Related Experiment Video
Updated: Mar 18, 2026

Preparation and Delivery of Protein Microcrystals in Lipidic Cubic Phase for Serial Femtosecond Crystallography
Published on: September 20, 2016
Discovery of Highly Potent Dual Orexin Receptor Antagonists via a Scaffold-Hopping Approach
Bibia Heidmann1, John Gatfield2, Catherine Roch2
1Actelion Pharmaceuticals Ltd., Drug Discovery and Preclinical Research & Development, Gewerbestrasse 16, 4123, Allschwil, Switzerland. heidmab@actelion.com.
Abstract:
Starting from suvorexant (trade name Belsomra), we successfully identified interesting templates leading to potent dual orexin receptor antagonists (DORAs) via a scaffold-hopping approach. Structure-activity relationship optimization allowed us not only to improve the antagonistic potency on both orexin 1 and orexin 2 receptors (Ox1 and Ox2, respectively), but also to increase metabolic stability in human liver microsomes (HLM), decrease time-dependent inhibition of cytochrome P450 (CYP) 3A4, and decrease P-glycoprotein (Pgp)-mediated efflux. Compound 80 c [{(1S,6R)-3-(6,7-difluoroquinoxalin-2-yl)-3,8-diazabicyclo[4.2.0]octan-8-yl}(4-methyl-[1,1'-biphenyl]-2-yl)methanone] is a potent and selective DORA that inhibits the stimulating effects of orexin peptides OXA and OXB at both Ox1 and Ox2. In calcium-release assays, 80 c was found to exhibit an insurmountable antagonistic profile at both Ox1 and Ox2, while displaying a sleep-promoting effect in rat and dog models, similar to that of the benchmark compound suvorexant.
Related Concept Videos
Opioid Receptors: Overview
Drug Discovery: Overview
Sedatives and Hypnotics Drugs: Miscellaneous Agents
Melatonin congeners like ramelteon (Rozerem) and tasimelteon (Hetlioz) selectively bind to melatonin receptors (MT1 and MT2) and thus mimic the actions of melatonin, a hormone that regulates sleep-wake cycles. Tasimelteon is primarily used for non-24-hour sleep-wake disorder, common in blind patients. They are also used to treat conditions like insomnia...
Drug-Receptor Interaction: Agonist
Agonists can bind to receptors in different ways. Some agonists bind directly to the receptor's active site, mimicking the endogenous...
Drug-Receptor Interaction: Antagonist
Antagonists can be classified as competitive or noncompetitive based on their...
Adrenergic Agonists: Indirect-Acting Agents
One mechanism involves depleting stored catecholamines by displacing them from synaptic vesicles. These agents, known as "displacers," are transported into vesicles at the expense of noradrenaline. Examples include amphetamine and tyramine, which lack a catechol moiety, resulting in prolonged action, improved oral...

