Prevention and treatment of experimental influenza A virus infection in volunteers with a new antiviral ICI 130,685.

The initial prophylactic and therapeutic trials of ICI 130,685 against influenza A virus infection are reported. Prophylaxis with either 200 mg/day (38 volunteers received drug and 40 received placebo) or 100 mg/day (28 volunteers received drug and 28 received placebo) for seven days significantly reduced illness, mean clinical score and nasal secretion weight when volunteers were challenged with 10(4.1) EID50 of influenza virus A/Eng/40/83 (H3N2). Overall, prophylaxis with 200 mg/day and 100 mg/day gave 91% and 72% protection against illness relative to placebo, respectively. In addition, prophylaxis with both regimens for seven days also significantly reduced the number of volunteers who excreted virus. In a therapeutic study, volunteers were inoculated with the same dose of virus and those who developed symptoms which persisted for 6-15 h were treated with 200 mg/day of drug (20 volunteers) or placebo (19 volunteers) for four days. Generally, treatment reduced both the amount of virus excreted and the mean daily clinical score. However, these reductions were only statistically significant (P less than 0.05) on the third day of medication for the amount of virus excreted and on the fourth day of treatment for the mean clinical score. It was concluded that ICI 130,685 is effective in the prevention and treatment of influenza virus infection. An initial tolerance study in 16 volunteers who received either drug (200 mg/day) (8 volunteers) or placebo (8 volunteers) for seven days, indicated that the drug was generally well tolerated. Combining data from all studies, 43% of volunteers who received the drug at the 200 mg/day dosage and 21% who received placebo complained of one or more symptoms. However, symptoms were generally minor and of short duration. At the lower dosage (100 mg/day) the symptoms were qualitatively similar to those reported with placebo.