A comparative double-blind study of the bronchodilator effects and side effects of inhaled fenoterol and terbutaline administered in equipotent doses.

Increasing doses of fenoterol and terbutaline were administered by inhaler to 12 stable asthmatics in a double-blind crossover trial. 100 microgram doses of fenoterol were shown to be equal in potency to 250 microgram doses of terbutaline, as measured by increases in forced expiratory volume in the first second (FEV1) and specific airways conductance (sGaw). FEV1 and sGaw remained significantly greater than pretreatment levels up to five hours after both drugs and terbutaline showed a significantly greater effect on FEV1 than fenoterol after four hours suggesting a small but significantly longer duration of activity. Fenoterol used at the dosage of 100 micrograms per puff (half the standard commercially available dose of 200 micrograms per puff) caused significantly more cardiac effects than terbutaline, as measured by the magnitude and duration of increases in heart rate, and the incidence of reported palpitations.