Names | |
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Preferred IUPAC name 3-Aminopropane-1-sulfonic acid | |
Other names Tramiprosate; Alzhemed; 3-APS | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChEMBL | |
ChemSpider | |
DrugBank | |
ECHA InfoCard | 100.020.889 |
EC Number |
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KEGG | |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C3H9NO3S | |
Molar mass | 139.17 g·mol−1 |
Melting point | 293 °C (559 °F; 566 K) (decomposition) |
Hazards | |
GHS labelling: [2] | |
Warning | |
H315, H319, H335 | |
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Homotaurine (also known as tramiprosate (INN), 3-amino-1-propanesulfonic acid, or 3-APS) is a natural sulfonic acid found in seaweed. [3] It is analogous to taurine, but with an extra carbon in its chain. It has GABAergic activity, apparently by mimicking GABA, which it resembles. [4]
Homotaurine was investigated in a Phase III clinical trial as a potential treatment for Alzheimer's disease (AD) that did not show efficacy. However, post-hoc analyses have shown positive and significant effects of homotaurine on secondary endpoints and subgroups of patients, including a reduction in hippocampal volume loss and lower decline in memory function in the overall cohort, as well as a reduction in global cognitive decline in APOE4 allele carriers, suggesting a disease-modifying effect. [5] A study in cognitive impairment done in 2018 did show positive benefits. [6]
Homotaurine is currently in a phase 3 study with expected FDA approval as the first disease modifying drug for AD. [7] [8]
Acamprosate (N-acetyl homotaurine) was approved by the FDA in 2004 to treat alcohol dependence. [4]
In preclinical studies it had been found to bind to soluble amyloid beta and inhibit the formation of neurotoxic aggregates. [5] [9] Homotaurine has also shown anticonvulsant activities, reduction in skeletal muscle tonus, and hypothermic activity. [10]
Homotaurine has been reported as a GABA antagonist, [4] as well as a GABA agonist. [10] [11] In vitro studies have found that homotaurine is a GABAA partial agonist [12] as well as a GABAB receptor partial agonist with low efficacy, becoming an antagonist and displacing the full agonists GABA and baclofen at this receptor. [13] In a study in rats, homotaurine reversed the catatonia induced by baclofen (the prototypical GABAB agonist), [14] and was able to produce analgesia via the GABAB receptor, an effect that was abolished when CGP-35348, a GABAB receptor antagonist was applied. [15] [16]
In a human study homotaurine selectively and fully inhibits the formation of Aβ42 oligomers at the clinical dose, without evidence of vasogenic edema. [7]
One study in rats showed that homotaurine suppressed ethanol-stimulated dopamine release, as well as ethanol intake and preference in rats in a way similar to the N-acetyl derivative of homotaurine, acamprosate. [17]
The GABA receptors are a class of receptors that respond to the neurotransmitter gamma-aminobutyric acid (GABA), the chief inhibitory compound in the mature vertebrate central nervous system. There are two classes of GABA receptors: GABAA and GABAB. GABAA receptors are ligand-gated ion channels ; whereas GABAB receptors are G protein-coupled receptors, also called metabotropic receptors.
Baclofen, sold under the brand name Lioresal among others, is a medication used to treat muscle spasticity such as from a spinal cord injury or multiple sclerosis. It may also be used for hiccups and muscle spasms near the end of life, and off-label to treat alcohol use disorder or opioid withdrawal symptoms. It is taken orally or by intrathecal pump. It is also sometimes used transdermally in combination with gabapentin and clonidine prepared at a compounding pharmacy.
Neuropharmacology is the study of how drugs affect function in the nervous system, and the neural mechanisms through which they influence behavior. There are two main branches of neuropharmacology: behavioral and molecular. Behavioral neuropharmacology focuses on the study of how drugs affect human behavior (neuropsychopharmacology), including the study of how drug dependence and addiction affect the human brain. Molecular neuropharmacology involves the study of neurons and their neurochemical interactions, with the overall goal of developing drugs that have beneficial effects on neurological function. Both of these fields are closely connected, since both are concerned with the interactions of neurotransmitters, neuropeptides, neurohormones, neuromodulators, enzymes, second messengers, co-transporters, ion channels, and receptor proteins in the central and peripheral nervous systems. Studying these interactions, researchers are developing drugs to treat many different neurological disorders, including pain, neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, psychological disorders, addiction, and many others.
