Sport Ireland has said a runner from the 2017 Dublin City Marathon has tested positive for a banned substance.
Canadian Natasha Yaremczuk subsequently admitted the violation.
Prohibited substances - 1,3-dimethylbutylamine (DMBA) and higenamine - were discovered in a sample she provided for testing.
She has now been given a 14-month ban by Sport Ireland.
Her result in the Dublin Marathon on October 29th last year has been automatically disqualified.
She came in 10th place in the women's race with a time of 2:52:38.
In a statement, Sport Ireland said: "Ms Yaremczuk promptly admitted the violation and pursuant to Article 7.6.4 of the Irish Anti-Doping Rules she engaged in a consultation process with Sport Ireland regarding the appropriate period of ineligibility.
"In accordance with Article 7.6.4 of the Irish Anti-Doping Rules, Sport Ireland has issued this decision, which records that, the athlete has committed a violation of Article 2.1 of the rules, that she is subject to a 14 month period of ineligibility which expires on 29 December 2018".
According to the International Association of Athletics Federations (IAAF), Ms Yaremczuk has previously taken part in races in Boston, Toronto, Vancouver and New York.
