We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
DOSES OF METHADONE EQUIVOCALLY AFFECT THE PROLONGATION OF QTC INTERVAL IN METHADONE MAINTENANCE THERAPY.
- Authors
Mohamad, Nasir; Abu Bakar, Nor Hidayah; Ibrahim, Muslih Abdul Karim; Idrus, Ilya Irinaz; Ismail, Usli; Jalaludheen, Noorulainah; Manikam, Rishya
- Abstract
Methadone maintenance therapy (MMT) improves quality of life and reclaims the health of opiate drug users. However, adequate dose methadone is critical. Too low a dose causes failure with patients returning to illicit opiates. On the other hand, too high a dose has been associated with prolonged QTc interval, a prodrome to fatal tachyarrhythmias. In this case series, we describe five patients on MMT who developed prolonged QTc. At the time the event occurred, methadone doses and plasma concentrations were variable. In these 5 cases, there was a wide inter-individual variability in the pharmacology of methadone that makes initial dose determination and dose adjustment of methadone difficult and potentially dangerous. Although it has previously been reported that abnormal QTc intervals were associated with high methadone doses, in these cases, variations in QTc intervals on the ECG and plasma methadone were observed despite the similar doses of methadone being used. Factors that could have contribute to these variability are many and varied, which included the variability in CYP2B6 activity (that can indeed cause up to 400-fold difference in plasma methadone concentrations ); variability in pharmacokinetics, drug-drug interactions and other factors that can alter enzyme expression. Thus, no specific dose will fit all. As with many drugs used in the management of chronic diseases, methadone doses should be individualized and titrated for optimal outcomes that must be determined objectively. We conclude that high methadone doses or plasma concentrations are not a necessary precondition for the development of neither prolonged QTc intervals nor tachyarrhythmia. Patients on MMT should be monitored closely for cardiac toxicity that can occur without warning.
- Subjects
METHADONE treatment programs; QUALITY of life; TACHYARRHYTHMIAS; DRUG interactions; ELECTROCARDIOGRAPHY; CHRONIC diseases
- Publication
International Journal of Pharmacology & Biological Sciences, 2011, Vol 5, Issue 3, p1
- ISSN
0973-6808
- Publication type
Article