Dosing of Enoxaparin in Morbidly Obese Patients
How to optimally dose enoxaparin in morbidly obese patients? This question was addressed by a randomized study, the results of which were published in the journal Annals of Pharmacotherapy.
Obesity and the Problem of Anticoagulant Dosing
In recent years, there has been a dramatic increase in the number of obese patients in developed countries. Obesity is considered a body mass index (BMI) value of ≥ 30 mg/m2, and patients with a BMI of ≥ 40 mg/m2 are considered morbidly obese.
Obese people have a higher risk of cardiovascular complications and thromboembolic events, often coinciding with other acquired civilization disorders (hyperlipidemia, hypertension, etc.). Treatment of thromboembolic complications often requires anticoagulation, and there are no clear recommendations for dosing anticoagulants, such as enoxaparin, for morbidly obese patients.
Available retrospective and observational studies report achieving target anti-Xa levels with a median enoxaparin dose of 0.8 mg/kg of body weight. However, enoxaparin has a relatively lower distribution into adipose tissue, which means many patients may be overdosed with standard dosing. Thus, authors from several university institutions in the USA focused on the possibility of reducing the enoxaparin dose compared to the standard dose to achieve the desired anti-Xa levels in this patient group.
Methods and Study Course, Evaluated Population
This was a prospective randomized controlled study in patients with a BMI of ≥ 40 mg/m2. They were randomized to receive either a standard enoxaparin dose (1 mg/kg) or a reduced dose (0.8 mg/kg) every 12 hours. The primary endpoint was the proportion of patients achieving therapeutic anti-Xa levels in the range of 0.5−1.1 IU/ml.
A total of 62 patients participated in the study − 32 in the standard dosing group and 30 in the reduced dose group. 54 participants completed the study.
Results
Target anti-Xa levels were achieved in comparable proportions with both the reduced dose (25 out of 28 treated) and the standard dose (20 out of 26), which is 89.3% and 76.9%, respectively (p = 0.29). Dose adjustments were needed in 9 patients, 6 of whom were in the standard dosing arm. All had anti-Xa levels above the therapeutic range.
No bleeding or thrombotic complications were recorded.
Conclusion
This is the first randomized controlled study addressing the dosing of enoxaparin in morbidly obese patients. Nearly 90% of patients who initially received a reduced dose of 0.8 mg/kg every 12 hours achieved target anti-Xa levels.
Based on these results, it can be stated that anticoagulation therapy with a reduced enoxaparin dose can be initiated in morbidly obese patients.
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Source: Curry M. A., LaFollette J. A., Alexander B. R. et al. Evaluation of treatment-dose enoxaparin in acutely ill morbidly obese patients at an academic medical center: a randomized clinical trial. Ann Pharmacother 2019; 53 (6): 567−573, doi: 10.1177/1060028018821149.
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