Ukrainian cross-country skier Marina Lisogor has tested positive for a banned substance, the country's National Olympic Committee said on Saturday (local time).
"The International Olympic Committee's Disciplinary Commission officially informed Ukrainian NOC today that Ukrainian cross-country skier Marina Lisogor was tested positive for the substance trimetazidine included into the forbidden substances' list since January 1st, 2014," the Committee said in a statement.
"Marina Lisogor gave her explanation at the Disciplinary Commission meeting that she took the drug product 'Preductal' not knowing that it consists of the forbidden ingredient, thus unintentionally breaking the IOC anti-doping rules."
Lisogor and Kateryna Serdyuk pulled out the women's team sprint on Wednesday with the Ukrainian delegation citing a back injury affecting Serdyuk.
Ukraine's Olympic Committee did not say whether Lisogor had failed her doping test at the Sochi Games.
On Friday, it was revealed that German biathlete Evi Sachenbacher-Stehle and Italian bobsledder William Frullani had both failed dope tests.
Lisogor, who finished 58th in the 10km classic at the Sochi Games, blamed the positive test on negligence.
"In 2004 I underwent a thyroid gland operation and in order to help me through this, my cardiologist gave me a prescription for preductal," she explained in a statement posted on the Ukraine National Olympic Committee's website.
"These drugs can be bought at any chemist's and are widely used in medical practice. Before I took them, I felt sure that they did not contain any forbidden substances and I took the medication again during the Olympic Games.
"However, since 1st January 2014, some components of this medication are now on the banned list of drugs that can be used in competition. It is my own fault and unfortunately this has happened."
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