Methacholine Chloride
(BAN, rINN)
Synonyms: Acetylβ-methylcholine Chloride; Amechol Chloride; Cloruro de metacolina; Méthacholine, Chlorure de; Methacholini Chloridum; Methacholinium Chloratum. (2-Acetoxypropyl)trimethylammonium chloride.
Cyrillic synonym: Метахолиния Хлорид.
💊 Chemical information
Chemical formula: C8H18ClNO2 = 195.7.
CAS — 55-92-5 (methacholine); 62-51-1 (methacholine chloride).
Pharmacopoeias.
In Fr., Swiss, and US.USP 31
(Methacholine Chloride). Colourless or white crystals, or a white crystalline powder. It is odourless or has a slight odour, and is very hygroscopic. Soluble 1 in 1.2 of water, 1 in 1.7 of alcohol, and 1 in 2.1 of chloroform. Its solutions are neutral to litmus. Store in airtight containers.💊 Adverse Effects and Treatment
As for Acetylcholine Chloride. Severe adverse cholinergic effects have followed the oral and parenteral use of methacholine and these routes are no longer used.
💊 Precautions
As for Neostigmine. Methacholine has the potential to produce severe bronchoconstriction and it should not be used for inhalation challenge tests in patients with clinically apparent asthma, wheezing, or poor pulmonary function. Methacholine should not be given orally or parenterally.
💊 Interactions
As for Neostigmine. Methacholine is slowly hydrolysed by acetylcholinesterase, and its effects are markedly enhanced if used after anticholinesterases.
💊 Uses and Administration
Methacholine is a quaternary ammonium parasympathomimetic with the muscarinic actions of acetylcholine. It is hydrolysed by acetylcholinesterase at a considerably slower rate than acetylcholine and is more resistant to hydrolysis by nonspecific cholinesterases so that its actions are more prolonged. Inhalation of nebulised solutions of methacholine chloride are used to provoke bronchoconstriction in the diagnosis of bronchial airway hypersensitivity (but see Precautions, above). Methacholine chloride has been used in eye drops as a miotic for diagnostic purposes.
◊ References.
1. Crapo RO, et al. Guidelines for methacholine and exercise challenge testing-1999. Am J Respir Crit Care Med 2000; 161: 309–29. Also available at: http://ajrccm.atsjournals.org/cgi/ reprint/161/1/309 (accessed 30/05/08
2. Swartz E, Lang D. When should a methacholine challenge be ordered for a patient with suspected asthma? Cleve Clin J Med 2008; 75: 37–40.
2. Swartz E, Lang D. When should a methacholine challenge be ordered for a patient with suspected asthma? Cleve Clin J Med 2008; 75: 37–40.
💊 Preparations
Proprietary Preparations
Canad.: Provocholine; Ger.: Provokit; USA: Mecholyl; Provocholine. Multi-ingredient: Braz.: Frixodon†.
Published May 08, 2019.