Assessment of the Degradation Pattern and Extent of PEG Interferon α-2b Using a Stability-Indicating SE-HPLC Assay

A comprehensive stability assessment of insulin degludec using New customized validated RP-HPLC and SEC-HPLC methods in an orthogonal testing protocol

Stress testing of biopharmaceuticals plays an important role in preparation of their stability profiles through investigation of possible degradation pathways and identification of degradation products, so in this study Insulin Degludec which is a new generation ultra-long-acting basal insulin is subjected to stress conditions as different temperatures, different pH, oxidation, mechanical agitation, and repeated freeze and thaw cycles to generate possible degradation products and aggregation that are investigated by two new validated RP-HPLC and SEC-HPLC methods in addition to dynamic light scattering (DLS) and native polyacrylamide gel electrophoresis (Nu-PAGE). SEC-HPLC was used to investigate formation of aggregates whose results were correlated with those obtained from DLS and Nu-PAGE, while RP-HPLC was used to investigate any possible chemical modifications. The Proposed RP-method had limit of detection (LOD) and limit of quantitation (LOQ) of 0.012 mg/mL and 0.045 mg/mL respectively and accuracy of 99.22 ± 1.07 %, while the SEC methods had limit of detection (LOD) and limit of quantitation (LOQ) of 0.012 mg/mL and 0.031 mg/mL, respectively. The degradation pattern due to high temperature effect and oxidation is investigated by LC- tandem mass spectrometry. Results showed that Insulin degludec is highly stable under low temperature, mechanical agitation and repeated freeze and thaw stress conditions but elevated temperature and high acidic condition lead to formation of aggregates and also chemical modifications including deamidation, isomerization and oxidation. Such different chemical degradation pathways are due to presence of variable reactive moieties in Insulin degludec structure. Insulin degludec is highly vulnerable to oxidation at the sulfur containing cysteine residue in B chain in position B7 forming trioxidation derivative when exposed to hydrogen peroxide. Formation of A21-Asp and A18-Asp deamidated variants as well as B3-Asp and B3-isoAsp deamidated variants are prominent degradation pathways at neutral pH but at elevated temperature.

MSAll strategy for comprehensive quantitative analysis of PEGylated-doxorubicin, PEG and doxorubicin by LC-high resolution q-q-TOF mass spectrometry coupled with all window acquisition of all fragment ion spectra

The covalent attachment of polyethylene glycol (PEG) to therapeutic compounds (known as PEGylation) is one of the most promising techniques to improve the biological efficacy of small molecular weight drugs. After administration, PEGylated prodrugs can be metabolized into pharmacologically active compounds so that PEGylated drug, free drug and released PEG are present simultaneously in the body. Understanding the pharmacokinetic behavior of these three compounds is needed to guide the development of pegylated theranostic agents. However, PEGs are polydisperse molecules with a wide range of molecular weights, so that the simultaneous quantitation of PEGs and PEGylated molecules in biological matrices is very challenging. This article reports the application of a data-independent acquisition method (MS^All) based on liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-q-q-TOF-MS) in the positive ion mode to the simultaneous determination of methoxyPEG2000-doxorubicin (mPEG2K-Dox) and its breakdown products in rat blood. Using the MS^All technique, precursor ions of all molecules are generated in q1, fragmented to product ions in q2 (collision cell), and subjected to TOF separation before precursor and product ions are recorded using low and high collision energies (CE) respectively in different experiments for a single sample injection. In this study, dissociation in q2 generated a series of high resolution PEG-related product ions at m/z 89.0611, 133.0869, 177.1102, 221.1366, 265.1622, 309.1878, and 353.2108 corresponding to fragments containing various numbers of ethylene oxide subunits, Dox-related product ions at m/z 321.0838 and 361.0785, and an mPEG2K-Dox specific product ion at m/z 365.0735. Detection of mPEGs and mPEG2K-Dox was based on high resolution extracted ions of mPEG and the specific compound. The method was successfully applied to a pharmacokinetic study of doxorubicin, mPEG2K (methylated polyethylene glycol 2K), and mPEG2K-doxorubicin in rats after a single intravenous injection of mPEG2K-doxorubicin. To the best of our knowledge, this is the first assay that simultaneously determines mPEG, Dox, and mPEG2K-Dox in a biological matrix. We believe the MS^All technique as applied in this study can be potentially extended to the determination of other PEGylated small molecules or polymeric compounds.

Evaluation of the combined effects of pegylation and glycosylation on the stability of erythropoietin using a stability-indicating SE-HPLC

Recombinant human erythropoietin (rhEPO) is a commonly used biopharmaceutical for the treatment of anemia-associated disorders. Epogen; glycosylated erythropoietin (G-EPO) has short half-life and poor stability. Pegylated Epogen (Peg-G-EPO) was introduced to the market to overcome these limitations. The combined effects of pegylation and glycosylation on the stability of Peg-G-EPO was studied. Determination of Peg-G-EPO in the presence of its degradation products was achieved using SE-HPLC. The assay was validated according to ICH guidelines over concentration range of 50.00-320.00 μg/mL (r 0.9999). A mobile phase of 50 mM phosphate buffer (pH 6.5) with 300 mM sodium chloride and 20% ethanol was employed. Isocratic elution was carried out at 0.5 mL/min over run time of 30 min. Peg-G-EPO was found stable towards mechanical agitation only at low concentrations while it was stable towards repeated freeze/thaw; regardless of the concentration. Effect of temperature and pH were also investigated and Peg-G-EPO was found stable within narrow ranges. Results indicated formation of small molecular weight and very high molecular weight aggregates that have been filtered-off the column. Although Peg-G-EPO was found relatively more stable than its non-pegylated but glycosylated version, results indicated the need for careful stability-assessment of Peg-G-EPO.

Immunoaffinity extraction using conformation-dependent antibodies coupled to SE-HPLC for the development of stability and potency-indicating assay for quadrivalent human papillomavirus vaccine

Quadrivalent human papillomavirus (HPV) vaccine is formulated of four types of non-infectious recombinant virus like particles (VLPs) that are structurally and immunologically similar to the corresponding infectious HPV virus types 6, 11, 16 and 18. With almost identical physical, chemical and structural properties of the four types of VLPs, ELISA remains the only approved in vitro potency testing assay. In this study, an alternative industry-friendly, stability- and potency-indicating assay protocol was developed and validated for the determination of HPV vaccine. Vacuum-driven immunoaffinity extraction (IAE) was employed using type-specific, conformation-dependent antibodies against each type of HPV VLPs. ELISA assay was employed to evaluate the ability of IAE columns to specifically separate each of the four types of VLPs from their quadrivalent mixture. Mean percentage recoveries of 76.76±2.69, 69.12±5.79, 84.86±5.25 and 71.14±4.50% were obtained for VLPs types 6, 11, 16 and 18, respectively with no significant interference in each case. Antigen content was then determined using SE-HPLC over a concentration range of 5.00-20.00μg/mL (r>0.998) for VLPs type 6, 11, 16 and 18, respectively. The SE-HPLC assay was found accurate and precise (RSD<10.00%) with LOD ranging from 1.23-3.85μg/mL. The assay protocol was found superior to conventional ELISA assay with respect to simplicity, total analysis time and cost. Good correlation between the results of analysis obtained using IAE-SE-HPLC and ELISA demonstrated the suitability of the suggested assay protocol for stability and potency assessment with a good potential for implementation for batch release. This approach should be applicable for quality assessment of other vaccine preparations based on VLPs.