What is the mechanism of netarsudil in reducing intraocular pressure and a common local adverse effect?

• A. It inhibits carbonic anhydrase
• B. It increases uveoscleral outflow
• C. Rho kinase inhibition to increase trabecular outflow; commonly causes conjunctival hyperemia
• D. It reduces aqueous humor production by blocking beta receptors

Answer: (C)

Netarsudil lowers intraocular pressure by inhibiting Rho kinase, which relaxes the cytoskeleton and reduces contractile tone in the trabecular meshwork and Schlemm's canal. This loosening increases drainage through the conventional outflow pathway, lowering aqueous humor pressure. It can also reduce episcleral venous pressure, providing extra IOP reduction. This mechanism is different from drugs that decrease aqueous production (carbonic anhydrase inhibitors or beta blockers) or that mainly boost uveoscleral outflow (prostaglandin analogs). A common local adverse effect is conjunctival hyperemia, due to dilation of conjunctival vessels.