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Agonist-antagonist Opioids
In pharmacology the term agonist-antagonist or mixed agonist/antagonist is used to refer to a drug which under some conditions behaves as an agonist (a substance that fully activates the receptor that it binds to) while under other conditions, behaves as an antagonist (a substance that binds to a receptor but does not activate and can block the activity of other agonists). Types of mixed agonist/antagonist include receptor ligands that act as agonist for some receptor types and antagonist for others or agonist in some tissues while antagonist in others (also known as selective receptor modulators). Synaptic receptors For synaptic receptors, an agonist is a compound that increases the activation of the receptor by binding directly to it or by increasing the amount of time neurotransmitters are in the synaptic cleft. An antagonist is a compound that has the opposite effect of an agonist. It decreases the activation of a synaptic receptor by binding and blocking neurotransmitters f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agonist & Antagonist
An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agonist, while an inverse agonist causes an action opposite to that of the agonist. Etymology From the Greek αγωνιστής (agōnistēs), contestant; champion; rival < αγων (agōn), contest, combat; exertion, struggle < αγω (agō), I lead, lead towards, conduct; drive Types of agonists can be activated by either endogenous agonists (such as |
Sigma Receptor
Sigma receptors (σ-receptors) are protein cell surface receptors that bind ligands such as 4-PPBP (4-phenyl-1-(4-phenylbutyl) piperidine), SA 4503 (cutamesine), ditolylguanidine, dimethyltryptamine, and siramesine. There are two subtypes, sigma-1 receptors (σ1) and sigma-2 receptors (σ2), which are classified as sigma receptors for their pharmacological similarities, even though they are evolutionarily unrelated. The fungal protein ERG2, a C-8 sterol isomerase, falls into the same protein family as sigma-1. Both localize to the ER membrane, although sigma-1 is also reported to be a cell surface receptor. Sigma-2 is an EXPREA domain protein (citation needed) with a mostly intracellular (ER membrane) localization. Classification Because the σ-receptor was originally discovered to be agonized by benzomorphan opioids and antagonized by naltrexone, σ-receptors were originally believed to be a type of opioid receptor. When the σ1 receptor was isolated and cloned, it was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverse Agonist
In pharmacology, an inverse agonist is a drug that binds to the same receptor as an agonist but induces a pharmacological response opposite to that of the agonist. A neutral antagonist has no activity in the absence of an agonist or inverse agonist but can block the activity of either. Inverse agonists have opposite actions to those of agonists but the effects of both of these can be blocked by antagonists. A prerequisite for an inverse agonist response is that the receptor must have a constitutive (also known as intrinsic or basal) level of activity in the absence of any ligand. An agonist increases the activity of a receptor above its basal level, whereas an inverse agonist decreases the activity below the basal level. The efficacy of a full agonist is by definition 100%, a neutral antagonist has 0% efficacy, and an inverse agonist has < 0% (i.e., negative) efficacy. Examples Receptors for which inverse agonists have been identified include the[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Competitive Antagonist
A receptor antagonist is a type of receptor ligand or drug that blocks or dampens a biological response by binding to and blocking a receptor rather than activating it like an agonist. Antagonist drugs interfere in the natural operation of receptor proteins.Pharmacology Guide: In vitro pharmacology: concentration-response curves " '' GlaxoWellcome.'' Retrieved on December 6, 2007. They are sometimes called blockers; examples include s, |
Drug Tolerance
Drug tolerance or drug insensitivity is a pharmacological concept describing subjects' reduced reaction to a drug following its repeated use. Increasing its dosage may re-amplify the drug's effects; however, this may accelerate tolerance, further reducing the drug's effects. Drug tolerance is indicative of drug use but is not necessarily associated with drug dependence or addiction. The process of tolerance development is reversible (e.g., through a drug holiday) and can involve both physiological factors and psychological factors. One may also develop drug tolerance to side effects, in which case tolerance is a desirable characteristic. A medical intervention that has an objective to increase tolerance (e.g., allergen immunotherapy, in which one is exposed to larger and larger amounts of allergen to decrease one's allergic reactions) is called drug desensitization. The opposite concept to drug tolerance is drug reverse tolerance (or drug sensitization), in which case the sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psychotomimetic
