Analytical methods for the characterization and quality control of pharmaceutical peptides and proteins, using erythropoietin as an example

A Reference Standard for Analytical Testing of Erythropoietin

Purpose

Erythropoietin (EPO) is a 165 amino acid protein that promotes the proliferation of erythrocytic progenitors. A decrease in endogenous EPO production causes anemia that can be treated with recombinant Human EPO (rHuEPO).

Objective

To ensure the safety and efficacy of the rHuEPO, manufacturers must use analytical methods to demonstrate similarity across batches and between different products. To do this they need reference standards to validate their equipment and methods.

Method

We used peptide mapping, size-exclusion chromatography, glycoprofiling, and isoelectric focusing to analyze a rHuEPO reference standard.

Results

Characterization demonstrates that our rHuEPO reference standard meets the criteria for quality.

Conclusion

The rHuEPO reference standard is fit for purpose as a tool for validating system suitability and methods.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11095-022-03213-1.

Interaction between phloretin and insulin: a spectroscopic study

Diabetes is among the top ten deadly diseases in the world. It occurs either when the pancreas does not produce enough insulin (INS) or when the body cannot effectively use the insulin it produces. Phloretin (PHL) has a biological effect that can treat diabetes. A spectroscopic study was carried out to explore the interaction between phloretin and insulin. UV/Vis spectroscopy, fluorescence spectroscopy, and circular dichroism spectropolarimeter were used in the study. UV/Vis spectra showed that the interaction between PHL and INS produced strong absorption at a wavelength of 282 nm. The fluorescence analysis results showed that the excitation and emission occurred at 280-nm and 305-nm wavelengths, respectively. Temperature changes did not affect INS emissions. However, the interaction of PHL–INS caused a redshift at 305 to 317 nm. Temperature affected the binding constant (Ka) and the binding site (n). Ka decreased with increasing temperature and increased the binding site. The thermodynamic parameters such as enthalpy (ΔH0) and entropy (ΔS0) each had a value of − 16,514 kJ/mol and 22.65 J/mol·K. PHL and INS interaction formed hydrogen bonds and hydrophobic interaction. The free energy (ΔG0) recorded was negative. PHL and INS interactions took place spontaneously. The quenching effect was dynamic and static. KD values were greater than KS. The higher the temperature, the less was KD and KS. The appearance of two negative signals on circular dichroism (CD) spectropolarimeter implies that phloretin could induce regional configuration changes in insulin. The addition of PHL has revealed that the proportion of α-helix in the insulin stabilizes its structure. Phloretin’s stabilization and enhancement of the α-helix structural configuration in insulin indicate that phloretin can improve insulin resistance.

High-Throughput Process Development for Biopharmaceuticals

The ability to conduct multiple experiments in parallel significantly reduces the time that it takes to develop a manufacturing process for a biopharmaceutical. This is particularly significant before clinical entry, because process development and manufacturing are on the "critical path" for a drug candidate to enter clinical development. High-throughput process development (HTPD) methodologies can be similarly impactful during late-stage development, both for developing the final commercial process as well as for process characterization and scale-down validation activities that form a key component of the licensure filing package. This review examines the current state of the art for HTPD methodologies as they apply to cell culture, downstream purification, and analytical techniques. In addition, we provide a vision of how HTPD activities across all of these spaces can integrate to create a rapid process development engine that can accelerate biopharmaceutical drug development. Graphical Abstract.

Long-term delivery of protein therapeutics

INTRODUCTION

Proteins are effective biotherapeutics with applications in diverse ailments. Despite being specific and potent, their full clinical potential has not yet been realized. This can be attributed to short half-lives, complex structures, poor in vivo stability, low permeability, frequent parenteral administrations and poor adherence to treatment in chronic diseases. A sustained release system, providing controlled release of proteins, may overcome many of these limitations.

AREAS COVERED

This review focuses on recent development in approaches, especially polymer-based formulations, which can provide therapeutic levels of proteins over extended periods. Advances in particulate, gel-based formulations and novel approaches for extended protein delivery are discussed. Emphasis is placed on dosage form, method of preparation, mechanism of release and stability of biotherapeutics.

EXPERT OPINION

Substantial advancements have been made in the field of extended protein delivery via various polymer-based formulations over last decade despite the unique delivery-related challenges posed by protein biologics. A number of injectable sustained-release formulations have reached market. However, therapeutic application of proteins is still hampered by delivery-related issues. A large number of protein molecules are under clinical trials, and hence, there is an urgent need to develop new methods to deliver these highly potent biologics.

