Cholinergic and Anticholinergic Drugs: Mechanism, Classification, Dosage, and Effects

Introduction

Cholinergic and anticholinergic drugs play a crucial role in managing various physiological functions by modulating the cholinergic system. This blog explores their mechanism of action, classification, dosage, adverse effects, therapeutic uses, and contraindications.

Classification of Cholinergic Drugs

Direct-Acting Cholinergic Agonists

• Acetylcholine – Acts directly on muscarinic and nicotinic receptors
• Pilocarpine – Used for glaucoma treatment
• Bethanechol – Helps with urinary retention

Indirect-Acting Cholinergic Agonists

• Neostigmine – Used for myasthenia gravis
• Pyridostigmine – Longer-acting cholinesterase inhibitor
• Rivastigmine – Prescribed for Alzheimer’s disease

Classification of Anticholinergic Drugs

Muscarinic Antagonists

• Atropine – Used in bradycardia treatment
• Scopolamine – Treats motion sickness
• Ipratropium – Helps in COPD and asthma management

Nicotinic Antagonists

• Hexamethonium – Ganglionic blocker
• Pancuronium – Neuromuscular blocker used in anesthesia

Mechanism of Action

Cholinergic drugs enhance parasympathetic activity either by stimulating cholinergic receptors directly or by inhibiting acetylcholinesterase. Anticholinergic drugs, on the other hand, block muscarinic receptors to reduce parasympathetic effects.

Dosage and Therapeutic Indications

Dosages vary depending on the specific drug, patient condition, and intended therapeutic use. Always consult a healthcare provider for appropriate dosing guidelines.

Adverse Effects

• Cholinergic Drugs: Can cause bradycardia, excessive salivation, muscle weakness, and bronchospasm.
• Anticholinergic Drugs: May lead to dry mouth, blurred vision, tachycardia, and urinary retention.

Contraindications

• Cholinergic Drugs: Avoid in asthma and peptic ulcer disease.
• Anticholinergic Drugs: Contraindicated in glaucoma and prostatic hypertrophy.