Drug Product Formulation Research Articles

Utilization of AF4 for characterizing complex nanomaterial drug products: Reexamining sample recovery and its impact on particle size distribution as a quality attribute.

Asymmetrical flow field-flow fractionation (AF4) with multi-detection has continued to gain wider acceptance for characterizing complex drug products. An important quality attribute for these products is the measurement of the particle size distribution (PSD). Current limitations of established procedures (e.g., dynamic light scattering) for accurately determining PSD can be overcome by AF4. However, while gaining acceptance this technique has not been fully adopted within the pharmaceutical industry. A technical understanding of fundamental operational factors is necessary for the successful application of utilizing any emerging technology. For example, recovery (R% = AS/AD*100, where AS and AD are the peak areas from the concentration detector with and without the crossflow field, respectively) is one factor that is used to assess the robustness during AF4 method development, but currently little is known about the interplay between analyte recovery and PSD. This work highlights factors that impact calculated AF4 recovery, and how differences in analyte and absolute recovery ultimately influence the PSD of nanoparticle size standards and complex drug product formulations such as emulsions and liposomes. Factors like ionic strength, buffer composition, and analyte chemistries, which are the most common factors associated with changes to R% in AF4, contributed to changes in AS. While AD is not typically examined in detail, the selection of the concentration detector (UV or dRI) along with their instrumental parameters (e.g., wavelength, attenuation value, linear range) and sample preparation was shown to under- or over-estimate AD thus changing R%. Examining both components of R% and their contributions to analyte and absolute recovery show that decreases in analyte recovery may not be exclusively due to sample loss but could be influenced by changes in analyte-membrane interactions or analyte instability. Because of this, four relationships between recovery and PSD were defined. While R% is used as a tool for assessing AF4 methodology, the factors investigated through this work warrant further considerations when establishing an appropriate R% threshold.

Integrating Analytical Procedures in Routine Practices of Centralized Antiblastic Compounding Units for Valorization of Residual Compounded Drugs.

Although extemporaneous formulations of anticancer drug products for personalized therapy are produced according to Good Hospital Pharmacy Manufacturing Practice, the lack of knowledge about drug stability under clinical conditions limits the second-time use of these highly costly medications in clinical practice. Therefore, the residual compounded drugs are considered waste and a cost item that negatively affects the healthcare system. In the context of the ever-increasing interest of the health system in applying practices in line with personalized medicine and spending review policies, this research aimed to demonstrate the feasibility of incorporating analytical techniques into daily routine practice. Specifically, the present research focused on fast stability analysis of Active Pharmaceutical Ingredients (APIs) in antiblastic residual compounded drugs with the purpose of demonstrating their potentialities as a resource for possible second-time use. Two different subsets of drug products were analyzed, i.e., medicines containing small molecules and medicines containing monoclonal antibodies. In relation to their different physicochemical properties, two analytical approaches were optimized and involved in the stability investigation: HPLC-DAD for small molecules and a combined approach of LC-MS/MS with size exclusion chromatography for monoclonal antibodies analysis. Results underlined that the stability data, as available in the summary of product characteristics related to each medicine, do not completely describe the physicochemical shelf-life of anticancer compounded drugs. In fact, for all tested products, our results suggested a longer shelf-life in comparison to the datasheet, giving hospital pharmacists the possibility to extend the clinical use of compounded drugs, improving the cost-benefit of anticancer personalized therapy.

Mechanism of low molecular weight impurity formation in an IgG1 monoclonal antibody formulation.

Formulation robustness study was performed for a biosimilar monoclonal antibody (IgG1) manufactured at Dr. Reddy's Laboratory, where the pH and concentration level of excipients in the drug product formulation were systematically varied from the target formulation. It was observed that the IgG1 formulation having relatively low pH and high citrate (buffer salt) concentration were predisposed to the formation of low molecular weight impurities. Mass spectrometry analysis of the mAb1 fragments detected the pyroglutamate species from LC-LC dimer and fragmentation in the -DKTH- amino acid sequence of the heavy chain. Blind docking indicated binding of citrate with Lysine 222 residue in the proximity of Cys224 could have potentially fragmented IgG1.

