Doping control analysis of trimetazidine in dried blood spot

Dried blood spot (DBS) analysis has been an inherent part of sports drug testing through the technological advancements of the past decade. Trimetazidine, a non-threshold banned substance, is excreted into urine after a dose of the permitted drug lomerizine. Therefore, a lomerizine-specific metabolite (M6) is analyzed to confirm the origin of trimetazidine in traditional urine analysis. Application studies were conducted to develop an analytical method for trimetazidine applicable to DBS. These studies comprise (1) the effect of different sampling sites on the detection of trimetazidine, (2) the determination of the appropriate trimetazidine level required for DBS analysis, and (3) differentiating between trimetazidine and lomerizine use. A high-resolution mass spectrometric method for detecting trimetazidine in DBS was validated. After oral administration of trimetazidine (n = 7), venous and capillary blood (fingertip and upper arm) were spotted on cellulose paper. Trimetazidine could be identified in DBS in all subjects up to 60 h after administration. The limit of detection was 0.05 ng/ml, and the limit of identification was 0.06 ng/ml, suggesting the minimum required performance level of 0.2 ng/ml. In the fingertip capillary blood, biases of 9.7% (vs. upper arm) and 13.0% (vs. vein) were observed in the trimetazidine intensity; however, there were no concerns in the qualitative analysis. After administering lomerizine (n = 10), the intact lomerizine has a strong peak intensity in blood compared to trimetazidine. Contrary to urine analysis, the M6 was less detectable in blood. Laboratories should confirm intact lomerizine whenever trimetazidine is identified in DBS.