Jamaica's 2008 Olympic women's 100 metres silver medallist Sherone Simpson received an 18-month suspension for doping from the Jamaica Anti-Doping (JADCO) Disciplinary Panel on Tuesday. The 29-year-old, who won 4x100m relay gold in the 2004 Olympics and silver in the same event at the 2012 Games, tested positive for a stimulant, oxilofrine, at the Jamaica National Championships in June 2013. Simpson, who was also a member of the Jamaican 4x100m relay teams that took silver in the 2005 and 2011 world championships, said the substance was found in a new supplement given to her by Canadian physical trainer Chris Xuereb. The decision doesn't bode well for her team-mate and men's former 100m world record holder Asafa Powell, who tested positive for the same stimulant as Simpson. He will learn his fate from the same body on Thursday. JADCO's lawyer Lackston Robinson pushed for the maximum two-year suspension for Simpson, saying he was not convinced that Epiphany D1 contained the substance oxilofrine found in Simpson's sample. He also questioned the "honesty" of the evidence given by agent Paul Doyle. In announcing the verdict, the chairman of the Jamaica Anti-Doping Disciplinary Panel, Lennox Gayle, said Simpson had been negligent. "Having listened and reviewed all the evidence and listened to the detailed submissions of councils, this panel is unanimously of the view that Miss Simpson was negligent in all the circumstances as an elite athlete," he said. "As such, the period of ineligibility will be 18 months (to) commence from the date of the positive test on June 21, 2013." Simpson, who was not present, is one of Jamaica's most decorated female sprinters, having also won the Commonwealth Games 200m title in 2006. Meanwhile, discus thrower Allison Randall was hit with a two-year suspension by a separate Jamaica Anti-Doping Disciplinary Panel. Randall, 25, who represented Jamaica at the 2012 Olympic Games, tested positive for a banned diuretic at last year's Jamaica National Championships.