Low Molecular Weight Heparin

Aka: Low Molecular Weight Heparin, LMW Heparin, Enoxaparin, Lovenox, Ardeparin, Normiflo, Dalteparin, Fragmin, Danaparoid, Orgaran, Tinzaparin, Innohep

1. Indications
   1. Deep Vein Thrombosis Treatment
   2. Deep Vein Thrombosis Prophylaxis
      1. General Surgery
      2. Orthopedic Surgery (Hip, Knee)
2. Contraindications (Indications for standard Heparin)
   1. Previous Deep Vein Thrombosis history
      1. Ipsilateral DVT
      2. Two or more DVTs
      3. Any Venous Thromboembolism
   2. High risk lesion (e.g. Iliofemoral DVT)
   3. Pregnancy
   4. Renal Insufficiency (Creatinine Clearance <30 due to risk of dose stacking and bleeding risk)
   5. Morbidly obese patients (consider Unfractionated Heparin where BMI>40-45 kg/m2)
   6. Hepatic Insufficiency
   7. Active bleeding
   8. Surgery in prior 5-7 days (However see below)
   9. Hypercoagulable state
      1. Protein C Deficiency
      2. Protein S Deficiency
      3. Antithrombin III deficiency
   10. Inability to undergo outpatient treatment
   11. Noncompliance
   12. Thrombocytopenia
   13. Coagulopathy
   14. Active Peptic Ulcer Disease
3. Efficacy: Unstable Angina and Myocardial Infarction
   1. Significantly better outcomes than standard Heparin
      1. Randomized trial (n=3171)
      2. Lower endpoint (death, Myocardial Infarction, Angina)
         1. 14 days (16.6 vs 19.8%)
         2. 20 days (19.8 vs 23.3%)
      3. Fewer revascularization procedures (27 vs 32.2%)
   2. Reference
      1. Cohen (1997) N Engl J Med 337:447-52
4. Efficacy
   1. Comparable efficacy to Heparin in DVT
   2. References
      1. Hull (2000) Arch Intern Med 160:229-36
      2. Merli (2001) Ann Intern Med 134:191-202
5. Advantages: LMWH over Unfractionated Heparin
   1. Rarely causes Heparin Induced Thrombocytopenia
   2. Does not cause paradoxical thrombotic events
   3. Results in fewer bleeding complications
   4. References
      1. Warkentin (1995) N Engl J Med 332:1330-5
      2. (1995) Arch Intern Med 155:601
6. Dosing
   1. General
      1. Prophylaxis: Consider increasing the dose by 25% when BMI >40 kg/m2
      2. Treatment: Dose should be based on total body weight (even in obese patients)
      3. Exception: Fragmin has a maximum dose (unlike other LMWH agents)
   2. Deep Vein Thrombosis Treatment
      1. Enoxaparin (Lovenox)
         1. Twice daily dosing: 1 mg/kg SQ bid
         2. Once daily dosing: 1.5 mg/kg SQ qd (not for home)
         3. Available in 30 mg vials
      2. Tinzaparin (Innohep)
         1. Dose: 175 anti-Xa IU per kg daily
         2. Dose (ml): (weight in kg) x 0.00875 ml/kg daily
   3. Deep Vein Thrombosis Prophylaxis
      1. Ardeparin (Normiflo)
         1. Initial: 50 U/kg SQ following surgery
         2. Later: bid for 14 days or until ambulatory
      2. Dalteparin (Fragmin)
         1. Low risk
            1. Initial: 2500 IU SQ 1-2 hours before surgery
            2. Later: 2500 IU qd for 5-10 days
         2. High risk
            1. Initial: 5000 IU SQ the evening before surgery
            2. Later: 5000 IU qd for 5-10 days
      3. Danaparoid (Orgaran)
         1. Initial: 750 U SQ 1-4 hours before surgery
         2. Later: then 750 U SQ q12h for 7-10 days
      4. Enoxaparin (Lovenox)
         1. Initial: 30 mg SQ q12h OR 40 mg QD for 7-10 days
      5. Tinzaparin (Innohep)
         1. Innohep 3500 IU SQ daily
7. Precautions
   1. Severe renal insufficiency
      1. Unpredictable dose response to LMWH
   2. Reversal
      1. Less responsive to protamine compared with Heparin