methadone and prolongation of QT interval
Last reviewed 01/2018
- there is a risk of QT interval prolongation in patients taking methadone,
especially those on high doses (1)
- there is evidence that very-high-dose methadone may be associated with torsade de pointes (2)
- recommended
that patients with the following risk factors for QT interval prolongation are
carefully monitored whilst taking methadone:
- heart or liver disease, electrolyte
abnormalities, concomitant treatment with CYP 3A4 inhibitors, or medicines with
the potential to cause QT interval prolongation (1)
- also any patient requiring more than 100mg of methadone per day should be closely monitored (1)
- the
RCGP guidance also notes that the risk of QT-interval prolongation may be dose-dependent
(3)
- "..methadone may be a risk factor for QT prolongation and torsade de pointes with a possible dose-dependent action... recommends monitoring for patients on high dose methadone (>100 mg daily) and with other QT interval prolongation risk factors where appropriate.."
- heart or liver disease, electrolyte
abnormalities, concomitant treatment with CYP 3A4 inhibitors, or medicines with
the potential to cause QT interval prolongation (1)
Reference:
- (1) Current Problems in Pharmacovigilance 2006;31:1-12.
- (2) Krantz MJ et al. Torsade de pointes associated with very-high-dose methadone. Ann Intern Med. 2002 Sep 17;137(6):501-4.
- (3) RCGP (2007). Drug misuse and dependence: UK guidelines on clinical management