Bronchial reactivity in asthma to inhaled histamine during treatment with ketotifen.

A 12-week open trial using varying dosages of ketotifen, an oral drug with a prophylactic anti-asthmatic effect, was carried out in 20 patients with stable chronic bronchial asthma (age 20--50 years, no steroid treatment) to determine whether the frequency of asthma attacks and bronchodilator consumption could be reduced, and whether pulmonary function would improve. The protective action of ketoifen against a histamine inhalation test was measured at the beginning of the trial and at regular intervals during the trial. The patients experienced a significant improvement in their asthma and a significant decrease in the number of asthma attacks during the trial. Concomitantly, the need for other anti-asthma agents was reduced. Pulmonary function tests improved before and following histamine inhalation after 4, 8 and 12 weeks of treatment. In some patients cromoglycate was successfully replaced by ketotifen. Efficacy was rated as very good or good in 17 patients and moderate in 3 patients. Tolerance was good in all patients, no serious side-effects were observed. Summing up, it may be stated that ketotifen is a compound which by virtue of its activity profile and route of administration offers a new approach to the prophylactic treatment of bronchial asthma.