Which medications in the drug class Antiviral agents are used in the treatment of Animal Bites in Emergency Medicine?

Updated: Sep 18, 2018
  • Author: Alisha Perkins Garth, MD; Chief Editor: Joe Alcock, MD, MS  more...
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Antiviral agents

These agents inhibit viral replication.

Acyclovir (Zovirax)

Acyclovir is a prodrug activated by phosphorylation by virus-specific thymidine kinase that inhibits viral replication. Herpes virus thymidine kinase (TK), but not host cells' TK, uses acyclovir as a purine nucleoside, converting it into acyclovir monophosphate, a nucleotide analogue. Guanylate kinase converts the monophosphate form into diphosphate and triphosphate analogues that inhibit viral DNA replication.

Acyclovir has affinity for viral thymidine kinase and, once phosphorylated, causes DNA chain termination when acted on by DNA polymerase. It has activity against a number of herpesviruses, including herpes virus B. Acyclovir is primarily available in preparations for oral and intravenous use. Patients experience less pain and faster resolution of cutaneous lesions when used within 48 hours from rash onset. Acyclovir may prevent recurrent outbreaks. Early initiation of therapy is imperative.

Valacyclovir (Valtrex)

Valacyclovir is a hydrochloride salt of the L-valyl ester of acyclovir. It is rapidly converted into acyclovir after prompt absorption from the gut via first-pass intestinal or hepatic metabolism. It is an alternative to acyclovir for prophylaxis (or possibly treatment).

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