Mechanisms of Drug Solubility Enhancement Induced by β-Lactoglobulin-Based Amorphous Solid Dispersions

Surface Solid Dispersion of Ketoconazole on Trehalose Dihydrate using Spray Drying to Achieve Enhanced Dissolution Rate

Ketoconazole (K) is a poorly water-soluble drug that faces significant challenges in achieving therapeutic efficacy. This study aimed to enhance the dissolution rate of ketoconazole by depositing spray-dried ketoconazole (SK) onto the surface of ground trehalose dihydrate (T) using spray drying. Ketoconazole-trehalose surface solid dispersions (SKTs) were prepared in ratios of 1:1 (SK1T1), 1:4 (SK1T4), and 1:10 (SK1T10), and characterized them using particle size analysis, scanning electron microscopy, powder X-ray diffraction, and in vitro dissolution studies. Results showed that the dissolution rates of the dispersions were significantly higher than those of pure ketoconazole, with the 1:10 ratio showing the highest dissolution rate. The improved dissolution was attributed to the formation of a new crystalline phase and better dispersion of ketoconazole particles. These findings suggest that the surface solid dispersion approach could be a valuable method for enhancing the bioavailability of poorly water-soluble drugs.

β-Lactoglobulin-based amorphous solid dispersions: A graphical review on the state-of-the-art

Proteins have recently caught attention as potential excipients for amorphous solid dispersions (ASDs) to improve oral bioavailability of poorly water-soluble drugs. Notably, the studies have highlighted whey protein isolates, particularly β-lactoglobulin (BLG), as promising candidates in amorphous stabilization, dissolution and solubility enhancement, achieving drug loadings of 50 wt% and higher. Consequently, investigations into the mechanisms underlying the solid-state stabilization of amorphous drugs and the enhancement of drug solubility in solution have been conducted. This graphical review provides a comprehensive overview of recent findings concerning BLG-based ASDs. Firstly, the dissolution performance of BLG-based ASDs is compared to more traditional polymer-based ASDs. Secondly, the drug loading onto BLG and the resulting amorphous stabilization mechanisms is summarized. Thirdly, interactions between BLG and drug molecules in solution are described as the mechanisms governing the improvement of drug solubility. Lastly, we outline the impact of the spray drying process on the secondary structure of BLG, and the resulting differences in amorphous stabilization and drug dissolution performance between α-helix-rich and β-sheet-rich BLG-based ASDs.

Exploring the effect of protein secondary structure on the solid state and physical stability of protein-based amorphous solid dispersions

Amorphous solid dispersions (ASDs) using proteins as carriers have emerged as a promising strategy for stabilizing amorphous drug molecules. Proteins possess diverse three-dimensional structures that significantly influence their own properties and may also impact the properties of ASDs. We prepared β-lactoglobulin (BLG) with different contents of β-sheet and α-helical secondary structures by initially dissolving BLG in different mixed solvents, containing different ratios of water, methanol/ethanol, and acetic acid, followed by spray drying of the solutions. Our findings revealed that an increase in α-helical content resulted in a decrease in the glass transition temperature (Tg) of the protein. Subsequently, we utilized the corresponding mixed solvents to dissolve both BLG and the model drug celecoxib (CEL), allowing the preparation of ASDs containing either β-sheet-rich or α-helix/random coil-rich BLG. Using spray drying, we successfully developed BLG-based ASDs with drug loadings ranging from 10 wt% to 90 wt%. At drug loadings below 40 wt%, samples prepared using both methods exhibited single-phase ASDs. However, heterogeneous systems formed when the drug loading exceeded 40 wt%. At higher drug loadings, physical stability assessments demonstrated that the α-helix/random coil-rich BLG structure exerted a more pronounced stabilizing effect on the drug-rich phase compared to the β-sheet-rich BLG. Overall, our results highlight the importance of considering protein secondary structure in the design of ASDs.

Investigating the influence of protein secondary structure on the dissolution behavior of β-lactoglobulin-based amorphous solid dispersions

Proteins acting as carriers in amorphous solid dispersions (ASDs) demonstrate a notable sensitivity to the spray drying process, potentially leading to changes in their conformation. The main aim of this study was to investigate the dissolution performance of ASDs based on proteins with different content of secondary structures, specifically β-sheet and α-helix structures. We prepared β-sheet-rich and α-helix-rich β-lactoglobulin (BLG), along with corresponding ASDs containing 10 wt% and 30 wt% drug loadings, through spray drying using celecoxib as the model drug. Circular dichroism and Fourier Transform Infrared Spectroscopy results revealed that even though changes in secondary structure were obtained in the spray-dried powders, the BLGs exhibited reversibility upon re-dissolving in phosphate buffer with varying pH levels. Both β-sheet-rich BLG and α-helix-rich BLG exhibited enhanced dissolution rates and higher solubility in the media with pH values far from the isoelectric point (pI) of BLG (pH 2, 7, 8, and 9) compared to the pH closer to the pI (pH 3, 4, 5, and 6). Notably, the release rate and solubility of the drug and BLG from both types of BLG-based ASDs at 10 wt% drug loading were largely dependent on the solubility of pure SD-BLGs. α-helix-rich BLG-ASDs consistently exhibited equivalent or superior performance to β-sheet-rich BLG-ASDs in terms of drug release rate and solubility, regardless of drug loading. Moreover, both types of BLG-based ASDs at 10 wt% drug loading exhibited faster release rates and higher solubility, for both the drug and BLG, compared to the ASDs at 30 wt% drug loading in pHs 2, 7, and 9 media.