Comparative Pharmacology
Head-to-head clinical analysis: DARAPRIM versus PENTACARINAT.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARAPRIM versus PENTACARINAT.
DARAPRIM vs PENTACARINAT
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Daraprim (pyrimethamine) is a folic acid antagonist that inhibits dihydrofolate reductase (DHFR) in susceptible protozoa, thereby interfering with folate synthesis and blocking DNA synthesis and cell replication. It is synergistic with sulfonamides, which inhibit dihydropteroate synthase in the folate pathway.
Pentamidine is an antiprotozoal agent that interferes with the synthesis of nucleic acids and proteins, possibly through inhibition of dihydrofolate reductase and disruption of polyamine synthesis.
50 mg orally once daily for 2 days, then 25 mg orally once daily for 4 weeks; for toxoplasmosis, a loading dose of 200 mg orally once daily for 1 day, followed by 50-75 mg orally once daily for 4-6 weeks, with folinic acid 10-25 mg daily.
4 mg/kg IV once daily for 21 days for Pneumocystis jirovecii pneumonia (PCP) treatment; 300 mg (or 4 mg/kg) via nebulizer once monthly for PCP prophylaxis.
None Documented
None Documented
Terminal elimination half-life is approximately 111 hours (range 54-148 hours) in adults. The long half-life allows weekly dosing for toxoplasmosis treatment.
Terminal elimination half-life is 3-4 hours in patients with normal renal function, but can be prolonged to 18-24 hours in renal impairment.
Primarily hepatic metabolism; renal excretion accounts for approximately 30% of elimination as unchanged drug and metabolites. Fecal excretion is minimal (<5%).
Renal: 10-20% unchanged; biliary/fecal: minimal; remainder metabolized.
Category C
Category C
Antiprotozoal Agent
Antiprotozoal Agent