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Formula | C14H23N7S |
Molar mass | 321.45 g·mol−1 |
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Impromidine (INN) is a highly potent and specific histamine H2 receptor agonist. [1]
It has been used diagnostically as a gastric secretion indicator.
H2 antagonists, sometimes referred to as H2RAs and also called H2 blockers, are a class of medications that block the action of histamine at the histamine H2 receptors of the parietal cells in the stomach. This decreases the production of stomach acid. H2 antagonists can be used in the treatment of dyspepsia, peptic ulcers and gastroesophageal reflux disease. They have been surpassed by proton pump inhibitors (PPIs); the PPI omeprazole was found to be more effective at both healing and alleviating symptoms of ulcers and reflux oesophagitis than the H2 blockers ranitidine and cimetidine.
Histamine H3 receptors are expressed in the central nervous system and to a lesser extent the peripheral nervous system, where they act as autoreceptors in presynaptic histaminergic neurons and control histamine turnover by feedback inhibition of histamine synthesis and release. The H3 receptor has also been shown to presynaptically inhibit the release of a number of other neurotransmitters (i.e. it acts as an inhibitory heteroreceptor) including, but probably not limited to dopamine, GABA, acetylcholine, noradrenaline, histamine and serotonin.
H2 receptors are positively coupled to adenylate cyclase via Gs alpha subunit. It is a potent stimulant of cAMP production, which leads to activation of protein kinase A. PKA functions to phosphorylate certain proteins, affecting their activity. The drug betazole is an example of a histamine H2 receptor agonist.
ABT-239 is an H3-receptor inverse agonist developed by Abbott. It has stimulant and nootropic effects, and has been investigated as a treatment for ADHD, Alzheimer's disease, and schizophrenia. ABT-239 is more active at the human H3 receptor than comparable agents such as thioperamide, ciproxifan, and cipralisant. It was ultimately dropped from human trials after showing the dangerous cardiac side effect of QT prolongation, but is still widely used in animal research into H3 antagonists / inverse agonists.
Cipralisant (GT-2331, tentative trade name Perceptin) is an extremely potent histamine H3 receptor ligand originally developed by Gliatech. Cipralisant was initially classified as a selective H3 antagonist, but newer research (2005) suggests also agonist properties, i. e. functional selectivity. Cipralisant seemed to be well tolerated during early testing, entering Phase II trials for ADHD in 2000.
Ciproxifan is an extremely potent histamine H3 inverse agonist/antagonist.
Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic drug that can be bought without a prescription and provides relief from nasal congestion, sneezing, or hives caused by pollen, dust mites, or animal allergy with few side effects. Antihistamines are usually for short-term treatment. Chronic allergies increase the risk of health problems which antihistamines might not treat, including asthma, sinusitis, and lower respiratory tract infection. Consultation of a medical professional is recommended for those who intend to take antihistamines for longer-term use.
An H3 receptor antagonist is a classification of drugs used to block the action of histamine at the H3 receptor.
Imetit is a histamine H3 receptor agonist.
A-349,821 is a potent and selective histamine H3 receptor antagonist (or possibly an inverse agonist). It has nootropic effects in animal studies, although there do not appear to be any plans for clinical development at present and it is currently only used in laboratory research.
4-Methylhistamine is a histamine agonist selective for the H4 subtype.
VUF-5681 is a potent and selective histamine antagonist which binds selectively to the H3 subtype. However while VUF-5681 blocks the activity of more potent H3 agonists, recent studies suggest that it may have some weak partial agonist activity when administered by itself.
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.
Amthamine is a histamine agonist selective for the H2 subtype. It has been used in vitro and in vivo to study gastric secretion, as well as other functions of the H2 receptor.
Histamine trifluoromethyl toluidide (HTFMT) is a mixed H1/H2 histamine agonist which is significantly more potent than histamine itself.
Methimepip is a histamine agonist which is highly selective for the H3 subtype. It is the N-methyl derivative of immepip.
Immethridine is a histamine agonist selective for the H3 subtype.
VUF-8430 is a histamine agonist selective for the H4 subtype.
UR-AK49 is a drug used in scientific research which acts as a potent antagonist for the Neuropeptide Y / Pancreatic polypeptide receptor Y4, and also as a partial agonist at the histamine receptors H1 and H2. UR-AK49 is a pure antagonist at Y4 with no partial agonist effects, and although it is only slightly selective for Y4 over the related Y1 and Y5 receptors, as the first non-peptide Y4 antagonist developed UR-AK49 is expected to be useful in the study of this receptor and its role in the body.
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.