Metacholine, also known as acetyl-beta-methylcholine chloride, is a synthetic cholinergic agent that mimics the action of acetylcholine (ACh) in the body.
Chemical Structure:
- Molecular Formula: C8H18ClNO2
- Chemical Name: 2-[(Acetoxy)(methyl)amino]ethyltrimethylammonium chloride
Pharmacological Effects:
- Stimulates muscarinic receptors, producing:
- Bronchoconstriction
- Increased salivation and sweating
- Pupil constriction (miosis)
- Increased gastrointestinal motility and secretion
- Urinary bladder contraction
Clinical Uses:
- Diagnostic tool for bronchial hyperreactivity and asthma
- Used in bronchial challenge tests to assess airway responsiveness
- Research applications in studying cholinergic systems
Side Effects:
- Bronchospasm and respiratory distress
- Coughing and wheezing
- Nausea, vomiting, and diarrhea
- Headache, dizziness, and weakness
- Hypersalivation, sweating, and flushing
Contraindications:
- Asthma and other respiratory conditions (except for diagnostic purposes)
- Peptic ulcer disease
- Hyperthyroidism
- Pregnancy and lactation
- Hypotension and cardiac arrhythmias
Note: Metacholine is a potent cholinergic agent and should be used with caution, under medical supervision.