Comparative Pharmacology
Head-to-head clinical analysis: ACYCLOVIR versus FOSCAVIR.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ACYCLOVIR versus FOSCAVIR.
ACYCLOVIR vs FOSCAVIR
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Acyclovir is a synthetic nucleoside analog that inhibits viral DNA replication. It is phosphorylated to acyclovir monophosphate by viral thymidine kinase, then converted to acyclovir triphosphate by cellular kinases. Acyclovir triphosphate competes with deoxyguanosine triphosphate for viral DNA polymerase, incorporating into viral DNA and causing chain termination.
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.
400 mg orally twice daily for herpes zoster; 200 mg orally 5 times daily for genital herpes; 5-10 mg/kg intravenously every 8 hours for severe infections.
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.
None Documented
None Documented
Clinical Note
moderateAcyclovir + Teriflunomide
"The serum concentration of Teriflunomide can be increased when it is combined with Acyclovir."
Clinical Note
moderateTizanidine + Acyclovir
"The serum concentration of Acyclovir can be increased when it is combined with Tizanidine."
Terminal elimination half-life is 2.5–3.3 hours in adults with normal renal function; increases to 19.5 hours in anuria.
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.
Renal excretion of unchanged drug via glomerular filtration and tubular secretion accounts for 62-90% of elimination. Fecal elimination is <2%.
Primarily renal excretion (>80% as unchanged drug) via glomerular filtration and tubular secretion; minimal biliary/fecal elimination (<5%).
Category A/B
Category C
Antiviral
Antiviral