Difference – Unfractionated (Standard) Heparin and LMWH (Low Molecular Weight Heparin)

Unfractionated heparin is largely replaced by low molecular weight heparin in the management of venous thromboembolism treatment and management and acute coronary syndrome. LMWH (Low molecular weight heparin) is also preferably used for venous thrombosis prophylaxis.

Difference between unfractionated heparin and low molecular weight heparin.

Difference between unfractionated heparin and low molecular weight heparin is explained in the following table.

Unfractionated Heparin
Administration
Intravenous
Duration of Action
Short
Mechanism of Action
Unfractionated Heparin activates antithrombin III, it forms a complex with it, which intern inactivate four coagulation factors including factor 10a, 9a, 11a and 12a.
Side Effects
More common as standard heparin cause inhibition of four coagulation factors, therefore, there is a high risk of bleeding.

High risk of Heparin-induced thrombocytopenia.

High risk of osteoporosis

Monitoring
aPTT (activated partial thromboplastin time) is monitored daily, as there is high risk of bleeding because it inhibits 4 factors.

Platelet count.

Electrolytes as both may cause hyperkalemia

Antidote.
Protamine sulfate is the antidote, unfractionated heparin effect is mostly reversed.
Low MW Heparin (LMWH)
Administration
Subcutaneous
Duration of Action
Long
Mechanism of Action
LMWH also activates antithrombin III, but the complex it forms with it only inhibits factor 10.
Side effects
Lower risk of bleeding as compared to standared unfractionated heparin because LMWHs only cause inhibition of factor 10a.

Low risk of Osteoporosis

Low risk of Heparin-induced thrombocytopenia.

Monitoring
Routine monitoring is not required.

Electrolytes for hyperkalemia.

Platelets, although low risk of HIT.

Antidote.
LMWH overdose effect is only partially reversed by the  protamine sulfate.

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