What is the conversion from Apixaban (apixaban) to Heparin (unfractionated heparin)?

From the Guidelines

When converting from apixaban to heparin, stop apixaban and wait 24 hours before starting heparin therapy, as recommended by the most recent guidelines 1. For patients with normal renal function, unfractionated heparin (UFH) can be initiated after this waiting period without a loading dose, typically at 18 units/kg/hour. For low molecular weight heparin (LMWH), such as enoxaparin, the standard dose is 1 mg/kg twice daily. In patients with renal impairment (CrCl <30 mL/min), reduce the waiting time to 12-18 hours and consider dose adjustments for heparin. The waiting period is necessary because apixaban has a half-life of approximately 12 hours, and starting heparin too soon could increase bleeding risk due to anticoagulant overlap. For urgent situations requiring immediate anticoagulation switch, closer monitoring for bleeding is essential. After the transition, monitor activated partial thromboplastin time (aPTT) for UFH or anti-Xa levels for LMWH to ensure therapeutic anticoagulation. This approach balances the need to maintain anticoagulation while minimizing bleeding risk during the transition period, as supported by recent studies on anticoagulation management 1.

Some key points to consider in this transition include:

• The pharmacokinetics of apixaban, which is primarily metabolized in the liver and has a renal elimination of about 27% of total drug clearance 1.
• The importance of renal function in determining the appropriate waiting time before initiating heparin therapy, as patients with severe renal impairment may require dose adjustments 1.
• The role of monitoring in ensuring therapeutic anticoagulation and minimizing bleeding risk, including the use of aPTT for UFH and anti-Xa levels for LMWH 1.
• The potential for heparin resistance in certain patient populations, such as those with acute phase response or elevated fibrinogen levels, and the need for alternative anticoagulants or dose adjustments in these cases 1.

Overall, the transition from apixaban to heparin requires careful consideration of the patient's renal function, bleeding risk, and anticoagulation needs, as well as close monitoring to ensure therapeutic anticoagulation and minimize adverse effects.

From the Research

Heparin to Apixaban Conversion

• The conversion from heparin to apixaban is a common practice in the treatment of venous thromboembolism (VTE) 2, 3.
• Apixaban is an oral factor Xa inhibitor with a rapid onset of action and predictable pharmacokinetics, allowing for a fixed dose regimen 2.
• Studies have shown that apixaban is as effective as conventional treatment regimens, including heparin and warfarin, in preventing recurrent VTE 2, 4.
• Apixaban has also been shown to reduce the risk of major bleeding compared to traditional anticoagulant therapies 2, 5.

Dosage and Administration

• The recommended dose of apixaban for the treatment of VTE is 5 mg twice daily 2.
• For patients with active cancer, a reduced dose of 2.5 mg twice daily may be effective in preventing recurrent VTE while reducing the risk of bleeding 5.
• Apixaban can be initiated immediately after discontinuation of heparin, without the need for overlap or bridging therapy 3.

Safety and Efficacy

• Apixaban has been shown to be safe and effective in a wide range of patients, including those with renal impairment or cancer 4, 5.
• The risk of major bleeding with apixaban is lower compared to traditional anticoagulant therapies, including heparin and warfarin 2, 5.
• Apixaban has also been shown to reduce the risk of recurrent VTE and mortality in patients with active cancer 5.