Antiviral agents.

Only a few agents with antiviral activity are available for routine clinical use. Amantadine hydrochloride is effective in the prophylaxis of influenza A. In addition, accumulated evidence shows that amantadine has some therapeutic effect when used early in the course of an influenza A infection. Idoxuridine and adenine arabinoside have found application as topical agents in the treatment of herpes simplex keratitis. Adenine arabinoside has also been approved for the treatment of disseminated infections due to herpes zoster and herpes simplex. Acyclovir sodium has been approved as a topical agent in the treatment of limited mucocutaneous herpes simplex viral infections in immunosuppressed patients and of initial episodes of genital herpes simplex infections in patients with normal immunity. Ribavirin, an experimental agent with a wide spectrum of activity in vitro, has not fulfilled expectations in clinical trials. Because of the eradication of smallpox, methisazone has become obsolete as a prophylactic agent in smallpox.