Tag: 5-HT Receptor

What is Ipspirone?

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Introduction

Ipsapirone is a selective 5-HT1A receptor partial agonist of the piperazine and azapirone chemical classes.

Outline

It has antidepressant and anxiolytic effects.

Ipsapirone was studied in several placebo-controlled trials for depression and continues to be used in research.

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What is Flesinoxan?

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Introduction

Flesinoxan (DU-29,373) is a potent and selective 5-HT1A receptor partial/near-full agonist of the phenylpiperazine class.

Outline

Originally developed as a potential antihypertensive drug, flesinoxan was later found to possess antidepressant and anxiolytic effects in animal tests. As a result, it was investigated in several small human pilot studies for the treatment of major depressive disorder (MDD), and was found to have robust effectiveness and very good tolerability. However, due to “management decisions”, the development of flesinoxan was stopped and it was not pursued any further.

In patients, flesinoxan enhances REM sleep latency, decreases body temperature, and increases ACTH, cortisol, prolactin, and growth hormone secretion.

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What is F-15,599?

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Introduction

F-15,599, also known as NLX-101, is a potent and selective 5-HT1A receptor full agonist. In addition, it displays functional selectivity, or biased agonism, by preferentially activating postsynaptic serotonin 5-HT1A receptors over somatodendritic serotonin 5-HT1A autoreceptors. The drug has been investigated for potential use as a pharmaceutical drug in the treatment of conditions including depression, schizophrenia, cognitive disorders, Rett syndrome, and fragile X syndrome.

Brief History

F-15,599 was first described in the scientific literature by 2006.

Pharmacology

Pharmacodynamics

In terms of its functional selectivity, the drug preferentially activates and phosphorylates ERK1/2 over receptor internalisation or inhibition of adenylyl cyclase. In addition, it preferentially activates the Gαi G protein subtype over the Gαo subtype. As a result of its biased agonism for postsynaptic 5-HT1A receptors, F-15,599 shows regional selectivity in its central effects. It mainly activates the prefrontal cortex, cingulate cortex, retrosplenial cortex, septum, and colliculi. Conversely, the drug does not significantly alter cerebral blood flow in areas characterised by abundance of presynaptic serotonin 5-HT1A receptors, such as the raphe nucleus.

F-15,599 has shown antidepressant-like, anxiolytic-like, antidyskinetic, procognitive, and antiaggressive effects in animals. In cognitive tests in rodents, F-15,599 attenuates memory deficits elicited by the NMDA receptor antagonist phencyclidine (PCP), suggesting that it may improve cognitive function in disorders such as schizophrenia. Another study found that F-15,599 reduces breathing irregularity and apnoeas observed in mice with mutations of the MeCP2 gene, a mouse model of Rett syndrome.

Clinical Trials

F-15,599 was discovered and initially developed by Pierre Fabre Médicament, a French pharmaceuticals company. In September 2013, F-15,599 was out-licensed to Neurolixis, a California-based biotechnology company. Neurolixis announced that it intends to re-purpose F-15,599 for the treatment of Rett syndrome. and obtained orphan drug designation from the United States Food and Drug Administration (FDA) and from the European Commission for this indication.

Researchers at the University of Bristol are investigating the activity of F-15599 in animal models of Rett Syndrome, with support from the International Rett Syndrome Foundation. In June 2015, the Rett Syndrome Research Trust awarded a grant to Neurolixis to advance F-15599 to clinical development.

As of September 2024, F-15,599 is in phase 1 clinical trials for fragile X syndrome. Conversely, no recent development has been reported for depressive disorders or Rett syndrome and development has been discontinued for cognition disorders, mood disorders, and schizophrenia.

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What is Enciprazine?

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Introduction

Enciprazine (INN, BAN; enciprazine hydrochloride (USAN); developmental code names WY-48624, D-3112) is an anxiolytic and antipsychotic of the phenylpiperazine class which was never marketed.

It shows high affinity for the α1-adrenergic receptor and 5-HT1A receptor, among other sites.

The drug was initially anticipated to produce ortho-methoxyphenylpiperazine (oMeOPP), a serotonin receptor agonist with high affinity for the 5-HT1A receptor, as a significant active metabolite, but subsequent research found this not to be the case.

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What is BMY-14802?

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Introduction

BMY-14802, also known as BMS-181100, is a drug with antipsychotic effects which acts as both a sigma receptor antagonist and a 5-HT1A receptor agonist.

It also has affinity for the 5-HT2 and D4 receptors.

The drug reached phase III clinical trials for the treatment of psychosis but was never marketed.

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What is Eptapirone?

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Introduction

Eptapirone (F-11,440) is a very potent and highly selective 5-HT1A receptor full agonist of the azapirone family. Its affinity for the 5-HT1A receptor was reported to be 4.8 nM (Ki) (or 8.33 (pKi)), and its intrinsic activity approximately equal to that of serotonin (i.e. 100%).

