THE ROLE OF ADENOSINE RECEPTOR AGONISTS IN OCULAR DISORDERS

Adenosine is an endogenous signaling molecule that regulates a wide range of physiologic and pathophysiologic functions. These functions are modulated through its interaction with four known receptors: A(1), A(2A), A(2B) and A(3). Adenosine is produced and released by virtually all cells and is ubiquitous. Selective receptor agonists and antagonists have been developed and serve as pharmacologic probes, elucidating each receptor's specific function in a given tissue or organ. Accumulating evidence suggests that adenosine generally functions as a local cytoprotective modulator. To date, a wide range of clinical applications have been identified and active research is underway in its potential use in cardiac arrhythmias, inflammation, neuroprotection, ischemic preconditioning, and more recently ocular disorders such as glaucoma, dry eye syndrome, uveitis and diabetic retinopathy among others. In recent years, research has moved beyond the bench and selective adenosine agonists are undergoing clinical trials in humans. This review will focus on the role of adenosine and its receptors in the eye and highlight pharmacologic adenosine receptor modulators currently undergoing clinical trials for ophthalmic conditions.