MONTREAL – The World Anti-Doping Agency has extended the period in which athletes testing positive for meldonium can escape sanctions.

Under WADA’s new guidelines , athletes who test positive for a low concentration of meldonium between March 1 and Sept. 30 can be cleared based on a “no fault finding.”

WADA extended a policy that had previously covered the period from Jan. 1-March 1.

The agency updated the rules following further studies which showed the drug takes much longer to be cleared from the system than previously thought.

The guidelines cover athletes who maintain they took meldonium before Jan. 1, the date the drug was officially placed on the banned list.

Hundreds of positive tests have been recorded since then. Many athletes said they had stopped taking the substance long before Jan. 1 but the drug had remained in their system for weeks or months.

The WADA guidelines do not apply in the case of Maria Sharapova, who tested positive for the drug at the Australian Open in January and has been suspended for two years by the International Tennis Federation. The Russian acknowledged taking meldonium after Jan. 1. She is appealing her sanction to the Court of Arbitration for Sport.

WADA said “no fault” findings apply in cases where less than 1 microgram per millilitre of the drug is detected. Anything above that should be handled as a doping case.

“We are pleased that the necessary urinary excretion studies have now progressed, and that the guidance we are now able to provide our stakeholders to help them manage meldonium cases is clear and scientifically robust,” WADA President Craig Reedie said.

The Latvian-made drug, which is typically prescribed for heart conditions, was widely used as a supplement by athletes in Eastern European countries. The drug increases blood flow, which improves exercise capacity by carrying more oxygen to the muscles.