Objective: To assess long-term cardiovascular effects of mixed amphetamine salts extended release (MAS XR) in adults with attention-deficit/hyperactivity disorder (ADHD) combined subtype.
Methods: 223 otherwise healthy adults (>or=18 years of age) with ADHD combined subtype were exposed to <or=24 months of MAS XR (20-60 mg/day). Resting sitting diastolic blood pressure (DBP) and systolic blood pressure (SBP) and pulse were measured at baseline and weekly, then monthly during long-term treatment. Twelve-lead electrocardiograms were obtained at screening/baseline, weekly, then at 3- and 6-month intervals up to 24 months.
Findings: With MAS XR 20-60 mg/day, mean changes in DBP (1.3+/-9.2 mm Hg; P=.042), SBP (2.3+/-12.5 mm Hg; P=.006), and pulse (2.1+/-13.4 bpm; P=.019) were small and not clinically significant. A clinically insignificant increase in QTcB (corrected by Bazett's formula) interval (7.2 msec; P<.001) was observed at 24 months. No subject exhibited QTcB interval >480 msec (QTcF [corrected by Fridericia's formula] >454 msec). Seven subjects discontinued due to a cardiovascular adverse event (hypertension, n=5, palpitation/tachycardia, n=2); none of these events was reported as serious. Few subjects with normal baseline vital signs (using approved parameters at the time of study initiation) exhibited clinically significant abnormalities at end point; several subjects with borderline baseline values exhibited shifts to abnormal values during MAS XR therapy.
Conclusion: Cardiovascular effects of long-term MAS XR (<or=60 mg/day) were minimal in otherwise healthy adults with ADHD. Nevertheless, vital signs should be monitored prior to and during treatment with any stimulant.