Silicone Migration From Baked-on Silicone Layers. Particle Characterization in Placebo and Protein Solutions

The silicone depletion in combination products induced by biologics

Silicone oil (SO) migration into the drug product of combination products for biopharmaceuticals during storage is a common challenge. As the inner barrel surface is depleted of SO the extrusion forces can increase compromising the container functionality. In this context we investigated the impact of different formulations on the increase in gliding forces in a spray-on siliconized pre-filled syringe upon storage at 2-8 °C, 25 °C and 40 °C for up to 6 months. We tested the formulation factors such as surfactant type, pH, and ionic strength in the presence of one monoclonal antibody (mAb) as well as compared three mAbs in one formulation. After 1 month at 40 °C, the extrusion forces were significantly increased due to SO detachment dependent on the fill medium. The storage at 40 °C enhanced the SO migration process but it could also be observed at lower storage temperatures. Regarding the formulation factors the tendency for SO migration was predominantly dependent on the presence and type of surfactant. Interestingly, when varying the mAb molecules, one of the proteins showed a rather stabilizing effect on the SO layer resulting into higher container stability. In contrast to the formulation factors, those different stability outcomes could not be explained by interfacial tension (IFT) measurements at the SO interface. Further characterization of the mAb molecules regarding interfacial rheology and conformational stability were not adequately able to explain the observed difference. Solely a hydrophobicity ranking of the molecules correlated to the stability outcome. Further investigations are needed to clarify the role of the protein in the SO detachment process and to understand the cause for the stabilization. However, the study clearly demonstrated that the protein itself plays a critical role in the SO detachment process and underlined the importance to include verum for container stability.

High-Throughput Fluorometric Assay For Quantifying Polysorbate In Biopharmaceutical Products Using Micelle Activated Fluorescence Probe N-Phenyl-1-Naphthylamine

PURPOSE

Polysorbates are among the most used surfactants in biopharmaceutical products containing proteins. Our work aims to develop a high-throughput fluorometric assay to further diversify the analytical toolbox for quantification of PSs.

METHOD

The assay leverages the micelle activated fluorescence signal from N-Phenyl-1-Naphthylamine (NPN). The development and optimization of assay parameters were guided by the pre-defined analytical target profile. Furthermore, NMR was used to probe the interaction between protein, PS80 and NPN in the measurement system and understand protein interference.

RESULTS

All assay parameters including excitation and emission wavelengths, standard curve, NPN concentration, and incubation time have been optimized and adapted to a microplate format, making it compatible with automated solutions that will be pursued in the near future to drive consistency and efficiency in our workflows. The specificity, accuracy, and precision of the assay have been demonstrated through a case study. Furthermore, NMR results provided additional insight into the change of the interaction dynamics between PS80 and NPN as the protein concentration increases. The results indicate minimal interaction between the protein and PS80 at lower concentration. However, when the concentration exceeds 75 mg/mL, there is a significant interaction between the protein and PS-80 micelle and monomer.

CONCLUSION

A high-throughput fluorometric assay has been developed for quantification of polysorbates in biopharmaceutical samples including in-process samples, drug substance and drug product. The assay reported herein could serve as a powerful analytical tool for polysorbate quantification and control, complementing the widely used liquid chromatography with charged aerosol detection method.

Characterization of Silicone from Closed System Transfer Devices and its Migration into Pharmaceutical Drug Products

Closed System Transfer Devices (CSTDs) are increasingly used in healthcare settings to facilitate compounding of hazardous drugs but increasingly also therapeutic proteins. However, their use may significantly impact the quality of the sterile product. For example, contamination of the product solution may occur by leaching of silicone or particulates from the CSTDs. It was therefore the aim of the present study to identify and quantify the types of silicone oil in a panel of typically used CSTDs. Particles found after simulated CSTD compounding processes were evaluated using Light Obscuration and Micro-Flow Imaging and were confirmed to be silicone oil particles. The number of particulates shed from CTSDs was in single cases exceeding pharmacopeial limits for a final parenteral product. Using X-ray microtomography, lubrication was shown to be primarily applied at connecting parts of the CSTD. Quantitative and qualitative analysis by Fourier transform infrared spectroscopy (FTIR) revealed a total released amount between 0.8 and 16 mg per CSTD of polydimethylsiloxane or polymethyltrifluoropropylsiloxane per CSTD. While pronounced differences in total silicone content between CSTDs were observed, it did not fully correlate with particle contamination in the test solutions, potentially due to variations in CSTD design. The impact of typical surfactants in biological formulations on silicone migration into product was additionally evaluated. We conclude that CSTDs may compromise final product quality, as (different types of) silicone oil may be released from these devices and contaminate the administered product.

