Apixaban Dosing for DVT
For acute DVT treatment in adults, start apixaban 10 mg orally twice daily for 7 days, then reduce to 5 mg twice daily for at least 3 months, with no need for initial parenteral anticoagulation. 1, 2
Initial Treatment Phase (Days 1-7)
- Loading dose: 10 mg orally twice daily for exactly 7 days 1, 2
- No parenteral anticoagulation (heparin or enoxaparin) is required before starting apixaban 1, 3
- This regimen demonstrated non-inferiority to conventional enoxaparin/warfarin therapy with a relative risk of 0.84 (95% CI 0.60-1.18) for recurrent VTE 4, 5
Critical caveat: If you have already initiated parenteral anticoagulation for >24 hours, consider that shortened lead-in therapy (<7 days of 10 mg twice daily) is associated with significantly higher bleeding rates (18.5% vs 5.1%, P=0.02) 6. Complete the full 7-day loading phase even after parenteral therapy unless bleeding risk factors are present.
Maintenance Phase (Day 8 onwards)
- Standard dose: 5 mg orally twice daily 1, 2
- Continue for minimum 3 months for provoked DVT 4, 1
- Consider longer duration for unprovoked DVT or ongoing risk factors 1
Extended Secondary Prevention (After ≥6 months)
- Reduced dose: 2.5 mg orally twice daily 1, 2
- This lower dose is used only after completing at least 6 months of standard treatment 4, 2
- Both 2.5 mg and 5 mg twice daily showed similar efficacy for secondary prevention without significant differences in recurrent VTE or major bleeding 4
Renal Impairment Dosing
- CrCl ≥15 mL/min: No dose adjustment needed for standard DVT treatment regimen 4, 2
- CrCl <15 mL/min: Avoid apixaban (patients with CrCl <25 mL/min were excluded from clinical trials) 4
- Apixaban is only 27% renally eliminated, making it safer than rivaroxaban (66% renal excretion) in mild-moderate renal impairment 4, 5
Drug Interactions Requiring Dose Adjustment
- Combined P-gp and strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir): Reduce dose by 50% 2
- If taking 10 mg twice daily → reduce to 5 mg twice daily
- If taking 5 mg twice daily → reduce to 2.5 mg twice daily
- If already on 2.5 mg twice daily → avoid coadministration 2
Missed Dose Management
- Take the missed dose as soon as possible on the same day 2
- Resume twice-daily schedule 2
- Never double the dose to make up for a missed dose 2
Advantages Over Traditional Therapy
- Superior bleeding safety: Major bleeding rate of 0.6% vs 1.8% with enoxaparin/warfarin (RR 0.31; 95% CI 0.17-0.55; P<0.001) 4, 5
- No INR or aPTT monitoring required 7
- No initial parenteral anticoagulation needed 1, 3
- Composite major plus clinically relevant non-major bleeding: 4.3% vs 9.7% with conventional therapy (RR 0.44; P<0.001) 4, 5
Monitoring Requirements
- CBC: Check hemoglobin, hematocrit, and platelets every 2-3 days for first 14 days, then every 2 weeks 7
- Renal function: Obtain baseline creatinine clearance 7
- Hepatic function: Check liver enzymes and bilirubin at baseline 7
- Clinical assessment: Monitor for signs of major bleeding (gastrointestinal, intracranial, genitourinary) and DVT symptom resolution 7
Common Pitfalls to Avoid
- Do not use standard 5 mg twice daily from day 1 – the 7-day loading phase with 10 mg twice daily is essential for acute treatment 2
- Do not use 2.5 mg twice daily for initial treatment – this dose is only for extended secondary prevention after ≥6 months 2
- Do not combine with other anticoagulants during transition unless specifically bridging from warfarin 2
- Avoid in severe hepatic impairment (transaminases >2x ULN or bilirubin >1.5x ULN) 4
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