Nitroglycerin and Nitric Oxide--A Rondo of Themes in Cardiovascular Therapeutics

New glaucoma medications: latanoprostene bunod, netarsudil, and fixed combination netarsudil-latanoprost

Reduction of intraocular pressure is the only proven method to treat glaucoma. Initial treatment of glaucoma commonly involves using anti-glaucoma medications either as monotherapy or combination therapy. Studies on aqueous humour dynamics have contributed to our understanding of aqueous outflow mechanisms that have led to the discovery of new drugs. Three new drugs (latanoprostene bunod 0.24%, netarsudil 0.02%, and fixed combination netarsudil 0.02% -latanoprost 0.005%) have been introduced recently in the market with novel mechanisms of action. Latanoprostene bunod 0.024% is a nitric oxide-donating prostaglandin F2α analogue which increases the aqueous outflow both by uveoscleral and trabecular pathways. Netarsudil 0.02% is a potent Rho kinase/norepinephrine transporter inhibitor acting by increasing the trabecular outflow, decreasing the aqueous production, and possibly decreasing the episcleral venous pressure. This review highlights the role of these drugs in the management of glaucoma, with an overview of the major clinical trials on their efficacy, safety, and tolerability.

A Review of Nitric Oxide for the Treatment of Glaucomatous Disease

Glaucoma is the leading cause of irreversible blindness worldwide, affecting 64.3 million people. An estimated 60.5 million people are affected by primary open angle glaucoma globally, and this will increase to 111.8 million by 2040. The definition of glaucoma has evolved greatly over time. Although multiple risk factors such as ischemia, inflammation, myopia, race, age and low ocular perfusion pressure may play a role, intraocular pressure (IOP) is still the main risk factor we can easily identify and modify. Currently, both medical and surgical interventions aim to reduce IOP. Effective IOP reduction controls and prevents the progression in many cases of glaucoma. Although this multifactorial disease's true pathophysiology is difficult to elucidate, physiologic mediators including nitric oxide (NO) are being evaluated as novel ways to impact progression by both lowering IOP and improving optic nerve head perfusion. Latanoprostene bunod 0.024% is an emerging therapeutic agent that has shown promise in clinical trials. As a nitric oxide-donating prostaglandin F2-alpha receptor agonist, it has proven to effectively, and with good tolerability, reduce IOP in glaucoma and ocular hypertensive patients. Latanoprostene bunod capitalizes on NO's ability to modulate the conventional aqueous humor outflow system, directly improving outflow through the trabecular meshwork, Schlemm's canal and distal scleral vessels. Importantly, targeting the conventional outflow tissues with NO-donating drugs represents an opportunity to restore outflow function, which will most likely have a beneficial consequence of additional IOP-lowering effects with dampening of diurnal and other IOP fluctuations, the benefit of a healthy trabecular meshwork.