Apixaban Dosing for 80-Year-Old Patient with Impaired Renal Function and Low Weight
For an 80-year-old patient with GFR 33 mL/min and weight 65 kg, the recommended dose of apixaban is 2.5 mg twice daily due to meeting two dose-reduction criteria (age ≥80 years and renal impairment). 1, 2
Dose Reduction Criteria Assessment
The patient meets the following dose-reduction criteria:
- Age ≥80 years: Patient is 80 years old ✓
- Renal function: GFR 33 mL/min (moderate renal impairment) ✓
- Weight ≤60 kg: Patient weighs 65 kg ✗
Decision Algorithm:
- Standard dose: 5 mg twice daily
- Reduced dose (2.5 mg twice daily) if patient has at least 2 of:
- Age ≥80 years
- Weight ≤60 kg
- Serum creatinine ≥1.5 mg/dL (or GFR 15-29 mL/min)
Since the patient meets 2 criteria (age ≥80 years and renal impairment), the reduced dose of 2.5 mg twice daily is appropriate 2, 1.
Rationale for Dose Reduction
Advanced Age: Patients ≥80 years have increased apixaban exposure and higher bleeding risk 3.
Renal Function: While the patient's GFR of 33 mL/min doesn't fall into the severe impairment range (15-29 mL/min), the combination with advanced age warrants dose reduction 1.
Safety Profile: The reduced dose of 2.5 mg twice daily in patients meeting multiple criteria has been shown to maintain efficacy while reducing bleeding risk 2, 4.
Important Considerations
Regular Monitoring: Renal function should be assessed at least yearly, with more frequent monitoring during acute illness, dehydration, or hospitalization 3.
Drug Interactions: Be vigilant about potential interactions with medications that affect CYP3A4 and P-glycoprotein pathways, which could increase bleeding risk 3.
Bleeding Risk: The combination of advanced age and renal impairment increases bleeding risk, making the dose reduction particularly important 4.
Clinical Evidence Supporting This Decision
The European Heart Rhythm Association practical guide specifically recommends apixaban 2.5 mg twice daily for patients with at least two of the following: age ≥80 years, weight ≤60 kg, or serum creatinine ≥133 μmol/L (1.5 mg/dL) 2.
The FDA label for apixaban clearly states that the recommended dose is 2.5 mg twice daily in patients with at least two of the specified characteristics, which this patient meets 1.
Research has shown that patients with a single dose-reduction criterion who received the standard 5 mg twice daily dose had acceptable outcomes, but those with multiple criteria benefit from the reduced dose 4.
Caution
While some clinicians might consider using the standard 5 mg twice daily dose in this patient since the GFR is above 30 mL/min, this approach would contradict the established guidelines that recommend dose reduction based on the combination of advanced age and renal impairment 2, 1. Studies have shown that apixaban concentrations in older adults are often higher than expected based on clinical trial data, further supporting the use of the reduced dose in this population 5.