MELDONIUM, the banned substance tennis star Maria Sharapova has admitted taking, is a treatment for heart problem angina.
Sharapova said she had been taking the drug she always knew by alternative name Mildronate, for 10 years for health reasons.
The drug is manufactured in Latvia and is thought to be most widely used in Eastern Europe, The Sun reports.
But in America, where Sharapova has been a citizen since 1994, the Food and Drug Administration has not even approved its use as a medicine.
The compound was banned by the World Anti-Doping Agency (WADA) from January 1, 2016.
Users are usually sufferers of heart-related problems and find it improves their quality of life and exercise capacity.
linical trials have also shown Meldonium may also be beneficial for the treatment of seizures and alcohol intoxication and, if used in tandem with other drugs, can help control diabetes.
Studies on lab rats have also suggested Meldonium may improve the ability of learning and memory.
Long-term use was reported to improve sexual performance, sperm motility and testosterone levels in wild boar.
The 28-year-old said she turned to Meldonium to combat regular flu-like symptoms and the possible onset of diabetes which runs in her family.
Former world 1500m champion Abebe Aregawi, the Ethiopian-born runner who represents Sweden, has already been provisionally suspended after testing positive for Meldonium and a number of other athletes are understood to have been caught since it was put on the banned list.