GPCR agonists and antagonists in the clinic.

This review describes current and new therapeutic agonists and antagonists of G-protein-coupled receptors (GPCRs) currently used in the clinic. GPCRs are classified under the GRAFS system (Glutamate, Rhodopsin, Adhesion, Frizzled/taste2 and Secretin), with therapies having been developed for about 30 GPCRs from the glutamate, rhodopsin and secretin families. Most of these therapies target the biogenic amine receptors of the rhodopsin family. Advancing technology has assisted in the identification of an increasing number of GPCRs, as well as contributing to the understanding of function and potential as pharmaceutical targets. With this has come the development of new therapies that target specific GPCRs, including peptide activated GPCRs. Where possible, agonists and antagonists are described individually, focusing on new therapies and their corresponding target receptors. However, the large number of reported biogenic amine therapies precludes, discussion of individual compounds and instead, they are discussed in relation to the receptor pharmacophore. Despite the large number of significant physiological responses known to be mediated by GPCRs, only about 4% of known GPCRs are currently targeted by therapeutics. This provides a great number of promising new targets for pharmaceutical development.