Pharmacology · MU Sofia

18. Cholinergic drugs (cholinomimetics).

Covers cholinergic drugs (cholinomimetics), which mimic acetylcholine, starting with the split between direct-acting agonists such as pilocarpine and bethanechol and indirect-acting acetylcholinesterase inhibitors such as neostigmine and donepezil. It then goes through muscarinic and nicotinic effects on the heart, eye, gut and lungs, pharmacokinetics including cytochrome P450 metabolism, common side effects, interactions, therapeutic uses such as glaucoma and Alzheimer's disease, and pregnancy contraindications.

Inside: 7 sections · 4 labelled pictures · 10 flashcards · 4 min

Topic 17 of 93 in the MU Sofia syllabus for Pharmacology (Medicine, Year 3). The free AceMed note covers it in 7 sections, about 474 words (4 min of reading), with 10 flashcards.

In this note

  1. Cholinergic Drugs (cholinomimetics)
  2. Pharmacodynamics of Cholinergic Drugs
  3. Pharmacokinetics of Cholinergic Drugs
  4. Side Effects of Cholinergic Drugs
  5. Drug Interactions
  6. Therapeutic Use of Cholinergic Drugs
  7. Contraindications

Cholinergic Drugs (cholinomimetics)

Cholinergic drugs, also known as cholinomimetics, mimic the effects of acetylcholine and stimulate the parasympathetic nervous system. These drugs can be classified into two main categories: direct-acting and indirect-acting cholinergic agonists.

  1. 1. Classification of Cholinergic Drugs

1.1 Direct-Acting Cholinergic Agonists

  • Mechanism: Directly stimulate cholinergic receptors (muscarinic and nicotinic).
  • Examples:
  • Acetylcholine
  • Bethanechol
  • Carbachol
  • Pilocarpine

1.2 Indirect-Acting Cholinergic Agonists

  • Mechanism: Increase acetylcholine concentration by inhibiting acetylcholinesterase (AChE).
  • Reversible Inhibitors:
  • Neostigmine, Pyridostigmine, Physostigmine
  • Donepezil, Rivastigmine
  • Irreversible Inhibitors:
  • Nerve gases, Organophosphates

Pharmacodynamics of Cholinergic Drugs

2.1 Direct Cholinomimetics

  • Mechanism: Act by directly stimulating muscarinic and nicotinic receptors.
  • Physiological Effects:
  • M2 receptors (heart): Decrease heart rate (negative chronotropic effect) and contractility (negative inotropic effect).
  • M3 receptors (GI tract, eye, and lungs):
  • Increase gastrointestinal motility and secretion.
  • Bronchoconstriction and increased bronchial secretions.
  • Miosis (pupil constriction) and accommodation in the eye.
  • Relaxation of sphincters.

2.2 Indirect Cholinomimetics

  • Mechanism: Increase acetylcholine levels by inhibiting AChE.
  • Effects: Enhance cholinergic transmission, improving conditions like myasthenia gravis and Alzheimer’s disease.

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