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.