Jonathan Gray, the University of Oklahoma pitcher and No. 2 prospect heading into this year's MLB Rule 4 draft, tested positive for the medication Adderall during baseball's predraft drug testing program, according to multiple sources familiar with the details of Gray's test.

The positive test will not result in a suspension, but will make Gray subject to additional follow-up testing once he begins his pro career, according to a source with Major League Baseball. Adderall comprises salts of two amphetamines and is banned by MLB unless the player has a valid therapeutic use exemption. Multiple sources indicated that Gray did not have a prescription for the drug.

A message asking Gray for comment was not returned.

Gray, a 6-foot-4, 239-pound junior from Chandler, Okla., is likely to be one of the first five players taken in Thursday's Rule 4 draft. One source told that he did not think Gray's failed test would harm his draft stock.

Adderall use without an exemption is prohibited under the Joint Drug Agreement between Major League Baseball and its players' union. More than 110 players were granted exemptions in 2012, according to the independent program administrator's report released in November. Philadelphia Phillies catcher Carlos Ruiz was suspended for the first 25 games of the 2013 season after he tested positive for Adderall for the second time without a valid exemption.