Meldonium residues in milk: A possible scenario for inadvertent doping in sports?

Lately, the veterinary drug Emidonol® has been discussed as a possible scenario for inadvertent doping in sports. Emidonol® is approved for use in livestock breeding, exhibiting antihypoxic and weak sedative effects. The veterinary drug rapidly dissociates into meldonium, a substance prohibited in sports, and is excreted largely in its unchanged form into urine. To investigate if residues of meldonium in edible produce may result in adverse analytical findings in sports drug testing, a pilot study was conducted with three volunteers consuming a single dose of 100 ml meldonium-spiked milk at a concentration of 500 ng/ml (Study 1), and multiple doses of 100 ml of meldonium-spiked milk (500 ng/ml) on five consecutive days (Study 2). In the single dose study, urinary meldonium concentrations peaked between 2 and 6 h post-administration with maximum values of 7.5 ng/ml, whereas maximum meldonium concentrations of 18.6 ng/ml were determined after multiple doses 4 h post-administration. All samples were analyzed using an established and validated protocol based on HILIC-HRMS/MS.