It is the second suspension within a year for Patton, who was also suspended 25 games at the start of the 2014 season after reportedly testing positive for Adderall.
Patton has spent six years in the majors, the majority of which were with the Baltimore Orioles. He was traded to the San Diego Padres in May and pitched eight games for them before injuring his shoulder. San Diego designated him for assignment in September and he elected to become a free agent last month.
The 29-year-old's best season to date came in 2012, when he had a 2.43 ERA with 49 strikeouts in 54 appearances for Baltimore. Patton had a 8.10 ERA in 2014 before the Orioles traded him and gave up two runs in 7.1 innings with the Padres.
Patton's suspension will force him to miss almost half of the 2015 season.
- Molly Geary