Impregnation of mesoporous silica with poor aqueous soluble molecule using pressurized carbon dioxide: Is the solubility in the supercritical and subcritical phase a critical parameter?

Production challenges of tablets containing lipid excipients: Case study using cannabidiol as drug model

The aims of this study were, firstly, to select an optimal lipid solid dispersion of cannabidiol among different lipid excipients (Gelucire® 50/13, 48/16, 44/14 and Labrasol®) and inorganic carriers (colloidal silica, Syloid® XDP and Neusilin® US2) through a screening plan. The enhancement of aqueous solubility of cannabidiol from a free-flowing powder with adequate drug content was obtained by mixing cannabidiol (20%) with Gelucire® 50/13 (40%; Gattefossé, France), both incorporated inside mesopores of mesoporous silica Syloid® XDP (40%; Grace, Germany). Secondly, we have studied the tableting properties of this selected dispersion through a Design of Experiments (DoE) by manufacturing tablets with other excipients with using a compression simulator (Styl'One® Evo, Medelpharm, France). The design of experiments included the percentage of lipid solid dispersion, of glidant, of lubricant and different compression forces. The dissolution efficiency, the drug content, the tensile strength and the ejection force were analyzed. The DoE showed that % of dispersion as well as compression forces were the main influential variables. An exit of lipid materials outside the mesopores of silica due to compression process has been highlighted, reflected by reduced tensile strength. This study showed the possibility of manufacturing tablets with lipid materials even if limitations have been highlighted. Indeed, the dispersion percentage must not exceed 27% and compression forces up to 13 kN are required to produce lipid tablets with optimal properties.

Role of Fine Silica as Amorphous Solid Dispersion Carriers for Enhancing Drug Load and Preventing Recrystallization- A Comprehensive Review

Amorphous solid dispersion (ASD) is a popular concept for improving the dissolution and oral bioavailability of poorly water-soluble drugs. ASD faces two primary challenges of low drug loading and recrystallization upon storage. Several polymeric carriers are used to fabricate a stable ASD formulation with a high drug load. The role of silica in this context has been proven significant. Different types of silica, porous and nonporous, have been used to develop ASD. Amorphous drugs get entrapped into silica pores or adsorbed on their surface. Due to high porosity and wide surface area, silica provides better drug dissolution and high drug loading. Recrystallization of amorphous drugs is inhibited by limited molecular ability inside the delicate pores due to hydrogen bonding with the surface silanol groups. A handful of researches have been published on silica-based ASD, where versatile types of silica have been used. However, the effect of different kinds of silica on product stability and drug loading has been rarely addressed. The present study analyzes multiple porous and nonporous silica types and their distinct role in developing a stable ASD. Emphasis has been given to various types of silica which are commonly used in the pharmaceutical industry.

Influence of API physico-chemical properties on amorphization capacity of several mesoporous silica loading methods

The objective of this work was to evaluate the impact of physico-chemical properties of pharmaceutical drugs on the optimal mesoporous silica loading methods. Indeed, a good combination between drug and loading process has to be studied to promote the deepest penetration of the drug inside the mesopores, allowing high drug amorphization. Six molecules, namely lidocaine and its hydrochloride, ibuprofen, ketoprofen, artemether and miconazole, with different physico-chemical properties (the ionized character, the acid-base character, the HBDA number, the solubility in sc-CO₂ and the behavior under subcritical CO₂) were used to produce drug-silica formulations. Different impregnation processes (physical mixing, melting, wetting, sc-CO₂ and subcritical CO₂ impregnations) have been compared for each drug, in terms of drug recovery and crystallinity. Formulations showed drug percentage close to 100% except for supercritical soluble drug formulations impregnated by using sc-CO₂. However, the basic drug character provided less or no drug loss during impregnation. Processing insoluble sc-CO₂ molecule under supercritical conditions led to less crystallinity than the correspondent physical mixture suggesting an interesting repulsive effect that forces the drug penetration within the mesopores. Besides, it has been also highlighted that the HBDA number is not sufficient to predict the final drug loading. Melting methods have high interest considering the drugs tested and subcritical CO₂ could increase the loading, especially for drugs with high molten viscosity. This study showed that a plethora of loading methods can be used to provide high drug loaded MS formulations with a wide choice of equipment.

Recent Advances in Enhancement of Dissolution and Supersaturation of Poorly Water-Soluble Drug in Amorphous Pharmaceutical Solids: A Review

Amorphization is one of the most effective pharmaceutical approaches to enhance the dissolution and oral bioavailability of poorly water-soluble drugs. In recent years, amorphous formulations have been experiencing rapid development both in theoretical and practical application. Based on using different types of stabilizing agents, amorphous formulations can be mainly classified as polymer-based amorphous solid dispersion, coamorphous formulation, mesoporous silica-based amorphous formulation, etc. This paper summarizes recent advances in the dissolution and supersaturation of these amorphous formulations. Moreover, we also highlight the roles of stabilizing agents such as polymers, low molecular weight co-formers, and mesoporous silica. Maintaining supersaturation in solution is a key factor for the enhancement of dissolution profile and oral bioavailability, and thus, the strategies and challenges for maintaining supersaturation are also discussed. With an in-depth understanding of the inherent mechanisms of dissolution behaviors, the design of amorphous pharmaceutical formulations will become more scientific and reasonable, leading to vigorous development of commercial amorphous drug products.

Piroxicam Loading onto Mesoporous Silicas by Supercritical CO2 Impregnation

Piroxicam (PRX) is a commonly prescribed nonsteroidal anti-inflammatory drug. Its efficacy, however, is partially limited by its low water solubility. In recent years, different studies have tackled this problem and have suggested delivering PRX through solid dispersions. All these strategies, however, involve the use of potentially harmful solvents for the loading procedure. Since piroxicam is soluble in supercritical CO₂ (scCO₂), the present study aims, for the first time, to adsorb PRX onto mesoporous silica using scCO₂, which is known to be a safer and greener technique compared to the organic solvent-based ones. For comparison, PRX is also loaded by adsorption from solution and incipient wetness impregnation using ethanol as solvent. Two different commercial mesoporous silicas are used (SBA-15 and Grace Syloid^® XDP), which differ in porosity order and surface silanol population. Physico-chemical analyses show that the most promising results are obtained through scCO₂, which yields the amorphization of PRX, whereas some crystallization occurs in the case of adsorption from solution and IWI. The highest loading of PRX by scCO₂ is obtained in SBA-15 (15 wt.%), where molecule distribution appears homogeneous, with very limited pore blocking.

Physical formulation approaches for improving aqueous solubility and bioavailability of ellagic acid: A review

Ellagic acid (EA) is a polyphenolic active compound with antimalarial and other promising therapeutic activities. However, its solubility and its permeability are both low (BCS IV). These properties greatly compromise its oral bioavailability and clinical utilizations. To overcome these limitations of the physicochemical parameters, several formulation approaches, including particle size reduction, amorphization and lipid-based formulations, have been used. Although these strategies have not yet led to a clinical application, some of them have resulted in significant improvements in the solubility and bioavailability of EA. This critical review reports and analyses the different formulation approaches used by scientists to improve both the biopharmaceutical properties and the clinical use of EA.