Formoterol

Formoterol is a prescription drug used to treat asthma and chronic obstructive pulmonary disease (COPD). It belongs to a family of anti-asthma drugs called beta-2 agonists. Other members of this family are reproterol (Bronchodil) and salmeterol (Serevent) . These drugs relieve the airway constriction characteristic of asthma and COPD by activating beta-2 receptors. The U.S. Food and Drug Administration approved formoterol in February 2001.

This is a diagram of the lungs and the airways. Formoterol widens the trachea, bronchi, and bronchioles by stimulating beta-2 receptors located on the smooth muscle cells of these airways. Source: Wikimedia Commons

Other Names

Formoterol has several trade names:

• Foradil or Foradile, marketed by Schering-Plough and Novartis
• Oxis, marketed by AstraZeneca
• Perforomist, marketed by Dey

Uses

Formoterol has several uses:

• maintenance treatment of asthma and the prevention of bronchospasm (intermittent constriction of bronchi, or airways) in adults and children five years of age and older with reversible obstructive airways disease
• the prevention of exercise-induced bronchospasm (EIB) in adults and children five years of age and older
• maintenance treatment of bronchoconstriction (constriction of the airways) in people with COPD

Formoterol is typically used in combination with other drugs when other treatments are ineffective.

How Formoterol is Taken

Formoterol is provided in 12-μg capsules. Dry-powder inhaler, metered dose inhaler, and inhaled solution formulations are available. The capsules are designed to only be inhaled (see video below).

Maintenance treatment of asthma

For adults and children five years of age and older, the usual dosage is inhalation of the contents of one capsule every 12 hours.

Prevention of EIB

For adults and children five years of age or older, the usual dosage is inhalation of the contents of one capsule at least 15 minutes before exercise.

Maintenance treatment of COPD

The usual dosage for COPD is inhalation of the contents of one capsule every 12 hours.

How Formoterol Works

Bronchodilation, or widening of the airways, is caused by activation of beta-2 receptors in the smooth muscle cells lining the airways of the lung. Formoterol is a beta-2 agonist. Inhaled formoterol acts specifically on beta-2 receptors in the lungs to relax the smooth muscles and widen the airways.

Formoterol is a long-lasting beta-2 agonist. Its effects can last 12 hours; the action of some short-acting beta-2 agonists last for 4–6 hours. Formoterol has an extended duration of action because it accumulates within the membranes of lung cells and slowly diffuses out to the surface of the membranes where it can come into contact with beta-2 receptors.

How the Body Affects Formoterol

Following inhalation, formoterol is rapidly absorbed into the bloodstream, reaching peak circulating levels within five minutes of dosing. The half-life of formoterol, or time needed for the concentration in the blood to be reduced by half, is approximately ten hours. Four liver enzymes (CYP2D6, CYP2C19, CYP2C9 and CYP2A6) are involved in the metabolism of formoterol. Approximately 60% of the original dose is eliminated in the urine, and approximately 33% in the feces.

Side Effects

The most common side effects of formoterol are the following:

• viral infection
• bronchitis
• chest infection
• shortness of breath
• chest pain
• tremor
• dizziness
• insomnia
• tonsillitis
• rash
• hoarse voice

Risks and Precautions

Long-acting beta-2 agonists may paradoxically increase the risk of asthma-related symptoms and even death. It is for this reason that the drug is used only as an additional therapy for people not adequately controlled on other medications.

Drug Interactions

Formoterol, like other beta-2 agonists, cannot be used in combination with monamine oxidase inhibitors (MAOIs), tricyclic antidepressants, or other drugs known to prolong the QTc interval (a measure of heart rhythm). Formoterol, at doses several times higher than those used medicinally, may increase the QTC interval as well. Drugs that prolong the QTc interval have a higher propensity of causing heart arrhythmias.

Beta-blockers like metoprolol (Toprol) block the same receptors to which formoterol bind. The interaction between these drugs may produce severe bronchospasm in asthmatic patients. Therefore, formoterol is given in combination with beta-blockers only in people with asthma who absolutely require the combination.

Research

Several studies have shown the effectiveness of formoterol.^[1] The effectiveness of beta-2 agonists like formoterol is measured by the degree and duration of bronchodilation. Often this involves the forced expiratory volume (fev) measurement, which is the amount of air that is expelled during a breath.

Pediatric asthma trial

A study compared formoterol twice daily to placebo in a total of 518 children with asthma (ages 5–12 years) who required daily bronchodilators and anti-inflammatory treatment. Formoterol had a greater 12-hour bronchodilation compared to placebo on the first day of treatment, after 12 weeks of treatment, and after one year of treatment.

EIB trial

Four studies comparing Foradil and albuterolto placebo were conducted in a total of 77 patients (ages 4–41 years) with EIB. Formoterol and albuterol were each superior to placebo for FEV1 measurements obtained 15 minutes after inhalation. Formoterol 12 mcg also maintained superiority over placebo at 4, 8, and 12 hours after administration.

Adult COPD trials

In two trials with COPD patients, formoterol was shown to cause significant bronchodilation within five minutes of oral inhalation of the first dose. Bronchodilation was maintained for at least 12 hours after inhalation. The end results showed that formoterol taken twice daily resulted in significantly greater bronchodilation compared to placebo when evaluated after 12 weeks of treatment in both trials.

References

1. ↑ DailyMed Web site. foradil (formoterol fumarate) capsule [Schering Corporation]]

External Links

FDA: Patient Information Sheet