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 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 (