For which cases is the dosage of apixaban (Apixaban) halved?

Apixaban Dose Reduction Criteria

Standard Dosing and Reduction Requirements

Apixaban dosage is halved from 5 mg twice daily to 2.5 mg twice daily when patients with atrial fibrillation meet at least 2 of the following 3 criteria: age ≥80 years, body weight ≤60 kg, or serum creatinine ≥1.5 mg/dL (or creatinine clearance 15-29 mL/min). 1, 2, 3

Atrial Fibrillation Dose Reduction Algorithm

The dose reduction criteria apply specifically as follows:

• Age criterion: Patient must be ≥80 years old 1, 2
• Weight criterion: Patient must weigh ≤60 kg 1, 2
• Renal criterion: Serum creatinine must be ≥1.5 mg/dL OR creatinine clearance 15-29 mL/min 1, 2

At least 2 of these 3 criteria must be present simultaneously to justify dose reduction to 2.5 mg twice daily. 1, 2 If only 1 criterion is present, the standard 5 mg twice daily dose should be maintained, as clinical trial data demonstrate consistent safety and efficacy with the full dose in this population. 4

Special Renal Impairment Considerations

• For creatinine clearance >30 mL/min: No dose adjustment is needed unless the patient meets at least 2 of the 3 dose-reduction criteria listed above 2
• For creatinine clearance 15-29 mL/min alone: This qualifies as meeting the renal criterion, but dose reduction to 2.5 mg twice daily still requires at least one additional criterion (age ≥80 years OR weight ≤60 kg) 1, 2
• For end-stage renal disease on hemodialysis: Use 5 mg twice daily as the standard dose, reducing to 2.5 mg twice daily only if the patient meets age ≥80 years OR weight ≤60 kg (note: only 1 additional criterion needed, not 2) 1, 2

Drug Interaction-Based Dose Reduction

For patients receiving standard doses of 5 mg or 10 mg twice daily, reduce the apixaban dose by 50% when coadministered with combined P-glycoprotein and strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir). 3

• For patients already taking 2.5 mg twice daily: Avoid coadministration with combined P-gp and strong CYP3A4 inhibitors entirely 3
• Exception for clarithromycin: Despite being a combined P-gp and strong CYP3A4 inhibitor, no dose adjustment is necessary with clarithromycin based on pharmacokinetic data 3

Venous Thromboembolism Dosing

For VTE treatment, apixaban dosing differs significantly from atrial fibrillation:

• Acute treatment phase: 10 mg twice daily for 7 days, then 5 mg twice daily—no dose reduction criteria apply during acute treatment 1, 3
• Extended-phase therapy (secondary prevention): After completing at least 6 months of treatment, reduce to 2.5 mg twice daily for all patients regardless of age, weight, or renal function 1, 2, 3

Post-Orthopedic Surgery Prophylaxis

For VTE prevention after major orthopedic surgery, all patients receive 2.5 mg twice daily regardless of age, weight, or renal function. 1, 3

Critical Clinical Pitfalls

Common dosing errors to avoid:

• Do not reduce the dose based on a single criterion: Patients with isolated advanced age (≥80 years), low body weight (≤60 kg), or renal dysfunction (creatinine ≥1.5 mg/dL) should receive the standard 5 mg twice daily dose for atrial fibrillation, as they demonstrate consistent benefit without increased bleeding risk 4
• Do not apply atrial fibrillation dose-reduction criteria to VTE treatment: The acute treatment phase for DVT/PE uses 10 mg twice daily initially regardless of patient characteristics 1, 3
• Reassess criteria periodically: Body weight and renal function can change over time, potentially affecting whether patients meet dose-reduction thresholds 2
• Calculate creatinine clearance using Cockcroft-Gault method: This is the recommended approach for determining renal function-based dosing 2