Pilocarpine is a cholinergic agonist.

• A. It is a beta-blocker
• B. It is a prostaglandin analog
• C. It is a carbonic anhydrase inhibitor
• D. It is a cholinergic agonist

Answer: (D)

Pilocarpine works by stimulating muscarinic receptors, acting as a parasympathomimetic agent. In the eye, this receptor activation causes the ciliary muscle to contract and the pupil to constrict (miosis). The contraction of the ciliary muscle opens the drainage pathway at the trabecular meshwork, increasing aqueous humor outflow and lowering intraocular pressure. That mechanism is the hallmark of a cholinergic agonist.

This is different from beta-blockers, which lower eye pressure mainly by reducing aqueous humor production; prostaglandin analogs increase outflow through a different route (often the uveoscleral pathway) without relying on muscarinic receptor activation; and carbonic anhydrase inhibitors lower production by inhibiting bicarbonate formation. So pilocarpine is best described as a cholinergic (muscarinic) agonist because of its mechanism that directly enhances aqueous outflow via ciliary muscle contraction.