Methadone

Indications

  • Severe chronic pain
  • Management of opioid dependence

Adverse effects

Following adverse effects are specific to Methadone. See full list of adverse effects from opioid analgesics.

Common

Pain and swelling may occur at injection site

Rare

  • Prolonged QT interval
  • Torsades de pointes (with high doses)

Dose

  • Consult a chronic pain specialist or a pain management clinic. Dose titration must be very cautious in view of its long half-life. It may take up to 2 weeks to see adverse effects.

Patient advice

  • See Patient advice

Precautions

Suggest specialist use only

Cardiac

  • Risk factors for prolonged QT interval; in high doses, methadone may prolong the QT interval and increase risk of arrhythmia. Avoid use if risk factors cannot be corrected.

Renal

  • Safe in patients with renal impairment.

Hepatic

  • Avoid use in severe impairment; increased risk of hepatic encephalopathy. Lower doses required in hepatic impairment.

Elderly

  • Use with extreme caution; seek specialist advice.

Practice considerations

  • Not suitable for acute pain management as the long half-life makes rapid, safe titration difficult
  • Other opioids are preferred for severe chronic pain; methadone may be useful in patients who have inadequate pain relief or intolerable adverse effects with other opioids; use cautiously
  • Methadone has high oral bioavailability, but a long and variable duration of effect in chronic use makes dose adjustment difficult

Available products

  • Methadone hydrochloride 10 mg – tablet

    • Physeptone® (white, uncoated, round, biconvex tablet, scored on one side)

  • Methadone hydrochloride 10 mg/mL injection (5 x 1 mL ampoules)

    • Physeptone®

  • Methadone hydrochloride 5 mg/mL oral liquid