Alan King will face a British Horseracing Authority disciplinary panel on Thursday after Yanworth failed a drugs test following the Champion Hurdle at the Cheltenham Festival in March.
The seven-year-old was sent off the 2-1 favourite for the showpiece event, but trailed home seventh, beaten 14 lengths by Buveur D'Air.
Yanworth subsequently tested positive for triamcinolone acetonide (TCA), an anti-inflammatory substance which may be legitimately used on horses in training but is banned on raceday.
King will not attend the inquiry, during which the panel will consider whether to disqualify Yanworth, who subsequently won the Liverpool Hurdle at Aintree in April.
It is not the first time one of King's horses has tested positive for TCA, with Midnight Cataria disqualified from second place at Kempton in October 2015 after the drug was detected in her system.
King and the BHA agreed the source of the drug was the trainer's vet, who had treated the mare for lameness, with TCA remaining in her system longer than anticipated. The Barbury Castle handler was fined £1,000.
Yanworth is owned by JP McManus, whose racing manager Frank Berry declined to comment when contacted by Press Association Sport.