Inhibition by ketotifen of idiosyncratic reactions to aspirin.

Ketotifen administered prior to aspirin offered protection against bronchoconstriction in 13 of 14 patients with aspirin-sensitive asthma. In four other subjects, suffering from urticaria/angioedema following ingestion of aspirin-like drugs, pretreatment with ketotifen resulted in total prevention of the adverse reactions. These results support the suggestion of a common pathogenetic mechanism operating in two distinct clinical patterns of idiosyncrasy to aspirin and other cyclo-oxygenase inhibitors. They also indicate that ketotifen might find application in treatment of adverse reactions to aspirin.