Application of Formulation Principles to Stability Issues Encountered During Processing, Manufacturing, and Storage of Drug Substance and Drug Product Protein Therapeutics

The field of formulation and stabilization of protein therapeutics has become rather extensive. However, most of the focus has been on stabilization of the final drug product. Yet, proteins experience stress and degradation through the manufacturing process, starting with fermentaition. This review describes how formulation principles can be applied to stabilize biopharmaceutical proteins during bioprocessing and manufacturing, considering each unit operation involved in prepration of the drug substance. In addition, the impact of the container on stabilty is discussed as well.

Evaluation of a novel silicone oil free primary packaging system with PTFE-based barrier stopper for biologics

In order to overcome silicone oil related problems for biopharmaceuticals, novel container systems are of interest with a focus on the reduction, fixation or complete avoidance of silicone oil in the primary container. Ultimately, silicone oil free (SOF) container systems made from cyclic olefin (co-)polymer or glass combined with the respective silicone-oil free plungers were developed. In the following study we evaluated the potential of a SOF container system based on a glass barrel in combination with a fluoropolymer coated syringe plunger. In a long-term stability study, the system was compared to other alternative container systems in terms of functionality and particle formation when filled with placebo buffers. The system proved to be a valuable alternative to marketed siliconized container systems with acceptable and consistent break-loose gliding forces and it was clearly superior in terms of particle formation over storage time. Additionally, we evaluated the importance of the glass barrel surface for functionality. The interaction of the fill medium with the glass surface significantly impacted friction forces. Consequently, storage conditions and production processes like washing and sterilization, which can easily alter the surface properties, should be carefully evaluated, and controlled. The novel combination of non-lubricated glass barrel and fluoropolymer coated plunger provides a highly valuable SOF packaging alternative for biopharmaceuticals.

Impact of Autoclavation on Baked-on Siliconized Containers for Biologics

Many pharmaceutical manufacturing units utilize pre-sterilized ready-to fill primary containers for parenterals. The containers may have been sterilized by the supplier via autoclavation. This process can change the physicochemical properties of the material and the subsequent product stability. We studied the impact of autoclavation on baked on siliconized glass containers for biopharmaceuticals. We characterized the container layers of different thickness before and after autoclavation for 15 min at 121 °C and 130 °C. Furthermore, we analyzed the adsorption of a mAb to the silicone layer and subjected filled containers to 12 weeks storage at 40 °C monitoring functionality and subvisible particle formation of the product. Autoclavation turned the initially homogenous silicone coating into an incoherent surface with uneven microstructure, changed surface roughness and energy, and increased protein adsorption. The effect was more pronounced at higher sterilization temperatures. We did not observe an effect of autoclavation on stability. Our results did not indicate any concerns for autoclavation at 121 °C for safety and stability of drug/device combination products using baked-on siliconized glass containers.