Deep-ultraviolet (UV) resonance raman spectroscopy as a tool for quality control of formulated therapeutic proteins

A deep-ultraviolet (UV) Raman spectrometer with excitation source tunable from 193 to 210 nm has been built and characterized. The dispersion of the spectrometer over the entire range was measured and described theoretically. The relative sensitivity of the spectrometer was estimated using the integrated intensity ratio of two Raman bands of cyclohexane. Resonance Raman spectra of three formulated insulin products were measured and compared. A band-targeted entropy minimization algorithm was applied to the collected spectra for mixture analysis of insulin products. We conclude that it is feasible to develop robust qualitative methods for quality control of protein-based formulated drug using DUVRR spectroscopy.

Development and validation of RP-HPLC and RP-UPLC methods for quantification of erythropoietin formulated with human serum albumin

Rapid and sensitive reverse phase high performance liquid chromatography (RP–HPLC) and ultra performance liquid chromatography (UPLC) methods with UV detection for quantification of erythropoietin (EPO) in presence of human serum albumin (HSA) as a stabilizer in a pharmaceutical formulation of EPO have been developed and validated. Chromatography was performed with mobile phase containing 0.1% Trifluoroacetic acid (TFA) in MilliQ water and 0.1% TFA in acetonitrile with gradient program and a flow rate of 1.5 mL/min for HPLC and 0.35 mL/min for UPLC. Quantification was accomplished with internal reference standard (qualified using EP reference standard). The methods were validated for linearity (correlation coefficient=0.99), accuracy, precision and robustness. Robustness was confirmed by considering three factors; percentages of TFA in mobile phase, age of test sample and mobile phase and column temperature. Intermediate precision was confirmed by different analysts, different equipments and on different days. The relative standard deviation (RSD) value (<2%, n=30) indicated good precision of the developed method. The proposed RP-HPLC method had retention time less than 20 min while the developed UPLC method had retention time less than 4 min. Both the RP-HPLC and UPLC methods were simple, highly sensitive, precise and accurate, suggesting that the developed methods are useful for routine quality control.

Development of a sensitive size exclusion HPLC method with fluorescence detection for the quantitation of recombinant human erythropoietin (r-HuEPO) aggregates

Human erythropoietin produced by recombinant DNA technology, is now marketed worldwide for the treatment of anemias associated with chronic renal failure and chemotherapy. No sensitive methods, which can determine r-HuEPO dimer or oligomer aggregate content in formulated products, have been published to date. This report describes the development and validation of a sensitive size exclusion high performance liquid chromatography (HPLC) method for the quantitation of r-HuEPO aggregates in formulations containing 0.03% polysorbate 80. A Waters Alliance 2690 HPLC system connected to a TosoHaas TSKgel G3000 SWxl (7.8 mm x 30 cm, 250 A pore size, 5 microm particle size) column and a Waters 474 fluorescence detector was used. The mobile phase for the SEC-HPLC method consists of isopropyl alcohol-potassium phosphate (0.1 M)/potassium chloride buffer (pH 6.8+/-0.1, 0.2 M) (25:75, v/v). The flow rate was 0.3 mL/min and the method run time was 60 min. The SEC-HPLC method presented here was shown to be specific for r-HuEPO total aggregates (dimer and oligomers) and allows for their quantitation at 80 ng/mL or 4 ngs/injection, in the presence of r-HuEPO monomer and the pharmaceutical excipients, glycine (5 mg/mL), sodium chloride (4.3 mg/mL), and 0.03% polysorbate 80. The finalized method is stability-indicating and is suitable for determining r-HuEPO aggregates between 0.2 and 0.5% levels in the formulated product of r-HuEPO. This method offers a robust way to measure total aggregates on a routine basis with a high sensitivity for use in product quality control.

Electrophoresis of pharmaceutical proteins:Status quo

The biotechnology industry has undergone rapid growth in recent years largely due to the development and success of protein-based therapeutics for a wide range of disorders. Similar to traditional pharmaceuticals, characterization of a therapeutic protein for its physicochemical properties, process monitoring and lot release is crucial. Electrophoresis in the slab-gel format has and continues to be a mainstay of the protein laboratory; and more recently, CE has begun to make significant inroads for protein analysis in industrial settings. This review focuses on the electrophoresis of proteins with an emphasis on protein-based therapeutics in the capillary, slab-gel and to a lesser extent, the microchip format. Reported applications of electrophoresis at several stages of the biopharmaceutical industry covering the period of 2000-2005 will be discussed.