45 Chemotherapy

antiviral drugs

Questions

What are the drug targets for antiviral agents?

What are examples of different classes of antiviral drug?

Viruses are intracellular organisms that invade eukaryotic cells by binding to host membrane structures and replicate by inserting their genetic material into the host’s genome (Fig. 3.45.1). Because viruses share much of the metabolic machinery of the host cell, it is difficult to find drugs that are specific for the virus. Drugs target attachment or entry into host cells, inhibition of viral transcription, protein synthesis and viral exit from cells (Fig. 3.45.2). Certain drugs are specific for a particular virus:

herpes simplex: aciclovir, valaciclovir, penciclovir, famciclovir

varicella-zoster: aciclovir, valaciclovir, famciclovir

cytomegalovirus: aciclovir, valaciclovir, ganciclovir, foscarnet

hepatitis B virus: lamivudine

hepatitis C virus: tribavarin (ribavirin)

HIV: see Ch. 46.

Fig. 3.45.1 Life cycle of a typical virus.

Fig. 3.45.2 Defences against viruses. (A) Host T cell defences; (B) prevention of viral entry or exit from the host cell: (C) interference with viral replication.