SB-243213

5-HT receptors, 5-hydroxytryptamine receptors, or serotonin receptors, are a group of G protein-coupled receptor and ligand-gated ion channels found in the central and peripheral nervous systems. They mediate both excitatory and inhibitory neurotransmission. The serotonin receptors are activated by the neurotransmitter serotonin, which acts as their natural ligand.

The 5-HT_2A receptor is a subtype of the 5-HT₂ receptor that belongs to the serotonin receptor family and is a G protein-coupled receptor (GPCR). The 5-HT_2A receptor is a cell surface receptor, but has several intracellular locations.

A serotonin receptor agonist is an agonist of one or more serotonin receptors. They activate serotonin receptors in a manner similar to that of serotonin, a neurotransmitter and hormone and the endogenous ligand of the serotonin receptors.

The 5-HT_2C receptor is a subtype of the 5-HT2 receptor that binds the endogenous neurotransmitter serotonin (5-hydroxytryptamine, 5-HT). Like all 5-HT2 receptors, it is a G protein-coupled receptor (GPCR) that is coupled to G_q/G₁₁ and mediates excitatory neurotransmission. HTR2C denotes the human gene encoding for the receptor, that in humans is located on the X chromosome. As males have one copy of the gene and females have one of the two copies of the gene repressed, polymorphisms at this receptor can affect the two sexes to differing extent.

5-Hydroxytryptamine receptor 2B (5-HT_2B) also known as serotonin receptor 2B is a protein that in humans is encoded by the HTR2B gene. 5-HT_2B is a member of the 5-HT₂ receptor family that binds the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT). Like all 5-HT₂ receptors, the 5-HT_2B receptor is G_q/G₁₁-protein coupled, leading to downstream activation of phospholipase C.

Cyamemazine (Tercian), also known as cyamepromazine, is a typical antipsychotic drug of the phenothiazine class which was introduced by Theraplix in France in 1972 and later in Portugal as well.

SB-242084 is a psychoactive drug and research chemical which acts as a selective antagonist for the 5HT_2C receptor. It has anxiolytic effects, and enhances dopamine signalling in the limbic system, as well as having complex effects on the dopamine release produced by cocaine, increasing it in some brain regions but reducing it in others. It has been shown to increase the effectiveness of the selective serotonin reuptake inhibitor (SSRI) class of antidepressants, and may also reduce their side effects. In animal studies, SB-242084 produced stimulant-type activity and reinforcing effects, somewhat similar to but much weaker than cocaine or amphetamines.

SB-399885 is a drug which is used in scientific research. It acts as a potent, selective and orally active 5-HT₆ receptor antagonist, with a Ki of 9.0nM. SB-399885 and other 5-HT₆ antagonists show nootropic effects in animal studies, as well as antidepressant and anxiolytic effects which are comparable to and synergistic with drugs such as imipramine and diazepam, and have been proposed as potential novel treatments for cognitive disorders such as schizophrenia and Alzheimer's disease.

RS-102221 is a drug developed by Hoffmann–La Roche, which was one of the first compounds discovered that acts as a potent and selective antagonist at the serotonin 5-HT_2C receptor, with around 100× selectivity over the closely related 5-HT_2A and 5-HT_2B receptors. It has anxiolytic effects in animal studies, increases the effectiveness of SSRI antidepressants, and shows a complex interaction with cocaine, increasing some effects but decreasing others, reflecting a role for the 5-HT_2C receptor in regulation of the dopamine signalling system in the brain.

BW-723C86 is a tryptamine derivative drug which acts as a 5-HT_2B receptor agonist. It has anxiolytic effects in animal studies, and is also used for investigating the function of the 5-HT_2B receptor in a range of other tissues.

SB-269970 is a drug and research chemical developed by GlaxoSmithKline used in scientific studies. It is believed to act as a selective 5-HT₇ receptor antagonist (EC₅₀ = 1.25 nM) (or possibly inverse agonist). A subsequent study in guinea pig at a concentration of 10 μM showed that it also blocks the α₂-adrenergic receptor. The large difference in test concentrations however confirms the selectivity of SB-269970 for the 5-HT₇ receptor.

Serotonin antagonist and reuptake inhibitors (SARIs) are a class of drugs used mainly as antidepressants, but also as anxiolytics and hypnotics. They act by antagonizing serotonin receptors such as 5-HT_2A and inhibiting the reuptake of serotonin, norepinephrine, and/or dopamine. Additionally, most also antagonize α₁-adrenergic receptors. The majority of the currently marketed SARIs belong to the phenylpiperazine class of compounds.

Adatanserin is a mixed 5-HT_1A receptor partial agonist and 5-HT_2A and 5-HT_2C receptor antagonist. It was under development by Wyeth as an antidepressant but was ultimately not pursued.

Pruvanserin is a selective 5-HT_2A 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.

1-(1-Naphthyl)piperazine (1-NP) is a drug which is a phenylpiperazine derivative. It acts as a non-selective, mixed serotonergic agent, exerting partial agonism at the 5-HT_1A, 5-HT_1B, 5-HT_1D, 5-HT_1E, and 5-HT_1F receptors, while antagonizing the 5-HT_2A, 5-HT_2B, and 5-HT_2C receptors. It has also been shown to possess high affinity for the 5-HT₃, 5-HT_5A, 5-HT₆, and 5-HT₇ receptors, and may bind to 5-HT₄ and the SERT as well. In animals it produces effects including hyperphagia, hyperactivity, and anxiolysis, of which are all likely mediated predominantly or fully by blockade of the 5-HT_2C receptor.

CSP-2503 is a potent and selective 5-HT_1A receptor agonist, 5-HT_2A receptor antagonist, and 5-HT₃ receptor antagonist of the naphthylpiperazine class. First synthesized in 2003, it was designed based on computational models and QSAR studies. In rat studies, CSP-2503 has demonstrated anxiolytic effects, and thus has been suggested as a treatment for anxiety in humans with a multimodal mechanism of action.

SB-206553 is a drug which acts as a mixed antagonist for the 5-HT_2B and 5-HT_2C 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. Modified derivatives of SB-206553 have been used to probe the structure of the 5-HT_2B receptor.

S32212 is a drug which is under preclinical investigation as a potential antidepressant medicine. It behaves as a selective, combined 5-HT_2C receptor inverse agonist and α₂-adrenergic receptor antagonist (at all three subtypes—α_2A, α_2B, and α_2C) with additional 5-HT_2A and, to a lesser extent, 5-HT_2B receptor antagonistic properties, and lacks any apparent affinity for the monoamine reuptake transporters or for the α₁-adrenergic, H₁, or mACh receptors. This profile of activity is compatible with the definition of a noradrenergic and specific serotonergic antidepressant (NaSSA), and as such, S32212 could in turn be classified as a NaSSA.

SB-228357 is a drug which acts as an antagonist for the 5HT_2B and 5HT_2C receptors. It has antidepressant and anxiolytic effects in animal models, and inhibits 5-HT_2B mediated proliferation of cardiac fibroblasts.