Immunologic and therapeutic aspects of ketotifen.

Ketotifen, a benzocycloheptathiophene, possesses asthma-prophylactic and antiallergic activities in a number of in vitro and in vivo systems: prevention of cutaneous and lung anaphylaxis in the rat and guinea pig; inhibition of dermal and bronchial antigen challenges in man; inhibition of mediator release from rat mast cells, human basophils, human neutrophils, and human and guinea pig chopped lung; reduction of human neutrophil activation induced by PAF-acether; functional antagonism of mediator effects in the guinea pig; blockade of H1-receptors and prevention and reversal of beta-adrenergic tachyphylaxis in the rat. These properties make ketotifen suitable for the long-term prophylaxis of bronchial asthma and for the prevention and treatment of other allergic disorders, such as allergic rhinitis and conjunctivitis, food allergy, and urticaria. Oral ketotifen (1 mg twice daily) is particularly convenient in the management of the multiple allergies often encountered in patients with atopy.