Is Porcine Heparin Injection a Low Molecular Weight Heparin?
No, porcine-derived heparin injection is unfractionated heparin (UFH), not a low molecular weight heparin (LMWH). 1
Key Structural and Molecular Differences
Unfractionated heparin (UFH) and LMWH are fundamentally different products, even though LMWHs are manufactured from UFH:
- UFH has a mean molecular weight of approximately 15,000 Da (range 3,000-30,000 Da), corresponding to about 45 monosaccharide chains 1
- LMWHs have a mean molecular weight of 4,000-5,000 Da (range 2,000-9,000 Da), corresponding to about 15 saccharide units 1
- LMWHs are produced from porcine UFH through chemical or enzymatic depolymerization, making them derivative products rather than the same entity 1, 2
Manufacturing Relationship
While LMWHs originate from porcine intestinal heparin, the depolymerization process fundamentally alters their properties:
- LMWHs are manufactured from unfractionated porcine heparin through specific chemical or enzymatic processes 1, 2
- Different depolymerization methods produce distinct LMWHs (enoxaparin, dalteparin, tinzaparin) that are not interchangeable on a unit-for-unit basis 1
- The manufacturing process must be identical for biosimilar LMWHs to be considered equivalent to originator products 1
Critical Pharmacologic Distinctions
The molecular weight difference creates profound pharmacologic differences:
- UFH requires continuous IV infusion or frequent subcutaneous dosing with a half-life of approximately 1.5 hours 3
- LMWHs have a half-life of 3-6 hours, allowing once or twice daily dosing 3
- UFH has equal anti-Xa and anti-IIa activity, while LMWHs have reduced anti-IIa activity relative to anti-Xa due to their shorter chain length 1
- UFH requires aPTT monitoring, while LMWHs generally do not require routine coagulation monitoring 1, 3
Clinical Implications
These are distinct drug classes with different clinical applications:
- UFH binds simultaneously to both antithrombin and thrombin (requiring ≥18 saccharides), while shorter LMWH fragments cannot 1
- LMWHs have more predictable anticoagulant responses due to reduced binding to plasma proteins 1
- LMWHs have lower rates of heparin-induced thrombocytopenia and osteoporosis compared to UFH 1
Common pitfall: Assuming all porcine-derived heparin products are the same. Porcine heparin injection refers to UFH unless specifically labeled as an LMWH product (such as enoxaparin, dalteparin, or tinzaparin). 1, 2