From the Research
When converting from apixaban to a heparin drip, discontinue apixaban and wait 12 hours before starting the heparin infusion if the patient is on standard dosing (5 mg twice daily), as this allows for the clearance of apixaban and minimizes the risk of anticoagulant overlap, which is supported by the pharmacokinetic properties of apixaban 1. For patients on reduced dosing (2.5 mg twice daily), wait 6-8 hours before initiating heparin. Start the heparin infusion without a bolus dose at 12-18 units/kg/hour (typically around 1000 units/hour for an average adult), then adjust based on aPTT or anti-Xa levels per your institution's protocol. This waiting period is necessary because apixaban has a half-life of approximately 12 hours in patients with normal renal function, and starting heparin too soon could increase bleeding risk due to anticoagulant overlap. The conversion timing should be adjusted for patients with renal impairment, as apixaban clearance is decreased in these individuals. Some studies suggest that anti-Xa monitoring may be superior to aPTT for monitoring heparin therapy, especially in patients with renal insufficiency or obesity 2, 3. However, a study comparing anti-Xa and aPTT monitoring for heparin therapy found no difference in clinical outcomes between the two methods 4. Monitor the patient closely during this transition period for both thrombotic and bleeding complications. If the conversion is needed urgently (such as for an emergency procedure), clinical judgment should be used to balance the risks of bleeding versus thrombosis. It's also worth noting that apixaban has been shown to be effective in preventing deep venous thrombosis after total knee arthroplasty, and may be a safer option than low molecular weight heparin in older adults 5. Key considerations in this conversion include:
- Waiting period before starting heparin infusion
- Initial heparin infusion rate
- Monitoring parameters (aPTT or anti-Xa)
- Patient factors (renal function, obesity) that may affect heparin dosing and monitoring.