LOS ANGELES -- Giants pitching prospect Gregory Santos received an 80-game suspension on Tuesday after testing positive for Stanozolol, a performance-enhancing substance in violation of Major League Baseball’s Joint Drug Prevention and Treatment Program.

The Office of the Commissioner announced the suspension, which is effective immediately and without pay.

Santos, 21, debuted with the Giants on April 22, but he was sent down to Triple-A Sacramento after allowing six runs -- including three homers -- over two innings in his first three big-league appearances. A native of San Cristobal, Dominican Republic, Santos posted a 5.17 ERA over 14 relief outings for the River Cats in 2021.

“The San Francisco Giants are disappointed that Gregory Santos has violated the terms of Major League Baseball’s Drug Prevention and Treatment Program resulting in his suspension,” the club said in a statement. “The Giants organization fully supports the MLB program and its efforts to eliminate performance-enhancing substances from our game.”

Despite the early stumbles in the Majors, Santos displayed an upper-90s fastball and a nasty slider that suggested that he could develop into an effective weapon out of the bullpen for years to come.

Acquired from the Red Sox as part of the package for Eduardo Núñez at the July 2017 Trade Deadline, Santos hadn’t pitched above A-ball prior to this season, but he earned a spot on the Giants’ 40-man roster over the offseason following an impressive showing at the club’s fall instructional league in Arizona. He is ranked as the Giants’ No. 13 prospect by MLB Pipeline.

With Santos expected to be transferred to the restricted list, the Giants will have an open spot on their 40-man roster, which will likely be filled by outfielder Jaylin Davis or right-hander Tyler Beede. Davis (left knee patellar tendinitis) and Beede (Tommy John surgery) are currently on the 60-day injured list, but they’ll have to be added back to the 40-man after they complete their rehab assignments with Triple-A Sacramento.