Comparative Pharmacology
Head-to-head clinical analysis: SYMMETREL versus ZOVIRAX.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SYMMETREL versus ZOVIRAX.
SYMMETREL vs ZOVIRAX
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Inhibits influenza A virus uncoating and viral RNA replication; increases dopamine release and blocks dopamine reuptake in the CNS.
After intracellular phosphorylation to acyclovir triphosphate, selectively inhibits viral DNA polymerase and incorporates into viral DNA, causing chain termination.
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.
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
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.
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).
Primarily renal excretion (90-95% unchanged) via glomerular filtration and tubular secretion; minor fecal (<5%). Dose adjustment required in renal impairment.
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