Fenoterol

Fenoterol is a beta2 adrenergic agonist used primarily in the treatment of asthma and Chronic Obstructive Pulmonary Disease (COPD). It functions by stimulating beta2-adrenergic receptors in the lungs, leading to the relaxation of bronchial muscles and an increase in airway diameter. This action helps alleviate symptoms such as wheezing, coughing, and shortness of breath associated with obstructive airway conditions.

Mechanism of Action

Fenoterol binds to beta2-adrenergic receptors on the smooth muscle cells of the bronchi. Activation of these receptors leads to the conversion of ATP to cyclic AMP (cAMP) via the enzyme adenylate cyclase. Increased levels of cAMP result in bronchial muscle relaxation and bronchodilation. This mechanism is similar to other beta2 agonists, making fenoterol an effective bronchodilator for the management of asthma and COPD symptoms.

Pharmacokinetics

After inhalation, fenoterol begins to exert its effects within minutes, with peak bronchodilation occurring approximately 1.5 to 2 hours post-administration. The duration of action typically lasts for about 3 to 5 hours. Fenoterol is metabolized in the liver and excreted primarily in the urine.

Clinical Use

Fenoterol is used for the relief of bronchospasm in conditions such as asthma and COPD. It is available in various forms, including metered-dose inhalers (MDIs) and nebulizer solutions. Fenoterol can be used for acute symptom relief as well as for prevention of exercise-induced bronchospasm.

Side Effects

Common side effects of fenoterol include tremors, headache, palpitations, and muscle cramps. These are generally mild and transient. However, overuse or misuse of fenoterol can lead to exacerbation of symptoms, potentially leading to severe conditions such as cardiac arrhythmias and decreased blood potassium levels (hypokalemia).

Contraindications

Fenoterol is contraindicated in patients with a history of hypersensitivity to any of its components. Caution is advised in patients with cardiovascular diseases, hyperthyroidism, or diabetes mellitus, as the use of fenoterol may exacerbate these conditions.

Regulatory Status

The use of fenoterol has been subject to regulatory scrutiny due to concerns over its safety profile, particularly in relation to its association with increased risk of asthma-related deaths. In some countries, the availability of fenoterol is restricted or it has been withdrawn from the market.

Conclusion

Fenoterol is a beta2 adrenergic agonist with bronchodilator properties, used in the management of asthma and COPD. While effective in relieving symptoms of airway obstruction, its use must be carefully monitored due to potential side effects and safety concerns.