Formoterol (INN) or eformoterol (former BAN) is a long-acting β2 agonist used in the management of asthma and chronic obstructive pulmonary disease (COPD). It is marketed in four forms: a dry-powder inhaler, a metered-dose inhaler, an oral tablet, and an inhalation solution, under various trade names including Foradil/Foradile (Schering-Plough in the U.S., Novartis rest of world),"'Forpack Discair"' (Neutec inhaler),Oxeze/Oxis, and (with Budenoside) Symbicort (AstraZeneca), Atock (Astellas), Atimos (Modulite) (Chiesi), and Perforomist (Dey).
Formoterol is a long-acting β2 agonist (LABA) that has an extended duration of action (up to 12 hours) compared to short-acting β2 agonists such as salbutamol, which are effective for 4â€"6 hours. LABAs such as formoterol are used as "symptom controllers" to supplement prophylactic corticosteroid therapy (e.g., fluticasone). A "reliever" short-acting β2 agonist (e.g., salbutamol) is still required, since LABAs are not recommended for the treatment of acute asthma.
Mechanism of action
Inhaled formoterol works like other β2 agonists, causing bronchodilation by relaxing the smooth muscle in the airway so as to treat the exacerbation of asthma. The long duration of formoterol action occurs because the formoterol molecules initially diffuse into the plasma membrane of the lung cells, and then are slowly released back outside, where they can come into contact with β2 adrenergic receptors. Formoterol has been demonstrated to have a faster onset of action than salmeterol as a result of lower lipophilicity, and has also been demonstrated to be more potent â€" a 12 µg dose of formoterol has been demonstrated to be equivalent to a 50 µg dose of salmeterol.
Safety
In November 2005, the US FDA released a health advisory alerting the public to findings that show the use of long-acting β2 agonists could lead to a worsening of wheezing symptoms in some patients.
At the current time, available long-acting β2 agonists include salmeterol, formoterol, bambuterol, and sustained-release oral salbutamol. Combinations of inhaled steroids and long-acting bronchodilators are becoming more widespread â€" combination preparations include fluticasone/salmeterol and budesonide/formoterol.
Additional potential uses
β2 agonists in treatment of obesity
β2 agonists increase energy utilization and fat metabolism, however, therepeutic use for obesity has been limited by the concomitant activation of β1 receptors resulting in excessive increases in heart rate. A recent 2012 dose-finding study (in healthy men) demonstrated significantly increased resting energy expenditure, and fat oxidation at a dose of 160 μg of formoterol per day without significantly increased heart rate. Formoterol's specificity for the β2 receptor (relative to β1 receptors) may facilitate its use for this purpose. A combination of a highly selective β2 agonist like formeterol with a low dose highly selective β1 blocker may further improve the differential therapeutic ability to selectively agonize β2 receptors for metabolic benefits in treating obesity without adverse β1 agonist effects.
Stimulation of mitochondrial biogenesis
Formoterol may also help stimulate mitochondrial biogenesis. Mitochondrial dysfunction is related to many degenerative diseases â€" particularly neurodegenerative disorders.
Treatment for Down syndrome
Preliminary research offers hope that formoterol may be a useful treatment in Down syndrome. In a mouse model of the disease, the drug strengthened nerve connections in the hippocampus, a brain center used for spatial navigation, paying attention and forming new memories.
See also
- Arformoterol
- Budesonide/formoterol