Anticholinergic / Parasympatholytic Pregnancy: Should not be used during pregnancy unless clearly necessary. Rapidly crosses the placenta; IV administration during pregnancy or at term may cause fetal and maternal tachycardia. Small amounts pass into breast milk and may inhibit milk production.

Atropine (Anaesthesia/Bradycardia)

Brand names: Minims Atropine, Atropin

Atropine is an antimuscarinic (anticholinergic) agent used for symptomatic bradycardia, as an antisialagogue to reduce secretions, and as an antidote in organophosphate, carbamate and nerve-agent (cholinergic) poisoning.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 0.3–0.6 mg IV (pre-anaesthetic medication)

Route: IV immediately before surgery; IM 30–60 minutes before surgery is possible

Frequency: single dose before surgery

Max: 3 mg total (adults)

In combination with neostigmine to limit its muscarinic effects: 0.6–1.2 mg IV. Haemodynamically compromising bradycardia/AV block/CPR: sinus bradycardia 0.5 mg IV every 2–5 min until desired heart rate achieved; AV block 0.5 mg IV every 3–5 min (maximum 3 mg). Antidote to organophosphates/cholinesterase inhibitors/muscarinic mushroom poisoning: 0.5–2 mg IV, repeat after 5 min then every 10–15 min as required until signs and symptoms disappear (dose may be exceeded many times). Dosage adjusted to patient response and tolerance; total maximum 3 mg in adults. Presentation is 0.5 mg/5 ml; other strengths may be more appropriate where a dose above 0.5 mg is required.

Paediatric dose

Route: IV (or IM)

Frequency: single dose (pre-anaesthetic / bradycardia); antidote may be repeated

Max: 0.6 mg per dose (paediatric total maximum usually 0.6 mg)

Pre-anaesthetic medication: usual dose 0.01–0.02 mg/kg body weight (maximum 0.6 mg per dose), adjusted to response/tolerance. With neostigmine: 0.02 mg/kg IV. Bradycardia/AV block/CPR: 0.02 mg/kg IV single dose (maximum 0.6 mg). Organophosphate antidote: 0.02 mg/kg, possibly repeated until signs and symptoms disappear. Not appropriate for neonates under 3 kg with the 0.5 mg/5 ml presentation (minimum deliverable 0.5 ml).

Dose adjustments

Renal

Caution advised in patients with renal (or hepatic) impairment and in the elderly (§4.2); no specific numeric dose reduction stated.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

2 DOSAGE & ADMINISTRATION 2.1 General Administration Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Do not administer unless solution is clear and seal is intact. Each vial is intended for single dose only. Discard unused portion. For Intravenous administration. Titrate based on heart rate, PR interval, blood pressure and symptoms. 2.2 Adult Dosage 2.3 Pediatric Dosage Dosing in pediatric populations has not been well studied. Usual initial dose is 0.01 to 0.03 mg/kg. 2.4 Dosing in Patients with Coronary Artery Disease Limit the total dose of atropine sulfate to 0.03 to 0.04 …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2024-01-28. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

Hypersensitivity to atropine or any excipient
Closed-angle glaucoma
Risk of urinary retention due to prostatic or urethral disease
Achalasia of the oesophagus, paralytic ileus, and toxic megacolon
(These contraindications do not apply in life-threatening emergencies such as bradyarrhythmia or poisoning)

Side effects

Dry mouth, difficulty swallowing/talking, thirst
Visual disturbances (mydriasis, inhibition of accommodation, blurred vision, photophobia)
Tachycardia with palpitations and arrhythmias (transient exacerbation of bradycardia may precede)
Reduced bronchial secretion; flushing; anhidrosis
Constipation and reflux; urinary retention

Interactions

Other drugs with anticholinergic activity — tricyclic antidepressants, some H1-antihistamines, antiparkinsonian drugs, disopyramide, mequitazine, phenothiazines, neuroleptics, atropinic antispasmodics, clozapine, quinidine — risk of potentiation of atropinic adverse effects (urinary retention, constipation, dry mouth)

Clinical monograph

How it works

It competitively blocks muscarinic acetylcholine receptors, reducing vagal tone on the heart (increasing rate and AV conduction), drying secretions, and reversing the muscarinic effects of cholinergic excess.

Prescribing in practice

In organophosphate or nerve-agent poisoning, large repeated doses are titrated against secretions and chest signs (the aim is a dry chest), not against heart rate — far more may be needed than for bradycardia.
Predictable antimuscarinic effects include tachycardia, dry mouth, urinary retention, blurred vision with pupil dilatation, flushing and reduced sweating.
Central antimuscarinic toxicity (confusion, agitation, delirium) is common in older people; use cautiously where tachycardia is hazardous, such as acute coronary ischaemia.

Monitoring

Monitor heart rate, rhythm and blood pressure continuously when treating bradycardia; in poisoning, track respiratory secretions, chest auscultation and oxygenation as the endpoint of titration, and watch for urinary retention and confusion.

Counselling the patient

Warn the team and recovery staff to expect a dry mouth, blurred vision, dilated pupils and a faster heart rate.
In conscious patients or carers, advise reporting difficulty passing urine, marked agitation or confusion.
For poisoning, follow Toxbase/NPIS advice and titrate to drying of secretions rather than to a target pulse.

Evidence & guidelines

Recommended for symptomatic bradycardia (Resuscitation Council UK) and as a cholinergic-poisoning antidote (Toxbase/NPIS).

Reference: Resuscitation Council UK ALS Guidelines 2021; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways