The Anti-Factor Xa Range for Low Molecular Weight Heparin Thromboprophylaxis

Wei, Matthew Y K; Ward, Salena

doi:10.4081/hr.2015.5844

Cited by 108 publications

(123 citation statements)

References 43 publications

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“…Enoxaparin is a frequently prescribed LMWH and laboratory monitoring of its anticoagulant activity with anti‐Xa facilitates dose adjustments. The target anti‐Xa range for prophylactic dose enoxaparin at our center in South Africa is 0.2–0.6 IU/mL, which is in line with published recommendations . Enoxaparin has a bioavailability of 91%, is linearly absorbed after subcutaneous administration, and has a predictable non‐saturable, dose‐independent renal elimination rate .…”

Section: Introductionsupporting

confidence: 83%

Safety and efficacy of adjusted‐dose enoxaparin in pregnant patients with increased risk for venous thromboembolic disease

Bailly

Jacobson

Louw

2019

Intl J Gynecology & Obste

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Objective To assess the efficacy and safety of anti‐Xa guided dose‐adjusted low molecular weight heparin (LMWH) thromboprophylaxis in at‐risk pregnant women. Methods This single‐center retrospective study was conducted at a quaternary hospital in Johannesburg, South Africa. We analyzed clinical and laboratory data for pregnant patients referred between January 1, 1999, and May 1, 2017, with an increased risk of venous thromboembolic disease (VTED) and treated with prophylactic LMWH adjusted according to anti‐Xa levels. The efficacy endpoint was pregnancy‐related VTED and/or pregnancy loss despite anti‐Xa guided dose‐adjusted LMWH thromboprophylaxis. Results We reviewed data for 113 consecutive pregnant patients with 151 pregnancies referred for prophylactic LMWH. Prevalence of pregnancy‐related VTED was 1.3% (95% confidence interval [CI] 0.1–4.7), which is lower than that reported in the literature for fixed‐dose thromboprophylaxis in similar at‐risk groups. One venous thromboembolism event occurred in the antenatal period (despite adequate prophylaxis) and the second in the postpartum period (related to prolonged labor). Prevalence of pregnancy‐related bleeding was 2% (95% CI 0.4–5.7) with all bleeding events considered to be minor and unrelated to LMWH therapy. Conclusion This study demonstrated the efficacy and safety of anti‐Xa dose‐adjusted LMWH thromboprophylaxis in at‐risk pregnant patients.

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Section: Introductionsupporting

confidence: 83%

Safety and efficacy of adjusted‐dose enoxaparin in pregnant patients with increased risk for venous thromboembolic disease

Bailly

Jacobson

Louw

2019

Intl J Gynecology & Obste

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“…However, a target therapeutic range of 0.2 to 0.5 IU/mL is commonly reported for prophylaxis, whereas 0.5 to 0.8 IU/mL is suggested for treatment dosing. 17,18 When using an anti-Xa level to evaluate for an absence of effect, as done in this study, it is the presence of residual activity at the time of a planned invasive procedure that is of greatest clinical interest. We chose to compare our results against the peak target therapeutic ranges, because intuitively these levels suggest at least some degree of anticoagulant activity.…”

Section: Discussionmentioning

confidence: 99%

Residual Enoxaparin Activity, Anti-Xa Levels, and Concerns About the American Society of Regional Anesthesia and Pain Medicine Anticoagulation Guidelines

Henshaw

Turner

Thompson

et al. 2017

Regional Anesthesia and Pain Medicine

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Currently, the American Society of Regional Anesthesia and Pain Medicine (ASRA) anticoagulation guidelines recommend that before the performance of a neuraxial procedure a minimum of 24 hours should elapse following a treatment dose of enoxaparin (1 mg/kg twice daily or 1.5 mg/kg once daily). The guidelines have since their inception also consistently recommended against the routine use of anti-Xa level monitoring for patients receiving enoxaparin. However, we noted in our clinical practice that anti-Xa levels were frequently still elevated despite patients meeting the time-based recommendation for treatment dose enoxaparin. To further investigate the possibility that residual anticoagulant activity may persist longer than 24 hours after a treatment dose of enoxaparin, we assessed anti-Xa level activity in patients presenting for elective surgery. Despite nearly universal compliance with ASRA's anticoagulation guidelines (1 sample was drawn at 23.25 hours), anti-Xa activity was found to be elevated in 11 of 19 patients. While 10 patients had an anti-Xa level within the peak prophylactic range (0.2-0.5 IU/mL), 1 patient's level was found to still be in the peak therapeutic range (0.5-1.0 IU/mL). These findings suggest that significant anticoagulant activity may persist longer than previously appreciated after the last treatment dose of enoxaparin and that the current time-based ASRA recommendation may not be conservative enough. Further research is needed to delineate the level of anti-Xa activity below which it is likely safe to proceed with a neuraxial procedure, but it may be time to reconsider the utility of anti-Xa level monitoring when it is available.

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“…These pharmacokinetic properties allow for once‐ or twice‐daily administration without routine monitoring in most healthy individuals. However, patients with extreme body weights were excluded from early trials of LMWH and may warrant therapeutic drug monitoring . Low molecular weight heparins exhibit a small effect on the activated partial thromboplastin time and strongly inhibit factor Xa .…”

mentioning

confidence: 99%

“…As such, peak anti–factor Xa (aFXa) levels may be utilized to monitor the efficacy and safety of enoxaparin for VTE prophylaxis. The evidence surrounding aFXa monitoring in VTE prophylaxis does not provide clear guidance on goal ranges, but 0.2–0.5 unit/ml seems reasonable …”

mentioning

confidence: 99%

Enoxaparin Thromboprophylaxis Dosing and Anti–Factor Xa Levels in Low‐Weight Patients

et al. 2019

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Introduction Enoxaparin is a widely used anticoagulant to prevent venous thromboembolism (VTE). A fixed dose is recommended for VTE prophylaxis. However, fixed prophylactic doses of enoxaparin in low‐weight patients may be close to the weight‐based dosing recommended for VTE treatment. Objective To evaluate peak anti–factor Xa (aFXa) levels in low‐weight patients receiving enoxaparin for VTE prophylaxis. Methods Retrospective cohort of adult patients weighing < 55 kg who were hospitalized at Loma Linda University Medical Center between January 2008 and February 2017. All patients received enoxaparin for VTE prophylaxis with a peak aFXa level drawn. The primary endpoint was the proportion of patients achieving peak aFXa levels within the goal range of 0.2–0.5 unit/ml. Results Of 35 patients receiving enoxaparin for VTE prophylaxis with an appropriately timed peak aFXa level, 74% achieved goal peak aFXa levels and the median daily dose of enoxaparin was 30 mg. The mean weight was approximately 44 kg. No significant correlations between aFXa level and body mass index or body weight were found. Conclusion A lower dose of enoxaparin may be reasonable in low‐weight patients for VTE prophylaxis. There appears to be no safety concerns with reduced enoxaparin dosing in low‐weight patients. More robust data are needed to confirm these findings.

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The Anti-Factor Xa Range for Low Molecular Weight Heparin Thromboprophylaxis

Cited by 108 publications

References 43 publications

Safety and efficacy of adjusted‐dose enoxaparin in pregnant patients with increased risk for venous thromboembolic disease

Safety and efficacy of adjusted‐dose enoxaparin in pregnant patients with increased risk for venous thromboembolic disease

Residual Enoxaparin Activity, Anti-Xa Levels, and Concerns About the American Society of Regional Anesthesia and Pain Medicine Anticoagulation Guidelines

Enoxaparin Thromboprophylaxis Dosing and Anti–Factor Xa Levels in Low‐Weight Patients

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