An NFL arbitrator made a final ruling Wednesday on the four-game suspension of New Orleans Saints running back Mark Ingram for violating the league’s policy on performance-enhancing drugs, despite his vigorous denials.

According to an ESPN report, Ingram’s agents argued in a statement that the substance he tested positive for was “permissible with the proper use exemption with the NFL.” The league, however, upheld the four-game ban, saying a final determination has been made. Ingram’s agents reportedly said they would possibly explore other avenues after reviewing the arbitrator’s full explanation.

“At the end of the 2017 season, as a result of a NFL mandated random drug test, Mark Ingram tested positive for a substance that was not a performance enhancing substance, nor an illegal substance, but a substance in fact permissible with the proper use exemption with the NFL,” Ingram’s agents, Paul Bobbitt and David Jones, said in the statement. “He has vigorously challenged the test results through the arbitration process. … Upon having the opportunity to review the arbitrator’s opinion, we will explore what further options are needed.”

Meanwhile, neither the league nor Ingram’s agents have named the substance Ingram tested positive for. Should the suspension stand, the Saints leading rusher last season, with a career-high 1,224 yards and 12 touchdowns, would miss home dates against Tampa Bay in Week 1, Cleveland in Week 2 and road games against Atlanta in Week 3 and New York in Week 4.