Therapeutic opportunities through modulation of the endocannabinoid system.

The discovery of the cannabinoid receptors and endocannabinoid ligands has generated a great deal of interest in identifying opportunities for the development of novel cannabinergic therapeutic drugs. Such an effort was first undertaken three decades ago by a number of pharmaceutical industries, but was rewarded with only modest success. However, the newly acquired knowledge on the physiological roles of the endocannabinoid system has significantly enhanced these prospects. At the June 27, 2004 workshop ‘‘Future Directions in Cannabinoid Therapeutics II: From the Bench to the Clinic’’, sponsored by the University of California Center for Medicinal Cannabis Research, we on the Scientific Planning Committee were asked to identify the areas of research with the most immediate promise for the development of novel therapeutic agents. The Committee identified four broad areas involving modulation of the endocannabinoid system as particularly promising in this regard: agonists for central CB1 cannabinoid receptors and peripheral CB2 receptors, antagonists of CB1 receptors, inhibitors of endocannabinoid deactivation, and endocannabinoid-like compounds that act through mechanisms distinct from CB1 and CB2 receptors activation. Below, we summarize the data presented at the Workshop and the consensus of its participants on the most exciting opportunities for drug discovery.