Oral NAB 365 (clenbuterol) and terbutaline in chronic obstructive lung disease: a double-blind, two-week study

The bronchodilator effects of large oral doses of clenbuterol (30 micrograms, t.i.d.) and terbutaline sulfate (5 mg, t.i.d.) were compared using the forced expiratory volume in one second (FEV1), the specific airway resistance (sRaw) and the maximum expiratory flow at 50% of vital capacity (V50% VC) in a double-blind, two-week study, with groups of 12 patients each. The patients suffered from chronic obstructive lung disease with partially reversible airway obstruction. The bronchodilator actions of the two medications were significant between 30 and 240 minutes after the first administration on day 1 and between 30 and 60 minutes after the first administration on day 14. The administration of hydroxyphenylorciprenaline at 60 min on day 14 produced a significant additional bronchodilating effect over the bronchodilating effects of clenbuterol and terbutaline. The basal values recorded on days 7 and 14 demonstrated a significant improvement of pulmonary function over the basal values on day 1, similar in both groups. No tachyphylaxis to the bronchodilator effect to either drug occurred over the two-week study period. Neither the incidence nor the nature of side effects differed in the two treated groups. No changes in heart rate or blood pressure were noted. No abnormal effects on blood gas tension or laboratory results were observed. It was concluded that oral clenbuterol is about 170 times more potent than oral terbutaline.