Nalmefene: a long-acting opioid antagonist. Clinical applications in emergency medicine

The use of the opioid antagonist naloxone is well known to the experienced health care provider. The availability of the longer acting opioid antagonist nalmefene has several potential benefits in clinical practice. Nalmefene has a plasma half-life of almost 11 h, compared to 60-90 min for naloxone. Nalmefene has been shown to reverse opioid intoxication for as long as 8 h, reducing the need for continuous monitoring of intoxicated patients and repeated dosing of naloxone. Single dose administration has also been used effectively in the reversal of opiate-assisted conscious sedation. In addition, this agent has been used in the treatment of diseases as diverse as interstitial cystitis and chronic alcohol dependence. However, the long duration of action enables extended withdrawal reactions in the chronically opioid-dependent patient. The prolonged opioid antagonism of nalmefene has several applications in the clinical practice of emergency medicine, and is a useful addition in certain situations to the pharmacologic armamentarium of the practicing emergency physician.