As noted, UFC announced today that Brock Lesnar failed a second drug test related to his UFC 200 fight win over Mark Hunt, an in-competition drug test. In-competition is considered in the 12-hour window before and after the fight. Lesnar previously failed an out-of-competition drug test from a June 28th sample taken by the US Anti-Doping Agency.
Pugmire tweeted the following:
I'm told by an official with knowledge of Brock Lesnar's positive test that the substance is clomiphene, the same one found in @JonnyBones.— Lance Pugmire (@latimespugmire) July 19, 2016