Both players were lost to shoulder injuries. Brackett was hurt in the season opener at Houston and underwent surgery, while Bullitt sustained the injury in Week 2 against Cleveland and is scheduled to undergo surgery.
To fill the roster spots, the Colts signed quarterback Dan Orlovsky and defensive back Jermale Hines to the active roster and inked linebacker A.J. Edds off the New England practice squad.
Orlovsky has played in 13 career NFL games with Detroit and Houston. The 28- year-old started seven games for the Lions in 2008. For his career, Orlovsky has completed 150-of-272 passes for 1,679 yards with eight touchdowns and eight interceptions.
The Colts also waived quarterback Mike Hartline and linebacker Caleb Campbell from the practice squad and added wide receiver Jeremy Ross and offensive lineman Matt Murphy to the practice squad. Also, defensive back Justin Tryon was waived.