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This report summarizes the proceedings for Day 3 of the workshop titled " Physiologically Based Biopharmaceutics Modeling (PBBM) Best Practices for Drug Product Quality: Regulatory and Industry Perspectives ". This day focused on the current and future drug product quality applications of PBBM from the innovator and generic industries as well as the regulatory agencies perspectives. The presentations, which included several case studies, covered the applications of PBBM in generic drug product development, applications of virtual bioequivalence trials to support formulation bridging and the utility of absorption modeling in clinical pharmacology assessments. In addition, recent progress in the prediction of colon absorption and in vivo performance of extended-release drug products was shared. The morning session was concluded by representatives from FDA, ANVISA, MHRA, Health Canada, EMA, and PMDA giving their perspectives on the application of PBBM in regulatory submissions. The afternoon breakout sessions focused on four parallel topics: 1) PBBM in generic drug product development; 2) virtual bioequivalence trials applications; 3) safe space and extrapolation; and 4) regional absorption and modified release PBBM applications. This allowed the participants to engage in in-depth discussions of best practices as well to identify key points of consideration to allow further progress on the applications of PBBM.

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.

This Article shares the proceedings from the August 29th, 2023 (day 1) workshop "Physiologically Based Biopharmaceutics Modeling (PBBM) Best Practices for Drug Product Quality: Regulatory and Industry Perspectives". The focus of the day was on model parametrization; regulatory authorities from Canada, the USA, Sweden, Belgium, and Norway presented their views on PBBM case studies submitted by industry members of the IQ consortium. The presentations shared key questions raised by regulators during the mock exercise, regarding the PBBM input parameters and their justification. These presentations also shed light on the regulatory assessment processes, content, and format requirements for future PBBM regulatory submissions. In addition, the day 1 breakout presentations and discussions gave the opportunity to share best practices around key questions faced by scientists when parametrizing PBBMs. Key questions included measurement and integration of drug substance solubility for crystalline vs amorphous drugs; impact of excipients on apparent drug solubility/supersaturation; modeling of acid-base reactions at the surface of the dissolving drug; choice of dissolution methods according to the formulation and drug properties with a view to predict the in vivo performance; mechanistic modeling of in vitro product dissolution data to predict in vivo dissolution for various patient populations/species; best practices for characterization of drug precipitation from simple or complex formulations and integration of the data in PBBM; incorporation of drug permeability into PBBM for various routes of uptake and prediction of permeability along the GI tract.

Physiologically based biopharmaceutics modeling (PBBM) is used to elevate drug product quality by providing a more accurate and holistic understanding of how drugs interact with the human body. These models are based on the integration of physiological, pharmacological, and pharmaceutical data to simulate and predict drug behavior in vivo. Effective utilization of PBBM requires a consistent approach to model development, verification, validation, and application. Currently, only one country has a draft guidance document for PBBM, whereas other major regulatory authorities have had limited experience with the review of PBBM. To address this gap, industry submitted confidential PBBM case studies to be reviewed by the regulatory agencies; software companies committed to training. PBBM cases were independently and collaboratively discussed by regulators, and academic colleagues participated in some of the discussions. Successful bioequivalence "safe space" industry case examples are also presented. Overall, six regulatory agencies were involved in the case study exercises, including ANVISA, FDA, Health Canada, MHRA, PMDA, and EMA (experts from Belgium, Germany, Norway, Portugal, Spain, and Sweden), and we believe this is the first time such a collaboration has taken place. The outcomes were presented at this workshop, together with a participant survey on the utility and experience with PBBM submissions, to discuss the best scientific practices for developing, validating, and applying PBBMs. The PBBM case studies enabled industry to receive constructive feedback from global regulators and highlighted clear direction for future PBBM submissions for regulatory consideration.

Stress testing (also known as forced degradation) of pharmaceutical products has long been recognized as a critical part of the drug development process, providing foundational information related to intrinsic stability characteristics and to the development of stability-indicating analytical methods. A benchmarking study was undertaken by nine pharmaceutical companies and the Brazilian Health Regulatory Agency (Agência Nacional de Vigilância Sanitária, or ANVISA) with a goal of understanding the utility of various stress testing conditions for producing pharmaceutically-relevant chemical degradation of drugs. Special consideration was given to determining whether solution phase stress testing of solid drug products produced degradation products that were both unique when compared to other stress conditions and relevant to the formal drug product stability data. The results from studies of 62 solid dosage form drug products were compiled.  A total of 387 degradation products were reported as being observed in stress testing studies, along with 173 degradation products observed in accelerated and/or long-term stability studies for the 62 drug products.  Among these, 25 of the stress testing degradation products were unique to the solution phase stress testing of the drug products; however, none of these unique degradation products were relevant to the formal stability data. The relevant degradation products were sufficiently accounted for by stress testing studies that included only drug substance stressing (in solution and in the solid state) and drug product stressing (in the solid state). Based on these results, it is the opinion of the authors that for solid dosage form drug products, well-designed stress testing studies need not include solution phase stress testing of the drug product in order to be comprehensive., (Copyright © 2021 American Pharmacists Association. Published by Elsevier Inc. All rights reserved.)

This report summarizes the proceedings for Day 3 of the workshop titled "Current State and Future Expectations of Translational Modeling Strategies toSupportDrug Product Development, Manufacturing Changes and Controls". From a drug product quality perspective, patient-centric product development necessitates the development of clinically relevant drug product specifications (CRDPS). In this regard, Physiologically Based Biopharmaceutics modeling (PBBM) is a viable tool to establish links between in-vitro to in-vivo data, and support with establishing CRDPS. The theme of day 3 was practical applications of PBBM to support drug product quality. In this manuscript, case studies from US FDA, EMA and pharmaceutical industry on applications of PBBM in drug product quality are summarized which include 1) regulatory agency's perspectives on establishing the safe space and achieving study waivers, 2) model-informed risk assessment on the effects of acid reducing agents, bridging of dissolution methods, food effect, and formulation selection, and 3) understanding clinical formulation performance. Breakout session discussions focused on four topics - 1) terminologies related to physiologically based modeling in support of drug product quality, 2) regulatory harmonization on evidentiary standards, 3) CRDPS approaches and 4) bridging between biorelevant and quality control (QC) dissolution methods., (Copyright © 2020 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

A new technique has been developed to calculate rapidly the solid-state room-temperature degradation rate of drugs and drug candidates. The technique utilizes measurements of the initial rate of heat output at several elevated temperatures by isothermal calorimetry and the degradation rate of the compound determined at a single elevated temperature by chromatography. The activation energies and degradation rates at 25 degrees C calculated by conventional methods and by isothermal calorimetry are compared and discussed. The compounds studied were phenytoin, triamterene, digoxin, tetracycline, theophylline, diltiazem, and several proprietary ICI compounds.

The authors have studied 89 depressed patients diagnosed according to three different systems: DSM-III, Kiloh and Garside, Winokur. They administered 1 mg of Dexamethasone at 11 pm; blood samples were taken at 8 am and 8 pm the next day. They find the most significant differences in cortisol levels according to the DSM classification whereas there are no significant differences according to the Winokur classification. They refer the great variance obtained in the endogenous groups to a high incidence of suppressors in these non-suppressor groups. In 26 non-depressed patients, they found 10 non-suppressors. According to the authors, these results demonstrate the importance of DST and other biological tests in the reformation of nosology in psychiatry.