All fighters from the recently-completed UFC 148: Silva vs. Sonnen II event were cleared during the post-fight drug tests. That includes Chael Sonnen, who was granted a therapeutic use exemption for his testosterone replacement therapy.
Sonnen had applied for the use and was granted it by the Nevada Athletic Commission. He was forced to provide several drug tests before and after, and they all came back within the limits.
The commission tested every fight on the card, making a strong effort to help keep drugs out of MMA.