Fenoterol is a β adrenoreceptor agonist. It is classed as

sympathomimetic Sympathomimetic drugs (also known as adrenergic drugs and adrenergic amines) are stimulant compounds which mimic the effects of endogenous agonists of the sympathetic nervous system. Examples of sympathomimetic effects include increases in hea ...

β₂ agonist and an inhaled bronchodilator asthma medication. Fenoterol is produced and sold by Boehringer Ingelheim as Berotec N and in combination with

ipratropium Ipratropium bromide, sold under the trade name Atrovent among others, is a type of anticholinergic (SAMA: short acting muscarinic antagonist) medication which opens up the medium and large airways in the lungs. It is used to treat the symptoms ...

as Berodual N. It was patented in 1962 and came into medical use in 1971 but, in the 1980s, concerns emerged about its safety and its use being associated with an increased risk of death (see below).

Adverse effects and toxicity

Fenoterol is a short-acting β₂ agonist that also stimulates β₁ receptors. Fenoterol has more cardiovascular toxicity than isoprenaline or salbutamol. Fenoterol was widely used in

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

in the late 1970s and the 1980s until it was removed from the New Zealand drug tariff in 1989 because its introduction and widespread use was associated with an epidemic of asthma deaths. A series of case-control studies demonstrated that asthmatics using fenoterol were more likely to die of asthma compared with controls treated with alternative beta agonists; this risk of asthma deaths was particularly high in severe asthmatics. The mortality rate declined following withdrawal of fenoterol without evidence supporting an alternative explanation for the abrupt rise and fall in asthma deaths. Data did not support confounding by severity as the explanation for the excess mortality. There are alternative short-acting beta agonists that have not been associated with increased mortality e.g.

salbutamol Salbutamol, also known as albuterol and sold under the brand name Ventolin among others, is a medication that opens up the medium and large airways in the lungs. It is a short-acting β2 adrenergic receptor agonist which works by causing rel ...

Stereoisomers

5-(1-Hydroxy-2-ethyl)benzene-1,3-diol is a molecule with two different stereogenic centers. Thus, four

stereoisomer In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in ...

s may exist, the (''R'',''R'')-, (''R'',''S'')-, (''S'',''R'')- and (''S'',''S'')-stereoisomers (see the figure below). Fenoterol is a

racemate In chemistry, a racemic mixture, or racemate (), is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule or salt. Racemic mixtures are rare in nature, but many compounds are produced industrially as racemates. ...

of the (''R'',''R'')- and the (''S'',''S'')-

enantiomer In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ...

s. This racemate is 9 to 20 times more effective, as compared to the racemate of the (''R'',''S'')- and (''S'',''R'')-enantiomers. Fenoterol stereoisomers

References

{{Adrenergic agonists Beta2-adrenergic agonists Resorcinols Substituted amphetamines Phenylethanolamines