Davy Russell has been referred to the Irish Turf Club after failing to attend a dope test during racing at Naas on Sunday.
Russell was summoned to the dope testing unit at the County Kildare circuit but had failed to show before the last race.
A stewards' statement released on behalf of the track, read: "The stewards received a report from Mr Al Guy, doping control officer, that D.N. Russell, rider, had failed to present himself for a dope test at the time required."
The statement went on: "And, having been given a fair chance to attend the dope testing unit, had still failed to attend by 17.33pm. Evidence was also heard from Mr Joseph Mallon, security officer.
"Having considered the report, the stewards referred this matter to the Turf Club for further investigation."