Ritanserin is a serotonin receptor antagonist which was never marketed for clinical use but has been used in scientific research.
The mammalian 5-HT2A receptor is a subtype of the 5-HT2 receptor that belongs to the serotonin receptor family and is a G protein-coupled receptor (GPCR). 5-HT is short for 5-hydroxy-tryptamine, which is serotonin. This is the main excitatory receptor subtype among the GPCRs for serotonin, although 5-HT2A may also have an inhibitory effect on certain areas such as the visual cortex and the orbitofrontal cortex. This receptor was first noted for its importance as a target of serotonergic psychedelic drugs such as LSD. Later it came back to prominence because it was also found to be mediating, at least partly, the action of many antipsychotic drugs, especially the atypical ones.
The 5-HT3 antagonists, informally known as "setrons", are a class of drugs that act as receptor antagonists at the 5-HT3 receptor, a subtype of serotonin receptor found in terminals of the vagus nerve and in certain areas of the brain. With the notable exceptions of alosetron and cilansetron, which are used in the treatment of irritable bowel syndrome, all 5-HT3 antagonists are antiemetics, used in the prevention and treatment of nausea and vomiting. They are particularly effective in controlling the nausea and vomiting produced by cancer chemotherapy and are considered the gold standard for this purpose.
5-Hydroxytryptamine receptor 2B (5-HT2B) also known as serotonin receptor 2B is a protein that in humans is encoded by the HTR2B gene. 5-HT2B is a member of the 5-HT2 receptor family that binds the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT).
The 5HT6 receptor is a subtype of 5HT receptor that binds the endogenous neurotransmitter serotonin (5-hydroxytryptamine, 5HT). It is a G protein-coupled receptor (GPCR) that is coupled to Gs and mediates excitatory neurotransmission. HTR6 denotes the human gene encoding for the receptor.
Quipazine is a piperazine drug used in scientific research. It is a moderately selective serotonin receptor receptor agonist, binding to a range of different serotonin receptors, but particularly to the 5-HT2A and 5-HT3.
MS-245 is a tryptamine derivative which is used in scientific research. It acts as a selective 5-HT6 receptor antagonist with a Ki of 2.3 nM, and was derived through structure-activity relationship development of the selective 5-HT6 agonist EMDT. It has been used as a lead compound for further development of tryptamine-derived 5-HT6 antagonists. In animal studies it has been shown to boost the activity of, but not substitute for, both amphetamine and nicotine.
YM-348 is an indazole derivative drug which acts as a potent and selective 5-HT2C receptor agonist, with an EC50 of 1nM and 15x selectivity over 5-HT2A, although it only has moderate selectivity of 3x over the closely related 5-HT2B receptor. It has thermogenic and anorectic effects in animal studies, making it potentially useful for the treatment of obesity.
SB-699551 is a drug which was the first compound developed to act as a selective antagonist for the serotonin receptor 5-HT5A, with selectivity of around 100x over other serotonin receptor subtypes. The function of the 5-HT5A receptor remains poorly defined, but SB-699551 was found to modulate serotonin release from neurons, suggesting it acts as a presynaptic inhibitory autoreceptor similar to the 5-HT1B and 5-HT1D receptors. Multiple therapeutic roles have been suggested for 5-HT5A ligands due to the presence of this receptor in several areas of the brain, but research is still at an early stage, with one possible application being the currently difficult to treat negative symptoms of schizophrenia. In animal studies, SB-699551 was found to block cue-mediated responding to LSD, again suggesting an antipsychotic type of activity.
SB-204741 is a drug which acts as a potent and selective antagonist at the serotonin 5-HT2B receptor, with around 135x selectivity over the closely related 5-HT2C receptor, and even higher over the 5-HT2A receptor and other targets. It is used in scientific research for investigating the functions of the 5-HT2B receptor.
EGIS-12,233 is a drug with applications in scientific research, acting as a potent and selective antagonist for both the 5-HT6 and 5-HT7 serotonin receptor subtypes, with good selectivity over other receptors. It has been shown to increase dopamine release in cochlear tissue, suggesting a role for the 5-HT6 and 5-HT7 receptors in regulation of the hearing system.
AMDA (9-Aminomethyl-9,10-dihydroanthracene) is an organic compound which acts as a potent and selective antagonist for the 5-HT2A receptor. It has been used to help study the shape of the 5-HT2A protein, and develop a large family of related derivatives with even higher potency and selectivity.
WAY-100135 is a serotonergic drug of the phenylpiperazine family which is used in scientific research. It acts as potent 5-HT1A receptor antagonist, and was originally believed to be highly selective, but further studies have demonstrated that it also acts as a partial agonist of the 5-HT1D receptor (pKi = 7.58; virtually the same affinity for 5-HT1A), and to a much lesser extent, of the 5-HT1B receptor (pKi = 5.82). These findings may have prompted the development of the related compound WAY-100635, another purportedly selective and even more potent 5-HT1A antagonist, which was synthesized shortly thereafter. However, WAY-100635 turned out to be non-selective as well, having been shown to act additionally as a potent D4 receptor agonist later on.
AS-8112 is a synthetic compound that acts as a selective antagonist at the dopamine receptor subtypes D2 and D3, and the serotonin receptor 5-HT3. It has potent antiemetic effects in animal studies and has been investigated for potential medical use.
Pruvanserin is a selective 5-HT2A receptor antagonist which was under development by Eli Lilly and Company for the treatment of insomnia. It was in phase II clinical trials in 2008 but appears to have been discontinued as it is no longer in the company's development pipeline. In addition to its sleep-improving properties, pruvanserin has also been shown to have antidepressant, anxiolytic, and working memory-enhancing effects in animal studies.
CP-93129 is a drug which acts as a potent and selective serotonin 5-HT1B receptor agonist, with approximately 150x and 200x selectivity over the closely related 5-HT1D and 5-HT1A receptors. It is used in the study of 5-HT1B receptors in the brain, particularly their role in modulating the release of other neurotransmitters.
SB-206553 is a drug which acts as a mixed antagonist for the 5-HT2B and 5-HT2C serotonin receptors. It has anxiolytic properties in animal studies and interacts with a range of other drugs. It has also been shown to act as a positive allosteric modulator of α7 nicotinic acetylcholine receptors.
Clorotepine, also known as octoclothepin or octoclothepine, is an antipsychotic of the tricyclic group which was derived from perathiepin in 1965 and marketed in the Czech Republic by Spofa in or around 1971 for the treatment of schizophrenic psychosis.
5-MeO-NBpBrT is a N-substituted member of the methoxytryptamine family of compounds. Like other such compounds it acts as an antagonist for the 5-HT2A receptor, with a claimed 100x selectivity over the closely related 5-HT2C receptor. While N-benzyl substitution of psychedelic phenethylamines often results in potent 5-HT2A agonists, it had been thought that N-benzyl tryptamines show much lower efficacy and are either very weak partial agonists or antagonists at 5-HT2A, though more recent research has shown stronger agonist activity for 3-substituted benzyl derivatives. Extending the benzyl group to a substituted phenethyl can also recover agonist activity in certain cases.
