(2009 臺灣醫學發展基金會 得獎論文摘要)
Yu-An Chen, Kuan-Cheng Chang
Purpose
The aim of this study is to figure out whether there is a positive correlation between therapeutic methadone doses and QTc interval, thus evaluate a safe critical value of methadone dose for patients. While studying methadone effects on cardiac repolarization, assessing QT-related factors is equally important on the purpose to minimize errors in diagnoses and reduce the probability of developing torsade de pointes.
Materials and Methods
All cases in this study were available from China Medical University Hospital during September 2008 to April 2009. 12-lead ECG was utilized to evaluate drug response. The study was divided into three parts, respectively examined by regression analysis, Wilcoxon rank sum test, and Wilcoxon signed-rank test.
Results
The result of part I in this study showed there was a positive correlation between therapeutic methadone doses and QTc interval, [n = 209, rs = 0.36, p=0.001] and this relationship applied to both male [n = 165, rs = 0.34, p=0.001] and female individuals [n =44, rs =0.41, p=0.006]. Furthermore, 82 (49.7％) of 165 male patients and 14 (31.8％) of 44 female patients lived up to the standard of borderline QTc. The result of part II in this study showed that in the methadone group, male and female QTc values presented significant differences [p=0.02; Male: n= 165, mean ± S.D.= 431.13±21.54ms; Female: n= 44, mean ± S.D.= 438.82±22.34ms]. The result of part III in this study showed that among 30 fully traced cases, 25 (83.3％) patients’ QTc intervals lengthened after taking methadone, 4 (13.3％) patients’ QTc intervals shortened after taking methadone, and 1 (3.3％) patient’s QTc interval didn’t change after taking methadone. [n= 30, p=0.001]
Conclusions
There is a positive correlation between therapeutic methadone doses and QTc interval for both sexes. Cases of prolonged QTc are mainly associated with, but not limited to, higher doses of methadone maintenance treatment. As a result, factors contributing to QTc variations are worth to be considered to further assess QT prolongation more accurate.
Key words
ECG; HERG channel; methadone; QTc interval; QTc prolongation
