[Prevention of influenza A. Effectiveness and tolerance of rimantadine hydrochloride]

The prophylactic effectiveness of rimantadine hydrochloride (RH) during an outbreak of influenza A was evaluated in a double-blind study versus placebo (P). After identification of 111 homes with one affected member, 301 household contacts were enrolled and given either RH (151 contacts from 56 households) or a placebo (150 contacts from 55 households). Each treatment was given for ten days. Overall, at least one contact developed influenza in 8 of the 56 RH group households and 19 of the 55 placebo group households (p = 0.013). Numbers of contacts who developed influenza were 8/151 in the RH group and 26/150 in the placebo group. When only the 49 homes where influenza was confirmed by virological studies were considered, these numbers were 4/28 in the RH group and 10/21 in the placebo group (p = 0.011). Adverse effects were seen in 18 of the 151 subjects given RH (11.9 per cent) and 6 of the 150 subjects given the placebo (4 per cent). RH appeared as an effective prophylactic agent in a confirmed influenza A outbreak and was satisfactorily tolerated.