Evaluation of isoprinosine in experimental human rhinovirus infection.

The prophylactic efficacy of isoprinosine was evaluated in a double-blind fashion in volunteers challenged with two types of rhinovirus. In the rhinovirus 44 and 32 trials, each of 9 men received a placebo, and eight and 11 men received the drug, respectively. Oral isoprinosine, 6 g a day, was given for 2 days prior to intranasal challenge with 100 mean tissue culture infective doses of the virus and for 7 postchallenge days. In both trials the occurrence and severity of colds were greater in the placebo group, but the difference between the two groups was not significant. Higher antibody titers for both viruses and a greater number of rhinovirus 32 isolations were demonstrated in the drug group but without statistically significant differences. The prophylactic isoprinosine treatment may suppress the cold syndrome, but its effect was not convincingly apparent.