Therapeutic Effects of Aerosolized Amantadine in Naturally Acquired Infection Due to Influenza A Virus

The effect of small-particle aerosol therapy with amantadine was assessed in a randomized, double-blind study of 20 patients with naturally acquired influenza A virus infection. Aerosol treatments of 20 min with either distilled water or with amantadine hydrochloride (1.0 g/100 ml of distilled water) were given three times a day for four days. The amantadine-treated patients experienced a significantly more rapid resolution of clinical signs and symptoms when compared with placebo-treated patients. The resolution of fever was similar for both groups. Aerosol delivery of amantadine did not affect the frequency of viral isolation from upper respiratory tract secretions but was associated with a trend toward reduced quantity of viral shedding. Serial pulmonary function tests found no important differences between the groups. Amantadine-treated patients experienced a greater frequency of mild local side effects (rhinorrhea, nasal irritation) during aerosol exposures, but aerosol treatments did not cause any apparent decline in pulmonary function.