Assessing mass balance in pharmaceutical drug products: New insights into an old topic

Biodegradation of acetaminophen: Current knowledge and future directions with mechanistic insights from omics

Acetaminophen (APAP), one of the most frequently used antipyretic and analgesic medications, has recently grown into a persistent organic contaminant of emerging concern due to its over-the-counter and widespread use. The excessive accumulation of APAP and its derivatives in various environmental matrices is threatening human health and the ecosystem. The complexity of APAP and its intermediates augments the need for adequate innovative and sustainable strategies for the remediation of contaminated environments. Bioremediation serves as an efficient, eco-friendly, cost-effective, and sustainable approach to mitigate the toxic impacts of APAP. The present review provides comprehensive insights into the ecotoxicity of APAP, its complex biodegradation pathways, and the various factors influencing biodegradation. The omics approaches viz., genomics/metagenomics, transcriptomics/metatranscriptomics, proteomics, and metabolomics have emerged as powerful tools for understanding the diverse APAP-degraders, degradation-associated genes, enzymatic pathways, and metabolites. The outcomes revealed amidases, deaminases, oxygenases, and dioxygenases as the lead enzymes mediating degradation via 4-aminophenol, hydroquinone, hydroxyquinol, 3-hydroxy-cis, cis-muconate, etc. as the major intermediates. Overall, a holistic approach with the amalgamation of omics aspects would accelerate the bioaugmentation processes and play a significant role in formulating strategies for remediating and reducing the heavy loads of acetaminophen from the environmental matrices.

Mass balance analysis for therapeutic peptides: Case studies, applications, and perspectives

The concept of mass balance is discussed as it pertains to the pharmaceutical development of therapeutic peptides. Case studies are presented demonstrating how to perform a mass balance assessment on solid drug substance and solution drug product, and the role of mass balance in the context of the overall product control strategy is discussed. Utilizing mass balance as a specification test where the result is calculated from other critical quality attribute tests, each with their own specification, offers little value as a formalized quality acceptance criterion and may create more deviations, non-value added investigations, and potential batch failures. While useful in characterizing the performance of analytical methods and as part of a rigorous understanding of the manufacturing process and control strategy development, mass balance should not be required as a specification control and should instead be demonstrated during method development and through well-designed forced degradation experiments. Analytical method variability is discussed in relation to the analytical target profile, and the overall impact of sources of variability on the mass balance calculation is described in support of this position.

Nymphaea alba leaf powder effectiveness in removing nisin from fermentation broth using docking and experimental analysis

The accumulation of nisin in the fermentation medium can reduce the process's productivity. This research studied the potential of Nymphaea alba leaf powder (NALP) as a hydrophobic biosorbent for efficient in-situ nisin adsorption from the fermentation medium by docking and experimental analysis. Molecular docking analysis showed that di-galloyl ellagic acid, a phytochemical compound found in N. alba, had the highest affinity towards nisin. Enhancements in nisin adsorption were seen following pre-treatment of NAPL with HCl and MgCl2. A logistic growth model was employed to evaluate the growth dynamics of the biosorption capacity, offering valuable insights for process scalability. Furthermore, optimization through Response Surface Methodology elucidated optimal nisin desorption conditions by Liebig's law of the minimum, which posits that the scarcest resource governs production efficiency. Fourier Transform Infrared (FTIR) spectroscopy pinpointed vital functional groups involved in biosorption. Scanning electron microscopy revealed the changing physical characteristics of the biosorbent after exposure to nisin. The findings designate NALP as a feasible adsorbent for nisin removal from the fermentation broth, thus facilitating its application in the purification of other biotechnological products based on growth and production optimization principles.

