Ketotifen. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in asthma and allergic disorders.

Ketotifen is an orally active prophylactic agent for the management of bronchial asthma and allergic disorders. Accumulated evidence indicates that after 6 to 12 weeks of administration, ketotifen significantly reduces respiratory symptoms and the need for concomitant antiasthmatic drugs in about 70% and 50%, respectively, of patients with mild to moderate bronchial asthma. However, absolute improvement in lung function is generally slight. Ketotifen also has pronounced antihistaminic and antianaphylactic properties which result in moderate to marked symptom improvement in the majority of patients with atopic dermatitis, seasonal or perennial rhinitis, allergic conjunctivitis, chronic or acute urticaria or food allergy. Comparative trials with established agents--notably sodium cromoglycate (cromolyn sodium) in asthma and histamine H1-antagonists in allergic disorders--indicate that ketotifen has comparable clinical utility. Unlike inhaled sodium cromoglycate, ketotifen ameliorates the symptoms of asthma, rhinitis and dermatitis when present together in atopic patients. Patient acceptance of ketotifen is good, although sedation can be troublesome in older children and adults for the initial 2 weeks of treatment. Weight gain is another notable effect in a small percentage of patients. Thus, ketotifen appears to be a useful agent for the management of allergic disorders and bronchial asthma, particularly in patients for whom oral therapy is preferred. Although a lengthy run-in period is needed in the treatment of asthma, in those patients who respond, continued reduction in the frequency and severity of symptoms and in the use of additional antiasthmatic drugs can be anticipated.