Drysdale (7-0), who submitted Keith Berish at the TUF 19 Finale on July 6, produced an elevated testosterone-to-epitestosterone ratio of 12-to-1. Casey (9-3), who won a first-round knockout over Bubba Bush at UFC 175 on July 5, tested positive for drostanolone, an anabolic steroid.
Deputy attorney general Chris Eccles confirmed the failed tests to ESPN.com on Wednesday. MMAJunkie.com first reported the results.
"Both fighters have been temporarily suspended from competition and informed their positive tests violated the UFC Fighter Conduct Policy and Promotional Agreement with Zuffa, LLC," UFC said in a statement. "The UFC has a strict, consistent policy against the use of any illegal and/or performance-enhancing drugs, stimulants or masking agents by our athletes and will support the NSAC's determination pending a formal hearing at a later date."
In addition to a suspension and fine, both results will likely change to no-contests. Each will have to appear before the Nevada State Athletic Commission at a future hearing.
Drysdale, 33, was denied a license to compete in the state of Nevada in October, when he produced an elevated T/E ratio of 19.4-to-1. A Las Vegas resident, Drysdale has previously applied for an exemption to use testosterone-replacement-therapy (TRT), but was never granted one.
TRT has since been banned in Nevada. Drysdale was not suspended after the first failed test.
Eccles would not confirm whether or not the NSAC would treat the latest test result as his second offense, which could significantly alter his punishment.
Casey, 33, has never failed a prior test. A former contestant on The Ultimate Fighter reality series, he lost his UFC debut in April 2013, but earned an opportunity to get back into the Octagon with three consecutive wins outside the promotion.