Increasing the Robustness of Biopharmaceutical Precipitation Assays - Part II: Recommendations on the use of FaSSIF

Self-Emulsifying delivery systems for oral administration of exenatide: Hydrophobic ion pairs vs. Dry reverse micelles

This research provides a comparative analysis of two innovative strategies - hydrophobic ion pairing (HIP) and dry reverse micelles (dRM) - to enhance the oral bioavailability of exenatide, a GLP-1 receptor agonist, as a diabetes treatment. These techniques were integrated into self-emulsifying drug delivery systems (SEDDS) featuring a lipid matrix composed of propylene glycol dilaurate and salicylic acid methyl ester (32.5 %:32.5 %; v/v) with polyethoxylated-35 castor oil (35 %; v/v) as surfactant. HIP enhances the lipophilicity of exenatide through ion-pairing with cationic surfactants, thereby promoting efficient incorporation into the lipid matrix of SEDDS. In contrast, dRM forms stabilized micellar structures using sorbitan monooleate, improving safety and compatibility. The droplet sizes for SEDDS were analyzed via dynamic light scattering and varied from 95 to 110 nm, with a polydispersity index of approximately 0.25, and zeta potentials between -1 mV and -6 mV. The maximum log DSEDDS/AQ values were 2.13 ± 0.31 for exenatide-loaded HIPs (ExeHIP) and 2.05 ± 0.08 for exenatide-loaded dRM (ExedRM), indicating sufficient lipophilicity, which is crucial for effective absorption and bioavailability. Toxicological assessments showed low toxicity levels. In vivo studies indicated a relative bioavailability of 18.08 % for ExeHIP and 17.06 % for ExedRM compared to intravenous injection. Both strategies demonstrated a similar potential in relative bioavailability, reflecting a significant increase in bioavailability compared to the control. Notably, the HIP formulation provided better control over exenatide release and ensured stable GLP-1 levels, while dRMs are preferable for safety reasons as all excipients have GRAS status and are therefore FDA approved.

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.

Dissolution Behavior of Weakly Basic Pharmaceuticals from Amorphous Dispersions Stabilized by a Poly(dimethylaminoethyl Methacrylate) Copolymer

Amorphous solid dispersions (ASDs) are a well-documented formulation approach to improve the rate and extent of dissolution for hydrophobic pharmaceuticals. However, weakly basic compounds can complicate standard approaches to ASDs due to pH-dependent solubility, resulting in uncontrolled drug release in gastric conditions and unstabilized supersaturated solutions prone to precipitation at neutral pH. This work examines the release mechanisms of amorphous dispersions containing model weakly basic pharmaceuticals posaconazole and lumefantrine from a basic poly(dimethylaminoethyl methacrylate) copolymer (Eudragit EPO) and compares their dissolution behavior with ASDs stabilized by acidic and neutral polymers to understand potential benefits to release from a basic polymeric stabilizer. It was found that dissolution of Eudragit EPO ASDs resulted in supersaturation under gastric conditions, which could be sustained upon adjustment to neutral pH. However, the dissolution behavior of Eudragit EPO ASDs was sensitive to the initial pH of the gastric media. For lumefantrine, elevated initial gastric pH resulted in precipitation of amorphous nanoparticles; for posaconazole, elevated gastric pH led to crystallization of the pharmaceutical from solution. This sensitivity to gastric pH was found to originate from the impact of Eudragit EPO on gastric pH and the solubility of each pharmaceutical in the first stage of dissolution. In total, these data illustrate benefits and liabilities for the use of Eudragit EPO for ASDs containing weak pharmaceutical bases to guide the design of robust pharmaceutical formulations.