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Active ingredient: Ambenonium - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

  • Antiarrhythmic Agents
  • Antimyasthenics

Dosage Forms

  • Tablet (10 mg)

Brands / Synonyms

Ambenonium Base; Ambenonium Kation; Ambenonium [Usan]; Ambenonum; Mytelase; Mytelase

Indications

Ambenonium is used to treat muscle weakness due to muscle disease (myasthenia gravis).

Pharmacology

Ambenonium, similar to pyridostigmine and neostigmine, is used for the treatment of muscle weakness and fatigue in people with myasthenia gravis. It is postulated to exert its therapeutic effect by enhancing cholinergic function by inhibiting the hydrolysis of acetylcholine by acetylcholinesterase. Increased levels of acetylcholine has peripheral effects, as acetylcholine is also used in the brain, where it tends to cause excitatory actions. The glands that receive impulses from the parasympathetic part of the autonomic nervous system are also stimulated in the same way. This is why an increase in acetylcholine causes a decreased heart rate and increased production of saliva. Ambenonium is used less commonly than neostigmine or pyridostigmine but may be preferred in patients hypersensitive to the bromide ion. Ambenonium produces fewer muscarinic side effects than neostigmine, but more than pyridostigmine.

Mechanism of Action

Ambenonium exerts its actions against myasthenia gravis by competitive, reversible inhibition of acetylcholinesterase. The disease myasthenia gravis occurs when the body inappropriately produces antibodies against acetylcholine receptors, and thus inhibits proper acetylcholine signal transmission (when acetylcholine binds to acetylcholine receptors of striated muscle fibers, it stimulates those fibers to contract). Ambenonium reversibly binds acetylcholinesterase, and as acetylcholinesterase is responsible for the hydrolysis of acetylcholine, this inhibition increases levels of acetylcholine. In turn this facilitates transmission of impulses across the myoneural junction and effectively treats the disease.

Absorption

Oral - poorly absorbed from the gastrointestinal tract.

Toxicity

LD50=150±44 mg/kg (orally in mice). Symptoms of overdose include muscle twitching, weakness and paralysis of voluntary muscles including the tongue, shoulders, neck and arms, blood pressure increase (with or without a slowing of heart rate), a sensation of internal trembling, severe anxiety, and panic. Death may occur rapidly if untreated.

Biotrnasformation / Drug Metabolism

Plasma and hepatic

Contraindications

Ambenonium is contraindicated in the following: intestinal or urinary tract obstruction, mechanical (may be exacerbated), sensitivity to any of these medications or to bromides, urinary tract infections (increase in urinary bladder muscle tone may aggravate symptoms).

Drug Interactions

Interactions can occur with the following medications: demecarium (Humorsol), echothiophate (Phospholine Iodide), isoflurophate (Floropryl), malathion (using these medicines with antimyasthenics may result in serious side effects), guanadrel (Hylorel), guanethidine (Ismelin), mecamylamine (Inversine), procainamide (Pronestyl), and trimethaphan (the effects of these medicines may interfere with the actions of the antimyasthenics).

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