Published: Aug 20, 2010 8:29 PM EDT
Updated: Aug 21, 2010 4:30 AM EDT

MIAMI (AP) — Marlins catcher Ronny Paulino has been suspended 50 games by Major League Baseball for testing positive for a performance-enhancing substance.

Paulino's suspension begins immediately. The Marlins are scheduled to host the Houston Astros on Friday night.

Paulino says he used a dietary pill to control his weight this season and recently learned it contained a banned substance. He says he is "ashamed and saddened" for disappointing his family, teammates and the Marlins organization.

Paulino is batting .259 with four homers and 37 RBIs in his sixth season in the majors. He got off to a solid start this year but has struggled since the All-Star break, hitting .195 with just one home run.