Comparison of actions of disodium cromoglycate and ketotifen on exercise-induced bronchoconstriction in childhood asthma.

Ketotifen (Zaditen), a benzocycloheptathiophene derivative, is a new oral agent for treating asthma, with action similar in some respects to that of sodium cromoglycate. It is well established that sodium cromoglycate protects against antigen challenge by inhibiting the release of chemical mediators from mast cells. It also inhibits exerciseinduced bronchoconstriction and has bronchodilator properties.' Ketotifen has a similar capacity to inhibit the release of chemical mediators from mast cells.2 Its clinical effectiveness is still uncertain.3