Parameterization of Physiologically Based Biopharmaceutics Models: Workshop Summary Report.

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.

Dibenzazepine-Loaded Nanoparticles Induce Local Browning of White Adipose Tissue to Counteract Obesity.

Inhibition of Notch signaling via systemic drug administration triggers conversion of white adipocytes into beige adipocytes (browning) and reduces adiposity. However, translation of this discovery into clinical practice is challenged by potential off-target side effects and lack of control over the location and temporal extent of beige adipocyte biogenesis. Here, we demonstrate an alternative approach to stimulate browning using nanoparticles (NPs) composed of FDA-approved poly(lactide-co-glycolide) that enable sustained local release of a Notch inhibitor (dibenzazepine, DBZ). These DBZ-loaded NPs support rapid cellular internalization and inhibit Notch signaling in adipocytes. Importantly, focal injection of these NPs into the inguinal white adipose tissue depots of diet-induced obese mice results in localized NP retention and browning of adipocytes, consequently improving the glucose homeostasis and attenuating body-weight gain of the treated mice. These findings offer new avenues to develop a potential therapeutic strategy for clinical treatment of obesity and its associated metabolic syndrome.

Tunable Drug Release Rate Using Modular Oral Dosage Forms.

Oral dosage forms with adjustable drug release profiles were prepared using progesterone (PGR) as a poorly-soluble model drug. The dosage forms were made as stack assemblies of functional modules. The modules were made as PGR-carrying HPMC films cut into wafer-like circular pieces. Two types of modules were used in the study; one exhibited comparatively fast drug release and the other slow release. The fast vs. slow release of each type of film utilized resulted from the grade of HPMC used in each case. Drug loading in the assembly was controlled through the total number of modules. By adjusting the proportions of the two types of modules, it is possible to fine-tune the drug release rate of the multi-layer assemblies to a wide range of profiles, bracketed between a high and low end, corresponding to the inherently fastest or slowest release obtainable with the specific materials and procedures employed. This procedure is suitable for adjusting the spring-and-parachute parameters for enhancing/optimizing the bioavailability of poorly-soluble drugs, and for developing patient-centric formulations.

Modular solid dosage form design - Application to pH-independent release of a weak-base API.

A novel approach to solid dosage form design is investigated, whereby instead of blending the ingredients and subsequently compacting the mixture, the dosage form is made by assembling prefabricated components, each with a specific function. The approach was used to formulate a weak-base API (active pharmaceutical ingredient), such that the modular dosage forms exhibited pH-independent drug release. Tablet-like dosage forms of ciprofloxacin (CPR), used as model weak-base drug, were prepared in order to generate dosage forms exhibiting pH-independent drug release. The dosage forms were made by assembling two types of prefabricated modules onto 3D stacks. The modules were hydroxypropyl methylcellulose circular film wafers, loaded with either CPR or citric acid (CA). CA-wafers served the function of pH-modifier modules in the microenvironment of the dosage form during the dissolution process. In vitro drug release from dosage forms consisting of CA- and CPR-wafers stacked in alternate sequence was compared with the release from assemblies containing CPR-wafers only, under pH = 1.2 and pH = 6.8 conditions. In the absence of CA-wafers, CPR release was ~25-fold slower at pH = 6.8 compared to pH = 1.2. Inclusion of CA-wafers in the dosage form assembly accelerated and decelerated drug release at pH = 6.8 and pH = 1.2, respectively, which resulted in overlapping drug release profiles under the two pH conditions. The two drug release profiles met the criteria for sameness as assessed by the f1 (difference) and f2 (similarity) factors. Modeling of drug release kinetics pointed toward polymer erosion as the primary mechanism of drug release for the overlapping pH = 1.2 and pH = 6.8 profiles. In terms of their drug release properties, the multi-modular dosage form assemblies exhibited the attributes and behavior of single bodies, rather than the combined contributions from multiple individually-operating modules. The initial geometry of the dosage form, characterized by the surface area (SA), volume (V) and SA/V ratio accounted for drug release kinetics in the same fashion as for traditional tablet compacts.

Nanoparticle-Mediated Inhibition of Notch Signaling Promotes Mitochondrial Biogenesis and Reduces Subcutaneous Adipose Tissue Expansion in Pigs.

Inhibition of Notch signaling has been shown to induce white to beige transformation of adipocytes and reduce the risk of obesity in mice. However, it remains unknown whether the metabolic benefits of Notch inhibition are dependent on uncoupling protein 1 (UCP1)-mediated thermogenesis and evolutionarily relevant in other mammalian species. Here we report the effect of Notch inhibition in adipocytes of pigs, which lost the UCP1 gene during evolution. Notch inhibition using a γ-secretase inhibitor dibenzazepine (DBZ) promoted beige adipogenesis and mitochondrial biogenic gene expression in porcine adipocytes. Moreover, encapsulation of DBZ into poly(lactide-co-glycolide) nanoparticles enabled rapid cellular internalization and enhanced bioactivity to achieve sustained Notch inhibition, thereby inducing beige-specific gene expression and reducing subcutaneous adipose tissue expansion in pigs. These results demonstrate for the first time a role of Notch signaling in regulating adipose plasticity in large animals, highlighting the therapeutic potential of targeting Notch signaling in obesity treatment.

Biodegradable Polymeric Microsphere-Based Drug Delivery for Inductive Browning of Fat.

Brown and beige adipocytes are potent therapeutic agents to increase energy expenditure and reduce risks of obesity and its affiliated metabolic symptoms. One strategy to increase beige adipocyte content is through inhibition of the evolutionarily conserved Notch signaling pathway. However, systemic delivery of Notch inhibitors is associated with off-target effects and multiple dosages of application further faces technical and translational challenges. Here, we report the development of a biodegradable polymeric microsphere-based drug delivery system for sustained, local release of a Notch inhibitor, DBZ. The microsphere-based delivery system was fabricated and optimized using an emulsion/solvent evaporation technique to encapsulate DBZ into poly(lactide-co-glycolide) (PLGA), a commonly used biodegradable polymer for controlled drug release. Release studies revealed the ability of PLGA microspheres to release DBZ in a sustained manner. Co-culture of white adipocytes with and without DBZ-loaded PLGA microspheres demonstrated that the released DBZ retained its bioactivity, and effectively inhibited Notch and promoted browning of white adipocytes. Injection of these DBZ-loaded PLGA microspheres into mouse inguinal white adipose tissue depots resulted in browning in vivo. Our results provide the encouraging proof-of-principle evidence for the application of biodegradable polymers as a controlled release platform for delivery of browning factors, and pave the way for development of new translational therapeutic strategies for treatment of obesity.