Porter was signed to a one-year contract this summer after four seasons with the New Orleans Saints and opened the season as the Broncos' starting right cornerback. Porter, who suffered a seizure in August, complained of similar symptoms on Oct. 14 and has not played since.
The veteran cornerback was cleared for practice earlier in the week but issues with his medication kept him off the field on Friday.
Replaced by Chris Harris and nickel corner Tony Carter, the Broncos have done a good job of filling the void left by Porter's absence and it was unlikely he will regain the starter's spot upon his return.
The Broncos had full participation in practice from all other players on the injury report, including quarterback Peyton Manning who suffered a minor thumb injury in last week's win over the New Orleans Saints.
The Broncos take on the Bengals on Sunday at 11 a.m. MT, with coverage on CBS.