Non-therapeutic anti-Xa levels in medical patients receiving anticoagulant therapy with enoxaparin

Thromb Res. 2013 Oct;132(4):433-6. doi: 10.1016/j.thromres.2013.08.017. Epub 2013 Aug 30.

Abstract

Introduction: Anticoagulant activity of enoxaparin is not routinely monitored even when previous studies have shown a high pharmacological variability. The aim of this study is to determine the prevalence of non-therapeutic anti-Xa levels among medical patients using enoxaparin as anticoagulant therapy and to point out potential risk factors related to the risk of having a sub-therapeutic level.

Materials and methods: Anti-Xa levels were measured in a cohort of sixty patients with medical indication for enoxaparin. Patients were categorized according to anti-Xa levels as follows: suboptimal anticoagulation (<0.5 IU/ml), optimal anticoagulation (between 0.5 and 1.2 IU/ml) or overanticoagulated (>1.2 IU/ml). Demographic and clinical variables and the use of concomitant medications were described for each group. Univariate and multivariate analysis were performed to assess the relationship between sub-optimal anticoagulation and potential predictive variables. A linear regression analysis was done to assess the relationship between anti-Xa activity, age, weight, body mass index, administered dose/weight and creatinine clearance.

Results: The mean anti-Xa activity was 0.71±0.32 UI/ml. Thirty one percent of patients had anti-Xa levels out of the therapeutic range, most of them (twenty-eight percent of total population) with a sub-therapeutic level. None of the variables were associated with the risk of a sub-therapeutic anti-Xa level.

Conclusion: Almost one third of patients receiving enoxaparin had anti-Xa levels out of the therapeutic range. We need more studies to determine the clinical relevance of these findings.

Keywords: Drug monitoring; Enoxaparin; Factor Xa; LMWH; Low-molecular-weight heparin; Low-molecular-weight-heparin.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Angina, Unstable / blood*
  • Angina, Unstable / drug therapy*
  • Angina, Unstable / metabolism
  • Anticoagulants / administration & dosage*
  • Anticoagulants / adverse effects
  • Anticoagulants / pharmacokinetics
  • Anticoagulants / pharmacology
  • Cohort Studies
  • Drug Monitoring / methods
  • Enoxaparin / administration & dosage*
  • Enoxaparin / adverse effects
  • Enoxaparin / pharmacokinetics
  • Factor Xa / metabolism
  • Factor Xa Inhibitors*
  • Female
  • Heparin, Low-Molecular-Weight / administration & dosage
  • Humans
  • Male
  • Myocardial Infarction / blood
  • Myocardial Infarction / drug therapy*
  • Myocardial Infarction / metabolism
  • Prospective Studies

Substances

  • Anticoagulants
  • Enoxaparin
  • Factor Xa Inhibitors
  • Heparin, Low-Molecular-Weight
  • Factor Xa