Comparative Pharmacology
Head-to-head clinical analysis: FAMVIR versus ZIRGAN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: FAMVIR versus ZIRGAN.
FAMVIR vs ZIRGAN
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.
Ganciclovir is a synthetic guanine derivative that inhibits cytomegalovirus (CMV) replication by competitively inhibiting viral DNA polymerase (UL54) and by incorporating into viral DNA, causing chain termination. Ganciclovir is phosphorylated to ganciclovir triphosphate by viral thymidine kinase (UL97) in CMV-infected cells.
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.
Instill 1 drop (approximately 0.05 mL) into affected eye(s) 5 times daily (approximately every 3 hours while awake) until corneal ulcer heals, then reduce to 1 drop 3 times daily for 7 days.
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 elimination half-life in patients with normal renal function is approximately 3-4 hours; in renal impairment, half-life may be prolonged up to 30 hours, requiring dose adjustment.
Renal: 60–70% as penciclovir via tubular secretion and glomerular filtration; fecal: <10%; biliary: <1%.
Primarily renal excretion as unchanged drug via glomerular filtration and tubular secretion; >90% of a systemically absorbed dose is recovered unchanged in urine.
Category C
Category C
Antiviral
Antiviral