Melt Amorphisation of Orlistat with Mesoporous Silica Using a Supercritical Carbon Dioxide: Effects of Pressure, Temperature, and Drug Loading Ratio and Comparison with Other Conventional Amorphisation Methods

Fabrication of Nanocrystals for Enhanced Distribution of a Fatty Acid Synthase Inhibitor (Orlistat) as a Promising Method to Relieve Solid Ehrlich Carcinoma-Induced Hepatic Damage in Mice

BACKGROUND

Orlistat (ORL) is an effective irreversible inhibitor of the lipase enzyme, and it possesses anticancer effects and limited aqueous solubility. This study was designed to improve the aqueous solubility, oral absorption, and tissue distribution of ORL via the formulation of nanocrystals (NCs).

METHODS

ORL-NC was prepared using the liquid antisolvent precipitation method (bottom-up technology), and it demonstrated significantly improved solubility compared with that of the blank crystals (ORL-BCs) and untreated ORL powder. The biodistribution and relative bioavailability of ORL-NC were investigated via the radiolabeling technique using Technetium-99m (99mTc). Female Swiss albino mice were used to examine the antitumor activity of ORL-NC against solid Ehrlich carcinoma (SEC)-induced hepatic damage in mice.

RESULTS

The prepared NCs improved ORL's solubility, bioavailability, and tissue distribution, with evidence of 258.70% relative bioavailability. In the in vivo study, the ORL-NC treatment caused a reduction in all tested liver functions (total and direct bilirubin, AST, ALT, and ALP) and improved modifications in liver sections that were marked using hematoxylin and eosin staining (H&E) and immunohistochemical staining (Ki-67 and ER-α) compared with untreated SEC mice.

CONCLUSIONS

The developed ORL-NC could be considered a promising formulation approach to enhance the oral absorption tissue distribution of ORL and suppress the liver damage caused by SEC.

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.