The 2014 European Medicines Agency (EMA) guidance recommends overlapping rivaroxaban with a vitamin K antagonist (VKA) during conversion to maintain continuous anticoagulation. Rivaroxaban and the VKA should be administered concurrently until the INR is ≥ 2.0. Standard initial VKA dosing should be used for the first 2 days of the transition, followed by INR-guided dose adjustment. Because rivaroxaban can influence the INR, INR testing should not be performed earlier than 24 hours after the previous rivaroxaban dose. [1]
A 2016 guidance document on practical management of direct oral anticoagulants (DOACs) for venous thromboembolism emphasizes that transitions between anticoagulants can increase both thromboembolic and bleeding risk if therapeutic anticoagulation is interrupted. In the ROCKET AF and ARISTOTLE trials, an approximate 4-fold increase in stroke or bleeding was observed at study completion, which was attributed to gaps in anticoagulation during transition to warfarin and highlights the need for a structured transition plan. For rivaroxaban to warfarin, one recommended approach is to stop rivaroxaban and begin warfarin plus low-molecular-weight heparin (LMWH) at the time the next rivaroxaban dose would have been due, continuing LMWH until the INR is ≥ 2.0. The guidance also describes an alternative strategy which involves overlapping warfarin with the DOAC, measuring the INR immediately before the next scheduled DOAC dose, and discontinuing the DOAC once the INR is ≥ 2.0. [2]
A 2014 review on switching between oral anticoagulants noted that no clinical trials had evaluated conversion from rivaroxaban to warfarin and that manufacturer guidance favored avoiding any interruption in anticoagulation. One approach is to discontinue rivaroxaban and begin a parenteral anticoagulant when the next rivaroxaban dose would have been due, with warfarin started on day 1 or 2 of heparin therapy and parenteral anticoagulation continued for at least 5 days and until the INR is ≥ 2 for at least 24 hours. An alternative strategy used in European practice is to overlap rivaroxaban with warfarin for at least 2 days and continue both until the INR is ≥ 2; because rivaroxaban can increase the INR, the review notes that INR should not be assessed until at least 24 hours after the previous rivaroxaban dose. A pharmacokinetic-based approach was also described, with warfarin started 4 days before stopping rivaroxaban for CrCl ≥ 50 mL/min, 3 days before for CrCl 31–50 mL/min, and 2 days before for CrCl 15–30 mL/min. No transition recommendation was provided for CrCl <15 mL/min. The review emphasizes that transitions should be managed carefully because even a brief lapse in anticoagulation, including a missed rivaroxaban dose, may increase thrombotic risk. [3]
A 2014 open-label, nonrandomized pharmacodynamic and pharmacokinetic study (Table 1) evaluated transition from rivaroxaban to warfarin in healthy adults aged 18 to 60 years. Subjects received rivaroxaban 20 mg once daily for 5 days, followed by rivaroxaban plus warfarin 5 or 10 mg daily a target trough international normalized ratio (INR) of ≥ 2.0 was achieved, after which rivaroxaban was discontinued and warfarin monotherapy continued. Co-administration produced greater-than-additive anticoagulant effects, with mean maximum INR values of 2.79 to 4.15, while rivaroxaban had minimal effect on INR at trough concentrations. Therapeutic INR was achieved within 2 to 4 days of overlap, supporting INR measurement at rivaroxaban trough when adjusting warfarin. Pharmacokinetic analyses showed no meaningful changes in drug exposure during co-administration, and no major bleeding events occurred. Overall, the study supports short-term overlap of rivaroxaban and warfarin during transition, with INR monitoring performed near the rivaroxaban trough to minimize interference. [4]