PBBM Considerations for Base Models, Model Validation, and Application Steps: Workshop Summary Report.

The proceedings from the 30th August 2023 (Day 2) of the workshop "Physiologically Based Biopharmaceutics Models (PBBM) Best Practices for Drug Product Quality: Regulatory and Industry Perspectives" are provided herein. Day 2 covered PBBM case studies from six regulatory authorities which provided considerations for model verification, validation, and application based on the context of use (COU) of the model. PBBM case studies to define critical material attribute (CMA) specification settings, such as active pharmaceutical ingredient (API) particle size distributions (PSDs) were shared. PBBM case studies to define critical quality attributes (CQAs) such as the dissolution specification setting or to define the bioequivalence safe space were also discussed. Examples of PBBM using the credibility assessment framework, COU and model risk assessment, as well as scientific learnings from PBBM case studies are provided. Breakout session discussions highlighted current trends and barriers to application of PBBMs including: (a) PBBM credibility assessment framework and level of validation, (b) use of disposition parameters in PBBM and points to consider when iv data are not available, (c) conducting virtual bioequivalence trials and dealing with variability, (d) model acceptance criteria, and (e) application of PBBMs for establishing safe space and failure edges.

Role of Physiologically Based Biopharmaceutics Modeling (PBBM) in Fed Bioequivalence Study Waivers: Regulatory Outlook, Case Studies and Future Perspectives.

Over the past few decades, physiologically based biopharmaceutics modeling (PBBM) has demonstrated its utility in both new drug and generic product development. Applications of PBBM for fed bioequivalence study waivers is an upcoming area. Recently Innovation & Quality (IQ) consortium demonstrated utility of PBBM to avoid repeat food effect studies for new drugs. In the similar lines, the current manuscript aims to discuss role of PBBM in generic fed bioequivalence study waivers. Generic industry practices related to PBBM model development to predict fed bioequivalence was portrayed with special emphasis on fed bio-predictive media. Media that can simulate fed bioequivalence study outcome were discussed from practical perspective. In-depth analysis, collating the data from 36 products was performed to understand predictability of PBBM for fed bioequivalence. Cases where PBBM was successful to predict fed bioequivalence was correlated with BCS class, formulation category and type of food effect. Further, two case studies were presented wherein fed bioequivalence study waiver obtained with PBBM approach. Lastly, future direction in terms of fed bioequivalence study waivers, regulatory perspectives and best practices for PBBM were portrayed. Overall, this article paves a way to utilize PBBM for generic fed bioequivalence study waivers.

Physiologically Based Pharmacokinetics Modeling in Biopharmaceutics: Case Studies for Establishing the Bioequivalence Safe Space for Innovator and Generic Drugs.

For successful oral drug development, defining a bioequivalence (BE) safe space is critical for the identification of newer bioequivalent formulations or for setting of clinically relevant in vitro specifications to ensure drug product quality. By definition, the safe space delineates the dissolution profile boundaries or other drug product quality attributes, within which the drug product variants are anticipated to be bioequivalent. Defining a BE safe space with physiologically based biopharmaceutics model (PBBM) allows the establishment of mechanistic in vitro and in vivo relationships (IVIVR) to better understand absorption mechanism and critical bioavailability attributes (CBA). Detailed case studies on how to use PBBM to establish a BE safe space for both innovator and generic drugs are described. New case studies and literature examples demonstrate BE safe space applications such as how to set in vitro dissolution/particle size distribution (PSD) specifications, widen dissolution specification to supersede f2 tests, or application toward a scale-up and post-approval changes (SUPAC) biowaiver. A workflow for detailed PBBM set-up and common clinical study data requirements to establish the safe space and knowledge space are discussed. Approaches to model in vitro dissolution profiles i.e. the diffusion layer model (DLM), Takano and Johnson models or the fitted PSD and Weibull function are described with a decision tree. The conduct of parameter sensitivity analyses on kinetic dissolution parameters for safe space and virtual bioequivalence (VBE) modeling for innovator and generic drugs are shared. The necessity for biopredictive dissolution method development and challenges with PBBM development and acceptance criteria are described.

NFAT inhibitor tributylhexadecylphosphoniumbromide, ameliorates high fructose induced insulin resistance and nephropathy.

High fructose diet (HFrD)-induced insulin resistance (IR) has been reported to be associated with an increase in albuminuria, glomerular hypertrophy and inflammation in kidney. However, the molecular mechanisms associated with high fructose-induced IR and renal dysfunction are still unclear. In the present study, we have investigated the role of nuclear factor of activated T-cell (NFAT) and its inhibitor, Tributylhexadecylphosphoniumbromide (THPB) in high fructose-induced IR and renal injury. NFAT inhibition by THPB treatment significantly improved HFrD-induced insulin resistance. Treatment with THPB markedly reduced high fructose diet-induced protein expression of NFATc4, PTEN and also alleviated expression of inflammatory markers in kidneys of HFrD rats. Further, THPB treatment not only improved acute ANG II responses but also repressed the processes of renal fibrosis, ECM accumulation, foot process effacement and renal apoptosis in HFrD rats. Taken together, we for the first time provide evidence that HFrD -induced insulin resistance and renal injury is associated with dysregulated NFATc4/PTEN signalling and THPB prevents this dysregulation through inhibition of NFATc4. Thus, targeting NFATc4 can be a novel therapeutic approach for preventing HFrD induced- IR and renal injury.

Tissue specific up regulation of ACE2 in rabbit model of atherosclerosis by atorvastatin: role of epigenetic histone modifications.

Growing body of evidence points out the crucial role of ACE2 in preventing atherosclerosis. However, data on how atherosclerosis affects ACE2 expression in heart and kidney remains unknown. Atherosclerosis was induced by feeding New Zealand White rabbits with high cholesterol diet (HCD - 2%) for 12 weeks and atorvastatin was administered (5mg/kg/day p.o) in last 3 weeks. ACE2 mRNA and protein expression was assessed by Western blotting and real time PCR. HCD fed rabbits developed atherosclerosis as confirmed by increase in plasma total cholesterol, LDL and triglycerides as well as formation atherosclerotic plaques in arch of aorta. The ACE2 protein but not mRNA expression was reduced in heart and kidney of HCD rabbits. Interestingly, atorvastatin increased the ACE2 protein expression in heart and kidney of HCD rabbits. However, atorvastatin increased ACE2 mRNA in heart but not in kidney of HCD rabbits. Atorvastatin increased the occupancy of histone H3 acetylation (H3-Ac) mark on ACE2 promoter region in heart of HCD rabbits indicating direct or indirect epigenetic up-regulation of ACE2 by atorvastatin. Further, atorvastatin suppressed Ang II-induced contractile responses and enhanced AT2 receptor mediated relaxant responses in atherosclerotic aorta. We propose that atherosclerosis is associated with reduced ACE2 expression in heart and kidney. We also show an unexplored potential of atorvastatin to up-regulate ACE2 via epigenetic histone modifications. Our data suggest a novel way of replenishing ACE2 expression for preventing not only atherosclerosis but also other cardiovascular disorders.