Rivaroxaban Laboratory Monitoring in Switzerland 2: Therapeutic Dose (RivaMoS 2)

Rivaroxaban (RXA; brand name Xarelto®) is an oral direct factor Xa inhibitor that is applied for prophylaxis of venous thromboembolism (VTE) after major orthopedic surgery of the lower limbs such as hip and knee replacement surgery. Additionally, RXA is approved by Swissmedic to be used at a therapeutic dose for primary therapy of VTE and for prophylaxis of cerebrovascular events in non-valvular atrial fibrillation.

Monitoring of RXA concentration (conc.) is generally not required because of its stable pharmacokinetic and pharmacodynamic profile, even in patients with renal insufficiency. However, there are several clinical situations, in which it may be desirable to measure the RXA plasma conc. The range of RXA conc. is wide among individuals with typical peak levels of median 244 µg/L (IQR 175-360) and trough levels of median 32 µg/L (IQR 19-60) with once daily doses of 20 mg RXA.

This is an explorative laboratory study to evaluate the intra-individual variability of RXA conc. in time and to standardize assays among 9 Swiss laboratories to determine RXA conc.

Inclusion criteria

Male, aged 18-65 years

• No known comorbidity or disease
• No known galactose intolerance, lactase deficiency or glucose galactose malabsorption
• Taking no other medicaments
• No history for disorders regarding hemostasis
• Initial screening laboratory test showing normal values for liver/pancreas function (ALAT,ASAT,gGT, alkalic phosphatase, bilirubin, amylase, lipase), kidney function (creatinine), hematogram (white blood cell count, hemoglobin, platelet count), and coagulation parameters ("Gerinnungsstatus" with PT, aPTT, fibrinogen, thrombin time)
• written informed consent

Exclusion criteria

• none