Fenoterol: a review of its pharmacological properties and therapeutic efficacy in asthma.

Fenoterol, the 4-hydroxyphenyl derivative of orciprenaline, is a resorcinol derivative with relatively high selectivity for beta2-adrenoceptors. It is active in man after inhalation or oral administration and is indicated in the treatment of bronchospasm associated with asthma, bronchitis and other obstructive airway diseases. Clinical experience has shown that fenoterol is an effective bronchodilator with negligible effects on the cardiovascular system following aerosol administration of usual therapeutic doses. In children, inhaled fenoterol is effective in preventing exercise-induced asthma and administration of the aerosol in young children has been successfully used to terminate acute asthma attacks. In trials in adults, inhaled fenoterol was superior to placebo. In other controlled studies, it showed a tendency to cause a slightly greater maximum improvement in airway function as assessed spirometrically, and to have a longer duration of action than inhaled orciprenaline, salbutamol or terbutaline, although in these trials statistically significant differences were often not found. The onset of maximum effect is less rapid than with isoprenaline but is longer lasting. About 60% of the eventual maximum response to fenoterol is reached in the first few minutes after inhalation. Oral fenoterol is more effective than placebo, ephedrine or orciprenaline, and probably similar to salbutamol and terbutaline. Following usual aerosol doses, side-effects are minimal. Oral administration is associated with a higher incidence of side-effects than inhalation, including fine muscle tremor and tachycardia.