Bethanechol Johnson

Urinary retention -acute postoperative, postpartum and neurogenic.

Reflux oesophagitis.

Posology

Paediatric population

The experience with children is limited; therefore no recommended dose is given.

Adults

10 mg - 25 mg 3-4 times daily. Taken ½ hr before food. Occasionally it may be felt necessary to initiate therapy with a 50 mg dose.

Elderly

Adult dosage administered with caution.

Method of administration

Administration orally by tablets.

Intestinal or urinary obstruction, recent myocardial infarction, recent intestinal anastomosis.

A severe cholinergic reaction is likely to occur if bethanechol chloride is administered IV or IM. This reaction has also rarely occurred in cases of hypersensitivity or overdose.

In some cases the ability to drive and operate machinery may be impaired.

Nausea, vomiting, sweating and intestinal colic.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard.

Symptoms: Include nausea, salivation, lachrymation, eructation, involuntary defecation and urination, transient dyspnoea, palpitation, bradycardia and peripheral vasodilation leading to hypertension, transient heart block and a feeling of constriction under the sternum.

Emergency Procedure: The stomach should be emptied by aspiration and lavage.

Give atropine sulphate 1-2 mg intravenously, intramuscularly or subcutaneously to control muscarinic effects. This dose may be repeated every 2-4 hours as necessary.

Supportive treatment includes intravenous administration of diazepam 5-10 mg, muscle twitching may be controlled by small doses of tubocararine (together with assisted respiration), oxygen may be required.

Pharmacotherapeutic group: Parasympathomimetics, Choline esters, Bethanechol,

ATC code: N07AB02

Mechanism of action

Bethanechol is a synthetic choline ester of carbamic acid which possesses a significant acetylcholine-like activity. It is active after oral administration. As a consequence of the very slow hydrolysation by acetylcholinesterase, bethanechol has a prolonged action as has been demonstrated on the urinary tract. The onset of action after oral administration of bethanechol chloride occurs within one hour.

Pharmacodynamic effects

The major pharmacological effects of bethanechol result from interaction of the drug with muscarinic receptor sites of smooth muscles, especially those of the urinary bladder and gastrointestinal tract. In addition, minor but important nicotinic effects have been noted.

In usual therapeutic doses, bethanechol does not cross the blood brain barrier.

Studies addressing pharmacokinetic-pharmacodynamic are not available.

None stated.

None known.

None.