Brisbane apprentice Sheriden Tomlinson has been disqualified for three months after testing positive to prohibited drugs in a trackwork test conducted at Eagle Farm.

He is the sixth jockey or trackwork rider in Queensland to be suspended or disqualified on drug charges in the past two months.

Stewards opened an inquiry after Tomlinson's sample given on September 9 was found to contain the prohibited substances netamine, norketamine and dehydroketamine.

Tomlinson pleaded guilty to a charge of providing a positive test.

In determining penalty, stewards said they were mindful of Tomlinson's guilty plea, forthright evidence, his personal circumstances and penalty precedents.

They further took into account Tomlinson had been stood down from riding since September 30.

The disqualification starts immediately and will expire on February 7 if Tomlinson provides a clear sample.

Caloundra trackwork rider Charlie Manfield was disqualified for three months after returning a positive at the Sunshine Coast October 8 which contained benzoylecgonine, a metabolite of cocaine.

The disqualification commences immediately and will finish on February 4.