A toolbox for early detection of glass delamination in vials.

Glass delamination is a gradual process that may not become apparent until late in storage. Over the past three decades, it has been a leading cause of drug product recalls due to glass particulate contamination. The appearance of glass particles in the solution marks the final stage of glass delamination. Therefore, it is crucial to develop rapid methods for detecting glass delamination at its earliest stages. We utilized three model buffer solution systems and examined three glass vials from two vendors (Vial 1, Vial 2A, and Vial 2B) to assess their resistance to glass delamination. We leveraged the high refractive index of glass particles in air and employed the Background Membrane Imaging (BMI) method as a high-throughput and sensitive technique to detect subvisible glass particles (SVGP). We compared the effectiveness of BMI and Flow Imaging Microscopy (FIM) in detecting SVGP. Our findings indicate that the BMI results are more consistent with other glass delamination detection techniques. Vial 1 exhibited a 5-28 fold increase in the number of SVGP compared to Vial 2A and Vial 2B after one month of storage, depending on the buffer type. Additionally, Vial 1 showed higher methylene blue staining, 1.15-2.5 fold higher silicon leachable, and the most significant surface attack based on our Scanning Electron Microscopy (SEM) results. Overall, the BMI method can be considered the quickest and most sensitive quantitative technique for detecting glass delamination at its early stages, providing valuable insights for selecting glass containers that minimally interact with drug product formulations.

Attribute ranging as a coordinated strategy between drug substance and drug product to accelerate commercial process nomination.

To make investigational drug candidates available to patients sooner, timelines for drug development are becoming shorter. Synthesis route scouting for active pharmaceutical ingredients (API) and drug product development often must occur simultaneously, requiring formulators to make decisions regarding drug product process selection before commercial API route finalization. Alternatively, the formulation strategy may be locked, thereby constraining drug substance processes with strict API attribute requirements. Critical quality attributes of the drug product can depend heavily on the API, yet final physical attributes may not be known early on in development. Furthermore, the desire to reduce pill burden means higher drug loading in formulations, leaving little room for excipients to compensate for suboptimal API performance. The opposing challenges of API synthetic route and drug product formulation development typically lead to elongated development timelines requiring an iterative approach. In this work, a coordinated strategy was designed and implemented to deliberately range API attributes via crystallization and milling techniques to enable robust assessment of downstream manufacturing and significantly reduce the time for final process selection. The study presented was conducted on a protease inhibitor targeted for treatment of Covid-19. Given the emergent need for treatment options, this dramatically accelerated approach was crucial for potential emergency use authorization (EUA).

Pharmacokinetics of Oral Cannabinoid Δ8-Tetrahydrocannabivarin and Its Main Metabolites in Healthy Participants.

Tetrahydrocannabivarin (THCV) is a phytocannabinoid commonly found in cannabis with potential pharmacological properties; however, its post-acute pharmacokinetics (PK) in humans have not been studied yet. THCV has two isomers, Δ9- and Δ8-THCV, which seem to have different pharmacological properties. We investigated the PK of the Δ8-THCV isomer after oral administration as part of a two-phase, dose-ranging, placebo-controlled trial in healthy participants. Participants (n = 21) were enrolled in six study sessions and randomly received the following doses of a medium-chain triglyceride (MCT) oil oral formulation of Δ8-THCV: placebo, 12.5 mg, 25 mg, 50 mg, 100 mg, and 200 mg. Plasma samples from 15 participants were collected up to 8 h after administration and were analyzed by a validated two-dimensional high-performance liquid chromatography-tandem mass spectrometry assay. The trial was registered on clinicaltrials.gov (NCT05210634). After oral administration, 11-nor-9-carboxy-Δ8-THCV (Δ8-THCV-COOH) was the main metabolite detected. The median time-to-maximum concentration (tmax) ranged 3.8-5.0 h across doses for Δ8-THCV and 4.6-5.3 h for Δ8-THCV-COOH. The maximum concentration (Cmax) and area under the concentration-time curve over the observation period (AUClast) appeared to be dose-linear. Median AUClast increased 2.3- to 4.8-fold and 1.7- to 2.9-fold for Δ8-THCV and Δ8-THCV-COOH, respectively, every two-fold increase in the dose. The isomers Δ9-THCV and Δ9-THCV-COOH were detected in plasma, despite being undetected in the formulated drug product analyzed by a third-party laboratory. For the first time, we report the pharmacokinetics of Δ8-THCV and its major metabolites after oral administration in humans. Δ8-THCV AUClast showed dose linearity but the observed possible conversion to the Δ9-THCV isomer should be further studied.

