Maria Sharapova is not the only Russian sports star to have fallen foul of the new status of Meldonium, Russian media said on Tuesday.
The medicine, which was only added to the banned list earlier this year by the World Anti-Doping Agency (WADA), has caught out a number of other top Russian stars.
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.
The news came a day after Sharapova confessed to having failed a dope test at the Australian Open in January.
The former world number one said a 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.
Previously, 2014 Olympic ice skating champion Ekaterina Bobrova returned a sample at the European championships in Bratislava containing Meldonium and earlier this year cyclist Eduard Varganov, of the Katusha team, also tested positive.
Russia's sports minister Vitaly Mutko said he was shocked by the avalanche of positive tests for the medicine, which he claimed doesn't enhance an athletes' performance.
"This medicine is purposeless. It gives (athletes) nothing," the R-Sport agency quoted the minister as saying.
"I've told the athletes, coaches and doctors to be very careful but apparently not all of them drew the right conclusions.
"Maybe we will face more shocks because of this medicine."
The multiple dope test failures led Dmitry Svishchev, head of the sports and physical culture committee of the lower house of the Russian Parliament, the State Duma, to call an extraordinary meeting of the panel later this week.
"We need to study the facts and documents thoroughly," Svishchev told R-Sport agency.
"Than we will begin to work out a bill aimed at battling doping."
Meldonium -- manufactured in Latvia -- is used to treat heart trouble, including angina and heart failure.
Professor Ivar Kalvins, who created the medicine, said that he considered the inclusion of Meldonium on the banned list to be a violation of the human rights.
"Meldonium is not a performance-enhancing drug," he said in an interview with the Russian version of the www.delfi.lv information portal.
"It just helps to protect the athlete's heart from the consequences of physical overwork. That means it watches over athletes' health.
"To ban this medicine means to ban athletes from taking care of their health. I consider it to be a kind of violation of human rights."