The sample that tested positive was obtained on June 10, but Holt evidently took the meldonium in December before it was made illegal in January of this year. A doctor for the Russian club team Dynamo Moscow prescribed the drug to Holt and some of his Dynamo teammates, assuring them it was legal. The players only realized after the fact that they had been given meldonium.
The USADA has concluded that the positive test will not affect Holt's Olympic participation due to the low concentration of meldonium in the sample and Holt's explanation of how he came to take the drug.
"The fair determination was made that Holt's use of meldonium came prior to its inclusion on the WADA Prohibited List," USADA CEO Travis T. Tygart said in a press release. "This case serves as a reminder to all athletes that they must be diligent from a health and clean sport standpoint about exactly what they are using, and not simply ingest an unknown substance from just any coach or doctor."
Meldonium is a heart medication, which is believed to expand the arteries and increase blood flow. This is also the drug that led to Maria Sharapova's failed drug test and suspension.