Investigating Extracellular Vesicles in Viscous Formulations: Interplay of Nanoparticle Tracking and Nanorheology via Interferometric Light Microscopy

While extracellular vesicles (EVs) demonstrate growing potential as innovative cell‐derived nanobiotherapies in diverse medical contexts, their physical properties (size, integrity, transport, etc.) in drug product formulation remain a critical concern poorly addressed so far. Herein, a methodology that relies on nanoparticle tracking analysis by interferometric light microscopy (ILM) for analyzing the concentration and size distribution of nanoparticles as well as their interactions with their local environment through a nanorheological approach is introduced. The analysis of interference patterns enables nanoparticles tracking not only in aqueous solutions but also in complex media with high‐viscosity or non‐Newtonian behavior, particularly pertinent for characterizing EV formulations. A proof of concept for in situ tracking of EVs suspended in Poloxamer‐407 as drug delivery system is presented. The ILM‐based analysis enables to 1) measure the viscosity at the nanoscale for Newtonian and non‐Newtonian fluids via calibration beads; 2) analyze data to determine the size distribution of EVs in non‐Newtonian complex fluid such as poloxamer formulation, and 3) analyze the interactions of EVs with poloxamer‐407. The proposed approach represents a valuable tool to understand the nanorheological behavior of EVs in viscoelastic media in situ as well as a quality control test for EV formulations intended to clinical use.

Development and validation of a robust RP-HPLC method to quantitate residual 2–mercaptoethylamine in drug product formulations containing amino acid additives

Bispecific antibodies have a wide range of applications in cancer immunotherapy, some of which are manufactured by controlled Fab-arm exchange requiring the reductant 2-mercaptoethylamine (2-MEA). As a process impurity, monitoring the residual 2-MEA in bispecific antibody drug product process development is needed. A novel reversed phase-high performance liquid chromatography (RP-HPLC) method for measurement of residual 2-MEA that uses 7–fluorobenzofurazan-4-sulfonic acid ammonium salt (SBD-F) as a fluorescent-detection tag in drug product formulations containing high concentrations of arginine has been developed. Using a thiol tag for residual 2–MEA eliminates any potential interference from conventional tag binding to amine groups of the formulation arginine, and potentially resulting in overestimation of the amount of impurity in a given sample. The new method has been fully validated for specificity, linearity, accuracy, range, limit of quantitation, limit of detection, and robustness. This method therefore has potential to aid in detecting residual 2-MEA content for any process that utilizes 2-MEA for bispecific antibody manufacturing.

Perspectives on Drug Product Design Among Patients with Lung Cancer in the United Kingdom.

The use of oral anticancer medications has become more prevalent in cancer therapy. This is particularly the case in the management of advanced non-small cell lung cancer (NSCLC). However, when the treatment delivery interaction between the patient and the healthcare provider is removed, the risk of non-adherence increases. Insights into patient preferences can allow drug product formulation scientists to design more patient-centric medications that may promote an increase in adherence which, in turn, may lead to more beneficial health outcomes. We conducted an advisory board with patients with NSCLC in the United Kingdom to elicit and understand preferences for drug product attributes related to appearance, instructions, and modality. The advisory board was preceded by a quantitative preference survey that included three object-case best-worst scaling exercises and was followed by administering the same survey to a broader group of patients to confirm the results. Patients strongly prefer once-daily dosing over more frequent dosing, regardless of the number of pills because taking tablets or capsules multiple times each day can disrupt daily activities. In addition, patients place high importance on surface smoothness because a rough surface implies decreased swallowability. Finally, food restrictions involving directions regarding taking medication with or without food represent difficulties for patients with cancer. Results of the follow-up survey confirmed these results. Drug developers should attempt to limit the dosing of these medications to once-daily regimens, avoid surface roughness, and develop formulations that can be taken without regard to the timing of meals to the greatest extent possible.

