Methacholine

Methacholine

Clinical data
Trade names	Provocholine
AHFS/Drugs.com	International Drug Names
ATC code	none
Identifiers
IUPAC name 2-(Acetyloxy)-N,N,N-trimethylpropan-1-aminium
CAS Number	55-92-5 N
PubChem CID	6114
DrugBank	DB06709 Y
ChemSpider	5888 Y
UNII	03V657ZD3V
KEGG	D04970 Y
ChEBI	CHEBI:50142 Y
ChEMBL	CHEMBL978 N
Chemical and physical data
Formula	C8H18NO2+
Molar mass	160.234 g/mol
3D model (Jmol)	Interactive image
SMILES [Cl-].O=C(OC(C)C[N+](C)(C)C)C
InChI InChI=1S/C8H18NO2.ClH/c1-7(11-8(2)10)6-9(3,4)5;/h7H,6H2,1-5H3;1H/q+1;/p-1 Y Key:JHPHVAVFUYTVCL-UHFFFAOYSA-M Y
NY (what is this?)

Methacholine (INN, USAN) (trade name Provocholine) is a synthetic choline ester that acts as a non-selective muscarinic receptor agonist in the parasympathetic nervous system.

Methacholine is primarily used to diagnose bronchial hyperreactivity, which is the hallmark of asthma and also occurs in chronic obstructive pulmonary disease. This is accomplished through the bronchial challenge test, or methacholine challenge, in which a subject inhales aerosolized methacholine, leading to bronchoconstriction. Other therapeutic uses are limited by its adverse cardiovascular effects, such as bradycardia and hypotension, which arise from its function as a cholinomimetic.

It is highly active at all of the muscarinic receptors, but has little effect on the nicotinic receptors. Methacholine has a charged quaternary amine structure, rendering it insoluble to lipid cell membranes. Clinically, this means that it will not cross the blood–brain barrier and has poor absorption from the gastrointestinal tract. It is broken down at a relatively slow rate within the body, due to its relative resistance to acetylcholinesterases.

Methacholine has a β-methyl group which provides selectivity towards muscarinic receptors as compared to nicotinic receptors. The quaternary ammonium group is essential for activity. The ester makes it susceptible to the enzyme acetylcholine esterase.