Acute effect of methylphenidate on QT interval duration and dispersion in children with attention deficit hyperactivity disorder.

Among childhood psychiatric disorders, attention deficit hyperactivity disorder (ADHD) is of greatest interest to practitioners. Methylphenidate (MPH) is a drug that is widely used in the treatment of children in whom ADHD has been diagnosed. Although this treatment has been used for years, its effects on the heart remain the subject of debate. The QT interval comprises the ventricular activation and recovery periods as seen on electrocardiogram (ECG). The acute effect of MPH on QT interval dispersion is unknown. Researchers in the present study sought to investigate the acute effects of MPH on QT interval as seen on ECG. A total of 25 patients with ADHD (mean age, 9.4+/-2.1 y) who were treated with MPH were enrolled in the study. Twelve-lead derivation ECGs were taken before and 2 h after administration of 10 mg of MPH. Maximum QT interval, minimum QT interval, and interval durations were measured, and QT dispersion was calculated, for each ECG. QT dispersion measured after medication administration decreased significantly from 59.6+/-16.3 ms to 50.8+/-10.9 ms (P=.016); corrected QT dispersion decreased significantly from 70.9+/-17.6 ms to 61.3+/-13.3 ms (P=.011). Maximum QT interval duration decreased from 73.7+/-21.8 ms to 361.8+/-29.0 ms (P=.006); minimum QT interval duration rose from 317.0+/-23.3 ms to 322.3+/-21.6 ms (P=.312). In conclusion, the findings of this study show that MPH reduces QT dispersion during the acute period shortly after its administration.