Albinterferon α2b Adsorption to Silicone Oil–Water Interfaces: Effects on Protein Conformation, Aggregation, and Subvisible Particle Formation

Glass Silicone Oil Free Pre-filled Syringe as Primary Container in Autoinjector

OBJECTIVE

Pre-filled syringes (PFSs) have become popular as a convenient and cost-effective container closure system for delivering biotherapeutics. However, standard siliconized PFSs may compromise the stability of therapeutic proteins due to their exposure to the silicone oil-water interface. To address this concern, silicone oil-free (SOF) glass syringes coupled with silicone-oil free plunger stoppers have been developed. This study aims to compare the impact of silicone oil-free (SOF) and siliconized syringes as primary container on protein stability and device functionality of the combination products.

METHODS

The stability of proteins with different modalities was assessed in SOF and siliconized 1 mL glass syringes for up to 6 months at 5℃, 25℃, and 40℃ with levels of subvisible particles and soluble aggregate determined by micro-flow imaging (MFI) and ultra performance size-exclusion chromatography (UP-SEC). The functionality of SOF glass syringes, including break loose force, extrusion force and delivery time in autoinjectors, was evaluated at different time points during the stability study. Additionally, SOF glass syringes were filled with viscosity surrogate ranging from 1 to 90 cP to understand the impact of solution viscosity on break loose force, extrusion force, and autoinjector delivery time.

RESULTS

SOF demonstrates compatibility with proteins and exhibited significantly low particle counts compared to siliconized PFS. SOF syringes show significantly higher break-loose and extrusion forces. However, unlike siliconized syringes where silicone oil migration increases extrusion force, no significant change in functionality was observed in SOF glass syringe during stability testing. Overall, SOF glass syringes showed great potential as an alternative package for biologics with comparable performance on functionality as siliconized PFS.

CONCLUSIONS

The combination of SOF glass and its PTFE coated stopper presents a new primary container closure system with both adequate protein stability and desired functionality features.

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.

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.

A systematic review of commercial high concentration antibody drug products approved in the US: formulation composition, dosage form design and primary packaging considerations

Three critical aspects that define high concentration antibody products (HCAPs) are as follows: 1) formulation composition, 2) dosage form, and 3) primary packaging configuration. HCAPs have become successful in the therapeutic sector due to their unique advantage of allowing subcutaneous self-administration. Technical challenges, such as physical and chemical instability, viscosity, delivery volume limitations, and product immunogenicity, can hinder successful development and commercialization of HCAPs. Such challenges can be overcome by robust formulation and process development strategies, as well as rational selection of excipients and packaging components. We compiled and analyzed data from US Food and Drug Administration-approved and marketed HCAPs that are ≥100 mg/mL to identify trends in formulation composition and quality target product profile. This review presents our findings and discusses novel formulation and processing technologies that enable the development of improved HCAPs at ≥200 mg/mL. The observed trends can be used as a guide for further advancements in the development of HCAPs as more complex antibody-based modalities enter biologics product development.

Modeling cavitation bubble dynamics in an autoinjector and its implications on drug molecules

The collapse of cavitation bubbles induced by abrupt acceleration of the syringe in an autoinjector device can lead to protein aggregation. The details of bubble dynamics are investigated using an axisymmetric, three-dimensional simulation with passive tracers to illustrate the transport of protein molecules. When a bubble near the syringe wall collapses, protein molecules are concentrated in the re-entrant jet, pushed towards the syringe wall, and then spread across the wall, potentially leading to protein adsorption on the syringe wall and aggregation. This phenomenon is more prominent for bubbles positioned closer to the bottom wall, growing to a larger maximum radius. The bubble's maximum radius decreases with the bubble's distance from the syringe wall and air gap pressure, and increases with an increase in liquid column height and nucleus size. The strain rate induced by the bubble collapse is not large enough to unfold the proteins. When the re-entrant jet impacts the bubble surface or syringe wall, the bubble breaks up, generating smaller bubbles with high surface concentration of protein molecules, potentially inducing aggregation in the bulk. The bubble dynamics are influenced by dimensionless distance of the nucleus from the wall, normalized by maximum bubble radius (γ). The re-entrant jet velocity increases with γ, while the maximum liquid pressure, typically 100∼1000 bar, first decreases and then increases with γ. For a cloud of cavitation bubbles, i.e., closely clustered bubbles, coalescence of bubbles can occur, leading to a higher peak pressure at collapse.

