Promising apprentice Matt McGillivray has been disqualified from riding for four months after returning a positive drugs test.
McGillivray had an irregularity in a drug test taken during a Doomben jump-outs session last Tuesday.
A second test on Thursday confirmed the irregularity and McGillivray fronted a stewards' inquiry on Tuesday.
Chief steward Alan Reardon said McGillivray pleaded guilty to having methylamphetamine and MDMA (ecstasy) in his system.
McGillivray has ridden 71 winners this season, including 13 in the metropolitan area.
He has a week to appeal the severity of the ban.