Clinical use of antiviral drugs.

Remarkable progress has been made in antiviral chemotherapy. Six approved antiviral drugs are now available for the treatment of various viral infections. Trifluridine, idoxuridine and vidarabine are all effective in patients with herpes keratitis; trifluridine is preferred due to its low toxicity. Acyclovir is the drug of choice in patients with infections due to herpes simplex viruses, including genital herpes, herpes encephalitis, and neonatal herpes, and infections due to varicella-zoster virus. Amantadine is the only drug currently available for prophylaxis and treatment of influenza A, but an investigational drug, rimantadine, appears to be equally effective and less toxic than amantadine. Ribavirin is the most recently approved antiviral agent for the treatment of respiratory syncytial virus infections. Numerous antiviral drugs are being studied in patients with acquired immunodeficiency syndrome. Although currently available drugs have improved our ability to manage a variety of viral illnesses, much needs to be learned about specific dosage guidelines based on the studies of pharmacokinetics, pharmacodynamics, potential adverse effects and viral resistance, and the role of combination therapy to optimize therapy.