MIAMI -- Marlins rookie right-hander Paul Campbell was suspended 80 games without pay after testing positive for dehydrochlormethyltestosterone (DHCMT), a performance-enhancing substance in violation of MLB’s Joint Drug Prevention and Treatment Program, The Office of the Commissioner of Baseball announced on Monday. The suspension is effective immediately.

"We are disappointed to hear today’s news regarding Paul Campbell’s suspension for violating Major League Baseball’s Joint Drug Prevention and Treatment Program," general manager Kim Ng said in a statement. "The Marlins support MLB’s continued efforts to maintain a level playing field for our athletes."

Campbell, a Rule 5 Draft pick selected from the Rays last December, had gone 0-2 with an 8.74 ERA in five outings. He made his first Major League start on Saturday against the Nationals, giving up five runs (four earned) on nine hits with four strikeouts in 3 2/3 innings.

Ranked by MLB Pipeline as Miami's No. 27 prospect, Campbell had been put on a starter's schedule and had built up his pitch count with Elieser Hernandez and top prospect Sixto Sánchez rehabbing injuries. Immediate internal options to fill the void in the rotation include righty Nick Neidert (No. 10 prospect) and lefty Daniel Castano.

In a statement released by the MLBPA, the 25-year-old Campbell said he "never knowingly, willingly, or intentionally ingested this substance in any form, nor have I ever heard of DHCMT prior to this situation. Due to the fact that I do not know the origin of how this substance has entered into my system, I currently have no viable defense in support of my innocence."