What do low molecular weight heparins do?

What do low molecular weight heparins do?

Low-molecular-weight heparin (LMWH) is a class of anticoagulant medications. They are used in the prevention of blood clots and treatment of venous thromboembolism (deep vein thrombosis and pulmonary embolism) and in the treatment of myocardial infarction.

What factors cause LMWH?

Structure and Mechanism of Action Both heparin and LMWH exert their anticoagulant activity by activating antithrombin (earlier called antithrombin III), which accelerates the inactivation of coagulation enzymes thrombin (factor IIA), factor Xa and factor IXA.

What are LMWH examples?

Low-molecular-weight heparins (LMWHs), for example, dalteparin, enoxaparin, among others, are anticoagulants.

What is low molecular weight?

Low Molecular Weight Heparin (LMWH), as its name suggests, is derived from Unfractionated Heparin (UFH) by digestion or depolymerization of longer chains of heparin into shorter chains by chemical or enzymatic means. These short strands make LMWH last longer and act more predictably in the body than UFH.

Why is LMWH preferred?

The principal practical advantage of the LMWHs in the outpatient setting, both for extended-duration primary prophylaxis and long-term secondary prophylaxis, is the lack of a need to monitor anticoagulation in the majority of patients.

What is heparins mechanism of action?

The mechanism of action of heparin is ATIII-dependent. It acts mainly by accelerating the rate of the neutralization of certain activated coagulation factors by antithrombin, but other mechanisms may also be involved. The antithrombotic effect of heparin is well correlated to the inhibition of factor Xa.

What is the difference between heparin and LMWH?

Standard heparin is known to cause adverse reactions called immunogenic responses, such as Heparin Induced Thrombocytopenia (HIT). LMWH is made from standard heparin but is associated with a lower rate of HIT than standard heparin.

What is the significance of molecular weight?

The molecular weight of a polymer is directly related to its properties. As the molecular weight increases, mechanical properties generally increase. Every polymer has an ideal molecular weight at which the balance of different properties (such as processability, strength, brittleness etc.) is optimized.

When is LMWH preferred over DOAC?

LMWHs have been the treatment of choice for cancer associated VTE. DOACs are more effective than LMWHs to prevent recurrent VTE in cancer patients. DOACs are associated with a higher risk of major bleeding compared to LMWHs. Effectiveness and safety may reflect better compliance with DOACs compared to LMWHs.

What is long term anticoagulant?

Long-term anticoagulation is necessary to prevent the high frequency of recurrent venous thrombosis or thromboembolic events. Interruption of anticoagulation within the first 12 weeks of therapy appears to result in a 25% incidence of recurrent thrombosis.

What are the indications of heparins?

Heparin sodium is indicated for:

  • Prophylaxis and treatment of venous thromboembolism and pulmonary embolism;
  • Atrial fibrillation with embolization;
  • Treatment of acute and chronic consumptive coagulopathies (disseminated intravascular coagulation);
  • Prevention of clotting in arterial and cardiac surgery;

What does low antithrombin III mean?

Antithrombin deficiency (or antithrombin III deficiency) is a blood clotting disorder that makes you more likely to get abnormal blood clots. People with this problem are at a high risk for deep vein thrombosis (a blood clot in any deep vein of the body) and pulmonary embolism (a clot that ends up in your lungs).

When do you give heparin or LMWH?

LMWH is generally preferable for the following reasons: LMWH is easier to give logistically (doesn’t require IV infusion or monitoring). LMWH has a decreased risk of heparin induced thrombocytopenia with thrombosis (HIT).

What medication is a low molecular weight heparin?

LMWH options available in the United States are dalteparin (Fragmin®) and enoxaparin (Lovenox®).

What is the significance of the term average molecular weight?

The average molecular weight is distribution of values of weights of the polymer and is a useful statistical method to characterize polymers. For example, polymers molecular weight is not one molecular weight or size but a distribution of weights.

What is lower molecular weight?

Low Molecular Weight polymers have lower properties due to lack of chain entanglement and higher molecular mobility. Table2. Shorter chains have more end groups which increase free volume and molecular mobility which makes it easier for the polymer chains to respond to stresses.

How does molecular weight affect degradation?

Degradation is often due to a change in the chemical and/or physical structure of the polymer chain, which in turn leads to a decrease in the molecular weight of the polymer.

Are DOACs better than LMWH?

DOACs are more effective than LMWHs to prevent recurrent VTE in cancer patients. DOACs are associated with a higher risk of major bleeding compared to LMWHs. Effectiveness and safety may reflect better compliance with DOACs compared to LMWHs.

When is low-molecular-weight heparin used in the treatment of renal insufficiency?

Low-molecular-weight heparin in patients with renal insufficiency LMWH may be considered for patients with severe RI. However, experience, judicious choice and careful monitoring of patients with severe RI treated with LMWH are necessary. LMWH may be considered for patients with severe RI.

Is it safe to give heparins to patients with renal failure?

Clinical use of heparins in patients with renal failure. Severe and even fatal bleeding complications have been described in this setting after unadjusted dosage of LMWHs [ 4–8 ]. Therefore, all manufacturers of LMWHs impose restrictions or contraindications on the use of these agents in severe renal failure.

Why is dose reduction necessary in patients with impaired hepatic and renal function?

As a consequence, dose reduction in patients with impaired hepatic or renal function is necessary to avoid overdosage. LMWHs with their reduced polysaccharide chain length have superior pharmacokinetic properties compared with UFH in patients with normal renal function.

How does heparin bind to thrombin?

The key chemical sequence for binding heparin to AT is a pentasaccharide composed of three sulfated glucosamins and two uronic acids. By inactivating thrombin, UFH inhibits not only fibrin formation but also thrombin-induced platelet activation.