A multicenter trial of the prophylactic effect of ketotifen, theophylline, and placebo in atopic asthma.

Three hundred seventy-four patients with asthma were entered into a year-long, double-blind, double-placebo controlled study comparing the prophylactic effect of ketotifen (229 patients), theophylline (73 patients), and placebo (72 patients). The ketotifen group was larger to allow the accumulation of additional long-term safety data. The primary measure of therapeutic effect was a decrease in concomitant medication without a significant increase in symptomatology or a decrement in pulmonary functions. A patient daily diary was used to document symptoms (cough, shortness of breath, and wheeze) and concomitant medications taken during the 2-week baseline and the subsequent 12 monthly periods. After 2 months of study-drug therapy, the ketotifen patients had a greater decrease in both concomitant medication and symptomatology than either of the other groups. This delay in the onset of therapeutic activity has been observed in other studies and is characteristic of this compound. The principal side effect observed with ketotifen is initial sedation, which was found to be self-limiting and of little concern to the patient after the first month.