Suspended NASCAR driver A.J. Allmendinger, who initially said he was rummaging through supplements to find out what amphetamine he might have taken that caused him to fail a random drug test, now says it was Adderall.

The prescription drug is commonly used for attention deficit hyperactivity disorder. Allmendinger made the revelation in an ESPN interview Tuesday.

Allmendinger, who is militant about his fitness, claims that a friend gave him a pill and said it was a workout supplement. Allmendinger said that was two days before a June 29 urine test at Kentucky Speedway that tested positive. NASCAR removed him from the Sprint Cup race at Daytona International Speedway on July 7 when it learned of the positive test.