Determination of Rivaroxaban in Serum and Urine and As Point of Care Method in Urine

Abstract 1253

The oral direct factor Xa inhibitor rivaroxaban effectively prevents postoperative venous thromboembolism following elective knee and hip replacement surgery. Rivaroxaban is determined in plasma by coagulation and chromogenic methods. It is eliminated from blood to about 20% by kidneys. We aimed to determine rivaroxaban in urine by means of a quantitative measurement in serum and urine and as qualitative determination in urine as point of care method.

Rivaroxaban were extracted from commercially available drug. Identity and purity of the isolated compound were confirmed by mass spectrometry, elemental analysis (carbon, hydrogen, nitrogen content) and 1H-NMR spectroscopy. Serum and urine (patent pending) from healthy donors were spiked with rivaroxaban (50ng/ml to 1000 ng). Factor Xa inhibition was performed by means of a chromogenic substrate method comparing the results obtained from plasma. The reagents were lyophilized on mini-strips and incubated with urine (patent pending). The concentration of rivaroxaban was determined from plasma, serum, and urine and qualitatively by the mini-strips from 10 patients on treatment with rivaroxaban.

The concentrations of rivaroxaban spiked to plasma, serum and urine were independent of the medium (correlation between r=0.888 and 0.970). Patients on treatment with rivaroxaban showed a high correlation of plasma and serum values (r=0.9209). The correlation to urine samples was lower do to the time dependence of drug intake. The qualitative mini-strips detected rivaroxaban in all samples independently of drug intake. There were no false positive or false negative detections of rivaroxaban by the mini-strips.

Detection of rivaroxaban in serum avoids separate blood sampling to obtain plasma. Detection in urine avoids blood sampling at all and allows point of care testing also by the patient him/herself. Point of care detection of rivaroxaban in urine samples using ministrips may improve patient care.