Maybin is the first big league player suspended this year for violating the drug program. Alex Rodriguez of the Yankees is serving a season-long suspension but that suspension was originally issued during last season.
Maybin said that his use for the violated substance stemmed from his attention deficit disorder, for which he previously had a Therapeutic Use Exemption granted.
"Unfortunately, in my attempts to switch back to a medicine that had been previously OK'd, I neglected to follow all the rules and as a result I tested positive," Maybin said in a statement issued by the MLB Players Association.
Maybin's agent, Brian Goldberg, told FoxSports.com that Maybin had a "new [TUE] for a different but similar medication that was not working to his liking. His mistake was that he assumed he could go back to the original medication that he had TUEs for the previous couple of years. The only substances involved were two properly prescribed ADD medications for different times."
Maybin added: "I want to assure everyone that this was a genuine effort to treat my condition and I was not trying in any way to gain an advantage in my baseball career. I understand that I must accept responsibility for this mistake and I will take my punishment and will not challenge my suspension. I apologize to my family, friends, fans, teammates, and the entire Padres organization. I look forward to returning to the field and contributing to the success of my club."
Padres president and CEO Mike Dee and manager Bud Black also issued statements.
"Our club fully supports Major League Baseball's Joint Drug Prevention and Treatment Program," Black said. "Cameron has accepted full responsibility for his violation and apologized to his teammates and coaches. We are all looking forward to his return."
Said Dee: "I'm disappointed in Cameron's violation of MLB's Joint Drug Prevention and Treatment Program, but am pleased that he's taking responsibility for his mistake. The joint agreement was put into place to protect both the player and the game, and the Padres fully support it."
Maybin was in Chicago for the Padres' series against the Cubs, but didn't play in Tuesday's opener. He was substituted in two of San Diego's three games against the Mets last weekend and played a complete game on Saturday.
Veteran outfielder Jeff Francoeur was added to the roster on Wednesday from Triple-A El Paso to take Maybin's spot on the roster. He'll be uniform for Wednesday's game against the Cubs at Wrigley Field.
Maybin is hitting .247, one point lower than his career average, with one home run and nine RBIs in 62 games. He played in just 14 games last season due to a combination of a wrist injury and a torn posterior cruciate ligament in his left knee.
In November 2012, Padres catcher Yasmani Grandal was suspended for 50 games after testing positive for testosterone. He served his suspension by missing the first 50 games of last season. Shortstop Everth Cabrera -- the team's lone 2013 All-Star -- was given a 50-game suspension last August after being linked to the Biogenesis investigation. He missed the final 50 games of the regular season.
Maybin, 27, is making $5 million this season as part of a five-year, $25 million contract extension he signed during Spring Training in 2012 after a promising first season with the team in 2011.