GABAB receptors (GABABR) are G-protein coupled receptors for gamma-aminobutyric acid (GABA), therefore making them metabotropic receptors, that are linked via G-proteins to potassium channels. The changing potassium concentrations hyperpolarize the cell at the end of an action potential. The reversal potential of the GABAB-mediated IPSP is –100 mV, which is much more hyperpolarized than the GABAA IPSP. GABAB receptors are found in the central nervous system and the autonomic division of the peripheral nervous system.
Progabide is an analogue and prodrug of γ-aminobutyric acid (GABA) used in the treatment of epilepsy. Via conversion into GABA, progabide behaves as an agonist of the GABAA, GABAB, and GABAA-ρ receptors.
Acamprosate, sold under the brand name Campral, is a medication used along with counseling to treat alcohol use disorder.
Succinic semialdehyde dehydrogenase deficiency (SSADHD) is a rare autosomal recessive disorder of the degradation pathway of the inhibitory neurotransmitter γ-aminobutyric acid, or GABA. The disorder has been identified in approximately 350 families, with a significant proportion being consanguineous families. The first case was identified in 1981 and published in a Dutch clinical chemistry journal that highlighted a number of neurological conditions such as delayed intellectual, motor, speech, and language as the most common manifestations. Later cases reported in the early 1990s began to show that hypotonia, hyporeflexia, seizures, and a nonprogressive ataxia were frequent clinical features as well.
NMDA receptor antagonists are a class of drugs that work to antagonize, or inhibit the action of, the N-Methyl-D-aspartate receptor (NMDAR). They are commonly used as anesthetics for animals and humans; the state of anesthesia they induce is referred to as dissociative anesthesia.
GTS-21 is an investigational drug that has been studied for its potential therapeutic uses, particularly in the treatment of neurodegenerative diseases and psychiatric disorders.
An H3 receptor antagonist is a type of antihistaminic drug used to block the action of histamine at H3 receptors.
Xanomeline is a small molecule muscarinic acetylcholine receptor agonist that was first synthesized in a collaboration between Eli Lilly and Novo Nordisk as an investigational therapeutic being studied for the treatment of central nervous system disorders.
Zacopride is a potent antagonist at the 5-HT3 receptor and an agonist at the 5-HT4 receptor. It has anxiolytic and nootropic effects in animal models, with the (R)-(+)-enantiomer being the more active form. It also has antiemetic and pro-respiratory effects, both reducing sleep apnea and reversing opioid-induced respiratory depression in animal studies. Early animal trials have also revealed that administration of zacopride can reduce preference for and consumption of ethanol.
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.
CGP-7930 was the first positive allosteric modulator of GABAB receptors described in literature. CGP7930 is also a GABAA receptor positive allosteric modulator and a blocker of Potassium channels.
GS-39783 is a compound used in scientific research which acts as a positive allosteric modulator at the GABAB receptor. It has been shown to produce anxiolytic effects in animal studies, and reduces self-administration of alcohol, cocaine and nicotine.
BSPP is a compound used in scientific research which acts as a positive allosteric modulator at the GABAB receptor. It has a synergistic effect with GABAB agonists such as baclofen at GABAB autoreceptors but not heteroreceptors, suggesting it may be useful for distinguishing between these GABAB receptor subtypes.
SKF-97,541 is a compound used in scientific research which acts primarily as a selective GABAB receptor agonist. It has sedative effects in animal studies and is widely used in research into potential treatment of various types of drug addiction.
CGP-35348 is a compound used in scientific research which acts as an antagonist at GABAB receptors.
Alzheon is an American clinical-stage biopharmaceutical company based in Framingham, Massachusetts. The company is developing medicines for patients with Alzheimer's disease and other neurological and psychiatric disorders.
3-Aminopropylphosphinic acid, also known in the literature as 3-APPA or CGP 27492, is a compound used in scientific research which acts as an agonist at the GABAB receptor. It is part of a class of phosphinic acid GABAB agonists, which also includes SKF-97,541. It has a binding affinity (pKi) to the GABAB receptor of 8.30.