indication

For the treatment of peptic ulcer disease, irritable bowel syndrome, pancreatitis, gastritis, biliary dyskinesia, pylorosplasm, and reflex neurogenic bladder in children.

pharmacology

Methantheline is a synthetic quarternary ammonium antimuscarinic used to relieve cramps or spasms of the stomach, intestines, and bladder. It can be used together with antacids or other medicines, such as H2-receptor antagonists, in the treatment of peptic ulcer. Methantheline inhibits muscarinic actions at postganglionic parasympathetic neuroeffector sites.

mechanism of action

Methantheline inhibits the muscarinic actions of acetylcholine on structures innervated by postganglionic cholinergic nerves as well as on smooth muscles that respond to acetylcholine but lack cholinergic innervation. These postganglionic receptor sites are present in the autonomic effector cells of the smooth muscle, cardiac muscle, sinoatrial and atrioventricular nodes, and exocrine glands. Depending on the dose, anticholinergics may reduce the motility and secretory activity of the gastrointestinal system, and the tone of the ureter and urinary bladder and may have a slight relaxant action on the bile ducts and gallbladder.

toxicity

Symptoms of overdose: blurred vision (continuing) or changes in near vision, clumsiness or unsteadiness, confusion, convulsions, difficulty in breathing, muscle weakness (severe), or tiredness (severe), dizziness, drowsiness (severe), dryness of mouth, nose, or throat (severe), fast heartbeat, fever, hallucinations, slurred speech, unusual excitement, nervousness, restlessness, or irritability, unusual warmth, dryness, and flushing of skin.

biotransformation

Hepatic, by enzymatic hydrolysis.

absorption

Rapidly absorbed.

drug interactions

Haloperidol: The anticholinergic increases the risk of psychosis and tardive dyskinesia

Tacrine: The therapeutic effects of the central acetylcholinesterase inhibitor, Tacrine, and/or the anticholinergic, Methantheline, may be reduced due to antagonism. The interaction may be beneficial when the anticholinergic action is a side effect. Monitor for decreased efficacy of both agents.

Trimethobenzamide: Trimethobenzamide and Methantheline, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Triprolidine: Triprolidine and Methantheline, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Trospium: Trospium and Methantheline, two anticholinergics, may cause additive anticholinergic effects and enhanced adverse/toxic effects. Monitor for enhanced anticholinergic effects.