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Methadone is a synthetic compound with pharmacologic action similar to that of morphine and heroin, almost equal in addiction liability.

The hydrochloride is used as an antitussive and analgesic and as a substitute narcotic in the management of opiate withdrawal, since it is longer acting than most opiates.

It is substituted for an abused opiate and then the dose is reduced.

  • methadone is available as an oral solution (1 mg/ml), an oral concentrate (10 mg/ml), tablets or injectable ampoules
  • methadone has a long elimination half-life (usually 20-37 hours), which allows for a once-daily dosing schedule
  • methadone appears to have no serious long-term side effects associated with chronic administration (1)
  • in the context of opioid dependence management, and using a methadone maintenance regimen, the drug does not have the pronounced narcotic effects seen with shorter-acting opioids such as illicit diamorphine
  • interactions with other drugs
    • elimination of methadone is increased by some drugs including including rifampicin, phenytoin, phenobarbital and some antiviral drugs used in the treatment of HIV infection
    • rate of elimination is reduced by drugs such as fluvoxamine and fluoxetine

Conult the Summary of Product Characteristics before prescribing this drug.

Notes (2):

  • methadone or buprenorphine should be offered as the first-line treatment in opioid detoxification. When deciding between these medications, healthcare professionals should take into account:
    • whether the service user is receiving maintenance treatment with methadone or buprenorphine; if so, opioid detoxification should normally be started with the same medication
    • the preference of the service user.


  1. NICE (January 2007).Methadone and buprenorphine for the management of opioid dependence
  2. NICE (July 2007).Drug misuse - Opioid detoxification

Last reviewed 01/2018