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Mar 20, 2017

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Rivaroxaban by anti-Xa

Rivaroxaban by anti-Xa (RIVA) Coagulation Lab Test

Name: Rivaroxaban by anti-Xa

Test Name: Rivaroxaban by anti-Xa

Health Link Test Code: RIVA

LIS Test Code: RIVA

CPT Code(s): 85300

Methodology: Chromogenic Anti-Xa Assay

Clinical Information:

The plasma level of Rivaroxaban is determined by the measurement of anti-Xa activity.

Days Performed: Daily- Specimens are accepted at any time. Testing required during off hours must be approved by a Coagulation physician. Call (608)263-5005 before collection.

In-Lab Turnaround Time: 1 day.

Stat In-Lab Turnaround Time: 2 hours.

Specimen: Blood

Collection Container: Light blue top (3.2% NaCitrate)

Collection Instructions:

Do NOT draw through a line containing heparin as this method is unable to distinguish Rivaroxaban from heparin in the sample. The venipuncture MUST be atraumatic to avoid hemolysis and contamination with tissue factors and platelets.

Collection Volume: Full 3.5 mL tube

Pediatric Collection Volume: Pediatric tube filled to fill mark

Stability Ambient:

2 hours off cells

Stability Refridgerated:

Not acceptable

Stability Frozen:

3 months at -70oC

Sample Analyzed: Plasma

Testing Volume: 0.5 mL

Pediatric Testing Volume: 0.3 mL

Specimen Processing:

Centrifuge specimen to yield platelet poor plasma (platelet count of plasma should be less than 10K/µL). Separate plasma and transfer to a plastic tube or vial. Freeze plasma at -200C or below.

Specimen Transport:

Transport whole blood specimens at room temperature to UWHC Hospital Laboratory within 2 hours of collection. See Specimen Processing for instructions if transport criteria are not able to be met. Transport frozen plasma aliquot on dry ice to UWHC Hospital Laboratory.

Unacceptable Criteria:

Hemolyzed specimens, clotted specimens, partially filled tubes and whole blood specimens greater than 2 hours old when received by the laboratory are not acceptable.

Interpretation:

For Rivaroxaban, no "therapeutic range" has been established. Observed peak (~2hrs) and trough concentrations in patients exposed to therapeutic dosing are as follows:

Stroke prevention in AF (20mg daily): peak values: 160-360 ng/mL, trough values: 4-96 ng/mL

VTE treatment (20mg daily): peak values: 175-360 ng/mL, trough values 19-60 ng/mL

VTE prophylaxis (10mg daily): peak values: 91-196 ng/mL, trough values: 1.3-38 ng/mL

References: Mueck W et al. Population pharmacokinetics and pharmacodynamics of once-and twice-daily Rivaroxaban for the prevention of venous thromboembolism in patients undergoing total hip replacement. Thromb Haemost 2008;100:453-61.

Buller HR et al. A dose-ranging study evaluating once-daily oral administration of the factor Xa inhibitor Rivaroxaban in the treatment of patients with acute symptomatic deep vein thrombosis. The Einstein DVT Dose Ranging Study. Blood 200;112:2242-2247.

 

The performance characteristics of this test were validated by the UWHC Clinicial Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test; however, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. The UWHC Clinical Laboratories is authorized under Clinical Laboratory Improvement Amendments (CLIA) to perform high-complexity testing.