Salmeterol

Salmeterol is the first long-acting, selective β2 adrenergic agonist with a slow onset of action.

It is administered by inhalation on a twice-daily regimen for maintenance therapy, nocturnal asthma, and also COPD, usually not used for acute symptoms.

Highly lipophilic hence the longer duration of action of 12 hours or more.

Mechanism of action.

• Acts on beta -2 receptors causing relaxation of bronchial smooth muscles.

Clinical uses.

• Prophylactically in management of nocturnal asthma.
• COPD: reduce breathlessness by preventing expiratory closure of peripheral airways and eliminating the reversible component of airway obstruction.

Adverse effects.

• Nasal congestion, headache, hypertension, and dizziness.
• Urticaria, contact dermatitis, and muscular stiffness.
• High doses cause increased heart rate and cardiac arrhythmias.

Drug interactions.

• Darunavir increases levels of salmeterol by affecting hepatic/intestinal enzyme CYP3A4 metabolism; hence may cause toxicity.

Contraindications.

• Acute asthma and acute episodes of COPD.
• Use caution in patients with cardiovascular disorders, especially coronary insufficiency, cardiac arrhythmias, and hypertension.

Dosage.

• SALMETER, SEROBID 25 µg per metered dose inhaler;2 puffs BD; severe cases 4 puffs BD.