Importance of RNase monitoring during large-scale manufacturing and analysis of mRNA-LNP based vaccines

Ribonucleases (RNases) are ubiquitous in nature, being able to cleave a wide range of polyribonucleotides. While the presence of microbial and viral contamination in sterile manufacturing is highly studied and controlled, there are no standardized practices for evaluating RNase in the production facility. Since the COVID-19 pandemic, mRNA-LNP based vaccines have become part of routine large-scale manufacturing. The unstable nature of mRNA poses new challenges to safeguard the working efficacy of mRNA – Lipid nanoparticle (LNP) based vaccines or therapeutics, where the presence of RNase in the formulation process could have a profound impact on the mRNA integrity. In this article, lessons learned are presented with respect to the evaluation of RNase contamination during LNP drug product formulation and analysis. Using sensitive detection methods, the potential presence of RNase in the manufacturing of mRNA-LNPs was investigated. Additionally, capillary gel electrophoresis (CGE) data, used to measure mRNA integrity, demonstrate the quality of the active mRNA substance and importance of suitable RNase control strategies. The results and cases presented in this paper should pave the way forward for evaluation and control strategies dedicated to mRNA-LNP based vaccines and therapeutics.

Calculating the surface energies of crystals on a face-specific and whole particle basis: Case study of the α- and β-polymorphic forms of L-glutamic acid

Molecular-scale modelling for predicting surface energies on a face-specific and whole particle basis is applied to all the crystallographically-independent surfaces of L-glutamic acid forms. The predicted data is found to be in good general agreement with measured surface energies using inverse gas chromatography and Washburn capillary rise techniques with the former revealing higher values compared to the prediction, perhaps consistent with the polar (zwitterionic) nature of this material. This fusion of experimental and computational data provides a high-fidelity definition of the face-by-face breakdown of the energetic anisotropy of the crystals. There is increasing industrial interest in defining the potential impact of whole particle properties on the performance of formulated drug product and their manufacturability especially as the community accelerates the molecule to medicine journey. The overall molecular modelling approach highlights its application in designing ingredients for optimising face-specific particle surface energies for product formulatability particularly in early phase process development.

Reversible protein complexes: Advancing subcutaneous delivery with controlled and sustained release of high concentration biologics

High concentration formulations are crucial in developing biological drugs, especially for subcutaneous (SC) administration where the administered dose is adversely impacted by the limited injection volume. In this study, we evaluated the fate and behavior of high concentration formulations of biologics, using the previously described reversible protein complex (RPC) approach and a novel in vitro tool called Subcutaneous Injection Site Simulator (Scissor). The Scissor simulates the changes that a biological drug could encounter as it transitions from a drug product formulation to the homeostatic state of the hypodermis following SC injection. The RPC formulation was injected in a cartridge filled with synthetic extracellular matrix, which was immersed in a release chamber filled with a bicarbonate-based physiological buffer that mimicked the SC injection site and the infinite sink conditions of the body. The system enabled continuous monitoring of the RPC formulation within the cartridge and could be used to characterize physicochemical changes of the drug. The dissociation of RPC and the release of the therapeutic protein from the cartridge to the infinite sink compartment simulated the drug migration from the injection site and uptake to the systemic circulation. Here, we present the evaluation of high concentration RPC formulations using five therapeutic proteins of different formats. Our findings suggest that the Scissor can provide a suitable tool to predict the stability of biological drugs in the subcutaneous environment. Also, the in vitro drug release data obtained from the Scissor highlighted a sustained and controlled release of RPC formulations and a surface erosion-based release mechanism was elucidated thanks to in vitro release models.

