- Discussion:
- for treatment of DVT / PE;
- hypercoagulable states
- coagulation pathway
- anti-Xa to anti IIa ratio for enoxaparin is about 3 to 1 where as unfractionated heparin has a ratio of 1 to 1;
- hence LMWH has a greater inhibitory effect on factor Xa and has a lesser effect on thrombin;
- in contrast, arixtra inhibits anti-thrombin;
- labs:
- because LMWH have minimal effect on thrombin, there is minimal elevation of the PTT;
- prophylactic dosage:
- subcutaneous enoxaparin 40 mg SQ q24hrs or 30 mg every 12 hours;
- onset of activity occurs after about 3 hours;
- it is advised to delay administration of Lovenox for 12-24 hours following surgery;
- renal excretion is the main route of removal, and therefore dose reduction is required w/ significant renal dysfunciton;
- DVT treatment dosage: (lovenox dosage calculator)
- 1 mg/kg q12 hour with normal renal function;
- DVT treatment
- Outcomes:
- in a THR study by Colwell et al (1999), the overall rate of throboembolic disease was 3.6% for patients receiving lovenox versus 3.7 % for
patients receiving adjusted dose coumadin;
- rate of clinically significant bleeding was 0.9%;
- lovenox was continued only for the length of the hospitalization which averaged about 7 days;
- Breddin, et al. 2001:
- SQ administration of a low-molecular-weight heparin, reviparin, twice a day for one week, or SQ administration of reviparin once a day for 4 weeks.
- of the patients receiving unfractionated heparin, 40.2 percent (129 of 321) had thrombus regression, as compared with 53.4 percent (175 of 328) of the patients
receiving reviparin twice daily and 53.5 % (167 of 312) of the patients receiving reviparin once daily;
- in acute deep-vein thrombosis, reviparin regimens are more effective than unfractionated heparin in reducing the size of the thrombus;
- reviparin is also more effective than unfractionated heparin for the prevention of recurrent thromboembolism and equally safe;
- references:
- Effects of a Low-Molecular-Weight Heparin on Thrombus Regression and Recurrent Thromboembolism in Patients with Deep-Vein Thrombosis
- A Randomized Controlled Trial of a Low-Molecular-Weight Heparin (Enoxaparin) to Prevent Deep-Vein Thrombosis in Patients Undergoing Elective Hip Surgery.
- Failure of the American College of Chest Physicians-1A protocol for lovenox in clinical outcomes for thromboembolic prophylaxis.
- Comparison of Enoxaparin and Warfarin for the Prevention of Venous Thromboembolic Disease After Total Hip Arthroplasty. Evaluation During Hospitalization and Three Months After Discharge
- Complications:
- heparin induced thrombocytopenia
- thrombocytopenia and platlet dysfunction seems to occur less often than w/ unfractionated herapin;
-references:
- Thrombocytopenia and Intra-cerebral Complications Associated with Low-Molecular-Weight Heparin Treatment in Patients Undergoing Total Hip Replacement. A Report of Two Cases.
Cost-effectiveness of rivaroxaban in the prevention of venous thromboembolism: a Canadian analysis using the Ontario Ministry of Health Perspective.
Cost and outcomes associated with rivaroxaban vs enoxaparin for the prevention of postsurgical venous thromboembolism from a US payer's perspective.