Modes of Degradation and Impurity Characterization in rhPTH (1-34) during Stability Studies

Abstract

Unlike currently licensed therapies to manage osteoporosis, parathyroid hormone (PTH) and its analogs represent a new class of anabolic agents, which act primarily to inhibit bone resorption and remodeling. The hormone's recombinant form is a bioactive peptide, 1-34 residues, which is inherently very unstable. Prior understanding of the molecular degradation pathway will help in development of a process that will yield a better product with respect to its quality and stability. The current work focuses on detailed characterization of the product-related impurities generated during storage of recombinant human PTH. The study depicted the various routes through which the molecule can degrade during its shelf life. Through a combination of forced degradation and accelerated study, it was established that the impurities were generated owing to oxidation, deamidation, and peptide bond cleavage of/at various amino acid residues. Until this study, it was presumed that oxidation is the primary route of degradation in PTH and most of the published reports were on native (1-84) forms of the hormone. The present research confirms that the recombinant hormone (1-34) degraded not only because of oxidation but that deamidation and peptide bond cleavage are also prominent modes of degradation. Therefore, owing to the unstable nature of the molecule it is suggested that stringent conditions should be maintained during manufacturing to obtain a stable molecule with fewer impurities.

Comparative Physicochemical and Biological Characterisation of the Similar Biological Medicinal Product Teriparatide and Its Reference Medicinal Product

“…Teriparatide is highly sensitive to the various degradation processes, like oxidation or deamidation [14][15][16], which may influence the binding affinity and the biological activity [17]. Similar impurity profile of RGB-10 and RMP was observed with chromatographic methods that included RP-and IEX-HPLC.…”

Delivery of small molecules for bone regenerative engineering: preclinical studies and potential clinical applications

“…Recent US Food and Drug Administration (FDA)-approved medications for osteoporosis, such as recombinant human parathyroid hormone peptide (rhPTH 1-34) (trade name: Forteo ® ), have been shown to be effective in treating osteoporosis [47]. However, they can be problematic because, for example, rhPTH 1-34 can degrade during its shelf life [48]. These observations suggest that small molecules could be utilized as alternative novel bone anabolic agents for the treatment of osteoporosis.…”

Biotechnological Products

“…Kothari et al [30] evaluated degradation products formed during storage of the recombinant human parathyroid hormone. They found that the hormone degraded because of not only oxidation but also deamidation and peptide bond cleavage.…”

“…Silva et al [32] examined the structural integrity of preparations of interferon alfa-2a (IFN-α2a) and interferon alfa-2b (IFN-α2b), which had been ProTEIN AggrEgATIoN 527 FIGURE 13.5 reverse-phase high-performance liquid chromatography (rP-hPlc) chromatogram of drug product (recombinant human parathyroid hormone) stored for 6 months at (a) 5 ± 3°c and (b) 25 ± 2°c [30]. …”

“…10 Identification of the Peaks Observed in the Chromatograms inFigure 13.5[30] subjected to stress conditions, namely, storage at elevated temperature (37°c) for 9 weeks. The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAgE) analysis of the samples stored at 37 and −70°c showed that high-molecular-weight bands were detected at 37°c for both preparations, revealing the occurrence of protein aggregation at higher temperature…”