Multifunctional Role of Silica in Pharmaceutical Formulations

Preparation, characterization, oral bioavailability, and pharmacodynamic study of eugenol-porous silica solidified powder

Eugenol possesses anti-inflammatory and antioxidant properties, and may serve as a potential therapeutic agent for hepatic fibrosis. However, the development of solid eugenol formulations is challenging due to its volatility. To address this issue, this study employed porous silica to adsorb solidified eugenol. The solidified powder was characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). In addition, the differences in in vitro release and oral bioavailability between eugenol and solidified eugenol powder were investigated. The effectiveness of eugenol and eugenol powder in treating liver fibrosis was investigated using enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), and histopathological observations. Our results indicate that porous silica can effectively solidify eugenol into powder at a lower dosage. Furthermore, we observed that porous silica accelerates eugenol release in vitro and in vivo. The pharmacodynamic results indicated that eugenol has a positive therapeutic effect against hepatic fibrosis and that porous silica does not affect its efficacy. In conclusion, porous silica was able to solidify eugenol, which may facilitate the preparation and storage of solid formulations.

TGA and NMR relaxation measurement of nonmesoporous silica to investigate the amount of hydrolysis product in acetylsalicylic acid adsorbed on silica

This study investigated a crucial surface property of silica that contributes to the chemical stability of acetylsalicylic acid (ASA) physically adsorbed on silica. Hydrophilic nonmesoporous types of silica were selected, and the number of hydroxyl groups on silica (N(OH)) was evaluated using thermogravimetric analysis (TGA). The ASA-containing silica was stored at 40 °C in drying conditions, and the amount of ASA degradation was quantified based on salicylic acid. From the scatterplots between the number of hydroxyl groups per unit weight (specific surface area (SSA) × N(OH)) and the amount of ASA degradation, it was clarified that in ASA adsorbed on silica, the ASA chemical stability was determined by the formula (the SSA × N(OH)). In addition, a time-domain nuclear magnetic resonance measurement verified the N(OH) result by estimating the interaction between the silica surface and water in an aqueous silica suspension. The N(OH) result was found to be reasonable.

Amorphous silica nanoparticles and the human gut microbiota: a relationship with multiple implications

Amorphous silica nanoparticles (ASNP) are among the nanomaterials that are produced in large quantities. ASNP have been present for a long time in several fast-moving consumer products, several of which imply exposure of the gastrointestinal tract, such as toothpastes, food additives, drug excipients, and carriers. Consolidated use and experimental evidence have consistently pointed to the very low acute toxicity and limited absorption of ASNP. However, slow absorption implies prolonged exposure of the intestinal epithelium to ASNP, with documented effects on intestinal permeability and immune gut homeostasis. These effects could explain the hepatic toxicity observed after oral administration of ASNP in animals. More recently, the role of microbiota in these and other ASNP effects has attracted increasing interest in parallel with the recognition of the role of microbiota in a variety of conditions. Although evidence for nanomaterial effects on microbiota is particularly abundant for materials endowed with bactericidal activities, a growing body of recent experimental data indicates that ASNPs also modify microbiota. The implications of these effects are recounted in this contribution, along with a discussion of the more important open issues and recommendations for future research.

Study of Diminutive Granules as Feed Powders for Manufacturability of High Drug Load Minitablets

The maximal amount of drug contained in a minitablet is limited. To reduce the total number of minitablets in a single dose, high drug load minitablets can be prepared from high drug load feed powders by various pharmaceutical processing techniques. Few researchers have however examined the influence of pharmaceutical processing techniques on the properties of high drug load feed powders, and consequently the manufacturability of high drug load minitablets. In this study, silicification of the high drug load physical mix feed powders alone did not yield satisfactory quality attributes and compaction parameters to produce good quality minitablets. The abrasive nature of fumed silica increased ejection force and damage to the compaction tools. Granulation of fine paracetamol powder was crucial for the preparation of good quality high drug load minitablets. The diminutive granules had superior powder packing and flow properties for homogenous and consistent filling of the small die cavities when preparing minitablets. Compared to the physical mix feed powders for direct compression, the granules which possessed higher plasticity, lower rearrangement and elastic energies, yielded better quality minitablets with high tensile strength and rapid disintegration time. High shear granulation demonstrated greater process robustness than fluid bed granulation, with less discernment on the quality attributes of feed powder. It could proceed without fumed silica, with the high shear forces reducing interparticulate cohesivity. An in-depth understanding on the properties of high drug load feed powders with inherently poor compactability and poor flowability is important for the manufacturability of high drug load minitablets.

Surface Modifiers on Composite Particles for Direct Compaction

Direct compaction (DC) is considered to be the most effective method of tablet production. However, only a small number of the active pharmaceutical ingredients (APIs) can be successfully manufactured into tablets using DC since most APIs lack adequate functional properties to meet DC requirements. The use of suitable modifiers and appropriate co-processing technologies can provide a promising approach for the preparation of composite particles with high functional properties. The purpose of this review is to provide an overview and classification of different modifiers and their multiple combinations that may improve API tableting properties or prepare composite excipients with appropriate co-processed technology, as well as discuss the corresponding modification mechanism. Moreover, it provides solutions for selecting appropriate modifiers and co-processing technologies to prepare composite particles with improved properties.