| Size | Price | Stock | Qty |
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| 100mg |
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| 250mg |
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| 500mg |
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| Other Sizes |
| Targets |
Methacholine chloride is a potent and relatively selective agonist at muscarinic acetylcholine receptors, particularly the M3 subtype found in airway smooth muscle, heart, eye, and lung. It binds directly to muscarinic receptors, producing parasympathomimetic effects including bronchoconstriction, miosis, vasodilation, and cardiac vagomimetic activity. While it primarily targets M3 receptors in the airways, it also activates other muscarinic subtypes. Its action is more prolonged than acetylcholine due to its resistance to cholinesterase hydrolysis, making it effective for diagnostic bronchoprovocation challenges.
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| ln Vitro |
In vitro, methacholine chloride is used to study muscarinic receptor function and contractile responses in isolated smooth muscle preparations. It induces concentration-dependent contraction of airway smooth muscle strips or tracheal rings in organ bath assays, with potency reflecting M3 receptor activation. In cell-based systems expressing muscarinic receptors, it stimulates calcium mobilization and downstream signaling pathways. Its in vitro efficacy is characterized by EC50 values in the micromolar range, and it serves as a standard agonist for evaluating the potency of muscarinic antagonists in pharmacological research.
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| ln Vivo |
Dog bronchoconstriction is brought on by methacholine (0.5 µg/kg plus 5 µg/kg/min for 30 minutes) [4]. Bradykinin (4–40 µg/kg; i.v.) inhibits methacholine (0.5 mg/kg; i.v.)-induced bronchoconstriction in mice in a dose-dependent way [5].
In vivo, methacholine chloride is administered by inhalation as a bronchoprovocation agent to assess airway hyperresponsiveness. Inhaled methacholine causes dose-dependent bronchoconstriction, measured as a reduction in forced expiratory volume in 1 second (FEV1). The provocative concentration causing a 20% drop in FEV1 (PC20) is a standard clinical metric for diagnosing asthma. In animal models, intravenous or inhaled methacholine induces bronchospasm and is used to evaluate the efficacy of bronchodilators or anti-inflammatory agents. Its in vivo activity is well-established in both clinical and preclinical respiratory research. |
| Enzyme Assay |
In vitro enzyme/receptor binding studies for methacholine chloride typically involve radioligand binding assays using membrane preparations from tissues or cells expressing muscarinic receptors. Competitive binding experiments with labeled ligands such as [3H]-N-methylscopolamine or [3H]-QNB are performed to determine affinity (Ki) at M1-M5 receptor subtypes. Standard protocols involve incubating membranes with increasing concentrations of methacholine in the presence of a fixed concentration of radioligand, followed by filtration and scintillation counting to calculate binding affinity and receptor occupancy.
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| Cell Assay |
In vitro cellular assays for methacholine chloride include studies using cell lines endogenously or heterologously expressing muscarinic receptors. Common assays measure intracellular calcium mobilization using fluorescent indicators such as Fura-2 or Fluo-4, as M3 receptor activation couples to Gq and PLC-mediated calcium release. Cells are plated in 96-well plates, loaded with calcium dye, and stimulated with increasing concentrations of methacholine to generate concentration-response curves. These assays are used to evaluate agonist potency and to screen for muscarinic receptor modulators.
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| Animal Protocol |
Animal/Disease Models: 9weeks old female balb/c (Bagg ALBino) mouse [6]
Doses: 0.03, 0.1, 0.3, 1 mg/kg Route of Administration: intravenous (iv) (iv)injection Experimental Results:Induced severe bronchoconstriction. In vivo animal studies with methacholine chloride typically use rodent or guinea pig models to assess airway responsiveness. Animals are anesthetized, tracheostomized, and connected to a ventilator to measure pulmonary resistance or compliance. Methacholine is administered via aerosol or intravenous injection in increasing doses, and bronchoconstrictor responses are recorded. These studies are used to model asthma and evaluate the efficacy of bronchodilator compounds. Standard protocols include measurement of Penh (enhanced pause) in conscious animals using whole-body plethysmography following methacholine challenge. |
| ADME/Pharmacokinetics |
Methacholine chloride has a rapid onset and short duration of action when administered by inhalation. It is poorly absorbed systemically after inhalation, with minimal distribution to peripheral tissues. The compound is hydrolyzed by cholinesterases, though at a slower rate than acetylcholine, contributing to its prolonged local effect. Its quaternary ammonium structure limits blood-brain barrier penetration. Plasma half-life is short, and it is rapidly eliminated via renal excretion. Systemic bioavailability is low after inhalation, making it safe for diagnostic use with minimal systemic side effects at challenge doses.
