The Russian, who has controversially been handed a wildcard for the Stuttgart tournament later this month as she returns to the circuit, tested positive for the substance at the 2016 Australian Open after it was added to the prohibited list on January 1 that year.
Sharapova's initial two-year ban was later reduced on appeal but she admitted she had been taking meldonium for 10 years to combat health problems and did not read the list.
"I didn't even know what meldonium was," she told the Times. "I had to Google it to find out. To me, it was Mildronate."
The 29-year-old also hit out at the ITF for the way they managed the banning of meldonium, insisting that someone should have informed her at the Fed Cup in November 2015.
She added: "It was an ITF event so why didn't someone come up to me and have a private conversation, just an official to an athlete, which would have taken care of the confidentiality problem they talked about later?
"But nothing was said by anyone."
Read the original article on Eurosport: Sharapova had to Google drug that led to 15-month ban