Bruce Irvin's suspension fits a pattern

The Seattle Seahawks' first four games of the 2013 season became a bit more challenging from a personnel standpoint when the NFL announced Bruce Irvin's four-game suspension for allegedly using performance-enhancing drugs.

Irvin will miss games against the Carolina Panthers (road), San Francisco 49ers (home), Jacksonville Jaguars (home) and Houston Texans (road).

"I want to apologize to my teammates, coaches and Seahawks fans for making a mistake when I took a substance that is prohibited in the NFL without a medical exemption," Irvin said in a statement released by the team. "I am extremely disappointed in the poor judgment I showed and take full responsibility for my actions. I will not appeal the discipline and instead will focus my energy on preparing for the season so I can begin earning your trust and respect again. I look forward to contributing to the team the moment I return."

Irvin joins John Moffitt, Allen Barbre, Winston Guy and Brandon Browner as Seattle players suspended since 2011 under terms of the performance-enhancing drug policy. Richard Sherman avoided a four-game ban by winning his appeal last season. Sherman was also cited under the policy banning performance-enhancing drugs.

Reports linked Moffitt, Browner and Sherman to Adderall. Moffitt later said he took medically prescribed Adderall back in 2011, his rookie season, without knowing it violated the policy.

"The day we had the info on it, I was held out," Moffitt told the Seattle Times last season. "I was holding out my first day so I really didn't know. I don't think guys realize because it is a medication also. There's a lot of cases where guys already had prescriptions, but not through the league. It's just a really weird thing. It's not like steroids."

Irvin's reference to a "medical exemption" -- something that would be required for Adderall use by an NFL player -- and the Seahawks' history with Adderall invites questions about whether Irvin also used the substance. Statements from the NFL and from Irvin did not disclose the substance in question.

Adderall is a psychostimulant sometimes used to treat attention-deficit disorders.

The suspension means the Seahawks could be without two top defensive ends early in the season. Starter Chris Clemons is recovering from surgery to repair a torn ACL. The team expects him to return in 2013, but returning for the regular-season opener could be challenging. Clemons suffered the injury in January. Irvin, drafted 15th overall in 2012, had eight sacks in a situational pass-rushing role. He replaced Clemons in the lineup following Clemons' knee injury last season.

Seattle's decision to sign free-agent defensive end Cliff Avril appears more important now that Irvin and possibly Clemons will miss games early in the season. And with two-plus months before training camp, the Seahawks have time to make scheme adjustments to fit their available personnel.

Rules allow Irvin to continue practicing with the team. He can play in exhibition games, too. But he'll miss the first four games and cannot return to the team until Sept. 30, one game after the team plays at Houston.