Enoxaparin Clinical Pearl
FDA-Approved Dosing of Enoxaparin (Lovenox®)
Post-knee replacement surgery:
Cautions and Notes About Enoxaparin
Black Box Warning When spinal puncture or epidural/spinal anesthesia is employed, patients anticoagulated or scheduled to be anticoagulated with low molecular weight heparins or heparinoids are at risk of developing an epidural or spinal hematoma which can result in long-term or permanent paralysis.
Enoxaparin should not be used in patients with known or suspected heparin-induced thrombocytopenia.
The 30-, 40-, 60-, 80- and 100-mg syringes of enoxaparin are 100 mg/mL concentration. The 120- and 150-mg syringes of enoxaparin are 150 mg/mL concentration.
and Pharmacokinetics of Enoxaparin
The bioavailability of enoxaparin given subcutaneously is 92%. The volume of distribution of enoxaparin, based on anti-factor Xa activity, is 6 liters (in an average patient).
The elimination half-life of enoxaparin administered subcutaneously, based on anti-factor Xa activity, is 4.5 hours and is primarily renal. The maximum anti-factor Xa and anti-factor IIa activity occurs 3 to 5 hours after injection. In addition, the anti-factor Xa activity persists in the plasma for about 12 hours after a 40 mg dose.
of Enoxaparin Activity
For enoxaparin patients, this test is called the low molecular weight heparin assay. The therapeutic range for anticoagulation is 0.5 to 1 IU/mL. The low molecular weight heparin assay may be useful in patients who are at extremes of weight (less than 45 kg or greater than 130 or 150 kg) as well as in those patients with impaired renal function (ClCr 30 to 50 mL/min). This test should be ordered as the "low molecular weight heparin assay."
The draw time of the assay is generally 4 hours post-dose of enoxaparin. This measures the peak activity of enoxaparin. There are no recommended dose adjustments based on the results of the low molecular weight heparin assay. The dose can be adjusted empirically, and then, the assay should be repeated. Anticoagulant activity of enoxaparin cannot be accurately monitored by the PTT.
for Obese or Underweight Patients
extremes of weight should have the dose of enoxaparin adjusted and
anticoagulation should be monitored using the low molecular weight
Patients weighing < 45 kg were not included in clinical trials; therefore, these patients should also be monitored using the low molecular weight heparin assay.
for Patients with Renal Dysfunction
As a rough estimate of creatinine clearance, a serum creatinine as low as 2.0 may indicate severe renal dysfunction in a patient of average or greater than average weight, and a serum creatinine value of >1.6 may indicate severe renal dysfunction in underweight patient.
the creatinine clearance (CrCl), first calculate the patients ideal
body weight (IBW) in kg:
Then, use the Cockroft-Gault equation to calculate the estimated creatinine clearance (CrCl):
(mL/min) for a Male=
in Patients Awaiting CABG Surgery