Fenoterol is a β₂-adrenergic receptor agonist and

bronchodilator A bronchodilator or broncholytic (although the latter occasionally includes secretory inhibition as well) is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lun ...

medication used in the treatment of

asthma Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wh ...

. Fenoterol is produced and sold by

Boehringer Ingelheim C.H. Boehringer Sohn AG & Co. is the parent company of the Boehringer Ingelheim group, which was founded in 1885 by Albert Boehringer (1861–1939) in Ingelheim am Rhein, Germany. As of 2018, Boehringer Ingelheim is one of the world's List of la ...

as Berotec N and in combination with

ipratropium Ipratropium bromide, sold under the trade name Atrovent among others, is a type of anticholinergic medication which is applied by different routes: inhaler, nebulizer, or nasal spray, for different reasons. The inhalant opens up the medium ...

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.

Adverse effects

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 () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

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 In causal inference, a confounder is a variable that influences both the dependent variable and independent variable, causing a spurious association. Confounding is a causal concept, and as such, cannot be described in terms of correlatio ...

by severity as the explanation for the

excess mortality In epidemiology, the excess deaths or excess mortality is a measure of the increase in the number of deaths during a time period and/or in a certain group, as compared to the expected value or statistical trend during a reference period (typicall ...

. 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 that causes relaxation of ...

lbuterol.

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 a mixture that has equal amounts (50:50) 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 r ...

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

enantiomer In chemistry, an enantiomer (Help:IPA/English, /ɪˈnænti.əmər, ɛ-, -oʊ-/ Help:Pronunciation respelling key, ''ih-NAN-tee-ə-mər''), also known as an optical isomer, antipode, or optical antipode, is one of a pair of molecular entities whi ...

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 Tocolytics