[Torsade de pointes: a severe and unknown adverse effect in a patient taking methadone].
We present here the case of a young drug-addicted patient, who showed a cardio-respiratory arrest attributed to a torsade de pointe-type ventricular arrhythmia. After excluding the usual causes of such arrhythmia, we concluded that it was consecutive to high-dose methadone intake. Methadone can induce torsade de pointe through two mechanisms: a QT interval prolongation secondary to a bradycardia or a prolongation of the myocardial action potential. When prescribing methadone, one should avoid association with other CYP3A4 inhibiting drugs and, if higher doses are necessary, perform regular EKG screening.
Département de Médecine, CHUV, Lausanne.
J F
JF
Vodoz
F
F
Jaquier
O
O
Lamy
D000328:Adult; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D003937:Diagnosis, Differential; D004562:Electrocardiography; D006801:Humans; D008297:Male; D008691:Methadone / Q000008:administration & dosage / Q000009:adverse effects*; D008991:Monitoring, Physiologic; D009294:Narcotics / Q000008:administration & dosage / Q000009:adverse effects*; D019966:Substance-Related Disorders / Q000534:rehabilitation*; D013997:Time Factors; D016171:Torsades de Pointes / Q000139:chemically induced* / Q000175:diagnosis / Q000628:therapy
D009294:Narcotics; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D008691:Methadone