The drug was sensationally thrown into the international spotlight today when Russian tennis star Maria Sharapova admitted testing positive for the substance, which was banned by the World Anti-Doping Agency in January.
What is meldonium prescribed for?
Meldonium, also known as mildronate, is prescribed to treat chest pain and heart attacks, among other conditions.
It helps boost bloodflow around the heart, and some researchers have linked it to increased athletic performance and endurance.
Sharapova said her family doctor began prescribing her the drug 10 years go after she frequently became sick, had irregular EKG results, a magnesium deficiency and a family history of diabetes.
Where is the drug prescribed?
The drug has been around for a number or years, but it is not approved for use in the United States or Australia.
It is produced in Latvia and available in Russia and other countries in that region.
When did the World Anti-Doping Agency become concerned?
Meldonium was put on to the World Anti-Doping Agency monitoring list last year.
Doctor Peter Brukner, a sports medicine expert from the La Trobe Sport and Exercise Medicine Research Centre, said WADA had found out it was being widely used in certain sports after monitoring it for 12 months.
"They were sufficiently concerned by the extent of that use and they thought there was some evidence that it was a performance-enhancing drug that they made the decision late last year to add it to the banned list," he said.
The ban came in to force on January 1.
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Sharapova said she was unaware the substance had been banned. Dr Brukner said it was surprising her team was not aware the drug had been monitored and later banned.
"Presumably she has a medical person who is prescribing her this drug," he said. "That person should have been aware, if they are dealing with sports people."
Who has tested positive for meldonium?
Over the past month, Russian cyclist Eduard Vorganov, Russian figure skater Ekaterina Bobrova and Ethiopia-born athletes Endeshaw Negesse and Abeba Aregawi have all tested positive for meldonium.
Listen to the full interview with Doctor Peter Brukner:
