Troubled jockey Luke Tarrant has been suspended as result of a criminal court appearance and will be stood down from riding at Doomben.
The decision means Tarrant will have to show he is a fit person before his licence is reinstated.
It is understood some jockeys approached the Queensland Racing Integrity Commission raising concerns about riding with Tarrant.
On Wednesday, Tarrant, 25, pleaded guilty to a series of drug possession charges in the Maroochydore Magistrates Court.
Tarrant was sentenced to 30 months probation with an order he undergo rehabilitation in an approved facility.
No conviction was recorded and Tarrant will have to begin rehabilitation soon but he had been booked for rides at Doomben on Saturday.
Queensland Racing Integrity Commission boss Ross Barnett said Tarrant had been suspended under a rule which states the body is responsible for a duty of care to participants and the suspension was immediate.
“A duty of care to animals and jockeys is paramount for the commission,” Barnett said.
Tarrant has ridden nearly 350 winners including the 2015 Magic Millions on Le Chef and the 2015 Group Two Villiers on Rudy.
However, his career has been dogged by stewards room and court appearances.
He is currently riding on a stay after being suspended for a month for gambling but he denies the charge.