Pulmonology · USMLE Step 1 and Step 2

Anticholinergics - Ipratropium & Tiotropium song

Ipratropium & Tiotropium - Mechanism & Uses, as a song. Hear the short teaser here. The full song is on YouTube and Spotify.

Anticholinergics - Ipratropium & Tiotropium

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Key points in this song10

Ipratropium and tiotropium are competitive antagonists of muscarinic receptors (M1, M2, M3), blocking acetylcholine-mediated bronchoconstriction and reducing secretions in the airway.
Ipratropium is short-acting (4–6 hours) and used for acute COPD exacerbations and as an add-on in severe asthma; tiotropium is long-acting (24 hours, once daily) and used for maintenance therapy in COPD.
Tiotropium selectively dissociates slowly from M3 receptors (kinetic selectivity), prolonging its bronchodilatory effect compared to ipratropium.
Both agents are administered via inhalation, resulting in minimal systemic absorption and a favorable side effect profile compared to systemic anticholinergics.
Primary side effects include dry mouth, urinary retention, constipation, and blurred vision; paradoxical bronchospasm is a rare but high-yield adverse effect to recognize.
Contraindicated in narrow-angle glaucoma and benign prostatic hyperplasia due to anticholinergic effects; if accidental eye exposure occurs, acute angle-closure glaucoma can be precipitated.
Unlike beta-2 agonists, ipratropium and tiotropium do not cause tachycardia, making them preferred bronchodilators in patients with cardiovascular disease or arrhythmias.
Ipratropium is combined with albuterol (Combivent) for synergistic bronchodilation in COPD exacerbations, targeting both cholinergic and adrenergic pathways simultaneously.
Tiotropium reduces COPD exacerbation frequency, improves FEV1, and enhances quality of life but does not alter the long-term decline in lung function (not disease-modifying).
In asthma, tiotropium is FDA-approved as add-on maintenance therapy for patients ≥6 years old with inadequately controlled symptoms despite inhaled corticosteroids and long-acting beta-2 agonists.