Pharmacology · Inhaled antimuscarinics
Tiotropium bromide !
A long-acting inhaled antimuscarinic used once a day in COPD. It keeps the airways open and reduces flare-ups; it is not a reliever.
Updated 2026-11-01
The figure shows tiotropium bound to the rat M3 muscarinic receptor; no human M3 structure with tiotropium exists, and the binding pocket is highly conserved.
Mechanism of action
Tiotropium binds all five muscarinic receptor subtypes but leaves M3 and M1 very slowly and M2 quickly. Blocking M3 on airway smooth muscle removes vagal bronchoconstriction for about a day. Because it spares the M2 autoreceptor, which normally limits acetylcholine release, it avoids a rebound in acetylcholine that would oppose the M3 block.
- Tiotropium binds the M3 receptor of bronchial smooth muscle
- It dissociates very slowly, so the block lasts about a day
- Vagal bronchoconstriction falls and air trapping decreases
- Lung function improves and COPD flare-ups become fewer
Pharmacokinetics
- Absorption
- Acts locally; little reaches the blood after inhalation
- Distribution
- Does not readily cross the blood-brain barrier
- Elimination
- Largely through the kidneys; exposure rises in moderate to severe kidney disease
- Half-life
- Long terminal half-life, about 25 hours in COPD
Indications
- Long-term maintenance treatment of bronchospasm in COPD and reduction of exacerbations Chronic obstructive pulmonary disease (COPD) →
- Add-on maintenance treatment in severe asthma Asthma →
Adverse effects
Common
- Dry mouth
- Upper respiratory infection, sinusitis and pharyngitis
- Constipation and dyspepsia
- Urinary tract infection
Contraindications
- Hypersensitivity to tiotropium, ipratropium or a component of the product
- Not for acute symptoms (it is not a rescue medicine)
- Caution in narrow-angle glaucoma, urinary retention, moderate to severe kidney disease and severe milk-protein allergy (powder capsules)
Key interactions
- Other anticholinergic drugs, including ipratropium
- Additive anticholinergic effects; combination is avoided
What is monitored
- Symptoms, lung function and exacerbation frequency
- Anticholinergic effects in kidney disease
- Eye symptoms and urinary retention
Administration and safety
- Oral inhalation only: the powder capsules are placed in their own inhaler device and must never be swallowed
- Capsules stay in the blister until just before use; capsules exposed to air are discarded
- Care is taken that the powder or spray does not reach the eyes
- Unlike steroid inhalers, rinsing the mouth afterwards is not required
Nursing care
- Check that the patient uses the device correctly and does not swallow the capsules
- Ask about eye pain, blurred vision and difficulty passing urine
- Teach that it is a daily maintenance medicine and that a short-acting reliever is used for sudden symptoms
- In kidney disease, watch for dry mouth, constipation and urinary retention
Pregnancy and breastfeeding
Human data are limited and insufficient to show a drug-related risk; animal studies showed no malformations.
Test yourself
Think of the answer, then tap the question to see it.
What gives tiotropium its long duration of action?
It dissociates very slowly from M3 (and M1) receptors, so a single daily inhalation blocks them for about a day.
What is tiotropium's kinetic selectivity, and why does it matter?
It leaves M2 receptors quickly but M3 slowly, so it spares the M2 autoreceptor that limits acetylcholine release.
Can tiotropium be used to relieve a sudden attack?
No. It is a maintenance bronchodilator; a short-acting beta-2 agonist relieves acute symptoms.
What is the commonest adverse effect of tiotropium?
Dry mouth.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - TIOTROPIUM BROMIDE capsule (DailyMed (U.S. National Library of Medicine), 2025); Tiotropium inhalers: a medicine to treat asthma and COPD - NHS (NHS, 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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Representative model, for educational purposes only.