Analytical challenges in drug counterfeiting and falsification-The NMR approach.

http://files.tk-team-iquir.webnode.com/200000022-6a21c6b1ab/J%20Pharm%20Biomed%20Anal%202014%20101%20102.pdf

Pharmaceutical impurities and degradation products: Uses and applications of NMR techniques

NMR chemical shifts in structural biology of glycosaminoglycans.

Glycosaminoglycans (GAG) such as hyaluronan (HA) or chondroitin/dermatan sulfate (CS/DS) occur in many connective tissues, for instance, in bone, cartilage and skin. Due to their significant water-binding capacity, GAG are essential for the biomechanical properties of these tissues. However, there is also increasing evidence that the sulfation of GAG does not occur at random, but a "sulfation code" exists that mediates the physiological functions of GAG. Thus, the biological properties of these biomacromolecules are strongly influenced by the degree of sulfation (ds) and the sulfate group distribution along the polymer. Therefore, certain GAG might also have interesting pharmacological properties. It is, thus, commonly accepted that GAG represent promising biomaterials in the field of tissue engineering as well as to design new bioactive materials for tissue repair and reconstruction. In this review we will focus on chemically sulfated GAG and provide a survey of these compounds on four different levels. First, we will provide an overview on chemical functionalization strategies of naturally occurring HA and CS/DS with special emphasis on regioselective methods to introduce a defined number of sulfate residues into the carbohydrate backbone. Second, chemical and biochemical methods to characterize the synthesized compounds will be introduced with the focus on methods based on nuclear magnetic resonance (NMR) and mass spectrometry (MS). In the third part, we will discuss the interaction of natural and chemically sulfated GAG with proteins and other biomolecules with regulatory functions. Additionally, biological consequences of these interactions regarding healing processes of skin and bone will be presented by discussing selected cell culture experiments. Finally, in vivo effects of GAG as components of artificial extracellular matrices will be discussed.

Sulfated glycosaminoglycans as promising artificial extracellular matrix components to improve the regeneration of tissues.

Purpose

To characterize the nature of a heparin contaminant's clinical effects in cases reported to the Adverse Event Reporting System (AERS). The FDA received reports of heparin-associated adverse events (AEs) starting in late 2007–early 2008 during a national investigation of allergic-type events. The investigation identified Baxter Healthcare-brand heparin product due to its strongest association with the events. Later, oversulfated chondroitin sulfate (OSCS), a heparin-like contaminant, was discovered.



Methods

This study was a case series of heparin reports in AERS received 1 January 2008 to 31 March 2008. Variables considered were frequency of treatment settings, AEs, mortality; as well as heparin dose and OSCS contamination.



Results

Five hundred seventy-four AERS cases (unduplicated reports) were identified and included. Of 94 cases with a fatal outcome, 68 reported at least one AE term from the list used to identify an allergic-type event. Nearly 75% of AEs in cases of IV administration (n = 170/233) reportedly occurred within 10 minutes, whereas over half of subcutaneous administration cases (n = 13/23) resulted in times-to-event of greater than 24 hours. Although cases with a time-to-event of less than 10 minutes appeared to correlate with higher levels of OSCS contamination, no clear differences were noted between high- and low-to-absent OSCS concentration lots with respect to AEs observed.



Conclusions

Intravenous administration and a higher OSCS concentration appeared to correlate with a more rapid onset of event. The FDA continues to monitor AEs associated with heparin use and has taken appropriate regulatory action to ensure a safe heparin drug supply. Published in 2010 by John Wiley & Sons, Ltd.

Description of hypersensitivity adverse events following administration of heparin that was potentially contaminated with oversulfated chondroitin sulfate in early 2008.

Composition of OSCS-contaminated heparin occurring in 2008 in batches on the German market.

The widespread occurrence of heparin contaminated with oversulfated chrondroitin sulfate (OSCS) in 2008 initiated a comprehensive revision process of the Pharmacopoeial heparin monographs and stimulated research in analytical techniques for the quality control of heparin. Here, a set of 177 heparin samples from the market in 2008 as well as pure heparin sodium spiked with defined amounts of OSCS and DS were used to evaluate established and novel methods for the quality control of heparin. Besides 1H nuclear magnetic resonance spectroscopy (NMR), the assessment included two further spectroscopic methods, i.e., attenuated total reflection-infrared spectroscopy (ATR-IR) and Raman spectroscopy, three coagulation assays, i.e., activated partial thromboplastin time (aPTT) performed with both sheep and human plasma and the prothrombin time (PT), and finally two novel purity assays, each consisting of an incubation step with heparinase I followed by either a fluorescence measurement (Inc-PolyH-assay) or by a chromogenic aXa-assay (Inc-aXa-assay). NMR was shown to allow not only sensitive detection, but also quantification of OSCS by using the peak-height method and a response factor determined by calibration. Chemometric evaluation of the NMR, ATR-IR, and Raman spectra by statistical classification techniques turned out to be best with NMR spectra concerning the detection of OSCS. The validity of the aPTT, the current EP assay, could be considerably improved by replacing the sheep plasma by human plasma. In this way, most of the contaminated heparin samples did not meet the novel potency limit of 180 IU/mg. However, also more than 50% of the uncontaminated samples had <180 IU/MG. In contrast to the aPTT, the PT specifically detects OSCS and other heparin mimetics (LOD 3%). About ten times more sensitive are both the Inc-PolyH-assay and the Inc-aXa-assay, two rapid and simple quantification assays for heparin mimetics. The determined OSCS contents of the heparin samples excellently correlated with those calculated from the NMR spectra. In conclusion, NMR proved to be the current spectroscopic method of choice. The two two-step-assays represent options to supplement NMR, especially as tests for the initial screening, since they detect any heparin mimetic without requiring special expertise for interpretation of the results.

/pdf/comparison-of-established-and-novel-purity-tests-for-the-co0pa3irxu.pdf

Comparison of established and novel purity tests for the quality control of heparin by means of a set of 177 heparin samples

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Composition of OSCS-contaminated heparin occurring in 2008 in batches on the German market.

Comparison of established and novel purity tests for the quality control of heparin by means of a set of 177 heparin samples