Comparative Pharmacology
Head-to-head clinical analysis: SYMADINE versus ZOVIRAX.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SYMADINE versus ZOVIRAX.
SYMADINE vs ZOVIRAX
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
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.
After intracellular phosphorylation to acyclovir triphosphate, selectively inhibits viral DNA polymerase and incorporates into viral DNA, causing chain termination.
100 mg orally every 12 hours; immediate-release formulation.
Herpes simplex: 200 mg orally 5 times daily for 10 days; or 400 mg orally 3 times daily for 5-10 days. Herpes zoster: 800 mg orally 5 times daily for 7-10 days. IV: 5-10 mg/kg every 8 hours for immunocompromised patients with HSV/VZV.
None Documented
None Documented
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.
Terminal elimination half-life is 2.5-3.3 hours in adults with normal renal function; prolonged to 19.5 hours in anuria (creatinine clearance <10 mL/min).
Renal elimination of unchanged drug accounts for approximately 90% of the administered dose. Biliary/fecal excretion is minimal (<5%).
Renal excretion of unchanged drug via glomerular filtration and tubular secretion accounts for 76-82% of elimination; fecal excretion is less than 2%.
Category C
Category C
Antiviral and Antiparkinsonian
Antiviral