Bethanechol Chloride

Approved Indications:

• Urinary Retention (Non-obstructive)
• Acute or chronic postoperative urinary retention
• Neurogenic bladder (hypotonic or atonic bladder) due to neurologic disorders (e.g., spinal cord injury)
• Postpartum urinary retention
• Gastrointestinal Atony (Off-label use, but clinically accepted):
• Gastroesophageal reflux disease (GERD), particularly with hypomotility component
• Postoperative abdominal distention due to gastric atony or paralytic ileus
• Gastroparesis, including diabetic gastroparesis (limited evidence but sometimes used adjunctively)

Note: Bethanechol is not used for mechanical obstruction of the urinary or gastrointestinal tract.

Route of Administration: Oral

Adult Dosage:

• Urinary Retention:
• Initial dose: 10–50 mg orally, 3–4 times daily (individualized based on response)
• Maximum single dose: 50 mg
• Administer on an empty stomach (1 hour before or 2 hours after meals) to reduce nausea
• Gastrointestinal Atony / GERD (off-label):
• 10–25 mg orally, 3–4 times daily

Pediatric Use:

• Safety and efficacy not well established, but in selected cases:
• Dose based on weight (consult specialist)
• Example: 0.6–2 mg/kg/day in divided doses (oral) under supervision

Elderly:

• Start at lower dose (e.g., 5–10 mg) and titrate carefully
• Monitor for bradycardia and hypotension

Renal/Hepatic Impairment:

• No specific dosage adjustment defined, but use cautiously due to potential accumulation and exaggerated parasympathomimetic effects.

Bethanechol chloride is a direct-acting parasympathomimetic (cholinergic agonist) that selectively stimulates muscarinic receptors (M3 subtype) in the detrusor muscle of the bladder and smooth muscle of the gastrointestinal tract. It mimics the action of acetylcholine without significant effect on nicotinic receptors or central nervous system penetration (due to quaternary ammonium structure). This results in increased tone and contractions of the bladder detrusor and enhanced GI motility, promoting urination and gastric emptying. It has no effect on skeletal muscle or ganglionic transmission.

• Absorption: Incompletely absorbed from the gastrointestinal tract; food delays and reduces absorption
• Onset of Action: 30–90 minutes (oral)
• Peak Effect: 60–90 minutes after administration
• Duration of Action: ~1–6 hours (dose-dependent)
• Distribution: Confined largely to peripheral tissues due to quaternary structure; does not cross the blood-brain barrier
• Metabolism: Not significantly metabolized by cholinesterase enzymes
• Elimination: Primarily renal excretion as unchanged drug
• Half-life: Not well defined due to rapid onset and short duration of action

• Pregnancy:
• Former FDA Pregnancy Category C
• Animal studies have shown adverse fetal effects at high doses.
• Use only when clearly needed, and avoid during late pregnancy due to risk of uterine stimulation.
• Lactation:
• No human data available on excretion in breast milk.
• Because bethanechol has poor systemic absorption and low CNS penetration, the risk is likely low; however, caution is advised.

• Primary Class: Cholinergic Agent (Parasympathomimetic)
• Pharmacologic Subclass: Muscarinic Receptor Agonist (M3 selective)
• Clinical Use Type: Urologic and GI prokinetic agent

• Hypersensitivity to bethanechol or any component of the formulation
• Mechanical obstruction of the urinary tract or gastrointestinal tract
• Recent bladder surgery or bladder wall integrity issues
• Asthma (risk of bronchoconstriction)
• Peptic ulcer disease (stimulates gastric acid secretion)
• Hyperthyroidism (may precipitate atrial fibrillation)
• Epilepsy or Parkinson’s disease (due to pro-convulsive potential)
• Coronary artery disease, bradycardia, hypotension, or AV block
• Peritonitis

• Use cautiously in patients with asthma, cardiovascular disease, or peptic ulcer.
• Can cause bradycardia, hypotension, and bronchospasm; monitor vital signs.
• May precipitate vasovagal syncope in susceptible individuals.
• Should not be used when urinary or GI obstruction is suspected.
• Monitor for signs of cholinergic crisis: excessive salivation, sweating, bronchial secretions, or muscle weakness.
• Overdose may require atropine as an antidote.
• Avoid use with other parasympathomimetics or cholinesterase inhibitors.

Common:

• Gastrointestinal: Abdominal cramps, nausea, vomiting, diarrhea
• Cardiovascular: Hypotension, bradycardia
• Respiratory: Bronchospasm, shortness of breath (especially in asthmatics)
• Ocular: Blurred vision, miosis
• General: Sweating, salivation, flushing, dizziness

Less Common:

• Urinary urgency or incontinence
• Headache
• Lacrimation
• Anxiety

Serious/Rare:

• Syncope due to vagal overactivity
• Bronchoconstriction leading to respiratory distress
• Severe bradycardia or heart block (in predisposed individuals)

Onset & Severity:

• Most effects occur within 30–90 minutes and are dose-related.
• Cholinergic symptoms are usually mild and reversible with dose reduction or discontinuation.

• Other cholinergic agents (e.g., neostigmine, pyridostigmine): Risk of additive parasympathetic effects
• Cholinesterase inhibitors: Enhanced action and risk of cholinergic crisis
• Beta-blockers: Additive bradycardia and hypotension
• Anticholinergic drugs (e.g., atropine, hyoscine): May antagonize bethanechol’s effects
• Ganglionic blockers: Exaggerated hypotension

No CYP450 enzyme involvement noted, and minimal interaction with food/alcohol at therapeutic doses.

• Though rarely included in modern treatment guidelines, bethanechol remains approved for neurogenic bladder and non-obstructive urinary retention, especially in spinal cord injury and post-surgical patients.
• American Urological Association (AUA) and neurology guidelines continue to list bethanechol as an option for bladder atony.
• No major updates from FDA or EMA in recent years.
• Use has declined with availability of newer prokinetic and urologic agents but remains a reliable second-line agent in specialized settings.

• Store tablets at 20°C to 25°C (68°F to 77°F)
• Protect from light and moisture
• Keep in a tightly closed container
• Do not use beyond the expiry date
• Keep out of reach of children