Explainer: What is trimetazidine, the drug at the center of doping drama

2022 Beijing Olympics - Figure Skating - Training - Training Rink Capital Indoor Stadium, Beijing, China - February 11, 2022. Kamila Valieva of the Russian Olympic Committee during training REUTERS/Evgenia Novozhenina

BEIJING, Feb 11 (Reuters) - Here is what you need to know about trimetazidine, the banned drug that Russian gold medal figure skater Kamila Valieva tested positive to at the Beijing Games.

What is trimetazidine and how is it usually used?

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.

Why is trimetazidine banned in sports?

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

Who has used trimetazidine?

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 medalist Sun Yang, who was penalised with suspension in 2014 after testing positive for trimetazidine. Sun said he was prescribed the drug to treat his chest pains.

What is its link to meldonium?

TMZ is another example of a metabolic modulator like meldonium, which has featured in allegations against the Russians for doping.

In the PyeongChang Games, Russia's curling athlete Alexandr Krushelnitckii handed back his bronze medal after testing positive for meldonium.

Russian tennis player Maria Sharapova was also banned for 15 months after being tested with meldonium in 2016.

Reporting by Iain Axon in Beijing and Julie Steenhuysen in New York; writing by Krystal Hu; Editing by Michael Perry

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