Representatives for Mark Ingram say the Saints running back did not test positive for a performance enhancing drug and is weighing options for challenging his four-game suspension.

Paul Bobbitt and David Jones of VIP Sports Management say Ingram was using a substance that is permitted by the NFL with a "proper use exemption."

Ingram's agents did not specify which substance Ingram used.

The NFL's drug policy does not merely ban performance enhancing drugs, but also certain legal substances which have been known to skew drug test results.

The NFL announced Ingram's suspension on Tuesday.

Bobbitt and Jones say Ingram has challenged the NFL's decision through arbitration, and that his legal team will consider further options after reviewing the arbitrator's recent ruling.

Last season, Ingram rushed for a career-high 1,124 yards and 12 touchdowns to go with 416 yards receiving.