RAPID ONSET OF ACTION OF INHALED FORMOTEROL IN ASTHMATIC-PATIENTS

Twelve patients with stable asthma (mean age, 39 years; asthma duration, 11 years; mean forced expiratory volume in 1 s, 65 percent of predicted; and reversibility, 31 percent) were studied in a double-blind crossover trial. The patients were studied during three test days. Airway resistance and specific airway conductance (Raw and SGaw) were measured using a body plethysmograph and pulse rate, blood pressure, tremor, and subjective effects were recorded before and 1, 3, 5, 10, 15, 30, 60, and 120 min after the test doses. A baseline Raw variability of +/-20 percent was allowed between the test days. Formoterol 12-mu-g, 24-mu-g, and terbutaline 500-mu-g were given in a spacer (Nebulator) in a randomized double-blind crossover manner as two puffs with a 30-s interval in between. The effect of formoterol 12-mu-g on Raw was significantly better than terbutaline after 3, 5, 10, 60, and 120 min. Formoterol 24-mu-g was significantly better than terbutaline as soon as 3 min after inhalation and at every point in time after that. Formoterol 24-mu-g tended to be better than formoterol 12-mu-g but the differences were not significant at any point in time. All three treatments were well-tolerated. No differences were observed for pulse rate, blood pressure, tremor, or palpitations. The overall onset of bronchodilatation after formoterol 12 and 24-mu-g was faster than after terbutaline 500-mu-g. The tolerability of formoterol was good.