Using enhanced development tools offered by analytical Quality by Design to support switching of a quality control method

Quality by Design (QbD) principles play an increasingly important role in the pharmaceutical industry. Here, we used an analytical QbD (AQbD) approach to develop a capillary electrophoresis sodium dodecyl sulfate under reducing conditions (rCE-SDS), with the aim of replacing SDS-polyacrylamide gel electrophoresis (SDS-PAGE) as release and stability test method for a commercialized monoclonal antibody product. Method development started with defining analytical method performance requirements as part of an analytical target profile, followed by a systematic risk assessment of method input parameters and their relation to defined method outputs. Based on this, design of experiments studies were performed to identify a method operable design region (MODR). The MODR could be leveraged to improve method robustness. In a bridging study, it was demonstrated that the rCE-SDS method is more sensitive than the legacy SDS-PAGE method, and a conversion factor could be established to compensate for an off-set due to the higher sensitivity, without losing the correlation to the historical data acquired with the former method. Overall, systematic application of analytical Quality by Design principles for designing and developing a new analytical method helped to elucidate the complex dependency of method outputs on its input parameters. The link of the method to product quality attributes and the definition of method performance requirements were found to be most relevant for derisking the analytical method switch, regarding impact on the control strategy.

Restoring the biological activity of crizanlizumab at physiological conditions through a pH-dependent aspartic acid isomerization reaction

In this study, we report the isomerization of an aspartic acid residue in the complementarity-determining region (CDR) of crizanlizumab as a major degradation pathway. The succinimide intermediate and iso-aspartic acid degradation products were successfully isolated by ion exchange chromatography for characterization. The isomerization site was identified at a DG motif in the CDR by peptide mapping. The biological characterization of the isolated variants showed that the succinimide variant exhibited a loss in target binding and biological activity compared to the aspartic acid and iso-aspartic acid variants of the molecule. The influence of pH on this isomerization reaction was investigated using capillary zone electrophoresis. Below pH 6.3, the succinimide formation was predominant, whereas at pH values above 6.3, iso-aspartic acid was formed and the initial amounts of succinimide dropped to levels even lower than those observed in the starting material. Importantly, while the succinimide accumulated at long-term storage conditions of 2 to 8°C at pH values below 6.3, a complete hydrolysis of succinimide was observed at physiological conditions (pH 7.4, 37°C), resulting in full recovery of the biological activity. In this study, we demonstrate that the critical quality attribute succinimide with reduced potency has little or no impact on the efficacy of crizanlizumab due to the full recovery of the biological activity within a few hours under physiological conditions.

The use of ECG by triage nurses may improve the stratification of patients with cardiological symptoms admitted to the emergency department: a prospective observational study

Background

Triage is the crucial point for overall emergency department (ED) management. Its purpose is to quickly and safely identify among the many patients arriving those who need rapid medical evaluation [1]. Present triage systems are based on symptomatic assessment and clinical impression to assess patient severity on admission to the ED. Some clinical tools that are widely validated in practice, such as ECG, could be implemented in triage to improve the stratification activity of the system [2].

Purpose

To evaluate whether the use of ECG can improve nursing triage prediction for patients admitted to the ED for symptoms related to suspected cardiac pathology.

Methods

A prospective observational single-centered study was conducted. All patients who visited the ED for chest pain, syncope, dyspnoea or palpitation and underwent ECG at the time of triage were considered. The study was conducted by a pool of nurses who had previously received special training in ECG reading. Background characteristics, comorbidities and clinical conditions were recorded for each enrolled patient. In addition, the priority level assigned according to the application of the 5-level Manchester Triage System (1 to 5) and the level of priority after ECG performance (1 to 5) were recorded. The study outcome was composite: the presence of a major cardiac event within 6 weeks after triage, a cardiogenic syncope, the presence of a pulmonary embolism or aortic dissection, or an arrhythmia requiring specific emergency therapy [3]. The priority level assigned in triage and the priority level given after performing the ECG were compared by analysis of the receiver operating characteristic.

Results

A total of 1,211 patients were included in the study. Of these, 62.4% (756/1,211) presented chest pain, 13.8% (167/1,211) syncope, 18.2% (221/1,211) palpitation and 5.5% (67/1,211) dyspnoea. Overall, 10.5% (127/1,211) had a positive outcome. The concordance between triage nurses and cardiologists in detecting pathological and non-pathological ECGs presented a Cohen's kappa of 0.821 (p<0.001). ECG performed by nurses increased the patient's priority in 7.5% (91/1,211) of cases and reduced it in 39.6% (480/1,211) of cases. The discriminatory ability of the triage system before ECG was performed showed an area under the receiver operating characteristic curve of 0.708 (95% CI 0.659–0.757), whereas the discriminatory ability of triage after ECG was 0.845 (95% CI 0.808–0.883).

Conclusions

The use of ECG in triage can be a simple and safe tool that improves the assessment of the patient's priority when presenting to the ED for a cardiac symptom. The presence of a good diagnostic concordance and a good improvement in discriminatory ability may support the implementation of ECG in nursing triage.

Funding Acknowledgement

Type of funding sources: None.

Ion Beam Induced Chemical Vapor Deposition of Dielectric Materials

Direct writing by locally induced chemical vapor deposition has been applied to direct-write tailor-made microstructures of siliconoxide for modification and repair of microelectronic circuits. Focused ion beam (FIB) tools are used for locally confined deposition of dielectric material in the deep sub-µm range. State-of-the-art procedures typically provide insufficient dielectrics with high leakage currents and low breakdown voltage. The detailed investigation of the deposition mechanisms in this study proposes an approach to significantly improve dielectric material properties. Siloxane and oxygen as volatile precursors introduced in a vacuum chamber are used to deposit siliconoxide at ambient temperatures on various substrates such as Si, GaAs, or metals. The deposition process was initiated by a focused Ga+-beam. As elementary electronic test vehicles for a systematic electrical investigation ion beam induced depositions in of capacitor architectures are applied. The chemical composition of the layers is investigated by secondary ion mass spectroscopy (SIMS) and reveals effects of atomic mixing at the interfaces. The variation of process parameters such as ion energy and ion dose, scan time and delay time lead to a better understanding of the mechanisms. The composition of the precursor gas mixture is of significant influence on insulating properties. The results demonstrate that optimized FIB-induced deposition of dielectrics offers a new window for in-situ post-processing of integrated circuits

Effects of entrance crossflow directions to film cooling holes

Two-dimensional distributions of local adiabatic film cooling effectiveness as well as discharge coefficients have been measured to investigate the effect of different entrance crossflow orientations and magnitudes on film-cooling performance. Operating conditions have been varied in terms of hot gas Mach number (up to 0.6), coolant crossflow Mach number (up to 0.6), coolant crossflow orientation (perpendicular or parallel with respect to the mainflow), and blowing ratio (0.5-1.5). The temperature ratio of coolant and hot gas was kept constant at 0.56 for the effectiveness tests, leading to an enginelike density ratio of 1.8. Infrared thermography was applied to perform local measurements of the surface temperatures with high resolution. The results indicate that the impact of hot gas crossflow Mach number is not very pronounced within the range of Mach numbers investigated. In contrast to this finding, the effect of internal coolant crossflow is very pronounced and strongly depends on coolant crossflow orientation and the ejected mass flow rate.