The NFL has suspended Denver Broncos defensive end Derek Wolfe four games for a violation of the league's performance-enhancing drug policy, the team announced Friday.
"During the offseason I took a medication, which is on the banned substance list," Wolfe said in a statement. "The medication is not a substance which would enhance my on-field performance in any way, and I genuinely was unaware that it was prohibited, but players are responsible for what is in their bodies. I will certainly exercise far greater caution in the future and will seek advice relating to the permissibility of any and all medications."
Losing a starting defensive end is a blow to a defense that is already dealing with question marks at middle linebacker -- the fulcrum of Wade Phillips' 3-4 scheme -- as Danny Trevathan (knee) and Brandon Marshall (foot) are returning from surgeries.
Broncos coach Gary Kubiak said he was disappointed in Wolfe, adding that someone would have to step up in the fourth-year player's absence.
The first name Kubiak mentioned as a replacement was Vance Walker, whom the Broncos signed in free agency from the Kansas City Chiefs. Denver will also rely more heavily upon Malik Jackson and second-year pro Kenny Anunike.
Wolfe started all 16 regular-season games for the Broncos in 2014, contributing to a Denver defensive line that allowed 79.8 rushing yards per game, the lowest single-season figure in team history.
He was a shell of himself, however, after missing a good chunk of the 2013 season, which was marked by a seizure on the team bus. Doctors believe that was related to a bruised spinal cord he suffered during that preseason. Wolfe recorded 1.5 sacks in 2014, and his sack total has declined in each season since he tallied six in his rookie year in 2012.
He will miss games against the Baltimore Ravens, Chiefs, Detroit Lions and Minnesota Vikings. Wolfe won't be able to help the Broncos against some elite running backs, including Baltimore's Justin Forsett, Kansas City's Jamaal Charles and Minnesota's Adrian Peterson. That puts added pressure on safety T.J. Ward and outside linebackers Von Miller, DeMarcus Ware and first-round pick Shane Ray to stop the run.
Wolfe will be eligible to return to the field in Week 5 against the Oakland Raiders. He can practice during training camp and play in the preseason before his banishment begins Sept. 5.
The Chiefs also lost a member of their defense for the beginning of the 2015 season. Cornerback Sean Smith was suspended three games by the league on Friday for a violation of the substance abuse policy.
ESPN's Ed Werder and The Associated Press contributed to this report.