Comparative Pharmacology
Head-to-head clinical analysis: FAMVIR versus SYMADINE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: FAMVIR versus SYMADINE.
FAMVIR vs SYMADINE
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.
SYMADINE (amantadine) is a tricyclic amine that inhibits influenza A virus replication by blocking the viral M2 ion channel, which prevents uncoating of viral RNA. It also increases dopamine release and inhibits dopamine reuptake in the CNS, providing antiparkinsonian effects.
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 every 12 hours; immediate-release formulation.
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).
The terminal elimination half-life is approximately 24 hours in patients with normal renal function. In patients with renal impairment (CrCl <50 mL/min), the half-life is significantly prolonged, requiring dose adjustment. The long half-life allows for once-daily dosing.
Renal: 60–70% as penciclovir via tubular secretion and glomerular filtration; fecal: <10%; biliary: <1%.
Renal elimination of unchanged drug accounts for approximately 90% of the administered dose. Biliary/fecal excretion is minimal (<5%).
Category C
Category C
Antiviral
Antiviral and Antiparkinsonian