Maybin said in a statement released by the players' union that the failed test was the result of a change in the medication he was using to treat attention deficit disorder.
Under the drug agreement between MLB and the union, 25 games is the penalty for a second positive amphetamine test. A first positive results in six unannounced follow-up tests over the next year.
Maybin, 27, is batting .247 with one home run and nine RBIs in 62 games.
"I understand that I must accept responsibility for this mistake and I will take my punishment and will not challenge my suspension," Maybin said. "I apologize to my family, friends, fans, teammates, and the entire Padres organization."
The Houston Astros placed outfielder George Springer on the 15-day disabled list with a strained right quadriceps and recalled utility man Marc Krauss from triple-A Oklahoma City. Springer is batting .231 with 20 home runs and 51 RBIs through 78 games in his rookie season. ...
The Minnesota Twins designated right-handed relief pitcher Matt Guerrier for assignment and will recall right-hander Ryan Pressly from triple-A Rochester. ... Kansas City Royals first baseman Eric Hosmer was removed from Wednesday's game with the Chicago White Sox because of decreased grip strength in his right hand. Hosmer had missed the previous two games after being hit in the hand with a pitch Sunday. ...