A drug with psychotomimetic (also known as psychotogenic) actions mimics the symptoms of psychosis, including delusions and/or delirium, as opposed to only hallucinations. Psychotomimesis is the onset of psychotic symptoms following the administration of such a drug. Some rarely used drugs of the opioid class have psychotomimetic effects. Particularly, mixed kappa receptor agonist mu receptor antagonist opioid analgesics can cause dose-related psychotomimesis. This adverse effect, incidence 1–2%, limits their use. Pentazocine and butorphanol fall under this opioid class. There is evidence that cannabinoids are psychotomimetic, especially delta-9-tetrahydrocannabinol (Δ9-THC). D'Souza et al. (2004) found that intravenous THC produced effects that resemble schizophrenia in both the positive symptoms (hallucinations, delusions, paranoia, and disorganized thinking) and negative symptoms (avolition, asociality, apathy, alogia, and anhedonia). Certain strains of cannabis may be mor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceiling Effect (pharmacology)
In pharmacology, the term ceiling effect refers to the property of increasing doses of a given medication to have progressively smaller incremental effect (an example of diminishing returns). Mixed agonist-antagonist opioids, such as nalbuphine, serve as a classic example of the ceiling effect; increasing the dose of a narcotic frequently leads to smaller and smaller gains in relief of pain. In many cases, the severity of side effects from a medication increases as the dose increases, long after its therapeutic ceiling has been reached. The term is defined as "the phenomenon in which a drug reaches a maximum effect, so that increasing the drug dosage does not increase its effectiveness." Sometimes drugs cannot be compared across a wide range of treatment situations because one drug has a ceiling effect.{{cn, date=September 2020 Sometimes the desired effect increases with dose, but side-effects worsen or start being dangerous, and risk to benefit ratio increases. This is bec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nalbuphine
Nalbuphine, sold under the brand names Nubain among others, is an opioid analgesic which is used in the treatment of pain. It is given by injection into a vein, muscle, or fat. Side effects of nalbuphine include sedation, sweatiness, clamminess, nausea, vomiting, dizziness, vertigo, dry mouth, and headache. Unlike other opioids, it has little to no capacity for euphoria or respiratory depression. It also has little to no incidence of dysphoria, dissociation, hallucinations, and related side effects at typical therapeutic doses. Nalbuphine is a mixed agonist/antagonist opioid modulator. Specifically, it acts as a moderate-efficacy partial agonist or antagonist of the μ-opioid receptor (MOR) and as a high-efficacy partial agonist of the κ-opioid receptor (KOR), whereas it has relatively low affinity for the δ-opioid receptor (DOR) and sigma receptors. Nalbuphine was patented in 1963US Patent 3393197 - Nusubstituted-14-hydroxydihydronormorphines and was introduced for medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Opioid Receptor
Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D (NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also refer to: Places Canada * Delta, British Columbia ** Delta (electoral district), a federal electoral district ** Delta (provincial electoral district) * Delta, Ontario United States * Mississippi Delta * Delta, Alabama * Delta Junction, Alaska * Delta, Colorado * Delta, Illinois * Delta, Iowa * Delta, Kentucky * Delta, Louisiana * Delta, Missouri * Delta, North Carolina * Delta, Ohio * Delta, Pennsylvania * Sacramento–San Joaquin River Delta, California * Delta, Utah * Delta, Wisconsin, a town * Delta (community), Wisconsin * Delta County (other) Elsewhere * Delta Island, Antarctica * Delta Stream, Antarctica * Delta, Minas Gerais, Brazil * Nile Delta, Egypt * Delta, Thessaloniki, Greece * Delta State, N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Butorphanol
Butorphanol is a morphinan-type synthetic agonist–antagonist opioid analgesic developed by Bristol-Myers. Butorphanol is most closely structurally related to levorphanol. Butorphanol is available as the tartrate salt in injectable, tablet, and intranasal spray formulations. The tablet form is only used in dogs, cats and horses due to low bioavailability in humans. It was patented in 1971 and approved for medical use in 1979. Medical uses The most common indication for butorphanol is management of migraine using the intranasal spray formulation. It may also be used parenterally for management of moderate-to-severe pain, as a supplement for balanced general anesthesia, and management of pain during labor. Butorphanol is also quite effective at reducing post-operative shivering (owing to its Kappa agonist activity). Butorphanol is more effective in reducing pain in women than in men. Pharmacology Butorphanol exhibits partial agonist and antagonist activity at the μ-opioid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kappa Opioid Receptor
Kappa (uppercase Κ, lowercase κ or cursive ; el, κάππα, ''káppa'') is the 10th letter of the Greek alphabet, representing the voiceless velar plosive sound in Ancient and Modern Greek. In the system of Greek numerals, has a value of 20. It was derived from the Phoenician letter kaph . Letters that arose from kappa include the Roman K and Cyrillic К. The uppercase form is identical to the Latin K. Greek proper names and placenames containing kappa are often written in English with "c" due to the Romans' transliterations into the Latin alphabet: Constantinople, Corinth, Crete. All formal modern romanizations of Greek now use the letter "k", however. The cursive form is generally a simple font variant of lower-case kappa, but it is encoded separately in Unicode for occasions where it is used as a separate symbol in math and science. In mathematics, the kappa curve is named after this letter; the tangents of this curve were first calculated by Isaac Barrow in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
