How soon can I start a heparin drip after taking apixaban (Eliquis)?

Starting Heparin After Apixaban: Timing Recommendations

You can safely start prophylactic-dose heparin 12 hours after the last dose of apixaban, or therapeutic-dose heparin immediately if clinically indicated for acute thrombosis. 1

Prophylactic Heparin Dosing (DVT Prophylaxis)

For prophylactic anticoagulation, the European Society of Anaesthesiology recommends initiating heparin 12 hours after the last apixaban dose, which allows sufficient drug clearance while maintaining thromboprophylaxis. 1

Prophylactic Dosing Options:

• Unfractionated heparin: 5,000 units subcutaneously every 8-12 hours 2
• Enoxaparin: 40 mg subcutaneously once daily 2
• Dalteparin: 5,000 units subcutaneously once daily 2

Key Pharmacokinetic Rationale:

• Apixaban has a half-life of 8-14 hours, with peak concentrations occurring 3-4 hours after oral administration 1, 3
• At 12 hours post-dose, apixaban levels have declined sufficiently to minimize excessive anticoagulation risk when adding prophylactic heparin 1
• Research demonstrates that 80% of patients still have measurable apixaban levels at 24 hours, but these residual levels do not contraindicate prophylactic heparin initiation at 12 hours 4

Therapeutic Heparin Dosing (Active Treatment)

For therapeutic anticoagulation (e.g., acute VTE, ACS, or other urgent indications), you can start heparin immediately without waiting, as the clinical urgency outweighs theoretical concerns about overlap. 2

Therapeutic Dosing:

• IV unfractionated heparin: Loading dose of 70-100 units/kg, then continuous infusion adjusted to maintain aPTT 1.5-2.3 times control 2
• Therapeutic LMWH: Enoxaparin 1 mg/kg subcutaneously every 12 hours 2

Important Monitoring Considerations:

• Standard aPTT monitoring may be unreliable if significant apixaban remains in the system, as apixaban can interfere with anti-Xa assays used for heparin monitoring 4
• If apixaban was taken within the last 12 hours and you need to monitor therapeutic heparin, consider using specialized corrected heparin assays if available, or rely on clinical assessment 4

Critical Clinical Context

Renal Function Considerations:

• If creatinine clearance <30 mL/min: Prefer unfractionated heparin over LMWH, as apixaban clearance is prolonged and LMWH is renally cleared 1
• Consider extending the waiting period to 24 hours before starting prophylactic anticoagulation in severe renal impairment 2

Post-Procedural Settings:

• The 12-hour timing applies to medical patients requiring DVT prophylaxis 1
• For post-operative patients, ensure adequate hemostasis before initiating any heparin, typically 6-8 hours post-procedure for prophylactic doses 2

Common Pitfalls to Avoid

• Do not use therapeutic "bridging" doses: When transitioning from apixaban to prophylactic anticoagulation, bridging with therapeutic heparin is unnecessary and increases bleeding risk 2, 1
• Do not measure apixaban levels: Routine drug level monitoring is not required before starting prophylactic heparin at 12 hours 1
• Do not delay urgent therapeutic anticoagulation: If the patient has an acute thrombotic emergency (e.g., massive PE, acute arterial thrombosis), start therapeutic heparin immediately regardless of apixaban timing 2
• Avoid LMWH with neuraxial anesthesia: If an epidural catheter is present, use unfractionated heparin instead, as LMWH requires longer safety intervals for catheter manipulation 2