Long-acting β2-adrenoceptor agonists,
formoterol and
salmeterol, represent a milestone in the treatments of chronic
obstructive lung diseases. Although no specific indications concerning the choice of one molecule rather than another are provided by
asthma and
COPD guidelines, they present different pharmacological properties resulting in distinct clinical employment possibilities. In particular,
salmeterol has a low intrinsic efficacy working as a partial receptor agonist, while
formoterol is a full agonist with high intrinsic efficacy. From a clinical perspective, in the presence of low β2-adrenoceptors availability, like in inflamed airways, a full agonist can maintain its bronchodilatory and non-smooth muscle activities while a partial agonist may be less effective. Furthermore,
formoterol presents a faster onset of action than
salmeterol. This phenomenon, combined with the molecule safety profile, leads to a prompt amelioration of the symptoms, and allows using this
drug in
asthma as an "as needed" treatment in patients already on regular treatment. The fast onset of action and the full agonism of
formoterol need to be considered in order to select the best pharmacological treatment of
asthma and
COPD.