Clinical evaluation of a new orally active anti-anaphylactic compound: ketotifen (HC 20-511) in Japanese adult asthmatics.

The protective effect of ketotifen was examined by an open assessment trial in 261 asthmatics of variable types, a double blind trial comparing ketotifen and inert placebo in 189 asthmatics of extrinsic type including pure atopic asthma and asthma with atopic and infectious components (mixed type or combined type), and a double blind trial comparing ketotifen and disodium cromoglycate (DSCG) by double placebo technique in 132 asthmatics of a pure atopic type. The open clinical assessment trial suggested that ketotifen was most effective in atopic asthmatics having moderate and severe as well as mild asthmatic episodes. Efficacy increased with prolonged administration; 1 mg twice daily was better than a 1 mg daily dose. In the placebo-controlled double blind trial, the efficacy of ketotifen was demonstrated by the reduction of concomitant anti-asthmatic therapy. The results of the double blind trial comparing ketotifen and DSCG are not fully reported. However, preliminary data showed that the efficacy of both drugs was equivalent or that ketotifen was slightly superior to DSCG. Safety of ketotifen was confirmed by the three trials, transient day-time sedation being the major side effect of this agent. In conclusion, ketotifen is a promising drug for the prophylaxis of asthma.