Mechanism of Protein-PDMS Visible Particles Formation in Liquid Vial Monoclonal Antibody Formulation

Visible particles (VPs) formation in liquid monoclonal antibody formulations is a critical quality issue. Formulations that include poloxamer 188 (PX188) as a surfactant are prone to the formation of VPs comprising aggregated complexes of protein and polydimethylsiloxane (PDMS; silicone oil) derived from primary containers. However, the mechanisms through which these VPs form are complicated and remain to be fully elucidated. This study demonstrates for the first time the dominant spot and pathway of protein-PDMS VP formation in a particular liquid vial formulation. Specifically, when a vial sealed with a PDMS-coated stopper is stored in an upright position under conditions whereby the antibody solution has become well-adhered to the stopper and an air phase exists in the vicinity, protein-PDMS aggregates form on the stopper and are then desorbed into the drug solution to be detected as VPs. Here, we evaluated the effects of several factors on VP formation: adhesion of the drug solution to the stopper, storage orientation, silicone coating on the stopper, vial material, and hydrophobicity of PX188. Remarkably, we found that changing any one of the factors could significantly affect VP formation. Our findings are instructive for better understanding the mechanisms of VP formation in vial products and can provide strategies for VP mitigation in biotherapeutics.

Influence of Protein Adsorption on Aggregation in Prefilled Syringes

Protein aggregate formation in prefilled syringes (PFSs) can be influenced by protein adsorption and desorption at the solid-liquid interface. Although inhibition of protein adsorption on the PFS surface can lead to a decrease in the amount of aggregation, the mechanism underlying protein adsorption-mediated aggregation in PFSs is unclear. This study investigated protein aggregation caused by protein adsorption on silicone oil-free PFS surfaces [borosilicate glass (GLS) and cycloolefin polymer (COP)] and the factors affecting the protein adsorption on the PFS surfaces. The adsorbed proteins formed multilayered structures that consisted of two distinct types of layers: proteins adsorbed on the surface of the material and proteins adsorbed on top of the proteins on the surface. A pH-dependent electrostatic interaction was the dominant force for protein adsorption on the GLS surface, while hydrophobic effects were dominant for protein adsorption on the COP surface. When the repulsion force between proteins was weak, protein adsorption on the adsorbed protein layer was increased for both materials and as a result, protein aggregation increased. Therefore, a formulation with high colloidal stability can minimize protein adsorption on the COP surface, leading to reduced protein aggregation.

Development of syringes and vials for delivery of biologics: current challenges and innovative solutions

INTRODUCTION

Several new biopharmaceutical dosage forms have developed over time, such as lyophilized vial, liquid vial, and liquid prefilled syringe formulations. This review summarizes major pharmaceutical dosage forms and their advantages, disadvantages, and countermeasures against the shortcomings of each formulation. The appropriate combination of active pharmaceutical ingredients, excipients, and containers should be selected for the safe and less burdensome administration to the patients. Finally, we note certain opinions on the future development of not only therapeutic proteins but also gene therapeutics.

AREAS COVERED

This review is to discuss the challenges of the development of dosage forms to improve pharmaceutical stability and how they can be overcome.

EXPERT OPINION

Silicone oil-free syringes are highly preferable for minimizing subvisible particles in the drug. It can be proposed that materials with less protein adsorption property are preferable for the suppression of protein aggregation. It is required to minimize adverse effects of biopharmaceuticals through proper quality control of the drug in a container, based on the understating of physicochemical stability of the protein in solution, the physicochemical properties of the container, and their combinations.

Applying Pattern Recognition as a Robust Approach for Silicone Oil Droplet Identification in Flow-Microscopy Images of Protein Formulations

Discrimination between potentially immunogenic protein aggregates and harmless pharmaceutical components, like silicone oil, is critical for drug development. Flow imaging techniques allow to measure and, in principle, classify subvisible particles in protein therapeutics. However, automated approaches for silicone oil discrimination are still lacking robustness in terms of accuracy and transferability. In this work, we present an image-based filter that can reliably identify silicone oil particles in protein therapeutics across a wide range of parenteral products. A two-step classification approach is designed for automated silicone oil droplet discrimination, based on particle images generated with a flow imaging instrument. Distinct from previously published methods, our novel image-based filter is trained using silicone oil droplet images only and is, thus, independent of the type of protein samples imaged. Benchmarked against alternative approaches, the proposed filter showed best overall performance in categorizing silicone oil and non-oil particles taken from a variety of protein solutions. Excellent accuracy was observed particularly for higher resolution images. The image-based filter can successfully distinguish silicone oil particles with high accuracy in protein solutions not used for creating the filter, showcasing its high transferability and potential for wide applicability in biopharmaceutical studies.

