Maybin said in a statement released by the Major League Baseball Players Association the failed test was the result of a change in the medication he was using to treat Attention Deficit Disorder.
"I have been undergoing treatment for several years for a medical condition, Attention Deficit Disorder (ADD), for which I previously had a Therapeutic Use Exemption (TUE). 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. "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."
Under the drug agreement between MLB and its players' union, 25 games is the penalty for a second positive amphetamine test. A first positive results only in six unannounced follow-up tests over the next year.
The 27-year-old Maybin was batting .247 with one home run and nine RBIs in 62 games this season.
"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 responded in statements.
"I'm disappointed in Cameron's violation of MLB's Joint Drug Prevention and Treatment program, but I am pleased that he's taking responsibility for his mistake," Dee said. "The joint agreement was put into place to protect both the player and the game, and the Padres fully support it."
"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."
MLB permits an exemption for players with attention deficit disorder. The annual report from the drug program's independent administrator, Dr. Jeffrey M. Anderson, said 119 therapeutic use exemptions were granted for ADD drugs in the year ending with the conclusion of the 2013 World Series.
There were seven positive tests for Adderall in that span that resulted in discipline.