A patient with primary open-angle glaucoma (POAG) on latanoprost monotherapy has insufficient IOP control. The treating physician adds brimonidine. What is the mechanism of brimonidine that makes it useful as an add-on therapy in POAG beyond IOP reduction?

• A Alpha-2 adrenergic receptor agonism providing direct neuroprotection ✓
• B Prostaglandin E2 receptor agonism enhancing uveoscleral outflow
• C Carbonic anhydrase inhibition reducing aqueous humor production
• D Beta-1 receptor blockade reducing aqueous secretion from ciliary epithelium

Explanation

Brimonidine is a selective alpha-2 adrenergic agonist. Beyond lowering IOP by reducing aqueous production and increasing uveoscleral outflow, it has demonstrated neuroprotective properties in animal models by reducing glutamate excitotoxicity and upregulating BDNF (brain-derived neurotrophic factor), protecting retinal ganglion cells independently of IOP reduction. This is a clinically significant property that distinguishes it from beta-blockers and CAIs.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.