A comparison of Polysorbates and Alternative Surfactants for Interfacial Stress Protection and Mitigation of Fatty Acid Particle Formation in the Presence of an Esterase

The hydrolysis of polysorbate surfactants in large molecule drug product formulations caused by residual host cell proteins presents numerous stability concerns for pharmaceuticals. The fatty acids (FA) released by polysorbate hydrolysis can nucleate into particulates or challenge the conformational stability of the proteinaceous active pharmaceutical ingredient (API). The loss of intact polysorbate may also leave the Drug Product (DP) vulnerable to interfacial stresses. Polysorbate 20 and 80 are available in several different quality grades (Multi-compendial, Super Refined, Pure Lauric Acid (PLA)/Pure Oleic Acid (POA)). All variations of polysorbate as well as three alternative surfactants: Brij L23, Brij O20 and Poloxamer 188 were compared for their ability to protect against air-water interfacial stresses as well as their risk for developing particulates when in the presence of lipoprotein lipase (LPL) (Pseudomonas).Results show a meaningful difference in the timing and morphology of FA particle formation depending on the type of polysorbate used. All grades of polysorbate, while susceptible to hydrolysis, still offered sufficient protection to interfacial stresses, even when hydrolyzed to concentrations as low as 0.005 % (w/v). Alternative surfactants that lack an ester bond were resistant to lipase degradation and showed good protection against shaking stress.

Cholinesterase Inhibition and Antioxidative Capacity of New Heteroaromatic Resveratrol Analogs: Synthesis and Physico-Chemical Properties.

The targeted compounds in this research, resveratrol analogs 1-14, were synthesized as mixtures of isomers by the Wittig reaction using heterocyclic triphenylphosphonium salts and various benzaldehydes. The planned compounds were those possessing the trans-configuration as the biologically active trans-resveratrol. The pure isomers were obtained by repeated column chromatography in various isolated yields depending on the heteroaromatic ring. It was found that butyrylcholinesterase (BChE) was more sensitive to the heteroaromatic resveratrol analogs than acetylcholinesterase (AChE), except for 6, the methylated thiophene derivative with chlorine, which showed equal inhibition toward both enzymes. Compounds 5 and 8 achieved the highest BChE inhibition with IC50 values of 22.9 and 24.8 μM, respectively. The same as with AChE and BChE, methylated thiophene subunits of resveratrol analogs showed better enzyme inhibition than unmethylated ones. Two antioxidant spectrophotometric methods, DPPH and CUPRAC, were applied to determine the antioxidant potential of new heteroaromatic resveratrol analogs. The molecular docking of these compounds was conducted to visualize the ligand-active site complexes' structure and identify the non-covalent interactions responsible for the complex's stability, which influence the inhibitory potential. As ADME properties are crucial in developing drug product formulations, they have also been addressed in this work. The potential genotoxicity is evaluated by in silico studies for all compounds synthesized.

Quantitative 31P NMR Spectroscopy Platform Method for the Assay of Oligonucleotides as Pure Drug Substances and in Drug Product Formulations Using the Internal Standard Method.

One of the most widely used techniques for the quantification of small interfering ribonucleic acid (siRNA) is the ultraviolet (UV) spectroscopy method. However, due to uncertainties in the extinction coefficient affecting the accuracy of the method and a sample preparation including several dilution steps, the purpose of this study was to explore the possibility of determining the content of siRNA by a platform method using quantitative 31P nuclear magnetic resonance (31P-qNMR) and the internal standard method. In this paper, acquisition time, selection of a suitable internal certified reference material, signal selection used for quantification, relaxation delay, and precision are discussed. In addition, the robustness of the method and the ability to apply this platform method to both drug substance (DS) and drug product samples is also discussed. Quantifications of siRNA determined by the 31P-qNMR platform method were on average 98.5%w/w when adjusting for the sodium and water contents. The data confirmed the applicability of 31P-qNMR in siRNA content determinations. The quantifications were compared to quantifications determined by the traditional UV spectroscopy method by F- and t-tests. The statistical tests showed that the platform 31P-qNMR method provided more accurate results (mass balance close to 100% w/w) compared to the traditional UV spectroscopy method when analyzing DS samples.

