Intended for healthcare professionals


Naltrexone and problems in pain management

BMJ 2006; 332 doi: (Published 19 January 2006) Cite this as: BMJ 2006;332:132
  1. A P Vickers, consultant in anaesthetics and pain management (,
  2. A Jolly, clinical nurse specialist, acute pain
  1. Department of Anaesthesia, Royal Lancaster Infirmary, Lancaster LA1 4RP

    How to manage acute pain in people taking an opioid antagonist

    Injection of illicit drugs (mostly opiates) is a widespread medical and social problem throughout the developed world. Among the newer pharmacological approaches to managing addiction is the use of naltrexone as a pure opioid antagonist. In suitable patients it has several advantages over other drugs to manage addiction, but since it blocks the effects of opioids it also brings with it a clinical problem: how to manage acute pain in a patient taking naltrexone.

    Naltrexone is an opioid antagonist derived by the substitution of the N-methyl group of oxymorphone. Its structure is similar to that of naloxone but it has a higher oral efficacy and a longer duration of action.1 A single oral dose reaches peak plasma concentration in 1-2 hours with an apparent half life of about 14 hours. It is a pure antagonist at the opioid μ receptor with no intrinsic agonist effects and will totally block the effects of substantial doses of opioid analgesics. Veberey, using 25 mg intravenous heroin challenges in former drug addicts, described its effect: a 100 mg dose of naltrexone …

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