n.
A drug, C21H25NO3, used as an antagonist to narcotic drugs.
[NAL(TREXONE) + mefene (probably shortening and alteration of METHYLENE).]
nalmefene
Dictionary:
nal·me·fene (năl'mə-fēn') 
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n.
A drug, C21H25NO3, used as an antagonist to narcotic drugs.
| 5min Related Video: nalmefene |
| Drug Info: Nalmefene |
Brand names: Revex™
Chemical formula:
- Drug Forms:
- Nalmefene injection (below)
- Nalmefene Hydrochloride Solution for injection
Nalmefene injection
What is nalmefene injection?
NALMEFENE (Revex®) reverses effects that are produced by narcotic drugs such as difficult breathing and coma. Narcotics may be used during surgery to help produce anesthesia and relieve pain, and nalmefene can reverse these effects after surgery. Nalmefene is used to treat cases of narcotic drug overdose. If you are dependent on narcotic drugs, nalmefene will cause withdrawal symptoms. Generic nalmefene injection is not available.What should I tell my health care provider before I take this medicine?
They need to know if you have any of these conditions:• an ongoing drug or alcohol abuse problem
• brain tumor
• head injury
• heart disease or irregular heartbeats
• seizures (convulsions)
• an unusual or allergic reaction to nalmefene, other medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding
How should I use this medicine?
Nalmefene is for injection into a vein. Sometimes the injection may be given into a muscle or under the skin. It is given by a health-care professional in a hospital or clinic setting.What if I miss a dose?
This does not apply.What drug(s) may interact with nalmefene?
• flumazenil• medicines for pain
• nalbuphine
Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your health care professional before stopping or starting any of your medicines.
What should I watch for while taking nalmefene?
Your condition will be monitored after you receive nalmefene.You may feel dizzy or lightheaded. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells. Alcohol can increase possible dizziness, and other side effects. Avoid alcoholic drinks.
What side effects may I notice from receiving nalmefene?
Side effects given below are the result of reversal of narcotic therapy since nalmefene has little effect in the absence of narcotics.Serious side effects include:
• fast or irregular heartbeat
• lung congestion
• seizures (convulsions)
• skin rash
Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):
• diarrhea
• dizziness or lightheadedness
• fever
• nausea, vomiting
• nervousness, restlessness or excitement
• increase in pain
• runny nose
• sweating
• trembling
• weakness or tiredness
Where can I keep my medicine?
Keep out of the reach of children.Store at controlled room temperature between 15 and 30 degrees C (59 and 86 degrees F). Throw away any unused medicine after the expiration date.
Last updated: 7/1/2002
Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.
| Wikipedia: Nalmefene |
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Nalmefene
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| Systematic (IUPAC) name | |
| 17-cyclopropylmethyl-4,5α-epoxy-6-methylenemorphinan-3,14-diol | |
| Identifiers | |
| CAS number | 58895-64-0 (HCl) |
| ATC code | none |
| PubChem | ? |
| Chemical data | |
| Formula | C21H25NO3 |
| Mol. mass | 375.9 g/mol (hydrochloride) |
| Pharmacokinetic data | |
| Bioavailability | ? |
| Protein binding | 45% |
| Metabolism | hepatic |
| Half life | 10.8 ± 5.2 hours |
| Excretion | renal |
| Therapeutic considerations | |
| Pregnancy cat. |
? |
| Legal status |
Prescription Only Medicine |
| Routes | Oral, Intravenous |
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.
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.
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.
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 milligram 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.
Doses of nalmefene greater than 1.5mg 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.
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.
Side effects
- Common: drowsiness, hypertension, tachycardia, dizziness, nausea, vomiting
- Occasional: fever, hypotension, vasodilatation, chills, headache
- Rare: agitation, arrhythmia, bradycardia, confusion, hallucinations, myoclonus, itching[4]
Properties
- Soluble in water up to 130mg/mL, soluble in chloroform up to 0.13 mg/mL
- pKa 7.6
- Distribution half-life: 41 minutes
References
- ^ Arch Gen Psychiatry - Abstract: A Double-blind, Placebo-Controlled Study of Oral Nalmefene for Alcohol Dependence, August 1999, Mason et al. 56 (8): 719
- ^ Clinical Trial Of Nalmefene In The Treatment Of Pathological Gambling
- ^ http://www.fda.gov/cder/foi/label/2000/20459S2lbl.pdf
- ^ Nalmefene Hydrochloride Drug Information, Professional
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 | Nalmefene injection |
| Nalmefene Hydrochloride Solution for injection |
| Somaxon Pharmaceuticals Inc |
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 | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. Read more |
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| Drug Info. Gold Standard. Copyright © 2008 by Gold Standard. All rights reserved. Read more |
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| Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Nalmefene". Read more |
