pilocarpine

Pilocarpine is a naturally occurring alkaloid belonging to the tropane family, derived from plants of the Pilocarpus genus. It is a direct-acting muscarinic receptor agonist with affinity for M3 receptors, producing parasympathomimetic effects.

In ophthalmology, pilocarpine is applied as a topical solution to induce miosis and increase the outflow of aqueous humor through the trabecular meshwork, thereby reducing intraocular pressure in glaucoma and aiding management of acute angle-closure glaucoma.

Systemically, pilocarpine is used as a saliva stimulant (sialogogue) for xerostomia due to Sjögren syndrome, radiation therapy, or head and neck cancer; oral tablets activate muscarinic receptors to increase secretions from salivary and other exocrine glands.

Common adverse effects reflect cholinergic stimulation and include sweating, salivation, lacrimation, abdominal cramps, diarrhea, bronchospasm, and bradycardia. Topical use may cause conjunctival irritation or brow ache. It is contraindicated in uncontrolled asthma or COPD, narrow-angle glaucoma, peptic ulcer disease, and intestinal or urinary obstruction. Because pilocarpine is a non-selective muscarinic agonist, it can interact with other cholinergic drugs and with anticholinergic agents that oppose its effects.