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ECHA InfoCard | 100.233.393 ![]() |
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Formula | C23H26N4O4S |
Molar mass | 454.55 g·mol−1 |
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EMPA is a selective antagonist of the OX2 receptor, with 900-fold selectivity in binding for OX2 over OX1. [1] [2]
Orexin, also known as hypocretin, is a neuropeptide that regulates arousal, wakefulness, and appetite. The most common form of narcolepsy, type 1, in which the sufferer experiences brief losses of muscle tone (cataplexy), is caused by a lack of orexin in the brain due to destruction of the cells that produce it.
The endocannabinoid system (ECS) is a biological system composed of endocannabinoids, which are endogenous lipid-based retrograde neurotransmitters that bind to cannabinoid receptors (CBRs), and cannabinoid receptor proteins that are expressed throughout the vertebrate central nervous system and peripheral nervous system. The endocannabinoid system remains under preliminary research, but may be involved in regulating physiological and cognitive processes, including fertility, pregnancy, pre- and postnatal development, various activity of immune system, appetite, pain-sensation, mood, and memory, and in mediating the pharmacological effects of cannabis. The ECS plays an important role in multiple aspects of neural functions, including the control of movement and motor coordination, learning and memory, emotion and motivation, addictive-like behavior and pain modulation, among others.
The tachykinin receptor 1 (TACR1) also known as neurokinin 1 receptor (NK1R) or substance P receptor (SPR) is a G protein coupled receptor found in the central nervous system and peripheral nervous system. The endogenous ligand for this receptor is Substance P, although it has some affinity for other tachykinins. The protein is the product of the TACR1 gene.
The orexin receptor (also referred to as the hypocretin receptor) is a G-protein-coupled receptor that binds the neuropeptide orexin. There are two variants, OX1 and OX2, each encoded by a different gene (HCRTR1, HCRTR2).
Orexin receptor type 1 (Ox1R or OX1), also known as hypocretin receptor type 1 (HcrtR1), is a protein that in humans is encoded by the HCRTR1 gene.
Orexin receptor type 2 (Ox2R or OX2), also known as hypocretin receptor type 2 (HcrtR2), is a protein that in humans is encoded by the HCRTR2 gene.
GSK-189,254 is a potent and selective H3 histamine receptor inverse agonist developed by GlaxoSmithKline. It has subnanomolar affinity for the H3 receptor (Ki = 0.2nM) and selectivity of over 10,000x for H3 over other histamine receptor subtypes. Animal studies have shown it to possess not only stimulant and nootropic effects, but also analgesic action suggesting a role for H3 receptors in pain processing in the spinal cord. GSK-189,254 and several other related drugs are currently being investigated as a treatment for Alzheimer's disease and other forms of dementia, as well as possible use in the treatment of conditions such as narcolepsy, or neuropathic pain which do not respond well to conventional analgesic drugs.
Almorexant (INN; development code ACT-078573) is an orexin antagonist, functioning as a competitive receptor antagonist of the OX1 and OX2 orexin receptors, which was being developed by the pharmaceutical companies Actelion and GSK for the treatment of insomnia. Development of the drug was abandoned in January 2011 due to concerns over the hepatic safety of almorexant after transient increases in liver enzymes were observed in trials.
TCS-OX2-29 is an orexin antagonist. It was the first non-peptide antagonist developed that is selective for the orexin receptor subtype OX2, with an IC50 of 40nM and selectivity of around 250x for OX2 over OX1 receptors. Orexin antagonists are expected to be useful for the treatment of insomnia, with subtype-selective antagonists such as TCS-OX2-29 potentially offering more specificity of action compared to non-selective orexin antagonists like almorexant.
SB-334867 is an orexin antagonist. It was the first non-peptide antagonist developed that is selective for the orexin receptor subtype OX1, with around 50x selectivity for OX1 over OX2 receptors. It has been shown to produce sedative and anorectic effects in animals, and has been useful in characterising the orexinergic regulation of brain systems involved with appetite and sleep, as well as other physiological processes. The hydrochloride salt of SB-334867 has been demonstrated to be hydrolytically unstable, both in solution and as the solid. Orexin antagonists have multiple potential clinical applications including the treatment of drug addiction, insomnia, obesity and diabetes.
SB-408124 is a drug which is a non-peptide antagonist selective for the orexin receptor subtype OX1, with around 70x selectivity for OX1 over OX2 receptors, and improved oral bioavailability compared to the older OX1 antagonist SB-334867. It is used in scientific research into the function of orexinergic neurons in the body.
CGS-15943 is a drug which acts as a potent and reasonably selective antagonist for the adenosine receptors A1 and A2A, having a Ki of 3.3nM at A2A and 21nM at A1. It was one of the first adenosine receptor antagonists discovered that is not a xanthine derivative, instead being a triazoloquinazoline. Consequently, CGS-15943 has the advantage over most xanthine derivatives that it is not a phosphodiesterase inhibitor, and so has more a specific pharmacological effects profile. It produces similar effects to caffeine in animal studies, though with higher potency.
An orexin receptor antagonist, or orexin antagonist, is a drug that inhibits the effect of orexin by acting as a receptor antagonist of one or both of the orexin receptors, OX1 and OX2. Medical applications include treatment of sleep disorders such as insomnia.
Filorexant (INN, USAN) (code name MK-6096) is an orexin antagonist which is or was under development by Merck for the treatment of insomnia. It is a dual antagonist of the OX1 and OX2 receptors. As of March 2014, filorexant has completed phase II clinical trials. It was also investigated as a migraine prophylaxis, but was not found effective, and in major depressive disorder and painful diabetic neuropathy. As of May 2015, filorexant is no longer listed on Merck's online development pipeline.
Seltorexant (former developmental code names MIN-202, JNJ-42847922, JNJ-922) is a selective, small-molecule antagonist of the OX2 receptor that is under development by Minerva Neurosciences and Johnson & Johnson's Janssen Pharmaceuticals for the treatment of insomnia and major depressive disorder (MDD). As of December 2015, it is in phase II clinical trials for both insomnia and major depressive disorder.
Lemborexant, sold under the brand name Dayvigo, is a medication for the treatment of insomnia characterized by difficulties with sleep onset and/or sleep maintenance in adults. Lemborexant was approved in the United States for use by adults with insomnia in December 2019.
Daridorexant (developmental code name ACT-541468), formerly known as nemorexant, is a dual orexin receptor antagonist (DORA) which was originated by Actelion Pharmaceuticals and is under development by Idorsia Pharmaceuticals for the treatment of insomnia. It acts as a selective dual antagonist of the orexin receptors OX1 and OX2. The medication has a relatively short elimination half-life of 6 to 10 hours. As of April 2020, daridorexant has passed its first phase III clinical trial for the treatment of insomnia.
ACT-335827 is an orally available, selective orexin 1 receptor antagonist with anxiolytic effects in animals. Unlike other orexin receptor antagonists, ACT-335827 lacks sedative effects and was found to have no impact on sleep architecture in mice.
JNJ-10397049 is a potent and highly selective OX2 receptor antagonist. In animals, JNJ-10397049 was found to have sleep-promoting effects and to attenuate the reinforcing effects of ethanol.
Vornorexant (developmental code names ORN-0829, TS-142) is an orexin receptor antagonist which is under development for the treatment of insomnia and sleep apnea syndrome. It is a dual orexin OX1 and OX2 receptor antagonist (DORA). The medication has a relatively short elimination half-life of 6 hours. As of June 2021, vornorexant is in phase 2 clinical trials for insomnia and phase 1 trials for sleep apnea syndrome.