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Encyclopedia > Nalmefene

Nalmefene (Revex) is an opioid receptor antagonist used primarily in the management of alcohol dependence, and also has been investigated for the treatment of other addictions such as pathological gambling and addiction to shopping. To meet Wikipedias quality standards, this article may require cleanup. ... Antagonists In medicine and biology, a receptor antagonist is a ligand that inhibits the function of an agonist and inverse agonist for a specific receptor. ... Functional group of an alcohol molecule. ... Drug addiction, or dependency is the compulsive use of drugs, to the point where the user has no effective choice but to continue use. ... Pathological gambling, as defined by American Psychiatric Association is an impulse control disorder associated with gambling. ...


Nalmefene is an opiate derivative similar in both structure and activity to the opiate antagonist naltrexone. Advantages of nalmefene relative to naltrexone include longer half-life, greater oral bioavailability and no observed dose-dependent liver toxicity. As with other drugs of this type, nalmefene can precipitate acute withdrawal symptoms in patients who are dependent on opioid drugs, or more rarely when used post-operatively to counteract the effects of strong opioids used in surgery. The term opiate refers to the alkaloids found in opium, an extract from the seed pods of the opium poppy (). It has also traditionally referred to natural and semi-synthetic derivatives of morphine. ... An antagonist is a fictional character or group of characters, or, sometimes an institution of a story who represents the opposition against which the hero(es) or protagonist(s) must contend. ... Naltrexone is an opioid receptor antagonist used primarily in the management of alcohol dependence and opioid dependence. ... A cardiothoracic surgeon performs a mitral valve replacement at the Fitzsimons Army Medical Center. ...


Nalmefene differs from naltrexone by substitution of the ketone group at the 6-position of naltrexone with a methylene (CH2) group, which considerably increases binding affinity to the μ-opioid receptor. Nalmefene also has high affinity for the other opioid receptors, and is known as a "universal antagonist" for its ability to block all three. Ketone group A ketone is either the functional group characterized by a carbonyl group linked to two other carbon atoms or a chemical compound that contains this functional group. ... In chemistry, methylene is a divalent functional group CH2 derived formally from methane. ...


In clinical trials using this drug, doses used for treating alcoholism were in the range of 20mg - 80mg per day, orally. 1 The doses tested for treating pathological gambling were between 25mg - 100mg per day. 2 In both trials, there was little difference in efficacy between the lower and higher dosage regimes, and the lower dose (20mg and 25mg respectively) was the best tolerated, with similar therapeutic efficacy to the higher doses and less side effects. Nalmefene is thus around twice as potent as naltrexone when used for the treatment of addictions.


Intravenous doses of nalmefene at between 0.5 to 1 mg/kg have been shown effective at counteracting the respiratory depression produced by opiate overdose 3, although this is not the usual application for this drug as naloxone is less expensive. An intravenous drip in a hospital Intravenous therapy or IV therapy is the administration of liquid substances directly into a vein. ... Naloxone is a drug used to counter the effects of opioid overdose, for example heroin and morphine overdose. ...


Doses of nalmefene greater than 1.5mg/kg do not appear to give any greater benefit in this application. Nalmefene's longer half-life might however make it useful for treating overdose involving longer acting opioids such as methadone, as it would require less frequent dosing and hence reduce the likelihood of renarcotization as the antagonist wears off. Methadone is a synthetic opioid, used medically as an analgesic and in the treatment of narcotic addiction. ...


Nalmefene is extensively metabolised in the liver, mainly by conjugation with glucuronide and also by N-dealkylation. Less than 5% of the dose is excreted unchanged. The glucoronide metabolite is entirely inactive, while the N-dealkylated metabolite has minimal activity. Glucuronide is a substance produced by attaching glucuronic acid to another substance with glycosidic bonds. ...


Image:nalmefene.png


CAS number: 58895-64-0


Chemical name: 17-cyclopropylmethyl-4,5α-epoxy-6-methylenemorphinan-3,14-diol


Molecular weight: 375.9 (hydrochloride)


Soluble in water up to 130mg/mL, soluble in chloroform up to 0.13 mg/mL


pKa 7.6


Protein binding: 45%


Distribution half-life: 41 minutes


Elimination half-life: 10.8 ± 5.2 hours


Side effects: common: hypertension, tachycardia, dizziness, nausea, vomiting; occasional: fever, hypotension, vasodilatation, chills, headache; rare: agitation, arrhythmia, bradycardia, confusion, hallucinations, myoclonus, itching. 4 For other forms of hypertension see hypertension (disambiguation). ... Tachycardia is an abnormally rapid beating of the heart, defined as a resting heart rate of 100 or more beats per minute in an average adult. ... Dizziness is a common and inclusive term for several specific symptoms which include pre-syncope, disequilibrium and vertigo. ... For other uses, see Nausea (disambiguation). ... This article or section does not cite its references or sources. ... An analogue medical thermometer showing the temperature of 38. ... In physiology and medicine, hypotension refers to an abnormally low blood pressure. ... The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... This article does not cite its references or sources. ... A headache (medically known as cephalalgia, sometimes spelled as cephalgia) is a condition of pain in the head; sometimes neck or upper back pain may also be interpreted as a headache. ... A cardiac arrhythmia, also called cardiac dysrhythmia, is a disturbance in the regular rhythm of the heartbeat. ... Bradycardia, as applied in adult medicine, is defined as a heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min [1]. It is also less commonly known as brachycardia. ... Look up Confusion in Wiktionary, the free dictionary Confusion can have the following meanings: Unclarity or puzzlement, e. ... A hallucination is a false sensory perception in the absence of an external stimulus, as distinct from an illusion, which is a misperception of an external stimulus. ... Myoclonus is brief, involuntary twitching of a muscle or a group of muscles. ... An itch (Latin: pruritus) is a sensation felt on an area of skin that makes a person or animal want to scratch it. ...


(1) http://archpsyc.ama-assn.org/cgi/content/abstract/56/8/719


(2) http://www.medicalnewstoday.com/medicalnews.php?newsid=37126


(3) http://www.fda.gov/cder/foi/label/2000/20459S2lbl.pdf


(4) http://www.drugs.com/MMX/Nalmefene_Hydrochloride.html


 
 

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