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1/3/24 Enoxaparin Anti-Xa Level Monitoring Updates
January 3, 2024

From: "monroe crawley" <monroe.crawley@hhsys.org>
To: "Pharmacists" <grp_allpharm@hhsys.org>
Sent: Tuesday, January 2, 2024 3:06:40 PM
Subject: Enoxaparin Anti-Xa Level Monitoring Updates

Pharmacists,

Attached you will find the updated document regarding enoxaparin dosing and monitoring considerations. This document will be available on Form Web and you can find corresponding changes to our Sentri 7 guidance in the Anticoagulation Medication Management tab. Some of the key changes are listed below:

Therapeutic Enoxaparin

• For AXa levels > 2 units/mL, contact provider
  • Contact the provider to develop a plan or discuss alternatives for enoxaparin when serum levels are drawn appropriately and markedly elevated
    
  • The updated guidance maintains that, if the provider wants to continue enoxaparin, we should hold enoxaparin until AXa levels < 0.5 units/mL, then restart with the dose reduced by 40%
    

Prophylactic Enoxaparin

• Routine AXa monitoring is not for everyone
  • Enoxaparin pharmacokinetics are fairly predictable. Some scenarios may warrant monitoring, but routine AXa level monitoring is not recommended.
  • Pharmacists, as always, should use clinical judgement when determining the need for serum drug level monitoring
    
  • A recent publication published in November 2023, found that AXa level monitoring did not improve 30-day clinical outcomes in patients receiving enoxaparin for VTE prophylaxis (Pharmacotherapy. 2023;00:1–7)
    • Note: patients with extremely outlying body mass index (BMI) or creatinine clearance (CrCl) were excluded from this study

Serum Anti-Xa Level Monitoring Indications

Guidance on when to use AXa level monitoring has been slightly modified, but creating an all-encompassing list is not feasible. Pharmacists should use clinical judgement when determining the need for AXa monitoring.

Scenarios that may warrant AXa level monitoring for enoxaparin:

• Obesity (BMI ≥ 40 kg/m2 or > 150 kg)
• New or worsening bleeding
• Development of new thrombus (e.g. DVT, PE)
• Significant renal impairment or acute kidney injury (AKI)
  • NOTE: Patients receiving prophylactic dose enoxaparin requiring renal dose adjustment DO NOT typically benefit from anti-Xa level monitoring.
  • Consider ordering a level if sustained renal dysfunction with dose adjustment for more than 4 days.
• TREATMENT DOSE ONLY: Patients with moderate renal insufficiency (CrCl 30-60 ml/min) may be at risk for accumulating enoxaparin.
  • These patients may benefit from anti-Xa level monitoring after 4 days of therapy. If the level is acceptable, additional levels are NOT necessary unless patient status changes.

These changes will be updated tomorrow, 1/3/2024. Please refer to Form Web and Sentri 7 to review the updates. If you have any questions, please let me know.

Sincerely,