(W1130-07-41) Biorelevant Dissolution Testing for Protein-Based Amorphous Solid Dispersions: Improving In Vitro Formulation Ranking

Purpose: Dissolution testing is crucial for performance monitoring throughout product development stages. It offers valuable insights into drug release profiles that may be leveraged for in vitro-in vivo correlations (IVIVC) (Shah et al., 2022; Tsume et al., 2023). Predicting in vivo performance is of utmost importance in drug development aiming at formulation ranking and support development decisions (Tsume et al., 2023). New methodologies in bio predictive dissolution have been devised to comprehensively assess the performance of oral dosage forms in vivo. By integrating these methodologies with simulation tools, it becomes possible to forecast human plasma profiles (Tsume et al., 2023). The proxy of these methodologies is to simulate the physiological conditions of the gastrointestinal tract, thereby enhancing our comprehension of drug dissolution and absorption kinetics. By providing a better mimic of drug release and dissolution under physiological circumstances, these methods facilitate formulation optimization and contribute to the assessment of bioequivalence (Lex et al., 2022; Shah et al., 2022; Wu et al., 2023). Enabling the prediction and comprehension of in vivo performance is inherently complex, as it involves various factors such as the selection of suitable media, components, physiological considerations, and the inclusion of fasted and fed conditions during experimental design. Nonetheless, the challenge lies in the fact that these media often lack physiological relevance depending on the formulation carrier used for solubility enhancement, frequently leading to unreliable results. Consequently, this limitation hampers accurate predictions of in vivo performance (Shah et al., 2022). As research in this field continues to advance, the development of even more sophisticated, fit for purpose biorelevant dissolution methods is anticipated, enhancing our understanding of oral drug behavior, and improving drug development processes. This challenge is particularly noticeable for formulations containing alternative excipients for amorphous solid dispersions (ASDs) and oral biologics.  As interest in biologics and the use of natural carriers like proteins, polysaccharides, and lipid-based additives continues to rise, it is imperative to devise dissolution methods that accurately emulate the physiological conditions of the gastrointestinal tract (Pas et al., 2017). The oral administration of drugs formulated with natural carriers presents a challenge concerning the potential degradation of these carriers within the gastrointestinal tract. The in vivo performance of such formulations greatly depends on various factors, including digestion, absorption, and bioavailability. In this work, a fit-for-purpose biorelevant dissolution method that captures the impact of digestion in solubility enhancement by ASDs using alternative excipients as well as oral bioavailability of biologics will be discussed in detail.

Methods: The performance of ASDs was tested using an USP apparatus II (Copley Scientific, United Kingdom) (100 rpm, at 37 ± 0.5 °C) with 1 L vessels. The dissolution was performed in non-sink conditions as the amount of ASD was weighted to maintain the daily dose of target model API. A pH shift method was used, from FaSSGF medium (pH 1.6) to FaSSIF medium (pH 6.5) which was spiked with gastric pepsin and pancreatin, respectively. At different time points, 5 mL of solution was withdrawn from the vessel from which 2 mL was centrifuged (MiniSpin, Eppendorf,Germany) for 5 min at 13,400 rpm to separate the undissolved material. At 30, 50, 120, and 240 min, an additional 1 mL aliquot was ultra-centrifuged (Optima MAX-XP, Beckman Coulter, USA) for 20 min at 300,000g to separate the free dissolved drug from the solid material and the drug in colloids. The supernatant was diluted in a relevant solvent for API quantification by HPLC. The method was applied to real samples and for the purpose, SD prototyping of natural-based ASD formulations was conducted using a Buchi B290 (Buchi, CH). Spray dried intermediates underwent a 24h post-drying process using a vacuum tray oven. SD prototypes were also characterized for physical stability by differential scanning calorimetry (DSC) regarding their thermal transitions (e.g. glass transition (Tg) and melting temperatures (Tm)) and their molecular arrangement was studied by x-ray powder diffraction (XRPD).

Results: The inclusion of enzymes pepsin and pancreatin was successfully achieved by fine-tuning media composition (e.g. salt composition, pH controlling during medium transition phase), preserving enzyme activity in a right first-time approach – Figure 1. Application of the newly-developed method to spray dried dispersions with different types of protein-based carriers with model small molecule APIs and lysozyme active formulations is currently ongoing. Results and how formulation ranking is impacted by protein digestion will be described in detail during this poster presentation. Samples with lipidic excipients will also be included to validate the impact lipases in in vitro bioavailability assessment of these formulations.

Conclusion: This works represents one step further improving current in vitro methodologies to predict and guide formulation design towards lowering the number of formulations needing animal studies. Additionally, this method is a better mimetic to physiological conditions not only for ASDs based on natural based carriers but also to predict bioavailability hurdles for active biologics.

References: Lex TR, Rodriguez JD, Zhang L, Jiang W, Gao Z. (2022). Development of In Vitro Dissolution Testing Methods to Simulate Fed Conditions for Immediate Release Solid Oral Dosage Forms. AAPS J. 11;24(2):40.
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SDS-PAGE gel of pepsin’s activity in FaSSGF. Molecular weight standard (lane 1), FaSSGF (lane 2), BSA (lane 3), pepsin (lane 4), samples at timepoints 0, 10, 20, 30 min (lanes 5-8).