Heparin Impurities and Contamination Recalls
Considering the animal source of pharmaceutical heparin, the numbers of potential impurities are relatively large compared with a wholly synthetic therapeutic agent. The range of possible biological contaminants includes viruses, bacterial endotoxins, transmissible spongiform encephalopathy (TSE) agents, lipids, proteins and DNA. During the preparation of pharmaceutical-grade heparin from animal tissues, impurities such as solvents, heavy metals and extraneous cations can be introduced. However, the methods employed to minimize the occurrence and to identify and/or eliminate these contaminants are well established and listed in guidelines and pharmacopoeias. The major challenge in the analysis of heparin impurities is the detection and identification of structurally related impurities. The most prevalent impurity in heparin is dermatan sulfate (DS), also known as chondroitin sulfate B. The building block of DS is a disaccharide composed of 1,3-linked N-acetyl galactosamine (GalN) and a uronic acid residue, connected via 1,4 linkages to form the polymer. DS is composed of three possible uronic acid (GlcA, IdoA or IdoA2S) and four possible hexosamine (GalNAc, Gal- NAc4S, GalNAc6S or GalNAc4S6S) building blocks. The presence of iduronic acid in DS distinguishes it from chrondroitin sulfate A and C and likens it to heparin and HS . DS has a lower negative charge density overall compared to heparin. A common natural contaminant, DS is present at levels of 1–7% in heparin API, but has no proven biological activity that influences the anticoagulation effect of heparin.
In December 2007, the U.S. Food and Drug Administration (FDA) recalled a shipment of heparin because of bacterial growth (Serratia marcescens) in several unopened syringes of this product. The bacterium Serratia marcescens can lead to life-threatening injuries and/or death.
In March 2008, major recalls of heparin were announced by the FDA due to contamination of the raw heparin stock imported from China. According to the FDA, the adulterated heparin killed 81 people in the United States. The adulterant was identified as an "over-sulphated" derivative of chondroitin sulfate, a popular shellfish-derived supplement often used for arthritis, which was intended to substitute for actual heparin in potency tests.
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