Mass Balance in Pharmaceutical Stress Testing: A Review of Principles and Practical Applications

Stress testing (also known as forced degradation) of pharmaceutical drug substances and products is a critical part of the drug development process, providing insight into the degradation pathways of drug substances and drug products. This information is used to support the development of stability-indicating methods (SIMs) capable of detecting pharmaceutically relevant degradation products that might potentially be observed during manufacturing, long-term storage, distribution, and use. Assessing mass balance of stressed samples is a key aspect of developing SIMs and is a regulatory expectation. However, the approaches to measure, calculate, and interpret mass balance can vary among different pharmaceutical companies. Such disparities also pose difficulties for health authorities when reviewing mass balance assessments, which may result in the potential delay of drug application approvals. The authors have gathered input from 10 pharma companies to map out a practical review of science-based approaches and technical details to assess and interpret mass balance results. Key concepts of mass balance are introduced, various mass balance calculations are demonstrated, and recommendations on how to investigate poor mass balance results are presented using real-world case studies. Herein we provide a single source reference on the topic of mass balance in pharmaceutical forced degradation for small molecule drug substances and drug products in support of regulatory submissions with the goal of facilitating a shared understanding among pharmaceutical scientists and health authorities.

A strategic approach towards mass balance investigations in pharmaceutical drug substance release testing: A peculiar out of specification case study encountered during API manufacture

Mass balance in drug substances release testing is a critical quality attribute in pharmaceutical manufacturing that continues to challenge modern analytical characterization. This specific perspective of mass balance is lacking in literature, and the following work addresses the knowledge gap related to this topic by examining an in-depth case study and detailing the systematic investigation into mass imbalance observed during release testing of a small molecule API. The process followed a logical stepwise progression beginning with most probable causes and expanded to more obscure causes that require a deeper examination of the API in question until the undetected impurity in question was finally identified. The discovered impurity was eventually found to be formed from a unique side reaction that led to the formation of API-related oligomer impurities, which had eluded conventional small molecule release testing strategies. Ultimately, the characterization gap was traced back to deficiency in the LC results of the developed API purity methods. More importantly, this gap provides an ideal opportunity to highlight common oversights and pitfalls encountered in early phase pharmaceutical development especially as it relates to the method development of truly representative chromatography methods in the API characterization. The work reflects on the key lessons learned from the highlighted pitfalls that were encountered in this case study and offers strategic insights to guide and to improve the development workflow for drug substance characterization strategies.

Pharmaceutical Forced Degradation (Stress Testing) Endpoints: A Scientific Rationale and Industry Perspective

Forced degradation (i.e., stress testing) of small molecule drug substances and products is a critical part of the drug development process, providing insight into the intrinsic stability of a drug that is foundational to the development and validation of stability-indicating analytical methods. There is a lack of clarity in the scientific literature and regulatory guidance as to what constitutes an "appropriate" endpoint to a set of stress experiments. That is, there is no clear agreement regarding how to determine if a sample has been sufficiently stressed. Notably, it is unclear what represents a suitable justification for declaring a drug substance (DS) or drug product (DP) "stable" to a specific forced degradation condition. To address these concerns and to ensure all pharmaceutically-relevant, potential degradation pathways have been suitably evaluated, we introduce a two-endpoint classification designation supported by experimental data. These two endpoints are 1) a % total degradation target outcome (e.g., for "reactive" drugs) or, 2) a specified amount of stress, even in the absence of any degradation (e.g., for "stable" drugs). These recommended endpoints are based on a review of the scientific literature, regulatory guidance, and a forced degradation data set from ten global pharmaceutical companies. The experimental data set, derived from the Campbell et al. (2022) benchmarking study,1 provides justification for the recommendations. Herein we provide a single source reference for small molecule DS and DP forced degradation stress conditions and endpoint best practices to support regulatory submissions (e.g., marketing applications). Application of these forced degradation conditions and endpoints, as part of a well-designed, comprehensive and a sufficiently rigorous study plan that includes both the DS and DP, provides comprehensive coverage of pharmaceutically-relevant degradation and avoids unreasonably extreme stress conditions and drastic endpoint recommendations sometimes found in the literature.

Analysis of unstable degradation impurities of a benzodiazepine and their quantification without isolation using multiple linear regression

This manuscript presents a novel methodology for calculating the relative response factors (RRFs) of unstable degradation impurities of molibresib (1). The degradation impurities were observed by HPLC during stress testing and were accompanied by large mass balance deficits. However, the impurities could not be isolated for traditional RRF determination due to their instability. The RRFs of two degradation impurities were determined without isolation by multiple linear regression analysis of HPLC-UV data. The results permitted accurate quantification of the degradants. The benefits and drawbacks of the approach are discussed, including suggested validation acceptance criteria.