Eptapirone and related high-efficacy 5-HT1A full and super agonists such as befiradol and F-15,599 were developed under the hypothesis that the maximum exploitable therapeutic benefits of 5-HT1A receptor agonists might not be able to be seen without the drugs employed possessing sufficiently high intrinsic activity at the receptor. As 5-HT1A receptor agonism, based on animal and other research, looked extremely promising for the treatment of depression from a theoretical perspective, this idea was developed as a potential explanation for the relatively modest clinical effectiveness seen with already available 5-HT1A receptor agonists like buspirone and tandospirone, which act merely as weak-to-moderate partial agonists of the receptor.

Animal Studies

In the Porsolt forced swimming test, eptapirone was found to suppress immobility more robustly than buspirone, ipsapirone, flesinoxan, paroxetine, and imipramine, which was suggestive of strong antidepressant-like effects. In this assay, unlike the other drugs screened, buspirone actually increased the immobility time with a single administration, while repeated administration decreased it, an effect that may have been related to buspirone’s relatively weak intrinsic activity (~30%) at the 5-HT1A receptor and/or its preferential activation of 5-HT1A somatodendritic autoreceptors over postsynaptic receptors.

After repeated administration, high dose paroxetine was able to rival the reduction in immobility seen with eptapirone. However, efficacy was seen on the first treatment with eptapirone, which suggested that eptapirone may have the potential for a more rapid onset of antidepressant effectiveness in comparison. Imipramine was unable to match the efficacy of eptapirone or high dose paroxetine, which was probably the result of the fact that higher doses were fatal.

In the conflict procedure, eptapirone produced substantial increases in punished responding without affecting unpunished responding, which was suggestive of marked anxiolytic-like effects. In addition, the efficacy of eptapirone in this assay was more evident than that of buspirone, ipsapirone, and flesinoxan.

This page is based on the copyrighted Wikipedia article < https://en.wikipedia.org/wiki/Eptapirone >; it is used under the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). You may redistribute it, verbatim or modified, providing that you comply with the terms of the CC-BY-SA.

What is Flesinoxan?

Published on by Andrew Marshall1 Comment

Introduction

Flesinoxan (DU-29,373) is a potent and selective 5-HT1A receptor partial/near-full agonist of the phenylpiperazine class. Originally developed as a potential antihypertensive drug, flesinoxan was later found to possess antidepressant and anxiolytic effects in animal tests.

As a result, it was investigated in several small human pilot studies for the treatment of major depressive disorder, and was found to have robust effectiveness and very good tolerability. However, due to “management decisions”, the development of flesinoxan was stopped and it was not pursued any further.

In patients, flesinoxan enhances REM sleep latency, decreases body temperature, and increases ACTH, cortisol, prolactin, and growth hormone secretion.

This page is based on the copyrighted Wikipedia article < https://en.wikipedia.org/wiki/Flesinoxan >; it is used under the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). You may redistribute it, verbatim or modified, providing that you comply with the terms of the CC-BY-SA.

What is Befiradol?

Published on by Andrew Marshall1 Comment

Introduction

Befiradol (F-13,640; NLX-112) is an experimental drug being studied for the treatment of levodopa-induced dyskinesia. It is a potent and selective 5-HT1A receptor full agonist.

Brief History

Befiradol was discovered and developed by Pierre Fabre Médicament, a French pharmaceuticals company who initially developed it as a treatment for chronic pain. In September 2013, befiradol was out-licensed to Neurolixis, a US-based biotechnology company. Neurolixis announced that it intended to re-purpose befiradol for the treatment of levodopa-induced dyskinesia in Parkinson’s disease. In support of this indication, Neurolixis received several research grants from the Michael J. Fox Foundation and preclinical data was published describing the activity of befiradol in animal models of Parkinson’s disease. Studies published in 2020 using non-human primate models of Parkinson’s disease, (MPTP-treated marmosets and MPTP-treated macaques), found that befiradol potently reduced Levodopa-induced dyskinesia at oral doses as low as 0.1 to 0.4 mg/kg. In January 2018, the British charity Parkinson’s UK announced that it had awarded Neurolixis a grant to advance development of befiradol up to clinical phase in Parkinson’s disease patients.

Pharmacology

In recombinant cell lines expressing human 5-HT1A receptors, befiradol exhibits high agonist efficacy for a variety of signal transduction read-outs, including ERK phosphorylation, G-protein activation, receptor internalisation and adenylyl cyclase inhibition. In rat hippocampal membranes it preferentially activates GalphaO proteins. In neurochemical experiments, befiradol activated 5-HT1A autoreceptors in rat dorsal Raphe nucleus as well as 5-HT1A heteroreceptors on pyramidal neurons in the frontal cortex. In rat models, it has powerful analgesic and antiallodynic effects comparable to those of high doses of opioid painkillers, but with fewer and less prominent side effects, as well as little or no development of tolerance with repeated use.

A structure–activity relationship (SAR) study revealed that replacement of the dihalophenyl moiety by 3-benzothienyl increases maximal efficacy from 84% to 124% (Ki=2.7 nM).

