Left-hander Dan Serafini, who pitched in Japan for 3 1/2 seasons prior to resurfacing in the Majors late last summer, has received a 50-game suspension from Major League Baseball for testing positive for a performance-enhancing substance in violation of the sport's Joint Drug Prevention and Treatment Program.

Serafini, in a statement, said any use of banned substances was for medical reasons.

"I want to make it known that I did not use any banned substances in order to gain a competitive advantage," Serafini said. "However, while playing baseball in Japan, I suffered two significant injuries. ... While trying to accelerate the healing process of these injuries, I took substances that were prescribed for me by a doctor in Japan."

In the statement, Serafini said he stopped taking the prescribed substances once he returned to the States.

Currently a free agent, the 33-year-old Serafini appeared briefly last season with the National League champion Colorado Rockies, getting one out over three appearances.

He made his big league comeback after his 2004-07 stint in Japan, where he pitched for the Chiba Lotte Marines and the Orix Buffaloes.

A first-round Draft choice of Minnesota in 1992, the reliever made his big league debut in 1996 with the Twins, but in the interim has logged only 104 Major League outings.

In 2007, Serafini made 11 appearances with the Rockies' Triple-A club in Colorado Springs, posting an ERA of 3.48 over 20 2/3 innings.

"While I regret the circumstances that led to my suspension, I have learned that a Major Leaguer should only rely on medical care provided by U.S.-based doctors," said Serafini. "I apologize to the fans of Major League Baseball, and I know I will be more careful in the future."