Application of MPBT Assay for Multiplex Determination of Infectious Titers and for Selection of the Optimal Formulation for the Trivalent Novel Oral Poliovirus Vaccine.

Recently, a multiplex PCR-based titration (MPBT) assay was developed for simultaneous determination of infectious titers of all three Sabin strains of the oral poliovirus vaccine (OPV) to replace the conventional CCID50 assay, which is both time-consuming and laborious. The MPBT assay was shown to be reproducible, robust and sensitive. The conventional and MPBT assays showed similar results and sensitivity. The MPBT assay can be completed in two to three days, instead of ten days for the conventional assay. To prevent attenuated vaccine strains of poliovirus from reversion to virulence, a novel, genetically stable OPV (nOPV) was developed by modifying the genomes of conventional Sabin strains used in OPV. In this work, we evaluated the MPBT assay as a rapid screening tool to support trivalent nOPV (tnOPV) formulation development by simultaneous titration of the three nOPV strains to confirm stability as needed, for the selection of the lead tnOPV formulation candidate. We first assessed the ability of the MPBT assay to discriminate a 0.5 log10 titer difference by titrating the two tnOPV samples (undiluted and threefold-diluted) on the same plate. Once the assay was shown to be discriminating, we then tested different formulations of tnOPV drug products (DPs) that were subjected to different exposure times at 37 °C (untreated group and treated groups: 2 and 7 days at 37 °C), and to three freeze and thaw (FT) cycles. Final confirmation of the down selected formulation candidates was achieved by performing the conventional CCID50 assay, comparing the stability of untreated and treated groups and FT stability testing on the top three candidates. The results showed that the MPBT assay generates similar titers as the conventional assay. By testing two trivalent samples in the same plate, the assay can differentiate a 0.5 log10 difference between the titers of the tested nOPV samples. Also, the assay was able to detect the gradual degradation of nOPV viruses with different formulation compositions and under different time/temperature conditions and freeze/thaw cycles. We found that there were three tnOPV formulations which met the stability criteria of less than 0.5 log10 loss after 2 days' exposure to 37 ℃ and after three FT cycles, maintaining the potency of all three serotypes in these formulations. The ability of the MPBT assay to titrate two tnOPV lots (six viruses) in the same plate makes it cheaper and gives it a higher throughput for rapid screening. The assay detected the gradual degradation of the tnOPV and was successful in the selection of optimal formulations for the tnOPV. The results demonstrated that the MPBT method can be used as a stability indicating assay to assess the thermal stability of the nOPV. It can be used for rapid virus titer determination during the vaccine manufacturing process, and in clinical trials. The MPBT assay can be automated and applied for other viruses, including those with no cytopathic effect.

Revolutionizing Nitrofurantoin Delivery: Unraveling Challenges and Pioneering Solutions for Enhanced Efficacy in UTI Treatment

Abstract: Nitrofurantoin is an antimicrobial drug, highly effective in the treatment of critical or chronic bacterial infections of the urinary tract, and hence, it is the first line choice of drug for the treatment of urinary tract infections (UTI). Although the molecule is legacy in nature, there are many challenges in terms of drug product formulation and efficacy thereof. The authors are main-ly focused in this literature review on, but not limited to, understanding the molecule in terms of physico-chemical properties of the drug, pharmacokinetics and pharmacodynamics, approved and withdrawn formulations, challenges concerning drug formulation, the cause of drug shortage in the market, improvement areas in terms of formulation and its therapeutic effectiveness. The au-thors found during their widespread review that the major challenge in the existing conventional drug delivery system of nitrofurantoin is the fluctuation of plasma concentration owing to its var-iability in drug absorption. Further, they understood that the variability in absorption is due to in-herent variability in particle size distribution. Based on the findings, authors also explored the possibilities to deliver the drug in novel drug delivery systems such as nano self-emulsifying emulsions, nanoemulsions and multiple emulsions where the drug can be presented in soluble form and hence the variability in absorption and fluctuation in plasma concentration of drug can be avoided and described briefly the salient features of each drug delivery in this review.

