Comparative Pharmacology
Head-to-head clinical analysis: DARAPRIM versus PENTAM.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARAPRIM versus PENTAM.
DARAPRIM vs PENTAM
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 nucleotide and nucleic acid synthesis, possibly by binding to DNA and inhibiting RNA and protein synthesis. It also affects membrane integrity and inhibits oxidative phosphorylation.
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 intravenously once daily for 21 days (Pneumocystis jirovecii pneumonia); or 300 mg deep intramuscularly every 3 weeks for prophylaxis.
None Documented
None Documented
Clinical Note
moderatePentamidine + Gatifloxacin
"Pentamidine may increase the hypoglycemic activities of Gatifloxacin."
Clinical Note
moderatePentamidine + Rosoxacin
"Pentamidine may increase the hypoglycemic activities of Rosoxacin."
Clinical Note
moderatePentamidine + Trovafloxacin
"Pentamidine may increase the hypoglycemic activities of Trovafloxacin."
Clinical Note
moderatePentamidine + Nalidixic acid
"Pentamidine may increase the hypoglycemic activities of Nalidixic acid."
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: 6-24 hours (prolonged in renal impairment; up to 48 hours in anuria).
Primarily hepatic metabolism; renal excretion accounts for approximately 30% of elimination as unchanged drug and metabolites. Fecal excretion is minimal (<5%).
Renal: approximately 60-70% unchanged; biliary/fecal: minimal, <10%.
Category C
Category C
Antiprotozoal Agent
Antiprotozoal Agent