Method to Determine Syringe Silicone Oil Layer Heterogeneity and Investigation of its Impact on Product Particle Counts

Prefilled syringes (PFSs) are commonly used for parenteral delivery of protein therapeutics. In PFSs, the inner surface of the syringe barrel is typically coated with silicone oil for lubrication. The total amount of silicone oil as well as its distribution can impact syringe functionality and particle formation. However, methods to non-destructively characterize the silicone oil distribution are limited. In this paper, we developed a method to visualize and quantify the relative distribution of silicone oil in unfilled syringes using a custom-built multi-color interferometric imaging system. We then applied the system in a preliminary study to investigate the impact of the silicone oil distribution on the number of particles formed in solution after filling and extrusion for two different types of syringes. The syringe type with significantly lower particle counts also exhibited significantly more homogeneous silicone oil distributions. Within syringe types, no significant association was found between silicone oil distribution and particle formation. Our method can be used in further studies that investigate the impact of syringe siliconization on PFS functionality and particle formation.

Characterization of Polymeric Syringes Used for Intravitreal Injection

Intravitreal (IVT) injection is currently the state of the art for drug delivery to the back of the eye. Drug Products (DP) intended for IVT injections usually pose challenges such as a very low injection volume (e.g. 50 μL) and high injection forces. DPs in vials are typically transferred and injected using disposable polymer syringes, which can feature a silicone oil (SO) coating. In our syringe in-use study, we compared dead volume, total SO content and SO layer distributions of three IVT transfer injection syringes. We assessed multiple potential impact factors such as protein concentration, needle gauge, injection speed, surfactant type and the impact of the in-use hold time on sub-visible particle (SvP) formation and injection forces. Pronounced differences were observed between the syringes regarding SvP generation. Siliconized syringes showed higher SvP counts as compared to non-siliconized syringes. In some cases injection forces exceeded 20 N, which caused needles to burst off during injection. The syringes also showed relevant differences in total SO content and dead volume. In conclusion, specific consideration in the selection of an adequate transfer injection syringe are required. This includes extensive testing and characterization under intended and potential in-use conditions and the development of in-use handling procedures.

Science and art of protein formulation development

Protein pharmaceuticals have become a significant class of marketed drug products and are expected to grow steadily over the next decade. Development of a commercial protein product is, however, a rather complex process. A critical step in this process is formulation development, enabling the final product configuration. A number of challenges still exist in the formulation development process. This review is intended to discuss these challenges, to illustrate the basic formulation development processes, and to compare the options and strategies in practical formulation development.

Sweeping of Adsorbed Therapeutic Protein on Prefillable Syringes Promotes Micron Aggregate Generation

This study evaluated how differences in the surface properties of prefillable syringe barrels and in-solution sampling methods affect micron aggregates and protein adsorption levels. Three syringe types (glass barrel with silicone oil coating [GLS/SO+], glass barrel without silicone oil coating [GLS/SO-], and cyclo-olefin polymer [COP] barrel syringes) were tested with 3 therapeutic proteins (adalimumab, etanercept, and infliximab) using 2 sampling methods (aspiration or ejection). After quiescent incubation, solutions sampled by aspiration exhibited no significant change in micron aggregate concentration in any syringes, whereas those sampled by ejection exhibited increased micron aggregates in both GLS syringe types. Micron aggregate concentration in ejected solutions generally increased with increasing density of adsorbed proteins. Notably, COP syringes contained the lowest micron aggregate concentrations, which were independent of the sampling method. Correspondingly, the adsorbed protein density on COP syringes was the lowest at 1-2 mg/m², which was much less compared with that on GLS syringes and was calculated to be equivalent to only 1-2 protein layers, as visually confirmed by high-speed atomic force microscopy. These data indicate that low-adsorption prefillable syringes should be used for therapeutic proteins because protein aggregate concentration in the ejected solution is elevated by increased protein adsorption to the syringe surface.