Muscarinic Agonist

Bethanechol

Brand names: Myotonine

Bethanechol is a muscarinic cholinergic agonist used to stimulate bladder emptying in urinary retention without obstruction.

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: Usual adult oral dose 10 mg to 50 mg three or four times a day

Route: Oral — preferably given when the stomach is empty (nausea and vomiting may occur if taken soon after eating)

Frequency: Three or four times a day

Max: During initial titration, 50 mg is the maximum stated to be given while determining the minimum effective dose (no separate maximum daily dose is stated in the label)

Dosage must be individualised, depending on the type and severity of the condition to be treated. The minimum effective dose is determined by giving 5 mg to 10 mg initially and repeating the same amount at hourly intervals until a satisfactory response occurs, or until a maximum of 50 mg has been given. Effects sometimes appear within 30 minutes and are usually maximal within 60 to 90 minutes; drug effects persist for about one hour. If necessary, the effects can be abolished promptly by atropine. NO UK SPC (eMC) RECORD WAS FETCHED for this drug — the figures above come from the US prescribing information for bethanechol chloride tablets (Heritage Pharma Labs / Avet Pharmaceuticals, label date 2025-10-27) and must be verified against UK labelling before use. The fetched label contains no interactions, no pregnancy/lactation and no paediatric dosing section, so those fields are omitted; there is no per-kg paediatric dose in the source, hence paedDose is null and any under-18 use must be checked against a children's formulary.

Dose auto-extracted from 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.

Contraindications

Hypersensitivity to bethanechol chloride tablets
Hyperthyroidism
Peptic ulcer
Latent or active bronchial asthma
Pronounced bradycardia or hypotension, vasomotor instability, coronary artery disease
Epilepsy and parkinsonism
When the strength or integrity of the gastrointestinal or bladder wall is in question, or in the presence of mechanical obstruction; when increased muscular activity of the gastrointestinal tract or urinary bladder might prove harmful, such as following recent urinary bladder surgery or gastrointestinal resection and anastomosis, or when there is possible gastrointestinal obstruction
Bladder neck obstruction, spastic gastrointestinal disturbances, acute inflammatory lesions of the gastrointestinal tract, or peritonitis
Marked vagotonia

Side effects

Digestive: abdominal cramps or discomfort, colicky pain, nausea and belching, diarrhoea, borborygmi, salivation
Renal: urinary urgency
Cardiovascular: a fall in blood pressure with reflex tachycardia, vasomotor response
Respiratory: bronchial constriction, asthmatic attacks
Skin and special senses: flushing with a feeling of warmth, sensation of heat about the face, sweating, lacrimation, miosis; headache and malaise
Adverse reactions are rare following oral administration but are more common following subcutaneous injection, and are more likely when dosage is increased

Clinical monograph

How it works

It directly stimulates muscarinic receptors on the detrusor muscle, increasing bladder smooth muscle tone and contraction to promote voiding.

Prescribing in practice

Contraindicated where increased cholinergic activity is hazardous, including mechanical bladder outflow or gastrointestinal obstruction, and in asthma, peptic ulcer disease and certain cardiac conditions.
Cholinergic adverse effects such as sweating, salivation, bradycardia, abdominal cramps and bronchospasm can occur.
Atropine should be available to reverse severe cholinergic reactions.

Monitoring

Monitor heart rate, gastrointestinal and respiratory symptoms, and bladder response to treatment.

Counselling the patient

Report sweating, flushing, cramping, breathlessness or palpitations.
Take on an empty stomach to reduce nausea and vomiting.

Evidence & guidelines

Use reflects established cholinergic pharmacology and the SPC; mechanical obstruction must be excluded before treatment.

Reference: 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.

Pathways