Pyleva, who won silver at the 15km event Monday, was scratched just before the start of Thursday's 7.5km sprint, in which she was considered a leading medal contender. She also won gold and bronze medals at the 2002 Salt Lake City Games.
A hastily-convened, three-member IOC panel found Pyleva guilty of a doping violation. She had tested positive for the banned stimulant carphedon in a urine test following Monday's race.
Nikolai Durmanov, head of Russian Anti-Doping Committee, said a doctor who treated her for an ankle injury in January gave her an over-the-counter medication that did not list carphedon as one of its ingredients.
"This was 100 percent the physician's mistake," Durmanov said.
Martina Glagow of Germany, who finished fourth, will be awarded the silver. Albina Akhatova, Pyleva's Russian teammate, goes from fourth to bronze.
Further possible sanctions — such as a long-term ban from competition — are up to the International Biathlon Union.
Under the IOC's rules, athletes testing positive at the Olympics are considered guilty if a banned substance is found in their systems, regardless of the circumstances.
The IOC has conducted 380 tests since the athletes' village opened Jan. 31; Pyleva is the first to be caught by the IOC's most rigorous doping control program ever at a Winter Olympics. A total of 1,200 samples are being tested, a 72 percent increase over the number in Salt Lake City, where there were seven doping cases total.
A Brazilian bobsledder who tested positive for steroids in a pre-Olympic drug test was the first athlete sent home from the Torino Games for doping. Armando dos Santos, a former hammer thrower, failed the test in early January when a sample showed evidence of the steroid nandrolone.
A dozen cross-country skiers were suspended five days for elevated hemoglobin, considered health checks — though they can also indicate possible blood doping. Seven of those have since been retested and cleared to compete; one failed a retest, and the other four had not yet been cleared.
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