Former world tennis number one Maria Sharapova has admitted to taking the banned substance Meldonium, also known as mildronate.
In February, Sweden's Abebe Aregawi, the 2013 women’s 1500m world champion was provisionally suspended after meldonium was found in her 'A' sample.
But just what is the substance, and why is it banned? ITV News explains.
- What is it?
Meldonium is manufactured in Latvia and used medically to treat heart problems like angina and myocardial infarction. It is also an effective treatment for ischemia - or lack of blood flow.
It is most commonly used in Russia and it is not approved by the Food and Drug Administration for use in the US.
- When was it banned?
It became a prohibited substance on 1 January 2016, because of "evidence of its use by athletes with the intention of enhancing performance."
It had previously been on the World Anti Doping Agency's list of drugs to be monitored.
Athletes testing positive for the drug prior to 1 January won't have medals or records removed.
- Why was it banned?
Wada's monitoring of the drug found that some of its medical benefits could enhance athletic performance, especially in endurance athletes.
Meldonium doping benefits may include:
- Increased endurance and aerobic capabilities of athletes
- Increase rate of recovery
- Who else has tested positive for it?
In addition to Sharpova and Aregawi, Tokyo Marathon winner Ethiopia's Endeshaw Negesse has reported tested positive for meldonium doping.
Cyclist Eduard Vorganov also tested positive for the drug in an out-of-competition test in January, according to the BBC.