Monoclonal Antibody Aggregation near Silicone Oil-Water Interfaces

In this work, we study the hydrodynamic behavior of monoclonal antibodies in the presence of silicone oil-water interfaces. We model the antibody molecules using a coarse-grained 24-bead model, where two beads are used to represent each antibody domain. We consider the spatial variation of the antibody polarity in our model as each bead represents a set of hydrophilic or hydrophobic amino acids. We use the dissipative particle dynamics scheme to represent the coarse-grained force field which governs the motion of the beads. In addition, interprotein interactions are modeled using an electrostatic force field. The model parameters are determined by comparing the structure factor against experimental structure factor data ranging from a low concentration regime (10 mg/mL) to a high concentration regime (150 mg/mL). Next, we conduct simulations for a suspension of antibody molecules in the presence of silicone oil-water interfaces. Protein loss from the bulk solution is noticed as the molecules adsorb at the interface. We observe dynamic cluster formation in the solution bulk and at the interface, as the antibody molecules self-associate along their trajectories. We quantify the aggregation using a density clustering algorithm and investigate the effect of the antibody concentration on the diffusivity of the antibody solution, aggregation propensity, and protein loss from the bulk. Our study shows that numerical simulations can be an important tool for understanding the molecular mechanisms driving protein aggregation near hydrophobic interfaces.

Critical analysis of techniques and materials used in devices, syringes, and needles used for intravitreal injections

Intravitreal injections have become the most commonly performed intraocular treatments worldwide. Because intravitreal injections may induce severe adverse events, such as infectious and noninfectious endophthalmitis, cataract, ocular hypertension, vitreous hemorrhage, or retinal detachment, appropriate awareness of the materials and techniques used are essential to reduce these sight-threatening complications. This review provides insights into the needles, syringes, silicone oil coating, sterilization methods, devices to assist intravitreal injections, scleral piercing techniques using needles, syringe handling, anesthesia, and safety issues related to materials and techniques. It is paramount that physicians be aware of every step involved in intravitreal injections and consider the roles and implications of all materials and techniques used. The ability to understand the theoretical and practical circumstances may definitely lead to state-of-the-art treatments delivered to patients. The most important practical recommendations are: choosing syringes with as little silicone oil as possible, or, preferably, none; avoiding agitation of syringes; awareness that most biologics (e.g., antiangiogenic proteins) are susceptible to changes in molecular properties under some conditions, such as agitation and temperature variation; understanding that improper materials and techniques may lead to complications after intravitreal injections, e.g., inflammation; and recognizing that some devices may contribute to an enhanced, safer, and faster intravitreal injection technique.

Probing the Interfacial Interactions of Monoclonal and Bispecific Antibodies at the Silicone Oil-Aqueous Solution Interface by Using Sum Frequency Generation Vibrational Spectroscopy

Silicone oil has been widely utilized in the pharmaceutical industry especially as a lubricant coating commonly used in syringes for the smooth delivery of drugs. Protein structure perturbation and aggregation have been reported upon protein contacting silicone oil by using indirect methods and ex-situ techniques. The conclusions derived from such indirect and ex-situ methods may not truly reflect the exact nature of the protein-silicone oil interfacial interactions. Recently, we have successfully demonstrated that sum frequency generation (SFG) vibrational spectroscopy can be used as a powerful and direct method of studying the fusion protein-silicone oil interfacial interactions in situ and in real time. In this article, we studied monoclonal and bispecific antibody interactions with the silicone oil surface by using SFG spectroscopy. Being structurally and functionally different in the nature of fusion proteins and antibodies, this study is important in enhancing our current understanding of protein-silicone oil interfacial interactions. Both types of antibodies investigated here readily and strongly adsorb onto the silicone oil surface and remain stable at least for 10 h. SFG spectra in the amide I region for monoclonal and bispecific antibodies centered at 1660 and 1665 cm^-1, respectively, suggest the difference in their molecular structures. The absence of the antibody signals in the amide I region of time-dependent and static SFG spectra obtained for preadsorbed antibodies onto silicone oil after contacting polysorbate 80 (PS-80) surfactant suggests that PS-80 can effectively remove both types of antibodies from the silicone oil surface. This study demonstrated the feasibility of using SFG spectroscopy as a powerful tool for probing the antibody-interfacial interactions in situ and in real time.

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.

