The producers of the drug found in tennis star Maria Sharapova's system say it can take several months to leave the body.

The former World No 1 says she has taken meldonium for a decade for health reasons and failed a doping test at the Australian Open.

It was only banned at the start of this year but the World Anti-Doping Agency says athletes were told about the change in October.

Meldonium has been responsible for more than 100 positive tests since January.

The Latvian manufacturers of the drug say that "its terminal elimination from the body may last for several months" depending on factors such as the dose and length of time it has been taken.