What are the three generic beta-blockers used in glaucoma therapy?

• A. Pilocarpine; Carbachol; Physostigmine
• B. Timolol; Latanoprost; Brimonidine
• C. Timolol 0.5% 0.25%; Betaxolol 0.5% 0.25%; Levobunolol 0.5% 0.25%
• D. Timolol; Betaxolol; Propranolol

Answer: (C)

Beta-blockers used in glaucoma therapy work by lowering intraocular pressure through reduced production of aqueous humor in the ciliary body. The three generic beta-blockers commonly used topically are timolol, betaxolol, and levobunolol. Timolol is nonselective, blocking both beta-1 and beta-2 receptors to decrease aqueous formation. Betaxolol is more beta-1 selective, offering similar IOP-lowering effect with potentially fewer systemic beta-1 side effects. Levobunolol is another nonselective option with a comparable mechanism and efficacy. The concentrations listed, such as 0.5% and 0.25%, reflect common ophthalmic formulations used in practice.

Other drug classes in the options—pilocarpine, carbachol, and physostigmine (cholinergic/miotics); latanoprost (a prostaglandin analog); brimonidine (an alpha-2 agonist); and propranolol (a systemic beta-blocker not typically used as a topical glaucoma agent)—do not fit the category of the three generic beta-blockers used in glaucoma therapy.