title: Examining the binding properties of MK-0974: a CGRP receptor antagonist for the acute treatment of migraine.
abstract: Calcitonin gene-related peptide (CGRP) is a neuropeptide that plays a key role in the pathophysiology of migraine headache. MK-0974 (telcagepant) is a potent and selective antagonist of the human and rhesus CGRP receptors and is currently in Phase III clinical studies for the acute treatment of migraine. The pharmacology of MK-0974 has been studied extensively, but there has not been a thorough characterization of its binding properties. Here, we characterize the binding of a tritiated analog of MK-0974 on human neuroblastoma (SK-N-MC) membranes and rhesus cerebellum. [(3)H]MK-0974 displayed reversible and saturable binding to both SK-N-MC membranes and rhesus cerebellum with a K(D) of 1.9 nM and 1.3 nM, respectively. Agonists and antagonists of the CGRP receptor displaced [(3)H]MK-0974 in a concentration-dependent manner in competition binding experiments. Both CGRP and adrenomedullin demonstrated biphasic competition while MK-0974 and the peptide antagonist CGRP(8-37) displaced [(3)H]MK-0974 in a monophasic fashion. In competitive binding studies with [(3)H]MK-0974 and CGRP, the fraction of high-affinity binding was reduced significantly by incubating the membranes with GTPgammaS. In kinetic binding experiments, the off-rate of [(3)H]MK-0974 was determined to be 0.51 min(-1) with a half-life of 1.3 min. In conclusion, the radioligand [(3)H]MK-0974 has proven to be a useful tool for studying the binding characteristics of MK-0974 and has broadened our understanding of this promising molecule.
authors.affiliation: Merck Research Laboratories, Department of Pain Research, West Point, PA 19486, USA. eric_moore2@merck.com
authors.forename: Eric L
authors.initials: EL
authors.lastname: Moore
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Burgey
authors.forename: Daniel V
authors.initials: DV
authors.lastname: Paone
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Shaw
authors.forename: Yui S
authors.initials: YS
authors.lastname: Tang
authors.forename: Stefanie A
authors.initials: SA
authors.lastname: Kane
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Salvatore
mesh_terms: D000818:Animals; D001381:Azepines / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use*; D001667:Binding, Competitive; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D006801:Humans; D007093:Imidazoles / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use*; D007700:Kinetics; D008253:Macaca mulatta; D008881:Migraine Disorders / Q000188:drug therapy* / Q000378:metabolism*; D011485:Protein Binding; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000378:metabolism*; D014316:Tritium / Q000737:chemistry
chemical_list: D001381:Azepines; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D007093:Imidazoles; D018015:Receptors, Calcitonin Gene-Related Peptide; D014316:Tritium; C525458:telcagepant