In addition to his pre-fight testing failures, former UFC middleweight champion Anderson Silva tested positive for anabolic steroid metabolites in his Jan. 31 fight night drug test following his decision victory over Nick Diaz at UFC 183.
Silva, 39, tested positive for Drostanolone metabolites in his Jan. 31 urine test -- the same anabolic steroid he previously tested positive for in a random Jan. 9 pre-fight blood test. Oxazepam and Temazepam were also found within Silva's system in the fight night screening, which was administered on-site by representatives of the NAC.
Results of Silva's second testing failure were revealed during Tuesday's Nevada Athletic Commission meeting, following an initial report by MMA Junkie.
Drostanolone is classified as an exogenous anabolic androgenic steroid, according to the World Anti-Doping Agency's prohibited list.
Temazepam and Oxazepam are both classified as Benzodiazepines, which are not permitted for in-competition use by the NAC. Temazepam is commonly used as a sleeping aid, while Oxazepam is commonly prescribed as an anti-anxiety medication.
Silva previously tested positive for the anabolic steroids Drostanolone and Androstane in a random pre-fight blood screening on Jan. 9. Silva denied culpability regarding the Jan. 9 test results in a recent statement to MMAFighting.com.
"I've been competing in this sport for a very long time. This is my nineteenth fight in the UFC. I have been thoroughly tested many times and have never had a positive drug test," Silva said.
"I have not taken any performance-enhancing drugs. My stance on drugs is, and will always be, the same. I'm an advocate for a clean sport.
"I'm consulting with my advisors right now to explore all of my options and intend to fight this allegation and clear my name. I will not make any further comments until my team advises me to do so."
Fighting for the first time since suffering a nightmarish broken leg in his late-2013 rematch against Chris Weidman, Silva defeated Diaz via unanimous decision in the main event of UFC 183, which took place at the MGM Grand Garden Arena in Las Vegas, NV. The win was Silva's seventeenth in the UFC.
Altogether, Silva was screened for banned substances three times prior to the Diaz fight: two random tests on Jan. 9 and Jan. 19, as well as a customary fight night test on Jan. 31.
All three tests were analyzed at the Sports Medicine Research & Testing Laboratory in Salt Lake City, UT. Results from Silva's Jan. 19 test came back clean.
NAC officials are expected to place Silva on temporary suspension at Tuesday's meeting. The former champion will then be required to attend a full disciplinary hearing at an upcoming commission meeting, likely to take place in March.
Silva ultimately faces a potential suspension and fine as a result of his multiple testing failures, in addition to his victory over Diaz being overturned into a no contest.