The 31-year-old former 100-metre world record holder during a hearing here on Tuesday said that he was given nine nutritional supplements by his physical trainer, Canadian Chris Xuereb, but he listed only three of them on his form because the others were new to him and he could not recall the brand names, reports Xinhua.
"All the supplements were new to me, so I could not remember all of them," Powell explained to the three-member Jamaica Anti-Doping Disciplinary panel. "I could not remember after all the excitement at the trials."
According to anti-doping rules, athletes are obliged to list everything they have taken in the last seven days when they submit to a drug test.
When asked whether he was acquainted with these rules, the once fastest man replied: "I am now."
Among the absentees from his list was Epiphany D1, which lab tests later found to contain the prohibited stimulant oxilofrone.
He claimed he was advised to take the supplements after Xuereb, who the sprinter described as a good friend, prescribed these without checking whether they were on the World Anti-Doping Agency's list of banned products.
"I don't know the list but I knew of the list," he said, "I know there is a list we are supposed to check."
Powell's hearing comes after his former training partner Sherone Simpson, a three-time Olympic medalist, appeared before a disciplinary panel last week to explain her positive test for the same stimulant at the same championships.
Like Powell, she denies knowingly taking the banned stimulant and passed the buck to their shared newly-hired trainer Xuereb who provided them with new brand nutritional supplements.
The 29-year-old Olympic 4x100m-relay gold and 100m silver medalist said she was familiar with most of the supplements received from Xuereb except the Epiphany D1 on which she researched online for several hours before starting to take it but nothing she found raised "a red flag or an alarm bell".
However, according to media reports, Xuereb in June has denied providing them any performance-enhancing drugs and thought that "both athletes are clearly looking for a scapegoat".
The attorney of Jamaican Anti-Doping Commission (Jacdo) accused Powell of being "significantly negligent". This hearing will resume on Wednesday when Powell's long-time agent Paul Doyle - who also represents Sherone Simpson - is expected to testify.
Both athletes were provisionally suspended since their failed tests and missed the World Championships in Russia, and will face a ban from the sport if found guilty of doping violation.
The world's sprinting powerhouse, led by Usain Bolt, the world's fastest man, has raised many eyebrows when its several high-profile track and field athletes failed drugs tests in last year's championships, prompting the entire Jacdo board to resign five months later.