Salmeterol is a long-acting beta2-adrenergic receptor agonist drug that is currently prescribed for the treatment of asthma and chronic obstructive pulmonary disease COPD. It is currently available in both dry-powder inhalers (DPIs) and pressurised metered dose inhalers (pMDIs).
It is a long acting beta-adrenoceptor agonist (LABA), usually only prescribed for severe persistent asthma following previous treatment with a short-acting beta agonist such as salbutamol and is prescribed concurrently with a corticosteroid, such as beclometasone. The primary noticeable difference of salmeterol to salbutamol is that the duration of action lasts approximately 12 hours in comparison with 4-6 hours of salbutamol.
When used regularly every day as prescribed, inhaled formoterol decreases the number and severity of asthma attacks. However, it is not for use for relieving an asthma attack that has already started.
Inhaled salmeterol works like other beta 2-agonists, causing bronchodilatation by relaxing the smooth muscle in the airway so as to treat the exacerbation of asthma. The long duration of formoterol action occurs by the formoterol molecules initially diffusing into the plasma membrane of the lung cells, and then slowly being released back outside the cell where they can come into contact with the beta-2 adrenoceptors. Formoterol has been demonstrated to have a faster onset of action than salmeterol as a result of a lower lipophilicity, and has also been demonstrated to be more potent—a 12 µg dose of formoterol has been demonstrated to be equivalent to a 50 µg dose of salmeterol.
Salmeterol was developed by the company GlaxoSmithKline in the 1980s and was released as Serevent in 1990.
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