Introduction: The activation of the cannabinoid receptor 2 (CB2) affects a myriad of immune responses from inflammation to neuroprotection, demonstrates analgesic effects and suppresses responses in many animal models of pain. Questions around the involvement of CB1 activation in these effects remain, but efforts have been directed toward the discovery of highly selective CB2 modulators lacking the psychotropic effects of cannabinoids, which are mediated by the CB1 receptor.
Areas covered: This review covers the patent literature which was published since April 2009 on CB2 selective modulators. It provides a general summary of the CB2 biology supporting the interest in CB2 as a drug target, new potential therapeutic indications and the development status of selective CB2 agonists.
Expert opinion: There is a continuous interest in the CB2 receptor as a drug target. Many highly selective compounds of various chemotypes have been identified and their analgesic effects in animal models further support the potential of this mechanism in pain therapy. Several companies have initiated clinical trials. While some of these have been terminated for various reasons, one can anticipate the emergence of new drugs from CB2 modulation once a better understanding around the cannabinoid receptors is gained.