What is the difference between fractionated and unfractionated heparin

N Engl J Med , — Weitz JI: Low-molecular-weight heparins. Cohen M: The role of low-molecular-weight heparin in the management of acute coronary syndromes. Curr Opin Cardiol , 16 — Montalescot G, Cohen M: Low molecular weight heparins in the cardiac catheterization laboratory.

J Thromb Thrombolysis , 7 — Google Scholar. Large patient series, nonrandomized, noncontrolled, supporting safety and efficacy of enoxaparin use in patients requiring PCI. Collet JP: Pharmacokinetic study of enoxaparin in patients undergoing percutaneous coronary intervention 8 to 12 hours after subcutaneous injection: the results of the PEPCI trial.

J Am Coll Cardiol. Am J Cardiol. J Invasive Cardiol. NICE 1 and 4 data: enoxaparin with or without abciximab appears to provide safe and effective anticoagulation in patients proceeding to PCI.

Zidar JP: Low molecular weight heparin in coronary stenting. Can J Cardiol. This usually results from systemic inflammation. Increased heparin clearance e. Titrating heparin infusion to target an Xa level is generally superior to targeting PTT in the context of heparin resistance Levine If Xa levels aren't available, an alternative strategy might be to titrate heparin based on thromboelastography.

This avoids the entire issue of heparin resistance. There is no high-quality evidence regarding optimal management here. Transition to a direct thrombin inhibitor might be superior, for the following reasons: 1 Evidentiary support for the use of direct thrombin inhibitors in the ICU is greater than for the use of antithrombin-III concentrates.

For example, many studies describe the use of argatroban infusions among ICU patients, including specifically patients with heparin resistance Bachler et al. Alternatively, the use of antithrombin-III concentrate supplementation seems to be limited to case studies. As such, the safety of antithrombin-III is difficult to evaluate. The two drugs interact in a synergistic fashion, so they must be combined with considerable caution and sophistication.

In contrast, transitioning to argatroban monotherapy is straightforward and easily achieved with standard ICU protocols. Administration of antithrombin-III won't fully resolve this situation.

Thus, continuing heparin may theoretically perpetuate an iatrogenic cycle of heparin use, antithrombin-III reduction, and antithrombin-III repletion. Thus, enoxaparin is a preferred agent — especially in patients with unusual weight or pharmacokinetics.

However, enoxaparin doses may be roughly correlated into dalteparin doses as follows below. Dosing with tinzaparin and nadroparin is less clear, as different formulations may have variable amounts of anti-Xa activity. Dalteparin is typically measured in terms of anti-Xa units, rather than in milligrams. For example, units of dalteparin is roughly equivalent to 50 mg of enoxaparin.

However, the ratio of anti-Xa vs. Recently, some authors have suggested dosing enoxaparin in a more finely graded fashion as shown below for patients with borderline renal function Shaikh This dosing scheme has yet to gain widespread acceptance, but it might be a consideration in very select situations with close monitoring of anti-Xa levels.

Numerous recent studies seem to be converging on a dose of 0. This dose has the following advantages: i Twice-daily dosing avoids sub-therapeutic trough levels it's possible that the trough levels are the primary determinant of efficacy.

Correcting the dose for weight increases the likelihood of obtaining target drug levels. Using a single formula is simpler to apply and more closely mirrors the pharmacokinetics of enoxaparin which is linear. For patients with very unusual weight or borderline renal function, consider obtaining an anti-Xa level to monitor the heparin effect. This is typically done after the third dose, but could probably be done sooner unless renal function is really awful, the trough heparin levels will be low and won't contribute substantially to the following peak level.

For twice-daily prophylactic enoxaparin, the target anti-Xa level is 0. It is provided in relatively fixed doses, usually q24hrs.

It works via enhancing anti-thrombin's inhibition of factor Xa. Use of fondaparinux can help avoid unnecessary workup and empiric therapy for possible HIT. Use of 2. Disadvantages of fondaparinux compared to LMWH Fondaparinux has a very long half-life at hours. Parenteral anticoagulants: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines.

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Leave this field blank. Subscribe Subscribe. Two review authors independently extracted data and assessed the risk of bias. Disagreements were resolved by consensus with participation of a third author. In this update, we included three trials involving postoperative participants. Participants were submitted to general surgical procedures, minor and major, and the minimum mean age was 49 years. The number needed to treat for an additional beneficial outcome NNTB was The NNTB was Arterial thrombosis occurred in only one participant who received UFH.

There were no amputations or deaths documented. Review question Is the incidence of heparin-induced thrombocytopenia lower in postoperative patients receiving thromboprophylaxis with low molecular weight heparin in comparison with patients receiving unfractionated heparin?

Background Heparin is a natural agent used to prevent clot formation in the vessels.