Also Known As: Salmeterol, Serevent
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 as a dry powder inhaler that releases a powdered form of the drug. Before 2008, it was also available as a metered-dose inhaler (MDI).
It is a long-acting beta-adrenoceptor agonist (LABA), usually prescribed only 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 beclomethasone. 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 salmeterol decreases the number and severity of asthma attacks. However, like all LABA medications, it is not for use for relieving an asthma attack that has already started.
Inhaled salmeterol works like other beta 2-agonists, causing bronchodilation by relaxing the smooth muscle in the airway so as to treat the exacerbation of asthma. The long duration of action occurs by the 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, with the long carbon chain forming an anchor in the membrane. Interestingly, salmeterol binding to the beta-adrenoceptor does not induce desensitisation or internalisation of receptors which may also contribute to its long therapeutic duration of action. 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.