Glycopyrronium bromide

Why this drug is interesting

Glycopyrronium and atropine do the same thing at the muscarinic receptor. The difference is entirely structural: atropine is a tertiary amine and lipid-soluble, glycopyrronium is a quaternary ammonium compound carrying a permanent positive charge. Charged molecules do not cross the blood-brain barrier, and they cross the placenta poorly.

Everything clinically useful about glycopyrronium follows from that one fact. Markedly less central anticholinergic effect, so less postoperative confusion in the elderly — the label puts this comparatively rather than absolutely. Minimal mydriasis, so the pupils remain usable as a neurological observation. And a drug that can be given to an obtunded or head-injured patient without removing two of the signs you were relying on.

Licensed indications and dosing

The licence is entirely peri-operative:¹

1. To protect against the peripheral muscarinic actions of anticholinesterases such as neostigmine and pyridostigmine, when reversing residual neuromuscular blockade from non-depolarising relaxants
2. As a pre-operative antimuscarinic to reduce salivary, tracheobronchial and pharyngeal secretions, and to reduce gastric acidity
3. As a pre-operative or intra-operative antimuscarinic to "attenuate or prevent intra-operative bradycardia associated with the use of suxamethonium or due to cardiac vagal reflexes"

Premedication

• Adults and elderly: 200–400 µg IV or IM before induction; alternatively 4–5 µg/kg to a maximum of 400 µg
• Children: 4–8 µg/kg to a maximum of 200 µg IV or IM before induction

Intra-operative use

• Adults and elderly: a single dose of 200–400 µg IV, or 4–5 µg/kg to a maximum of 400 µg. May be repeated if necessary
• Children: a single dose of 200 µg IV, or 4–8 µg/kg

With neostigmine

The fixed combination of glycopyrronium 0.5 mg with neostigmine 2.5 mg per mL exists because the two drugs' onset profiles are unusually well matched — glycopyrronium blocks the bradycardia, salivation and bronchoconstriction that neostigmine would otherwise cause. Compare sugammadex, which reverses aminosteroid blockade by encapsulation and needs no antimuscarinic cover at all.

Bradycardia — an off-label but recommended use

The practical case for it is straightforward. In an elderly patient with symptomatic bradycardia, atropine's central effects — confusion, agitation, urinary retention — are not trivial, and glycopyrronium avoids them. The tachycardia it produces is generally more modest and more gradual.

Airway management and secretions

Glycopyrronium's antisialagogue effect is stronger and longer-lasting than atropine's, which gives it a place in airway management beyond the operating theatre.

• Awake fibreoptic intubation — a dry airway is both easier to see through and more receptive to topical local anaesthetic, which is diluted and washed away by secretions
• Ketamine sedation, where hypersalivation is a recognised effect. Routine co-administration is no longer standard and the evidence for it is weak, but it remains a reasonable option where secretions are problematic
• Palliative care — for respiratory secretions at the end of life, where the inability to cross the blood-brain barrier is again the reason it is preferred over hyoscine hydrobromide

Pharmacology

Mechanism

Competitive antagonism at muscarinic acetylcholine receptors, producing the standard antimuscarinic profile peripherally: increased heart rate through vagal blockade at the sinoatrial and atrioventricular nodes, reduced salivary and bronchial secretion, bronchodilatation, reduced gastrointestinal motility and detrusor relaxation.

Excretion is largely renal and unchanged, so the effect is prolonged in renal impairment.

Cautions and adverse effects

Cautions

• Prostatic hypertrophy, paralytic ileus, pyloric stenosis, closed-angle glaucoma
• Myasthenia gravis — quaternary ammonium compounds in large doses block nicotinic end-plate receptors, and this must be evaluated before administration
• Prolonged QT interval — anticholinesterase–antimuscarinic combinations such as neostigmine with glycopyrronium should be avoided
• Extreme caution in gastro-oesophageal reflux disease, diarrhoea, ulcerative colitis, acute myocardial infarction, thyrotoxicosis, coronary artery disease, arrhythmia, hypertension, heart failure and other conditions characterised by tachycardia
• Increased risk of adverse effects in Down's syndrome, in children and in the elderly

Adverse effects

• Dry mouth — the intended effect, and the commonest complaint
• Tachycardia and palpitations
• Urinary retention
• Constipation and reduced gut motility
• Blurred vision, though far less than with atropine
• Flushing and dry skin

The notable near-absence from that list is the central anticholinergic syndrome. The label puts it comparatively rather than absolutely: glycopyrronium "does not cross the blood-brain barrier" and is therefore "less likely to cause postoperative confusion which is a particular concern in the elderly patients", with "reduced" cardiovascular and ocular effects compared with atropine.¹

Critical appraisal

1. The licence has not kept pace with the practice. A drug that national resuscitation guidance offers as an alternative to atropine for bradycardia, but whose licence covers only peri-operative bradycardia, leaves the emergency clinician using it off-label on the strength of a guideline. That is defensible and should be a conscious decision.
2. The advantage over atropine is real but modest, and is about harm rather than efficacy. There is no evidence that glycopyrronium restores perfusion better. The case is that it does so without adding a delirium to an elderly patient's admission — worth having, but not a reason to prefer it when atropine is what is immediately to hand in a peri-arrest bradycardia.
3. Its most defensible use may be the least dramatic one. Preserving the pupils as a neurological observation in a patient who may need serial assessment is a small, specific and genuinely useful property that gets almost no teaching attention.
4. Routine co-administration with ketamine has quietly been abandoned without much of a formal reckoning. Hypersalivation is real; whether it needs pre-emptive treatment in most procedural sedation is doubtful, and giving a second drug to prevent a nuisance effect of the first is worth justifying rather than assuming.

References

1. 1
   Glycopyrronium Bromide 200 micrograms/ml Solution for Injection — Summary of Product Characteristics, ADVANZ Pharma. electronic Medicines Compendium. Sections 4.1–4.4, 4.8. Verified 24 Aug 2026. Compare Martindale, emc.
2. 2
   Glycopyrronium Bromide and Neostigmine Metilsulfate 0.5mg/2.5mg per ml Solution for Injection — Summary of Product Characteristics. electronic Medicines Compendium
3. 3
   Resuscitation Council UK. Adult advanced life support guidelines, 2025 — bradycardia. resus.org.uk — local copies at lifesupport.resusdoc.uk. Source of the statement that glycopyrronium may be used instead of atropine, and of the high-degree AV block and cardiac transplant warnings.
4. 4
   Glycopyrronium bromide — dosing and safety monograph. BNF, NICE. bnf.nice.org.uk