- Discussion:
- for treatment of
DVT /
PE;
- 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;
-
dosage:
- subcutaneous enoxaparin 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;
- Outcomes:
- in a THR study by Colwell et al (JBJS July 1999, Vol 81-A), 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;
- in the study by Hans Klaus Breddin et al. 2001, the authors performed a multicenter, open-label study randomly assigned patients with acute DVT to one
of three treatment regimens: intravenous administration of unfractionated heparin;
- 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.
- primary end point was evidence of regression of the thrombus on venography on day 21; secondary end points
were recurrent venous thromboembolism, major bleeding within 90 days after enrollment, and death;
- 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;
- w/ regard to thrombus regression, reviparin administered twice daily was significantly more effective than unfractionated
heparin (relative likelihood of thrombus regression, 1.28; 97.5 percent confidence interval, 1.08 to 1.52), as was
reviparin administered once daily (relative likelihood, 1.29; 97.5 percent confidence interval, 1.08 to 1.53);
- 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 w/ DVT
Hans Klaus Breddin et al. N Engl J Med 2001;344:626-31.
-
Original Article: A Randomized Controlled Trial LMWH (Enoxaparin) to Prevent DVT in Patients Undergoing Elective Hip Surgery.
-
Failure of the American College of Chest Physicians-1A protocol for lovenox in clinical outcomes for thromboembolic prophylaxis.
-
A randomized controlled trial of a low-molecular-weight heparin (enoxaparin) to prevent DVT in patients undergoing elective hip surgery.
- Comparison of Enoxaparin and Warfarin for the Prevention of DVT After THR. Evaluation During Hospitalization and 3 Months After Discharge
CW Colwell et al JBJS July 1999, Vol 81-A, No 7.
- 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 LMWH Treatment in Patients Undergoing THR. A Report of 2 Cases.
LMWH compared with warfarin for prophylaxis of DVT in patients who are operated on for fracture of the hip.
Prevention of DVT and PE after THR. Comparison of low-molecular-weight heparin and unfractionated heparin.
Prevention of DVT after elective hip surgery. A randomized trial comparing low molecular weight heparin with standard heparin.
Dihydroergotamine/heparin in the prevention of DVT after THR. A controlled, prospective, randomized multicenter trial
The thromboprophylactic effect of a low-molecular-weight heparin (Fragmin) in hip fracture surgery. A placebo-controlled study.
- Lovenox / Enoxaparin:
