Nalmexone

Nalmefene (trade name Selincro), originally known as nalmetrene, is an opioid antagonist used primarily in the management of alcohol dependence. It has also 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 function 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.

Pharmacology

Nalmefene is a 6-methylene analogue of naltrexone, a pure opioid antagonist. The substitution of a methyl group on the nitrogen atom with a methylene group increases the affinity of nalmefene for μ-opioid receptors and decreases its affinity for δ-opioid receptors. The N-cyclopropylmethyl group of nalmefene causes it to bind more tightly to the opioid receptor than naltrexone.

Medical uses

Nalmefene is used in the treatment of alcohol dependence. It is used in patients who are still drinking significantly, despite trying to stop. Nalmefene is used only in combination with psychosocial support to reduce alcohol consumption. Nalmefene is contraindicated in people with current or recent opioid use, including those undergoing opioid withdrawal.

Side effects

Common side effects of nalmefene include dizziness, nausea, insomnia, and headache. Less common side effects include restlessness, somnolence, and decreased libido.

See also

• Naltrexone
• Opioid antagonist
• Alcohol dependence

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