💊 Long-Acting Muscarinic Antagonists (LAMA)

LAMAs are bronchodilators used in the management of chronic obstructive pulmonary disease (COPD) and some cases of asthma. They belong to the anticholinergic class of drugs.

LAMAs competitively inhibit the action of acetylcholine at M3 muscarinic receptors in the bronchial smooth muscle. This blockade prevents acetylcholine-induced bronchoconstriction, leading to bronchodilation and improved airflow. Their long duration of action allows for once-daily dosing.

The primary indication for LAMAs in the UK is the maintenance treatment of chronic obstructive pulmonary disease (COPD) to reduce symptoms and exacerbations. They are also used as an add-on therapy for severe asthma that remains uncontrolled despite high-dose inhaled corticosteroids and long-acting beta-agonists. Examples include tiotropium, glycopyrronium, and umeclidinium.

Absolute contraindications include hypersensitivity to the active substance or any excipients. Relative contraindications include narrow-angle glaucoma and urinary retention, due to the anticholinergic effects. Caution is also advised in patients with prostatic hyperplasia.

Common adverse effects are typically anticholinergic, such as dry mouth, constipation, and blurred vision. Less common but serious effects can include urinary retention and acute narrow-angle glaucoma, particularly if the nebulised solution comes into contact with the eyes. Tachycardia and palpitations can also occur.

Regular monitoring for the effectiveness of symptom control and any adverse effects is important. Patients should be asked about dry mouth, urinary symptoms, and visual disturbances. Lung function tests (spirometry) may be performed periodically to assess disease progression and treatment efficacy.

Always check for known allergies, especially to other anticholinergics. Counsel patients on the correct inhaler technique and the importance of regular, not 'as needed', use. Warn about potential anticholinergic side effects like dry mouth and advise seeking medical attention for acute eye pain or visual changes.

LAMAs are cornerstone therapy for moderate to severe COPD. They are not for acute relief of bronchospasm. Key side effects are anticholinergic. Tiotropium is a widely used example. Remember the 'M' for muscarinic and 'L' for long-acting.

SBA questions often focus on differentiating LAMAs from LABAs in COPD management, or their role in severe asthma. Traps might involve asking about their use in acute exacerbations (where SAMAs are preferred) or their anticholinergic side effects. Understanding the M3 receptor specificity is also a common theme.