Clinical Ph2A Trial for Dyskinesia in Parkinson’s Disease

In March 2019, Neurolixis announced that the US Food and Drug Administration (FDA) gave a positive response to Neurolixis’ Investigational New Drug (IND) application for NLX-112 to be tested in a Phase 2 clinical study in Parkinson’s disease patients with troublesome levodopa-induced dyskinesia. On 22 November 2020, The Sunday Times reported that the two charities, Parkinson’s UK and Michael J. Fox Foundation, were jointly investing $2 million to support a clinical trial on befiradol in Parkinson’s disease patients with troublesome Levodopa-induced dyskinesia, a potentially “life changing” drug. On 23 November 2020, Parkinson’s UK and Michael J. Fox Foundation, confirmed their funding in an official announcement. Neurolixis announced on 30 November 2021 the start of patient recruitment in the clinical trial. The trial is listed on the US National Library of Medicine clinical trials register. On 20 March 2023, a joint press release from Neurolixis, Parkinson’s UK and Michael J. Fox Foundation announced that the clinical trial had met its primary endpoint of safety and tolerability, and also the secondary endpoint of efficacy in reducing Levodopa-induced dyskinesia in the patients. Moreover, a later announcement (07 July 2023) disclosed that the clinical trial had also found that befiradol reduced parkinsonism symptoms (such as slowness of movement, tremor and rigidity), as well as Levodopa-induced dyskinesia, raising the prospect of developing a “dual-efficacy therapy” for Parkinson’s disease.

18F-Befiradol as an Agonist PET Radiotracer for Brain Imaging

As well as studies on befiradol for treatment of movement disorders, other researchers have investigated it as a novel radiotracer for brain imaging studies by positron emission tomography. Thus befiradol labeled with [18F] (also known as 18F-F13640) has been used to study the distribution of serotonin 5-HT1A receptors in rat, cat, macaque and human. Because befiradol is an agonist, it enables the detection of 5-HT1A receptors which are specifically in a functionally active state, whereas antagonist radiotracers label the total receptor population.

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What is Quipazine?

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Introduction

Quipazine, also known as 1-(2-quinolinyl)piperazine, is a serotonergic drug of the arylpiperazine family and an analogue of 1-(2-pyridinyl)piperazine which is used in scientific research.

It was first described in the 1960s and was originally intended as an antidepressant but was never developed or marketed for medical use.

Pharmacology

Pharmacodynamics

Quipazine is a serotonin 5-HT3 receptor agonist and to a lesser extent a serotonin 5-HT2A receptor agonist, ligand of the serotonin 5-HT2B and 5-HT2C receptors, and serotonin reuptake inhibitor. Activation of the serotonin 5-HT3 is implicated in inducing nausea and vomiting as well as anxiety, which has limited the potential clinical usefulness of quipazine.

Quipazine produces a head-twitch response and other psychedelic-consistent effects in animal studies including in mice, rats, and monkeys. These effects appear to be mediated by activation of the serotonin 5-HT2A receptor, as they are blocked by serotonin 5-HT2A receptor antagonists like ketanserin. The head twitches induced by quipazine are potentiated by the monoamine oxidase inhibitor (MAOI) pargyline. Based on this, it has been suggested that quipazine may act as a serotonin releasing agent and that it may induce the head twitch response by a dual action of serotonin 5-HT2A receptor agonism and induction of serotonin release.

Quipazine did not produce psychedelic effects in humans up to a dose of 25 mg, which was the highest dose tested due to serotonin 5-HT3 receptor-mediated side effects of nausea and gastrointestinal discomfort. Alexander Shulgin has anecdotally claimed that a fully effective psychedelic dose could be reached by blocking serotonin 5-HT3 receptors using the serotonin 5-HT3 receptor antagonist ondansetron.

Quipazine can produce tachycardia, including positive chronotropic and positive inotropic effects, through activation of the serotonin 5-HT3 receptor.

Although quipazine does not generalise to dextroamphetamine in drug discrimination tests of dextroamphetamine-trained rodents, dextroamphetamine and cathinone have been found to partially generalise to quipazine in assays of quipazine-trained rodents. In relation to this, it has been suggested that quipazine might possess some dopaminergic activity, as the discriminative stimulus properties of amphetamine appear to be mediated by dopamine signalling. Relatedly, quipazine has been said to act as a dopamine receptor agonist in addition to serotonin receptor agonist. Conversely however, the generalisation may be due to serotonergic activities of amphetamine and cathinone. Fenfluramine has been found to fully generalise to quipazine, but levofenfluramine, in contrast to quipazine, did not generalise to dextroamphetamine.

Chemistry

Quipazine is a substituted piperazine and quinoline.

It is structurally related to 6-nitroquipazine and 1-(1-naphthyl)piperazine.

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What is 1-(2-Diphenyl)piperazine

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Introduction

1-(2-Diphenyl)piperazine, also known as RA-7 or Diphenylpiperazine, is a drug which acts as a potent and selective antagonist at the 5-HT7 serotonin receptor.

It was discovered as an active metabolite of the synthetic 5-HT7 agonists LP-12 and LP-211, and unexpectedly turned out to be a potent antagonist with selectivity approaching that of the parent molecules, despite its much simpler structure.

Refer to Naphthylpiperazine.

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