What is the recommended dosing regimen for Xarelto (rivaroxaban) in a patient with non-valvular atrial fibrillation or deep vein thrombosis/pulmonary embolism, considering factors such as age, weight, and renal function?

Xarelto (Rivaroxaban) Dosing

For atrial fibrillation, use 20 mg once daily with food in patients with normal renal function (CrCl ≥50 mL/min), reducing to 15 mg once daily in those with moderate renal impairment (CrCl 15-50 mL/min); for DVT/PE treatment, initiate with 15 mg twice daily with food for 21 days, then transition to 20 mg once daily with food for continued treatment. 1, 2

Atrial Fibrillation Dosing

Standard Dosing

• 20 mg once daily with food is the standard dose for stroke prevention in non-valvular atrial fibrillation 1, 2, 3
• This dose applies to patients with CrCl ≥50 mL/min 4, 3

Dose Reduction Criteria

• 15 mg once daily with food for patients with moderate renal impairment (CrCl 15-50 mL/min) 1, 4, 2, 3
• The 15 mg dose should also be considered in patients with high bleeding risk (HAS-BLED score ≥3) 1
• In elderly patients ≥80 years, renal function assessment is critical as impairment is likely even without laboratory confirmation 4

Critical Monitoring Points

• Calculate creatinine clearance using the Cockcroft-Gault formula, not estimated GFR 4
• Assess renal function at baseline and monitor annually, or 2-3 times per year in patients with moderate renal impairment 1, 4
• Rivaroxaban is not recommended in severe renal impairment (CrCl <30 mL/min) 1

DVT/PE Treatment Dosing

Acute Treatment Phase

• 15 mg twice daily with food for the first 21 days 1, 2
• This loading phase is essential for achieving therapeutic anticoagulation rapidly 1

Maintenance Phase

• 20 mg once daily with food after the initial 21-day period 1, 2
• This is the VTE-specific maintenance dose, which is higher than what may be used in some AF contexts 1

Extended Secondary Prevention

• After 6 months of initial therapy, 10 mg once daily (with or without food) can be considered for extended VTE prevention 1
• The reduced 10 mg dose is specifically for secondary prevention after completing standard treatment duration 1

Administration Requirements

Food Considerations

• 15 mg and 20 mg tablets must be taken with food to ensure adequate absorption 2
• 10 mg and 2.5 mg tablets may be taken with or without food 2

Alternative Administration Routes

• Tablets may be crushed and mixed with applesauce immediately prior to use 2
• For NG tube administration: crush tablet, suspend in 50 mL water, and administer via gastric tube (not distal to stomach) 2
• After administering crushed 15 mg or 20 mg tablets via NG tube, immediately follow with enteral feeding 2

Missed Dose Management

Once Daily Dosing (20 mg, 15 mg, or 10 mg)

• Take the missed dose immediately on the same day it is noticed 2
• Do not double the dose within the same day 2

Twice Daily Dosing (15 mg BID)

• Take immediately to ensure 30 mg total daily intake 2
• Two 15 mg tablets may be taken at once if needed 2

Perioperative Management

Preoperative Discontinuation

• Stop rivaroxaban at least 24 hours before surgery to reduce bleeding risk 2
• For major surgery or high bleeding risk procedures, consider stopping 2-3 days (48-72 hours) preoperatively 1
• In elderly patients undergoing high bleeding risk surgery, discontinue 5 days prior 4

Postoperative Resumption

• Low bleeding risk surgery: Resume 20 mg once daily on the day after surgery (24 hours postoperative) 1
• High bleeding risk surgery: Resume 2-3 days after surgery (48-72 hours postoperative) 1
• Consider reduced dose (10 mg once daily) for first 2 days after major surgery, then increase to 20 mg daily 1
• Restart only after adequate hemostasis is established 2

Drug Interactions and Contraindications

Avoid Concomitant Use

• Strong dual inhibitors of CYP3A4 and P-glycoprotein (ketoconazole, itraconazole, ritonavir) are contraindicated 4
• Use caution with antiplatelet agents or NSAIDs due to increased bleeding risk 4

Bleeding Risk Assessment

• Gastrointestinal bleeding risk is approximately 50% higher with rivaroxaban compared to warfarin in elderly patients 4
• Assess HAS-BLED score to identify modifiable bleeding risk factors 1
• Scores ≥3 indicate high bleeding risk requiring careful monitoring 1

Common Dosing Errors to Avoid

Underdosing in AF

• Studies show 52% of patients receiving reduced doses do not meet labeling criteria for dose reduction 5
• Do not reduce dose based solely on age without documented renal impairment 5
• eGFR alone should not drive dose reduction; use Cockcroft-Gault calculated CrCl 4

Wrong Dose for Indication

• Do not use the AF dose (15 mg once daily) for VTE treatment in patients with moderate renal impairment 1
• VTE maintenance dose should be 20 mg daily, not 15 mg daily, even in post-PCI AF patients 1

Food Administration Errors

• Failure to take 15 mg or 20 mg doses with food results in reduced absorption and subtherapeutic levels 2