Fenoterol is a Beta 2 adrenergic agonist designed to open up the airways to the lungs. It is classed as sympathomimetic beta2 agonist and asthma medication.
Fenoterol is produced and sold by Boehringer Ingelheim as Berotec N and in combination with ipratropium as Berodual N.
Side effects
Fenoterol is a short-acting beta2-agonist, which also stimulates beta1 receptors at doses above the recommended therapeutic doses. It was widely used in New Zealand in the early 1990s but withdrawn from that market because of its association with an excess number of deaths.
It is thought that the association of increased risk of death was because it was typically used in excessively large doses for severe acute asthma attacks in the absence of medical assistance. Instances were known of patients who had used up to 80 puffs before seeking medical attention. Both excessive prescribed doses and patient's excessive self-medication with beta-agonists in acute asthma not responding to usual doses, are now generally recognised as undesirable with all beta-agonist asthma inhalers.
Stereoisomers
5-(1-Hydroxy-2-{[2-(4-hydroxyphenyl)-1-methylethyl]amino}ethyl)benzene-1,3-diol is a molecule with two different stereogenic centers. Thus, four stereoisomers may exist, the (R,R)-, (S,S)-, (R,S)-, and (S,R)-stereoisomers (Scheme). Fenoterol is a racemate of the (R,R)- and the (S,S)-enantiomers. This racemate is 9 to 20 times more effective, as compared to the racemate of the (R,S)- and (S,R)-enantiomers.