Biological Activity
mk-0974 (telcagepant) is a highly potent, selective, and orally bioavailable antagonist of cgrp receptor with ic50 value of 0.77 nm [1].calcitonin gene-related peptide (cgrp) receptor is a heteromeric transmembrane receptor composed of a g protein-coupled receptor which is called calcitonin receptor-like receptor (calcrl) and a receptor activity modifying protein 1 (ramp1). cgrp receptor is functional for mediating the activity of cgrp, which is widely distributed in human peripheral and central neuron system. the cgrp/cgrp receptor signaling pathway modulate a variety of physiological functions of respiratory, immune and cardiovascular system, and play a key role in the pathophysiology of migraine headache.when binding study was carried out, it was found mk-0974 had high affinity for cgrp receptor but had no affinity for related human adrenomedullin receptors, which suggested the high specificity of mk-0974 [1]. in human hek293 cells expressing cgrp receptor, treatment of mk-0974 resulted in potent blockage of α-cgrp-stimulated camp producation, which indicated a significant inhibition of cgrp receptor activity. however, addition of 50% human serum reduced the inhibition potency of mk-0974 by 5-fold [1]. mk-0974 displayed reversible and saturable binding to both sk-n-mc membranes and rhesus cerebellum with a kd of 1.9 nm and 1.3 nm, respectively [2].in rhesus model, capsaicin-induced release of endogenous cgrp resulted in dermal vasodilation. following treatment of mk-0974 produced a dose-dependent inhibition of dermal vasodilation, with plasma concentrations of 127 and 994 nm required to block 50 and 90% of the blood flow increase, respectively. the suppression of cgrp function indicated the inhibition of cgrp receptor by mk-0974 [1]. in monkey model, mk-0974 showed moderate clearance (14-20 ml min-1 kg-1), while oral bioavailability was 6%. the pharmacokinetics of mk-0974 remained linear across 0.5-10 mg kg-1 intravenous dose in monkeys, but the oral area under the plasma concentration-time curve (auc) increase (5-30 mg kg-1) was 15-fold over dose-proportional [3].
References
[1] salvatore c a et al. , pharmacological characterization of mk-0974 [n-[(3r,6s)-6-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)azepan-3-yl]-4-(2-oxo-2,3-dihydro-1h-imidazo[4,5-b]pyridin-1-yl)piperidine-1-carboxamide], a potent and orally active calcitonin gene-related peptide receptor antagonist for the treatment of migraine. j pharmacol exp ther. 2008, 324(2): 416-421.
[2] moore e l et al. , examining the binding properties of mk-0974: a cgrp receptor antagonist for the acute treatment of migraine. eur j pharmacol. 2009, 602(2-3): 250-254.
[3]. roller s et al., preclinical pharmacokinetics of mk-0974, an orally active calcitonin-gene related peptide (cgrp)-receptor antagonist, mechanism of dose dependency and species differences. xenobiotica. 2009, 39(1): 33-45.
