Medicine & USMLE


  1. Bethanechol
  2. Carbachol
  3. Methacholine
  4. Pilocarpine
  5. Donepezil Rivastigmine and Galantamine
  6. Edrophonium
  7. Neostigmine
  8. Physostigmine
  9. Pyridostigmine


Carbachol is a drug that acts as an agonist or activator of muscarinic receptors. Given in eye drop form, carbachol induces miosis, which is useful in the treatment of open angle glaucoma.

Key Points

  • Carbachol
    • Mechanism
      • Muscarinic agonist (cholinomimetic)
        • Administered as an eye-drop solution to target M3 receptors in eye
    • Clinical Use
      • Open-angle glaucoma
        • Contracts the pupil (miosis)
        • Widens anterior chamber and increases aqueous outflow → lowers intraocular pressure
    • Adverse Effects
      • Cholinergic stimulation
        • Constellation of symptoms including: confusion, miosis, lacrimation, bradycardia, diaphoresis, bronchospasm
        • Think: overactivity of parasympathetic system