What is the recommended dosing for apixaban (apixaban) when switching from therapeutic enoxaparin (low molecular weight heparin) to apixaban in patients with atrial fibrillation (AF) and normal renal function?

Switching from Therapeutic Enoxaparin to Apixaban in Atrial Fibrillation

When switching from therapeutic enoxaparin to apixaban in patients with atrial fibrillation and normal renal function, apixaban should be started at 5 mg twice daily when the next dose of enoxaparin would have been due, with no overlap between medications.

Dosing Considerations

Standard Dosing for Apixaban

• For most patients with atrial fibrillation and normal renal function, the recommended dose is 5 mg taken orally twice daily 1
• Dose reduction to 2.5 mg twice daily is required if the patient has at least two of the following characteristics:
  • Age ≥80 years
  • Body weight ≤60 kg
  • Serum creatinine ≥1.5 mg/dL 2, 1

Timing of Transition

• When switching from enoxaparin to apixaban, discontinue enoxaparin and begin apixaban at the time the next dose of enoxaparin would have been taken 1
• No overlap period is necessary between enoxaparin and apixaban due to the rapid onset of action of apixaban (reaches peak plasma levels within 3-4 hours)

Special Considerations

Renal Function Assessment

• Renal function should be evaluated prior to initiation of apixaban and reevaluated when clinically indicated and at least annually 2
• For patients with normal renal function (CrCl >50 mL/min), no dose adjustment is needed
• For patients with moderate renal impairment (CrCl 30-50 mL/min), no dose adjustment is needed unless other dose reduction criteria are met 2
• For patients with severe renal impairment (CrCl 15-29 mL/min), standard dosing can be used, though monitoring for bleeding is recommended 3

Drug Interactions

• Assess for concomitant medications that may interact with apixaban, particularly strong inhibitors of both CYP3A4 and P-glycoprotein 4
• If the patient is taking strong dual inhibitors of CYP3A4 and P-glycoprotein and already meets one of the dose reduction criteria, reduce the dose to 2.5 mg twice daily 4

Clinical Evidence Supporting Apixaban Use

• Apixaban has demonstrated superior efficacy compared to warfarin in preventing stroke or systemic embolism with a 21% reduction (HR 0.79; 95% CI, 0.66-0.95) 4
• Apixaban is associated with a lower risk of major bleeding compared to warfarin with a 31% reduction in major bleeding events 4
• In patients with declining renal function, apixaban maintains its superior safety profile compared to warfarin 5

Common Pitfalls to Avoid

1. Incorrect timing of transition: Avoid administering both enoxaparin and apixaban simultaneously, as this increases bleeding risk

2. Inappropriate dose reduction: Do not reduce the dose to 2.5 mg twice daily unless the patient meets at least two of the three dose reduction criteria 6

3. Missed doses: If a dose is missed, it should be taken as soon as possible on the same day and twice-daily administration should be resumed. The dose should not be doubled to make up for a missed dose 1

4. Perioperative management: For patients requiring surgery, apixaban should be discontinued at least 48 hours prior to elective surgery with moderate to high bleeding risk, and at least 24 hours prior to procedures with low bleeding risk 2, 1

By following these guidelines, you can ensure a safe and effective transition from therapeutic enoxaparin to apixaban in patients with atrial fibrillation and normal renal function.