Bethanechol
Bethanechol chloride
Also known as: Urecholine · Myotonine · Bethanechol chloride · Betanecol
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Dosing by species
Dosing data for this drug is not yet available in the VetSheet formulary. Every other section below is complete. Consult the current product label before prescribing.
Overview
Bethanechol is a synthetic choline ester and a direct-acting parasympathomimetic (cholinergic) agent.
- Primary Veterinary Use: It is primarily used to stimulate bladder contractions in small animals, making it the drug of choice for treating detrusor atony (a flaccid, overstretched bladder that cannot contract properly). This condition is often secondary to severe overdistension or neurologic disease (e.g., lower motor neuron lesions).
- Clinical Pearl: It is crucial to ensure the urinary sphincter is relaxed before stimulating the bladder to squeeze. Therefore, bethanechol is frequently prescribed alongside alpha-1 antagonists (like prazosin or phenoxybenzamine) or skeletal muscle relaxants (like diazepam) to prevent bladder rupture.
- GI Uses: Historically used as an esophageal or general GI stimulant, though metoclopramide and neostigmine have largely supplanted it for these purposes.
- Pharmacologic Profile: It is highly resistant to hydrolysis by acetylcholinesterase, giving it a significantly longer duration of action compared to natural acetylcholine.
Mechanism of action
Bethanechol directly stimulates muscarinic (M) cholinergic receptors, with a strong affinity for the M3 receptors located on the smooth muscle of the detrusor (bladder wall) and gastrointestinal tract.
- Mechanism Pathway: Binds to M3 receptor → activates Gq-protein → stimulates Phospholipase C (PLC) → increases Inositol triphosphate (IP3) and Diacylglycerol (DAG) → triggers release of intracellular calcium (Ca2+) → smooth muscle contraction.
- Receptor Specificity: At usual therapeutic doses, it has negligible effects on nicotinic receptors, which minimizes skeletal muscle and ganglionic side effects.
- Physiological Effects: Increases detrusor muscle tone, decreases bladder capacity, increases GI peristalsis, and increases gastric/pancreatic secretions.
Safety & warnings
Contraindications
- Bladder neck or urinary outflow obstruction
- Questionable bladder wall integrity (e.g., recent bladder surgery)
- Hyperthyroidism
- Peptic ulcer disease or inflammatory GI lesions
- Recent GI surgery with resections/anastomoses
- GI obstruction or peritonitis
- Hypersensitivity to bethanechol
- Epilepsy
- Asthma
- Coronary artery disease or occlusion
- Hypotension
- Severe bradycardia
- Vagotonia or vasomotor instability
Adverse effects
- Salivation
- Lacrimation
- Urination
- Defecation
- Vomiting
- Diarrhea
- Anorexia
- Bradycardia (high dose/SC)
- Arrhythmias (high dose/SC)
- Hypotension (high dose/SC)
- Asthma/Dyspnea (high dose/SC)
- Abdominal pain (horses)
Precautions
Important Outflow Warning: If urinary outflow resistance is increased due to enhanced urethral tone (not mechanical obstruction), bethanechol should only be used in conjunction with another agent that will sufficiently reduce outflow resistance (e.g., diazepam, dantrolene for striated muscle, or phenoxybenzamine for smooth muscle).
- Route Warnings: IM or IV use is not recommended except in emergencies when the IV route may be used. Severe cholinergic reactions are likely if given IV.
- Antidote Readiness: If injecting the drug (SC or IV), it is highly recommended that atropine be immediately available to treat potential cholinergic crisis.
Drug interactions
Can antagonize bethanechol's effects
Additive toxicity and increased risk of cholinergic crisis
Antagonizes the effects of bethanechol
Monitoring
- Clinical efficacy (successful urination, reduction in residual bladder volume)
- Signs of cholinergic toxicity (SLUD: salivation, lacrimation, urination, defecation)
- Heart rate and rhythm (if given parenterally)
Pharmacokinetics
Absorption
Poorly absorbed from the GI tract. Onset of action is usually within 30-90 minutes after oral dosing. After subcutaneous administration, effects begin within 5-15 minutes and usually peak within 30 minutes. Duration of action after oral dosing may persist up to 6 hours after large doses, and 2 hours after SC dosing.
Distribution
Does not enter the CNS after usual doses; other distribution aspects are not known. It is unknown if bethanechol is distributed into milk.
Metabolism
The metabolic fate of bethanechol has not been described.
Elimination
The excretory fate of bethanechol has not been described.
Overdose
Clinical signs of overdosage are basically cholinergic in nature.
- Mild/Moderate Toxicity: Muscarinic effects (salivation, urination, defecation, vomiting) are usually seen with oral or SC administration.
- Severe Toxicity: If given IM or IV, a full-blown cholinergic crisis can occur, characterized by circulatory collapse, bloody diarrhea, shock, and possible cardiac arrest.
- Treatment: Atropine is the specific antidote for bethanechol toxicity. Epinephrine may also be employed to treat clinical signs of severe bronchospasm.
Available products
Formulations
- Tablets
- Injection
Human-labeled
- Urecholine®
Regulatory status
POM (Prescription Only Medicine)
POM (Prescription Only Medicine)
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Client information
Important: Bethanechol helps your pet's bladder muscle contract so they can urinate properly. It is often used when the bladder has become overstretched or weak.
- Administration: Give exactly as prescribed. Do not increase the dose without consulting your veterinarian.
- What to Watch For: Because this drug stimulates the "rest and digest" system, you might notice side effects commonly remembered by the acronym SLUD (Salivation, Lacrimation/tearing, Urination, Defecation). Mild vomiting or diarrhea can also occur.
- When to Call the Vet: Contact your veterinarian immediately if your pet experiences severe vomiting, diarrhea, excessive drooling, difficulty breathing, or seems unusually weak.
- Safety Warning: Never give this medication if your pet is straining but unable to pass urine (blocked), as forcing the bladder to contract against a blockage could cause severe damage or rupture.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.