemia 1
- Using chloroquine in known resistance areas leads to prophylaxis failure and potentially fatal malaria 2
- Confusing base versus salt formulations results in incorrect dosing 1
- Breakthroughs can occur even with proper prophylaxis, so any fever within one year of travel requires urgent malaria evaluation 2, 4