ipratropium

Antimuscarinic bronchodilators· Brands: Atrovent, Atrovent HFAINHNEB

Mechanism of action

Ipratropium is a quaternary ammonium antimuscarinic agent. It competitively blocks muscarinic acetylcholine receptors (particularly M3) in bronchial smooth muscle, inhibiting parasympathetic bronchoconstriction. This results in bronchodilation and reduced airway secretions. It is not a sympathomimetic and does not stimulate beta receptors.

Pharmacokinetics

After inhalation, ipratropium is poorly absorbed systemically; most of the dose remains in the lung and is swallowed. Systemic bioavailability is low (approximately 2% to 10%). It is partially metabolized in the liver, and the majority is excreted unchanged in faeces, with some renal excretion. Onset of bronchodilation is 15 to 30 minutes, peaking at 1 hour, and lasting 4 to 6 hours.

Indications & dosing

COPD, maintenance bronchodilation

Metered-dose inhaler (MDI) 20 mcg per puff. Also available as nasal and nebule formulations.

adult · INH: 40–80 mcg TID-QID · Metered-dose inhaler (MDI) 20 mcg per puff. Also available as nasal and nebule formulations.

Acute severe asthma, adjunct to beta-agonist

Nebulised ipratropium, typically combined with salbutamol. Repeat up to 3 doses in acute exacerbation.

adult · NEB: 500 mcg Q20MIN PRN · Nebulised ipratropium, typically combined with salbutamol. Repeat up to 3 doses in acute exacerbation.

Rhinorrhoea in allergic or non-allergic rhinitis

Intranasal spray, 20 mcg per spray. Two sprays per nostril.

adult · TOP: 80 mcg BID-TID · Intranasal spray, 20 mcg per spray. Two sprays per nostril.

Contraindications & precautions

Hypersensitivity to ipratropium bromide, atropine or its derivatives · Cross-sensitivity with atropine and related antimuscarinics is possible.
Known hypersensitivity to soya lecithin or peanuts · Applies to formulations containing soya lecithin, such as the dry powder inhaler.
Avoid contact with the eyes; if accidental ocular exposure occurs, seek medical advice.
Use with caution in patients with narrow-angle glaucoma, prostatic hyperplasia, or bladder neck obstruction.
Use with caution in patients with cardiovascular disease, as antimuscarinics may cause tachycardia and palpitations.
Instruct patients on correct inhaler technique to minimize the risk of ocular deposition.

Adverse effects

Dry mouth
Headache
Cough
Dizziness
Paradoxical bronchospasmserious
Worsening of narrow-angle glaucomaserious
Anaphylaxisserious
Urinary retentionserious

Monitoring, pregnancy & toxicity

Symptom control (e.g., shortness of breath, wheezing) · At each review
Lung function (e.g., peak expiratory flow) · Periodically according to clinical need
Adverse effects (e.g., dry mouth, blurred vision, paradoxical bronchospasm) · At each review
Pregnancy: Ipratropium is generally considered compatible during pregnancy. Inhaled administration results in minimal systemic absorption, so the risk to the fetus is low. Use only if clearly needed, with clinical assessment.
Toxicity: Dry mouth, blurred vision, and other anticholinergic effects · Supportive care; discontinue drug; monitor for resolution.
Toxicity: Tachycardia and palpitations · Monitor heart rate; supportive care; treat if symptomatic.
Toxicity: Urinary retention or constipation · Monitor; catheterisation may be required if retention occurs; laxatives for constipation if severe.

Clinical notes

Ipratropium is used for the symptomatic relief of bronchospasm in COPD and asthma, including acute exacerbations. It is often combined with a short-acting beta2 agonist (e.g., salbutamol) in nebulised form for acute severe asthma. It is not first-line for long-term control but may be added. Caution in patients with narrow-angle glaucoma, prostate enlargement, or bladder outflow obstruction. Adverse effects include dry mouth, cough, and paradoxical bronchospasm.

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BNF; local formulary