Apixaban Dosing for an 89-year-old Female with Atrial Fibrillation
For an 89-year-old female with atrial fibrillation, the recommended dose of apixaban (Eliquis) is 2.5 mg twice daily. 1, 2
Rationale for Dose Recommendation
The standard dose of apixaban for stroke prevention in atrial fibrillation is 5 mg twice daily. However, dose reduction to 2.5 mg twice daily is required when patients meet specific criteria:
- Age ≥80 years
- Body weight ≤60 kg
- Serum creatinine ≥1.5 mg/dL (133 μmol/L)
If a patient has at least two of these three characteristics, the dose should be reduced to 2.5 mg twice daily 1, 2.
Since the patient is 89 years old, she already meets one criterion (age ≥80 years). If she meets at least one more criterion (either weight ≤60 kg or serum creatinine ≥1.5 mg/dL), the reduced dose of 2.5 mg twice daily is appropriate.
Even if the patient's weight is >60 kg and serum creatinine <1.5 mg/dL, the European Heart Rhythm Association guidelines indicate that apixaban dose should be reduced to 2.5 mg twice daily for patients with creatinine clearance (CrCl) 15-29 mL/min 1. Given the patient's advanced age (89 years), her creatinine clearance is likely to be reduced, potentially warranting the lower dose.
Clinical Considerations
Age factor: At 89 years, this patient is well above the age threshold (≥80 years) that contributes to dose reduction criteria 1.
Renal function: Elderly patients often have decreased renal function. Creatinine clearance should be calculated using the Cockcroft-Gault formula, which takes into account age, weight, and serum creatinine 1, 3.
Bleeding risk: Advanced age is an independent risk factor for bleeding. The reduced dose helps mitigate this risk while maintaining efficacy 3, 4.
Efficacy of reduced dose: Clinical evidence supports that appropriately reduced doses of apixaban maintain effectiveness for stroke prevention while reducing bleeding risk 5, 4.
Common Pitfalls to Avoid
Inappropriate underdosing: Studies have shown that apixaban is frequently underdosed in clinical practice without meeting criteria for dose reduction 6, 7. This may compromise stroke prevention efficacy.
Failure to reassess: Renal function and weight can change over time, especially in elderly patients. Regular monitoring of renal function is essential 3.
Drug interactions: Combined P-glycoprotein (P-gp) and strong CYP3A4 inhibitors may increase apixaban exposure. For patients already taking 2.5 mg twice daily, concomitant use of these medications should be avoided 2.
Missed doses: Due to the short half-life of apixaban, missed doses can leave patients unprotected. 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 2.
Monitoring Recommendations
- Regular assessment for signs of bleeding
- Periodic monitoring of renal function
- Evaluation of medication adherence at each visit
- Assessment of body weight changes
The J-ELD AF Registry study demonstrated that even very elderly patients (≥85 years) taking on-label doses of apixaban had similar risks of stroke/systemic embolism and bleeding requiring hospitalization compared to younger elderly patients, supporting the safety and efficacy of appropriate apixaban dosing in this age group 4.