What is trimetazidine, the drug at the centre of Russian skater Valieva's doping drama?

BEIJING: Here is what you need to know about trimetazidine, the banned drug that Russian gold medal figure skater Kamila Valieva tested positive for at the Beijing Winter Olympics.

Trimetazidine, known as TMZ, is a drug that is used to treat angina and other heart-related conditions. It works by increasing blood flow to the heart and limiting rapid swings in blood pressure. The drug is not approved for use in the United States.

"If you're in a highly exertional sport, where you're using a lot of energy and you're putting your heart under significant stress, it certainly could help your heart function better theoretically," said Dr Kelly Johnson-Arbor, a medical toxicology physician at MedStar Georgetown University Hospital.

It has been on the World Anti-Doping Agency's (WADA) list of prohibited substances since 2014. It's currently categorised as "hormone and metabolic modulator", which is illegal for athletes to use both in and out of competition.

It is believed that TMZ can improve physical efficiency, especially in the case of endurance sports, although opinions vary on how long-lasting the effect could be.

It is a drug that is usually taken once or twice a day, and is easy to detect in tests as a synthetic drug.

Russian athletes are no stranger to the substance. In the 2018 Pyeongchang Winter Olympics, Russia's bobsledder Nadezhda Sergeeva was disqualified two days before her race after testing positive for trimetazidine.

One of the most high-profile cases involving trimetazidine is Chinese star swimmer and Olympic gold medallist Sun Yang, who was penalised with a suspension in 2014 after testing positive for trimetazidine. Sun said that he was prescribed the drug to treat his chest pains.

TMZ is another example of a