Comparative Pharmacology
Head-to-head clinical analysis: HALFAN versus PYRIMETHAMINE SULFADOXINE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: HALFAN versus PYRIMETHAMINE SULFADOXINE.
HALFAN vs Pyrimethamine-Sulfadoxine
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
HALFAN (halofantrine) is an antimalarial agent that acts as a blood schizonticide. It is thought to inhibit the polymerization of heme into hemozoin, leading to toxic accumulation of free heme within the parasite's food vacuole. It may also interfere with nucleic acid synthesis.
Pyrimethamine inhibits dihydrofolate reductase, blocking tetrahydrofolate synthesis. Sulfadoxine inhibits dihydropteroate synthase, blocking folate synthesis. Sequential blockade of folate metabolism.
Adults: 500 mg orally once daily.
Pyrimethamine 25 mg plus sulfadoxine 500 mg per tablet; typical adult dose for acute uncomplicated malaria is 3 tablets (pyrimethamine 75 mg, sulfadoxine 1500 mg) orally as a single dose. For toxoplasmosis in immunocompromised patients: loading dose pyrimethamine 200 mg orally once, then pyrimethamine 50-75 mg orally once daily plus sulfadoxine 1000-1500 mg orally once daily (dosing based on sulfadoxine component) for 4-6 weeks, then reduce to half.
None Documented
None Documented
Terminal elimination half-life is 10-18 hours (mean 14 hours) in healthy adults, allowing twice-daily dosing.
Pyrimethamine: ~80-120 hours; Sulfadoxine: ~100-200 hours. Long half-lives allow single-dose therapy for malaria.
Primarily hepatic metabolism; renal excretion of metabolites accounts for <10% unchanged drug; biliary/fecal elimination of metabolites approximately 20-30%.
Renal: ~60% unchanged sulfadoxine, ~5% unchanged pyrimethamine; fecal: ~10% pyrimethamine. Biliary excretion minimal.
Category C
Category C
Antimalarial
Antimalarial