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| Toxicity/Toxicokinetics |
The primary toxicity of methacholine chloride is related to its exaggerated pharmacological effects at muscarinic receptors, including severe bronchoconstriction, bradycardia, hypotension, and excessive salivation. In diagnostic use, adverse effects are typically mild and transient, including throat irritation, cough, wheezing, and headache. Contraindications include severe asthma, recent myocardial infarction, and uncontrolled hypertension. Overdose may cause cholinergic crisis characterized by muscle weakness, miosis, and respiratory distress. Atropine is the specific antidote for severe cholinergic toxicity. Long-term toxicity studies are limited due to its diagnostic use rather than chronic therapy.
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| References | |
| Additional Infomation |
Methacholine chloride is a quaternary ammonium salt containing a methacholine molecule. Methacholine chloride is the chloride form of methacholine, a direct-acting cholinergic muscarinic receptor agonist with bronchoconstrictive, miotic, vasodilatory, and cardiac vagal-like effects. Methacholine chloride acts directly on muscarinic receptors in the heart, eyes, and lungs, thereby producing parasympathomimetic effects. It is a quaternary ammonium parasympathomimetic drug with muscarinic-like effects similar to acetylcholine. Compared to acetylcholine, it is hydrolyzed much more slowly by acetylcholinesterase and is more resistant to hydrolysis by non-specific cholinesterases, thus its duration of action is longer. It can be used as a parasympathomimetic bronchoconstrictor and as an adjunct diagnostic agent for bronchial asthma. (Excerpt from Martindale Pharmacopoeia, 30th edition, p. 1116) See also: Methacholine (containing the active ingredient).
Drug Indications Diagnosis of Asthma Methacholine chloride is primarily used as a diagnostic tool for bronchial hyperresponsiveness in asthma assessment. It is commercially available as Provocholine and is administered under medical supervision in pulmonary function laboratories. The compound is a quaternary ammonium salt with a molecular weight of 195.69 g/mol and a CAS number of 62-51-1. It is not used therapeutically for chronic disease management but serves as an essential agent for confirming asthma diagnosis and monitoring disease severity. Its use is well-established in clinical guidelines for pulmonary function testing worldwide. |
| Molecular Formula |
C8H18CLNO2
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| Molecular Weight |
195.6870
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| Exact Mass |
195.102
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| CAS # |
62-51-1
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| Related CAS # |
Methacholine bromide;333-31-3
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| PubChem CID |
6114
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| Appearance |
White to off-white solid powder
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| Density |
1.1028 (rough estimate)
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| Melting Point |
171-173ºC(lit.)
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| Index of Refraction |
1.5790 (estimate)
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| Hydrogen Bond Donor Count |
0
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| Hydrogen Bond Acceptor Count |
3
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| Rotatable Bond Count |
4
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| Heavy Atom Count |
12
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| Complexity |
138
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| Defined Atom Stereocenter Count |
0
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| InChi Key |
JHPHVAVFUYTVCL-UHFFFAOYSA-M
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| InChi Code |
InChI=1S/C8H18NO2.ClH/c1-7(11-8(2)10)6-9(3,4)5;/h7H,6H2,1-5H3;1H/q+1;/p-1
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| Chemical Name |
2-acetyloxypropyl(trimethyl)azanium;chloride
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture. |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
DMSO : ~100 mg/mL (~511.01 mM)
H2O : ~100 mg/mL (~511.01 mM) |
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| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 2.5 mg/mL (12.78 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 2.5 mg/mL (12.78 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. View More
Solubility in Formulation 3: ≥ 2.5 mg/mL (12.78 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. Solubility in Formulation 4: 130 mg/mL (664.32 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication. |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 5.1101 mL | 25.5506 mL | 51.1012 mL | |
| 5 mM | 1.0220 mL | 5.1101 mL | 10.2202 mL | |
| 10 mM | 0.5110 mL | 2.5551 mL | 5.1101 mL |
*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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