Interactions Between Biological Products and Product Packaging and Potential Approaches to Overcome Them

Biological products such as protein-based biopharmaceuticals are playing an important role in the healthcare and pharmaceutical industry. The interaction between biological products and packaging materials has become the focus of many studies since it can reduce the effectiveness of biological products. These interactions are heavily influenced by the surface properties and physicochemical nature of the therapeutic agents and the packaging materials. Therefore, it is critical to understand the interactions between packaging materials and biological products in order to design biocompatible packaging materials and develop approaches to minimize adverse interactions. We describe the interactions that occur when using several common packaging materials, including glass and polymer. We discuss the interaction between these materials and biological products such as blood, blood derivatives, recombinant proteins, monoclonal antibodies, and gene therapeutics. We also summarize approaches for overcoming these interactions. Understanding the interactions between biological materials and packaging materials is critical for the development of novel packaging materials that improve the safety of pharmaceutical products.

Visible and Sub-visible Particle Formation for a Model Bioconjugate

The time-course and extent of visible particle (VP) and sub-visible particle (SVP) formation was monitored as a function of interfacial area (IA) for a model bioconjugate. To facilitate particle formation, the bioconjugate was agitated in a glass vial and exposed to IAs up to 478 mm². Since vials had equal fill and headspace volumes, the area of the air-water interface was varied by placing vials on angled blocks at 0°, 30°, 60°, or 90° from the horizontal. A significant increase in visible and sub-visible particle formation was observed with increasing air-water IA. Exposure to IAs below ∼305 mm² resulted in the formation of very few particles, while IAs > ∼305 mm² resulted in substantial particle formation. Visible and sub-visible particle morphology varied with interfacial area and time. The sub-visible particles initially increased with time but did not reach steady state; instead the initial increase was followed by complete depletion. These phenomena indicate that visible particle formation likely increased at the expense of the sub-visible particle population and demonstrate a potential link between the two particle populations for this model bioconjugate. Initiation of particle formation did not result in corresponding decreases in protein concentration or increases in soluble aggregates. However, extended agitation time resulted in a significant decrease in protein concentration.

Silicone Oil Microdroplets Can Induce Antibody Responses Against Recombinant Murine Growth Hormone in Mice

Therapeutic protein products can cause adverse immune responses in patients. The presence of subvisible particles is a potential contributing factor to the immunogenicity of parenterally administered therapeutic protein formulations. Silicone oil microdroplets, which derive from silicone oil used as a lubricating coating on barrels of prefilled glass syringes, are often found in formulations. In this study, we investigated the potential of silicone oil microdroplets to act as adjuvants to induce an immune response in mice against a recombinant murine protein. Antibody responses in mice to subcutaneous injections of formulations of recombinant murine growth hormone (rmGH) that contained silicone oil microdroplets were measured and compared to responses to oil-free rmGH formulations. When rmGH formulations containing silicone oil microdroplets were administered once every other week, anti-rmGH antibodies were not detected. In contrast, mice exhibited a small IgG1 response against rmGH when silicone oil-containing rmGH formulations were administered daily, and an anti-rmGH IgM response was observed at later time points. Our findings showed that silicone oil microdroplets can act as an adjuvant to promote a break in immunological tolerance and induce antibody responses against a recombinant self-protein.

In Vivo Analysis of the Potency of Silicone Oil Microdroplets as Immunological Adjuvants in Protein Formulations

Subvisible particles in a therapeutic protein product may act as adjuvants to promote unwanted immune responses against the protein. Silicone oil is used as a lubricant in prefilled syringes, and microdroplets of silicone oil are often detected in protein formulations expelled from prefilled syringes. In order to test the adjuvant potency of silicone oil microdroplets, antibody responses in mice to subcutaneous injections of formulations of ovalbumin (OVA) that contained silicone oil microdroplets were measured. These responses were compared against responses to oil-free OVA formulations and to OVA formulations that contained microparticulate aluminum hydroxide ("alum"), the common vaccine adjuvant. When administered with high concentrations of silicone oil microdroplets, OVA formulations elicited strong anti-OVA IgG1 and IgG2a antibody responses. These responses were equivalent to those observed when alum microparticles were added to OVA formulations, suggesting that silicone oil can act as a potent adjuvant. However, when OVA formulations were prepared with lower levels of silicone oil that had been obtained directly from commercial siliconized syringes, the anti-OVA antibody response was not enhanced significantly compared with responses against OVA alone.