On Oct 18, 1966, the US Food and Drug Administration approved the antiviral drug, amantadine hydrochloride, for prescription use—a decision that, although it has been welcomed by some, has been severely criticized by others.1 The only indication for the use of this drug is in the prophylaxis of influenza due to A2 virus strains. Amantadine has no therapeutic properties, and it is ineffective once the virus has penetrated the host cell.
In the criticisms that followed this action of the FDA, questions were raised concerning not only the utility of the drug but also the investigative data on which the approval was based. Many of the questions are amply justified, and perhaps only time and the results of future, controlled clinical observations can provide definitive answers to all of them. Nevertheless, the available evidence indicates that this drug offers an additional means for reducing the morbidity due to influenza