Rivaroxaban Anticoagulant Monitoring

What sample is required for rivaroxaban assay?Xarelto

Separated citrate plasma (plasma from a blue top tube) is the only valid sample. DO NOT SUBMIT SERUM. Request test code RIVA and ship at least 0.5 mL plasma in an insulated box with cold packs for overnight delivery. See the sampling page for detailed sampling instructions.

How long after treatment should I draw samples for rivaroxaban assay?

Draw samples 3 to 4 hours after oral rivaroxaban administration to measure peak anticoagulant effect.

What is the test code, turnaround time, and cost for rivaroxaban assay?

Use test code "RIVA" and include rivaroxaban therapy on the AHDC general submission form. Assays are performed daily (Monday thru Friday) and results reported within 24 hours of sample receipt. Refer to the AHDC test/fee list for current pricing.

What is the shipping address for rivaroxaban assay?

FedEx/UPS/Courier Address:

Comparative Coagulation Section/AHDC
College of Veterinary Medicine, Cornell University
240 Farrier Road
Ithaca, NY 14853

US Postal Service Address (PO Box):

Comparative Coagulation Section/AHDC
College of Veterinary Medicine, Cornell University
PO Box 5786
Ithaca, NY 14852-5786

How can I use the rivaroxaban assay to guide therapy?

The rivaroxaban assay measures circulating levels of rivaroxaban based on its anticoagulant action. Measuring rivaroxaban concentration will allow dose adjustment to prevent too much anticoagulant effect and risk for bleeding or no anticoagulant action and inadequate therapy.

What is the target range concentration for rivaroxaban therapy?

Disease-specific rivaroxaban therapeutic target ranges have not yet been established in human or veterinary medicine. In early studies, plasma concentrations of approximately 150 to 250 ng/mL rivaroxaban have been associated with positive clinical outcomes in people.

What are the clinical uses of rivaroxaban?

The current indications for rivaroxaban (Xarelto) in human medicine include thromboprophylaxis for orthopedic surgery, the treatment of deep vein thrombosis and pulmonary thromboembolism, and to prevent thromboembolic disease in patients with non-valvular atrial fibrillation. Early uses in veterinary medicine include management of dogs and cats with aortic thrombosis/thromboembolism (see SUPERCAT study http://cvccr.com/wordpress/what-is-supercat/) Safe and effective dosages have not yet been defined for animals; publications describe dosages of 0.9 mg/kg for dogs and 2.5 mg q. 24 hr for cats [JVECC 2016;26:488 (dogs) and 619(cats)].

Is the rivaroxaban assay different than the heparin assay?

The heparin and rivaroxaban assays use different calibrators and controls and are not interchangeable. Rivaroxaban is an orally active direct inhibitor of activated Factor X (Factor Xa). By measuring Factor Xa inhibition in the test plasma compared with a rivaroxaban standard, the rivaroxaban assay provides a biologic measure of anticoagulant intensity at the time of sampling.

Does rivaroxaban affect coagulation assays (APTT and PT)?

Patients receiving rivaroxaban may have mild to moderate prolongation of clotting time tests beyond reference range, however the degree of prolongation is variable among patients. A marked prolongation of clotting may be an indicator of excessive anticoagulant action and risk for abnormal bleeding.

Can I use the rivaroxaban assay to monitor apixaban?

Rivaroxaban (Xarelto) and apixaban (Eliquis) are different drugs, although both have a similar mechanism of anticoagulant action.

The rivaroxaban assay should not be requested for patients receiving apixaban. Request apixaban assay (code APBN) for apixaban monitoring.