Methacholine chloride

Methacholine chloride is a synthetic choline ester that acts as a non-selective muscarinic receptor agonist in the parasympathetic nervous system. It is primarily used as a diagnostic tool in asthma and chronic obstructive pulmonary disease (COPD).

Chemistry

Methacholine chloride is a quaternary ammonium compound and a beta-methylcholine derivative. It is a white, odorless crystalline substance that is soluble in water and alcohol. Its chemical formula is C8H18ClNO2.

Pharmacology

Methacholine chloride acts on the muscarinic receptors of the parasympathetic nervous system, primarily M3 receptors located in the smooth muscle of the airways, leading to muscle contraction and bronchoconstriction. This action is used in the diagnosis of airway hyperreactivity.

Medical uses

Methacholine chloride is used in a Methacholine challenge test to diagnose asthma, detect exercise-induced asthma, and evaluate the severity of bronchial hyperreactivity. It is also used in research to test airway hyperresponsiveness.

Side effects

Common side effects of methacholine chloride include cough, chest tightness, shortness of breath, throat irritation, and headache. Rare but serious side effects include severe bronchospasm and anaphylactic reactions.

Contraindications

Methacholine chloride is contraindicated in individuals with recent heart attack or stroke, uncontrolled hypertension, known severe airway disease, or aortic aneurysm.

See also

• Bronchial challenge test
• Muscarinic agonist
• Parasympathetic nervous system

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