Comparative Pharmacology
Head-to-head clinical analysis: FAMVIR versus SYMMETREL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: FAMVIR versus SYMMETREL.
FAMVIR vs SYMMETREL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Famciclovir is a prodrug that is rapidly converted to penciclovir, which inhibits viral DNA polymerase by competing with deoxyguanosine triphosphate, thereby inhibiting viral DNA synthesis and replication.
Inhibits influenza A virus uncoating and viral RNA replication; increases dopamine release and blocks dopamine reuptake in the CNS.
250 mg orally three times daily for 7 days for herpes zoster; 125 mg orally twice daily for 5 days for recurrent genital herpes; 250 mg orally twice daily for 7 days for first-episode genital herpes; 500 mg orally twice daily for 7 days for herpes zoster in immunocompromised patients; 500 mg orally twice daily for 7 days for recurrent mucocutaneous herpes in HIV patients.
100 mg orally twice daily; may increase to 200 mg orally twice daily if tolerated, usually in divided doses. For Parkinson's disease, 100 mg orally twice daily; for drug-induced extrapyramidal reactions, 100 mg orally twice daily.
None Documented
None Documented
Terminal elimination half-life of penciclovir is approximately 2–3 hours in patients with normal renal function; extends to 9–18 hours in severe renal impairment (CrCl <30 mL/min).
Terminal half-life: 24-48 hours (young adults); 48-72 hours (elderly); may extend to 7-10 days in severe renal impairment. Clinically, steady-state achieved in 4-7 days.
Renal: 60–70% as penciclovir via tubular secretion and glomerular filtration; fecal: <10%; biliary: <1%.
Primarily renal excretion (90-95% unchanged) via glomerular filtration and tubular secretion; minor fecal (<5%). Dose adjustment required in renal impairment.
Category C
Category C
Antiviral
Antiviral and Antiparkinsonian