Comparative Pharmacology
Head-to-head clinical analysis: FOSCAVIR versus SYMADINE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: FOSCAVIR versus SYMADINE.
FOSCAVIR vs SYMADINE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Foscarnet is a pyrophosphate analog that selectively inhibits viral DNA polymerase and reverse transcriptase by binding to the pyrophosphate binding site, preventing the cleavage of pyrophosphate from deoxynucleotide triphosphates, thereby inhibiting viral DNA synthesis. It does not require activation by viral thymidine kinase, making it active against acyclovir-resistant HSV and VZV, and ganciclovir-resistant CMV.
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.
Induction: 60 mg/kg IV every 8 hours for 2-3 weeks, then maintenance: 90-120 mg/kg IV once daily. Administer as a 2-hour infusion via central line.
100 mg orally every 12 hours; immediate-release formulation.
None Documented
None Documented
Terminal elimination half-life is approximately 3-5 hours in patients with normal renal function; can extend to 48-120 hours in severe renal impairment (CrCl <20 mL/min), requiring dose adjustment and therapeutic drug monitoring.
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.
Primarily renal excretion (>80% as unchanged drug) via glomerular filtration and tubular secretion; minimal biliary/fecal elimination (<5%).
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