Croatian tennis player Marin Cilic has been banned for nine months after testing positive for the stimulant nikethamide, the International Tennis Federation (ITF) has said.
In a statement the ITF said Cilic had "ingested the nikethamide inadvertently as a result of taking Coramine glucose tablets, and did not intend to enhance his performance in doing so".
The suspension has been backdated to May 1, allowing Cilic to return to the circuit on January 31 next year.
The ITF statement said Cilic had tested positive at the BMW Open in Munich this year.
It said Cilic had asserted that he had taken the stimulant by accident as a result of taking the glucose tablets that had been purchased on his behalf from a pharmacy.
Cilic, 24, has not played since withdrawing from his second-round match at Wimbledon in June.
He defeated then world number two Andy Murray in the fourth round of the 2009 U.S. Open and reached the semi-finals of the 2010 Australian Open, where he lost to the Briton.
Cilic broke into the top 10 in February 2010 and reached a career-high of ninth. Cilic, who is currently ranked 24th, spent 11 successive weeks in the top 10.
Image: Marin Cilic of Croatia reacts during a match
Photo: Charlie Crowhurst/Getty Images