Tim Credeur -- who takes Adderall to treat attention-deficit hyperactivity disorder (ADHD) -- was not permitted to take on Cale Yarbrough last night at The Ultimate Figher (TUF) 7 Finale because traces of the prescription drug were still in his system.

The Nevada State Athletic Commission (NSAC) handed down the ruling just hours before the middleweight bout was set to go off from The Pearl Concert Theater at Palms Casino Resort Las Vegas.

Here's a snip from NSAC Executive Director Keith Kizer via UFC.com on the decision:

"[Adderall] acts as a cardio-vascular restrictor and that's the main reason it's banned because it can cause athletes to have a cardiac episode with the stress they're under when they're in an athletic competition. Secondly, it can have a performance-enhancing effect as well."

Credeur -- a semifinalist on TUF 7 -- will not be suspended or fined for the positive test result because he was upfront with the NSAC about his medication. Perhaps the fight will be added to UFC Fight Night 14 on July 19, which would give Credeur more than enough time to clean out his system.