From Keith Kizer of the Nevada State Athletic Commission (NSAC), in an email to FightTicker.com:
The Commission recently tested Randy Couture, Brock Lesnar, Nick Catone, Amir Sadollah, Aaron Riley and Jorge Gurgel. All tests came back negative.
All six fighters are scheduled to fight at UFC 91 in November in Las Vegas.
The NSAC is currently the only commission that tests fighters randomly throughout the year, so the tests are commendable. On the other hand, so far the tests have only included fighters within a month or so of their next fight. What I'd like to see on top of this is testing fighters who may not have a fight scheduled in the near future.
I believe that if there are fighters cheating, they'll try to do it at less-than-predictable times of the year, for example when they believe the commissions won't be paying attention to them.
For fighters training for an upcoming fight, however, it'd be pure foolishness to take performance enhancers then.Link