About this Calculator

The Rivaroxaban Dose Eligibility Calculator is a clinical decision support tool designed for healthcare professionals. It helps determine the appropriate rivaroxaban dosage by calculating a patient's creatinine clearance (CrCl) using the Cockcroft-Gault formula. The recommendations provided are based on the patient's renal function, clinical indication, hepatic status, and potential drug-drug interactions, aligning with FDA-approved prescribing information.

Outputs

After entering the required patient data, the calculator provides the following outputs:

• Creatinine Clearance (CrCl): The patient's estimated CrCl in mL/min, which is a key indicator of renal function.
• Recommended Dose: The specific rivaroxaban dosing schedule (e.g., strength and frequency) for the selected indication.
• Rationale: A brief explanation for the dosing recommendation based on the calculated CrCl and clinical guidelines.
• Safety Alerts: Important contraindications or warnings, such as those related to severe renal or hepatic impairment, and significant drug interactions.

How to Use

Follow these steps to determine the appropriate rivaroxaban dose:

1. Select Indication: Choose the patient's clinical reason for rivaroxaban therapy from the list provided.
2. Enter Patient Demographics: Input the patient's age (in years) and select their biological sex.
3. Enter Weight and Creatinine: Provide the patient's weight (in kg or lbs) and serum creatinine level (in mg/dL or µmol/L). The tool will automatically convert units as needed.
4. Specify Clinical Factors: Select the patient's level of hepatic impairment (Child-Pugh class) and indicate if they are taking concomitant medications that are combined P-gp and strong CYP3A4 inhibitors or inducers.
5. Calculate: Click the "Calculate Dose" button to generate the dosing recommendation and safety alerts.

Dosing Overview

Rivaroxaban dosing is tailored to the specific indication and the patient's renal function. The following table summarizes standard dosing recommendations per FDA guidelines.

Switching Anticoagulants

• From Warfarin to Rivaroxaban: Discontinue warfarin and start rivaroxaban once the International Normalized Ratio (INR) is below 3.0.
• From Other Anticoagulants to Rivaroxaban: Start rivaroxaban 0 to 2 hours before the next scheduled evening dose of a parenteral anticoagulant (e.g., LMWH) would have been administered. For unfractionated heparin, start at the time of discontinuation.
• From Rivaroxaban to Warfarin: Discontinue rivaroxaban and begin both a parenteral anticoagulant and warfarin at the time the next dose of rivaroxaban would have been taken.
• From Rivaroxaban to Other Anticoagulants: Discontinue rivaroxaban and begin the other anticoagulant at the time the next rivaroxaban dose would have been taken.

Missed Dose

The correct action for a missed dose depends on the prescribed dosing schedule:

• 15 mg Twice Daily Schedule: The patient should take the missed dose immediately to ensure a total intake of 30 mg for the day. Two 15 mg tablets may be taken at once. The regular schedule should be resumed the following day.
• 20 mg, 15 mg, or 10 mg Once Daily Schedule: The patient should take the missed dose as soon as they remember on the same day. They should not take two doses on the following day to make up for the missed dose.
• 2.5 mg Twice Daily Schedule: The patient should skip the missed dose and take the next dose at its regularly scheduled time.

Safety Alerts

This calculator incorporates critical safety checks based on prescribing information:

Frequently Asked Questions

What formula does the calculator use for creatinine clearance?

The calculator uses the Cockcroft-Gault equation, which is the formula cited in the rivaroxaban prescribing information for determining dose adjustments based on renal function.

Can this tool be used for patients with mechanical heart valves?

No. Rivaroxaban is contraindicated in patients with prosthetic heart valves. This tool is intended for approved indications, such as nonvalvular atrial fibrillation.

How does the calculator handle different units for weight or creatinine?

The tool includes options for both pounds (lbs) and kilograms (kg) for weight, and for mg/dL and µmol/L for serum creatinine. It automatically converts these values to the standard units required for the Cockcroft-Gault calculation.

Is a dose adjustment required for elderly patients?

Dose adjustments for rivaroxaban are based on renal function (CrCl) and clinical indication, not on age alone. However, since advanced age is a factor in the CrCl calculation, elderly patients are more likely to require a dose adjustment due to decreased renal function.

What is the recommendation for patients on dialysis?

For patients with CrCl < 15 mL/min, including those on dialysis, use of rivaroxaban for the NVAF indication is not recommended. For other indications, it is generally avoided if CrCl is < 30 mL/min.

Why is the initial dose for DVT/PE treatment higher and given twice daily?

The initial 15 mg twice-daily regimen for 21 days serves as a loading dose to rapidly achieve therapeutic anticoagulant levels and effectively treat an acute deep vein thrombosis or pulmonary embolism.

Can this calculator be used for pediatric patients?

No, this calculator is designed for adult patients only. Dosing, safety, and efficacy of rivaroxaban in pediatric patients have been established for certain indications but require different formulations and considerations not covered by this tool.

How does moderate liver disease (Child-Pugh B) impact dosing?

Rivaroxaban should be avoided in patients with moderate (Child-Pugh B) or severe (Child-Pugh C) hepatic impairment, as this can lead to clinically significant increases in drug exposure and bleeding risk.

References

1. XARELTO® (rivaroxaban) [Prescribing Information]. Janssen Pharmaceuticals, Inc. Titusville, NJ. Accessed via FDA.gov.
2. Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41. doi:10.1159/000180580.
3. January CT, Wann LS, Calkins H, et al. 2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation. Circulation. 2019;140(2):e125-e151.