Demecarium bromide belongs to which pharmacologic class?

• A. Indirect parasympathomimetics
• B. Beta blockers
• C. Direct parasympathomimetics
• D. Carbonic anhydrase inhibitors

Answer: (A)

Demecarium bromide is an indirect parasympathomimetic because it inhibits acetylcholinesterase, the enzyme that breaks down acetylcholine. By blocking that enzyme, it raises acetylcholine levels at cholinergic synapses, including in the eye, where more acetylcholine activates muscarinic receptors on the iris sphincter and ciliary muscle. The outcome is pupil constriction (miosis) and increased aqueous humor outflow, which lowers intraocular pressure—this is why it’s used in glaucoma management. It’s not a direct muscarinic agonist like pilocarpine, which would stimulate receptors directly rather than boosting acetylcholine. Beta blockers and carbonic anhydrase inhibitors reduce intraocular pressure through different mechanisms (reducing aqueous production), so they are not indirect parasympathomimetics.