Prevention of bronchial hyperreactivity in atopic asthmatics during the period of maximal allergenic risk: a six-month study.

Several different parameters of respiratory functions were measured to determine the hyperreactive bronchial responses to the fog-test of 21 atopic asthmatic subjects (prick test and RAST positive for grasses). Measurements were made before and after three and six months of prophylaxis with 1 mg b.i.d. ketotifen, with the period of the trial (April to September) chosen to correspond to the period of maximal allergen exposure. A further 8-patient control group, without prophylactic treatment, underwent the same fog-test and respiratory function measurements were repeated at the same times. In the ketotifen-treated patients almost total protection against the bronchoreactive response to the fog-test was seen after only three months of treatment (in June). The effectiveness of the treatment was maintained to the same extent throughout the rest of the 6-month trial.