The purpose of a study by Krantz et al. (A-4) was to investigate dose-related effects of methadone in subjects with torsades de pointes, a polymorphic ventricular tachycardia. In the study of 17 subjects, 10 were men (sex ¼ 0) and seven were women (sex ¼ 1). The outcome variable, is the QTc interval, a measure of arrhythmia risk. The other independent variable, in addition to sex, was methadone dose (mg/day). Measurements on these variables for the 17 subjects were as follows.

Sex Dose (mg/day) QTc (msec)

0 1000 600 0 550 625 0 97 560 1 90 585 1 85 590 1 126 500 0 300 700 0 110 570 1 65 540 1 650 785 1 600 765 1 660 611 1 270 600 1 680 625 0 540 650 0 600 635 1 330 522 Source: Data provided courtesy of Mori J. Krantz, M.D.