Novel EDTA mediated ethanol protein precipitation method and the application for polysorbate quantification in high protein concentration biopharmaceuticals

Non-ionic surfactants such as Polysorbate 20/ 80 (PS20/ PS80), are commonly used in protein drug formulations to increase protein stability by protecting against interfacial stress and surface absorption. Polysorbate is susceptible to degradation which can impact product stability, leading to the formation of sub-visible and/or visible particles in the drug product during its shelf-life, affecting patient safety and efficacy. Therefore, it is important to monitor polysorbate concentration in drug product formulations of biotherapeutic drugs. The common method for measuring polysorbate concentration in drug product formulations uses mixed mode ion exchange reversed phase HPLC (MAX) coupled to evaporative light scattering detection (ELSD). However, high protein concentration can adversely impact method performance due to high sample viscosity, gel formation, column clogging, interfering peaks and loss of accuracy. To overcome this, a new method was developed based on EDTA mediated ethanol protein precipitation (EDTA/EtOH). This method was successfully implemented for the analysis of polysorbate in antibody formulations with wide range of protein concentration (10–250 mg/mL).

Impact of Excipient Extraction and Buffer Exchange on Recombinant Monoclonal Antibody Stability.

The foundation of a biosimilar manufacturer's regulatory filing is the demonstration of analytical and functional similarity between the biosimilar product and the pertinent originator product. The excipients in the formulation may interfere with characterization using typical analytical and functional techniques during this biosimilarity exercise. Consequently, the producers of biosimilar products resort to buffer exchange to isolate the biotherapeutic protein from the drug product formulation. However, the impact that this isolation has on the product stability is not completely known. This study aims to elucidate the extent to which mAb isolation via ultrafiltration-diafiltration-based buffer exchange impacts mAb stability. It has been demonstrated that repeated extraction cycles do result in significant changes in higher-order structure (red-shift of 5.0 nm in fluorescence maxima of buffer exchanged samples) of the mAb and also an increase in formation of basic variants from 19.1 to 26.7% and from 32.3 to 36.9% in extracted innovator and biosimilar Tmab samples, respectively. It was also observed that under certain conditions of tertiary structure disruptions, Tmab could be restabilized depending on formulation composition. Thus, mAb isolation through extraction with buffer exchange impacts the product stability. Based on the observations reported in this paper, we recommend that biosimilar manufacturers take into consideration these effects of excipients on protein stability when performing biosimilarity assessments.

Assessing Physicochemical Stability of Monoclonal Antibodies in a Simulated Subcutaneous Environment

Monoclonal antibodies (mAbs) are being increasingly administered by the subcutaneous (SC) route compared to the traditional intravenous route. Despite the growing popularity of the subcutaneous route, our current knowledge regarding the intricate mechanistic changes happening in the formulation after injection in the subcutaneous space, as well as the in vivo stability of administered mAbs, remains quite limited. Changes in the protein environment as it transitions from a stabilized, formulated drug product in an appropriate container closure to the SC tissue environment can drastically impact the structural stability and integrity of the injected protein. Interactions of the protein with components of the extracellular matrix can lead to changes in its structure, potentially impacting both safety and efficacy. Investigating protein stability in the SC space can enable early assessment of risk and performance of subcutaneously administered proteins influencing clinical decisions and formulation development strategies. The Subcutaneous Injection Site Simulator (SCISSOR) is a novel in vitro system that mimics the subcutaneous injection site and models the events that a protein goes through as it transitions from a stabilized formulation environment to the dynamic physiological space. In this paper, we utilize the SCISSOR to probe for biophysical and chemical changes in seven mAbs post SC injection using a variety of analytical techniques. After 24 h, all mAbs demonstrated a relative decrease in conformational stability, an increase in fragmentation, and elevated acidic species. Higher order structure analysis revealed a deviation in the secondary structure from the standard and an increase in the number of unordered species. Our findings suggest an overall reduced stability of mAbs after subcutaneous administration. This reduced stability could have a potential impact on safety and efficacy. In vitro systems such as the SCISSOR combined with downstream analyses have potential to provide valuable information for assessing the suitability of lead molecules and aid in formulation design optimized for administration in the intended body compartment, thus improving chances of clinical success.