BETHANECHOL CHLORIDE

(be-than'e-kole)

Duvoid, Urecholine
Classifications: direct-acting cholinergic agent;
Therapeutic: cholinergic
Pregnancy Category: C

Availability

5 mg, 10 mg, 25 mg, 50 mg tablets

Action

Synthetic choline ester with effects similar to those of acetylcholine (ACh). Acts directly on postsynaptic receptors, and since it is not hydrolyzed by cholinesterase, its actions are more prolonged than those of ACh. Produces muscarinic effects primarily on GI tract and urinary bladder. Increases tone and peristaltic activity of esophagus, stomach, and intestine; contracts detrusor muscle of urinary bladder, usually enough to initiate micturition.

Therapeutic Effect

Bethanechol is a synthetic parasympathomimetic indicated for the treatment of urinary retention associated with neurogenic bladder.

Uses

Acute postoperative and postpartum nonobstructive (functional) urinary retention, and for neurogenic atony of urinary bladder with retention.

Unlabeled Uses

In selected cases of adynamic ileus, gastric atony and retention, reflux esophagitis, congenital megacolon, familial dysautonomia; for prevention and treatment of bladder and salivary gland inhibition induced by tricyclic antidepressants, and for prophylaxis and treatment of phenothiazine-induced bladder dysfunction.

Contraindications

COPD; history of or active bronchial asthma; hyperthyroidism; recent urinary bladder surgery, cystitis, bacteriuria, urinary bladder neck or intestinal obstruction, peptic ulcer, recent GI surgery, peritonitis; marked vagotonia, pronounced vasomotor instability, AV conduction defects, severe bradycardia, hypotension or hypertension, coronary artery disease, recent MI; epilepsy, parkinsonism; pregnancy (category C), lactation, children <8 y.

Cautious Use

Urinary retention; bacteriemia; patients at risk for syncopy.

Route & Dosage

Urinary Retention
Adult: PO 10–50 mg b.i.d. to q.i.d. (max: 120 mg/d)
Child: PO 0.2 mg/kg or 0.6 mg/m² t.i.d.

Administration

Oral

Give on an empty stomach (1 h before or 2 h after meals) to lessen possibility of nausea and vomiting, unless otherwise advised by physician.
Determine minimum effective dose: Give 5–10 mg initially and repeat this dose at 1–2 h (max: 50 mg), until a satisfactory response occurs. Alternatively, give 10 mg followed, at 6 h intervals, by 25 mg, then 50 mg, until desired response obtained.

Adverse Effects (≥1%)

Body as a Whole: Dose-related. Increased sweating, malaise, headache, substernal pain or pressure, hypothermia. CV: Hypotension with dizziness, faintness, flushing, orthostatic hypotension (large doses); mild reflex tachycardia, atrial fibrillation (hyperthyroid patients), transient complete heart block. Special Senses: Blurred vision, miosis, lacrimation. GI: Nausea, vomiting, abdominal cramps, diarrhea, borborygmi, belching, salivation, fecal incontinence (large doses), urge to defecate (or urinate). Respiratory: Acute asthmatic attack, dyspnea (large doses).

Diagnostic Test Interference

Bethanechol may cause increases in serum amylase and serum lipase, by stimulating pancreatic secretions, and may increase AST, serum bilirubin, and BSP retention by causing spasms in sphincter of Oddi.

Interactions

Drug: Ambenonium, neostigmine, other cholinesterase inhibitors compound cholinergic effects and toxicity; mecamylamine may cause abdominal symptoms and hypotension; procainamide, quinidine, atropine, epinephrine antagonize effects of bethanechol.

Pharmacokinetics

Absorption: Well absorbed. Onset: 30 min. Peak: 60–90 min. Duration: 1–6 h. Distribution: Does not cross blood–brain barrier. Metabolism: Unknown. Elimination: Unknown.

Nursing Implications

Assessment & Drug Effects

Monitor BP and pulse. Observe patient for at least 1 h following SC administration. Report early signs of overdosage: Salivation, sweating, flushing, abdominal cramps, nausea.
Monitor I&O. Observe and record patient's response to bethanechol, and report any failure of the drug to relieve the particular condition for which it was prescribed.
Monitor respiratory status. Promptly report dyspnea or any other indication of respiratory distress.
Supervise ambulation as indicated by patient response to drug.

Patient & Family Education

Make position changes slowly and in stages, particularly from lying down to standing.
Do not stand still for prolonged periods; sit or lie down at first indication of faintness.
Do not drive or engage in potentially hazardous activities until response to drug is known.
Note: Drug may cause blurred vision; take appropriate precautions.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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