London - Some 490 athletes, including 13 medallists, may have taken meldonium -- the drug responsible for tennis star Maria Sharapova's failed dope test -- at last year's European Games in Baku, according to research published on Wednesday in the British Journal of Sports Medicine.
Meldonium was placed on the World Anti-Doping Agency's list of banned substances on January 1, with the research, carried out on behalf of the European Olympic Committees, contributing to the global watchdog's decision.
The findings were based on information volunteered by athletes and their medical teams as well as anti-doping tests given at the European Games last June.
Thirteen medallists were found to have been taking meldonium and the drug was detected in athletes competing in 15 of the 21 sports.
Sharapova is not the only Russian sports star to have fallen foul of the new status of meldonium, Russian media said on Tuesday.
The state-run agency TASS reported that volleyball international Alexander Markin, speed skating world champion Pavel Kulizhnikov and short track Olympic champion Semen Yelistratov have also tested positive for Meldonium.
Monday saw Sharapova confess to having failed a dope test at the Australian Open in January, with Russian ice dancer Ekaterina Bobrova's positive test for meldonium revealed earlier on Monday.
Former world number one Sharapova said the change in WADA's banned drugs list for 2016 led to an inadvertent violation, for which she will be "provisionally suspended" by the International Tennis Federation.
Sharapova said she originally began taking meldonium for a variety of symptoms, including a tendency to become ill often, an irregular EKG heart test and a family history of diabetes.
Meldonium is used to treat heart trouble, including angina and heart failure.
In adding it to the banned list, WADA said there was evidence it has been used by athletes with the intention of enhancing performance.
But its use since it became a prohibited substance has not been solely a Russian problem, with Sweden's Abeba Aregawi, originally from Ethiopia, the world 1500 metres champion in 2013, Ukrainian biathletes Olga Abramova and Artem Tychtchenko, the Ethiopian marathon runner Endeshaw Negesse and six Georgian wrestlers also returning positive tests.