Comparative Pharmacology
Head-to-head clinical analysis: LARIAM versus PYRIMETHAMINE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LARIAM versus PYRIMETHAMINE.
LARIAM vs PYRIMETHAMINE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Mefloquine is a 4-quinolinemethanol antimalarial agent that acts as a blood schizontocide. Its exact mechanism is unknown, but it is thought to inhibit heme polymerase, leading to toxic accumulation of free heme in the parasite.
Pyrimethamine inhibits dihydrofolate reductase (DHFR) in the parasite, blocking the conversion of dihydrofolate to tetrahydrofolate, thereby inhibiting nucleic acid synthesis.
For malaria prophylaxis: 250 mg (base) orally once weekly starting 1-2 weeks before travel, continuing weekly during stay and for 4 weeks after leaving endemic area. For malaria treatment: 1250 mg (base) orally as a single dose, divided if needed (750 mg followed by 500 mg after 6-12 hours). Route: oral. Frequency: weekly for prophylaxis; single dose for treatment.
For toxoplasmosis: 200 mg orally once, then 50-75 mg orally once daily for 4-6 weeks, plus sulfadiazine and folinic acid. For malaria prophylaxis: 25 mg orally once weekly.
None Documented
None Documented
Clinical Note
moderatePyrimethamine + Fesoterodine
"The serum concentration of the active metabolites of Fesoterodine can be increased when Fesoterodine is used in combination with Pyrimethamine."
Clinical Note
moderatePyrimethamine + Artemether
"The risk or severity of QTc prolongation can be increased when Pyrimethamine is combined with Artemether."
Clinical Note
moderatePyrimethamine + Lumefantrine
"The risk or severity of QTc prolongation can be increased when Pyrimethamine is combined with Lumefantrine."
Clinical Note
moderateTerminal elimination half-life: approximately 3 weeks (range 13–33 days); prolonged due to extensive tissue distribution and slow release from erythrocytes.
Terminal elimination half-life is approximately 96 hours (range 80-123 hours) in adults with normal renal function; prolonged in renal impairment (up to 200 hours). This long half-life supports weekly dosing regimens.
Hepatic metabolism (primarily CYP3A4) followed by biliary/fecal elimination; ~40% unchanged in feces, ~9% as metabolites in urine, minimal renal excretion of parent drug (<5%).
Primarily renal (approximately 30% unchanged and 20-30% as metabolites); additional biliary/fecal elimination (20-30% as metabolites). Total urinary excretion of parent drug and metabolites accounts for 60-80% of dose.
Category C
Category D/X
Antimalarial
Antimalarial / Antiprotozoal
Cyclophosphamide + Pyrimethamine
"The metabolism of Pyrimethamine can be decreased when combined with Cyclophosphamide."