Is Fragmin Heparin?
Yes, Fragmin (dalteparin sodium) is a type of heparin—specifically, it is a low-molecular-weight heparin (LMWH) derived from standard unfractionated heparin through chemical depolymerization.
Classification and Structure
Fragmin is classified as a low-molecular-weight heparin that is produced through nitrous acid depolymerization of standard unfractionated heparin (UFH) 1. The resulting product has a mean molecular weight of approximately 5000 Da (ranging from 1000 to 10,000 Da), which is roughly one-third the size of standard heparin 1, 2.
Key Differences from Unfractionated Heparin
While Fragmin is derived from heparin, it differs from UFH in several clinically important ways:
Mechanism of action: Both inhibit coagulation through antithrombin (AT)-dependent mechanisms, but LMWHs like dalteparin have a higher ratio of anti-factor Xa to anti-factor IIa (thrombin) activity compared to UFH 1
Pharmacokinetics: Dalteparin has superior bioavailability, longer plasma half-life, and more predictable dose-response compared to UFH, allowing for once or twice-daily dosing without monitoring 1
Monitoring: Unlike UFH which requires aPTT monitoring, dalteparin typically does not require routine laboratory monitoring due to its predictable pharmacokinetics 1
Clinical Implications
The structural differences between dalteparin and UFH result from reduced binding to plasma proteins, cells, and platelets 1. This explains:
- Lower incidence of heparin-induced thrombocytopenia (HIT) with dalteparin 3, 4
- Reduced binding to osteoblasts, resulting in less bone loss 3
- Renal clearance as the primary elimination route (important in renal failure) 1
In summary, Fragmin is indeed a heparin derivative—a low-molecular-weight heparin—but it is not interchangeable with unfractionated heparin or other LMWHs due to differences in preparation methods, molecular weight distribution, and pharmacologic properties 1.