Heredia, currently assigned to Houston's Rookie-level Dominican Summer League affiliate, tested positive for metabolites of Stanozolol and Boldenone. Both substances are banned by the the Minor League Drug Prevention and Treatment Program.
The 19-year-old from Palenque, Dominican Republic, signed with the Pirates as a non-drafted free agent in 2009, when he appeared in 19 games as a shortstop for the Bucs' DSL club.
He hit .224 with two RBIs in 19 games but has not played in the Minors since 2009. Now a pitcher, Heredia signed with Houston last month and was due to return to the DSL. His suspension will be effective at the start of this season.
Stanozolol a synthetic anabolic steroid derived from dihydrotestosterone and Boldenone is an anabolic steroid developed for veterinary use in horses.
Heredia is the 24th player to be suspended this year by Major League Baseball and the fourth this week. Seven players have been suspended this month.