Methadone hydrochloride (Dolophine) is a synthetic opioid analgesic (Schedule II). Management of moderate to severe pain unresposive to non-narcotics; used in narcotic detoxification maintenance programs and for the treatment of iatrogenic narcotic dependence.
It is opioid of choice for the detoxification treatment of opioid addicts in methadone maintenance programs. When used for treatment of opioid addiction, may only be dispensed in accordance to guidelines established by the Substance Abuse and Mental Health Services Administration’s center for Substance Abuse Treatment. Regulations regarding methadone use may vary by state and/or country. Obtain advice from appropriate regulatory agencies and/ or consult with pain management/ palliative care specialists.
Methodone binds to opiate receptors in the CNS, causing inhibition of ascending pain pathways, altering the perception of and response to pain; produces generalized CNS depression. There has been renewed interest in the use of methadone for chronic (e.g., neuropathic) and cancer-related pain. The drug is readily absorbed through the GI tract with peak plasma concentrations at 4 hours for single dosing. Methadone is unique in that its half-life is longer than its duration of action because it is bound into the tissues of the liver, kidneys, and brain. With repeated doses, the drug accumulates in these tissues and is slowly released, thus allowing for 24-hour dosing. Methadone is eliminated through the liver, which makes it a safer choice than some other opioids for patients with renal impairment. Recent FDA reports have cited the prolonged half-life of the drug as a cause of unintentional overdoses and deaths. There is also concern that methadone may cause cardiac dysrhythmias. Methadone is available in oral and injectable forms.
Warnings:
- Methadone may cause prolongation of the QT interval or torsade de pointes (especially at higher doses, eg., in adults with doses > 200MG/day)
- Methadone may cause respiratory depression. Use with extreme caution in patients with respiratory disease or pre-existing respirtory depression. Methadon’s effect on respiration lasts longer than anlgesic effects.
- Use with extreme caution (and only if essential) in patients with head injury, increased ICP, or other intracranial lessions. May cause severe hypotension.
- Abtupt discontinuation after prolonged use may result in withdrawal symptoms or seizures.
- Death and life-threatening adverse events in patients receiving methadone for pain control have been reported.