Role of Silica Intrawall Microporosity on Abiraterone Acetate Solubilization and In Vivo Oral Absorption

Amino polycarboxylic acids-modified abiraterone derivatives as potential injectable anti-prostate cancer agents

Abiraterone (Abi), an effective cytochrome oxidase P450 C17 (CYP17) inhibitor, inhibits androgen synthesis in testes, adrenal glands, and prostate tumors. However, their low bioavailability and dissolution rate due to their poor solubility and toxic side effects have hindered their clinical applications. In this study, water-soluble and injectable Abi derivatives were developed by introducing amino polycarboxylic acids into Abi, and their antiproliferation effects in vitro, mechanism of action, antitumor activities in vivo, pharmacokinetics, and toxicity were investigated. Compared to Abi, the water-soluble derivative Abi-DTPA exhibited excellent antitumor activity in vitro and in vivo. It decreased cell migration, invasion, and mitochondrial membrane potential. A mechanistic study revealed that it still targeted the CYP17 enzyme and increased the expression levels of apoptosis-related proteins, including cleaved caspase 9, cleaved PARP, and cleaved caspase 3. Abi-DTPA was the main form in the plasma and exhibited lower toxicity after intravenous administration. These findings suggest that Abi-DTPA can be used as a novel injectable anti-prostate cancer agent.

Enhancing the pharmacokinetics of abiraterone acetate through lipid-based formulations: addressing solubility and food effect challenges

Abiraterone acetate, a prodrug of abiraterone, is an effective antiandrogen for treating metastatic prostate cancer. However, its poor aqueous solubility restricts oral bioavailability to under 10% in fasted conditions. Additionally, its pharmacokinetics are significantly influenced by food intake, leading to variable exposure that can impact treatment safety and efficacy. To overcome these challenges, we developed a series of lipid-based formulations aimed at reducing food effects and enhancing the fasted bioavailability of abiraterone acetate by incorporating the drug into colloidal delivery systems. Medium- and long-chain self-nanoemulsifying drug delivery systems (MC-SNEDDS and LC-SNEDDS) were formulated with abiraterone acetate loading at 80% of their respective preconcentrate equilibrium solubility. In-vitro gastrointestinal lipolysis experiments demonstrated that the SNEDDS formulations increased drug solubilisation by over 6-fold compared to pure abiraterone acetate and over 2-fold compared to the reference product after 60 min in the intestinal environment. In-vivo pharmacokinetic studies in rats revealed that both MC-SNEDDS and LC-SNEDDS formulations, along with their enteric-coated (EC) forms, exhibited enhanced bioavailability, with EC-LC-SNEDDS providing the highest performance, demonstrating a 7.32-fold increase in abiraterone exposure compared to the reference. Strong correlations were observed between in-vitro solubilisation and in-vivo AUC0 - 8 h (R2 = 0.980) and Cmax (R2 = 0.925). In-vivo pharmacokinetic studies in pigs demonstrated that EC-LC-SNEDDS improved drug systemic exposure in fasted conditions and mitigated positive food effects, showing a fed-to-fasted AUC0 - 8 h ratio of 108% compared to 334% with the reference. The developed lipid-based formulations hold promise in overcoming the pharmacokinetic challenges associated with abiraterone, potentially offering improved outcomes for patients.

The Influence of Blonanserin Supersaturation in Liquid and Silica Stabilised Self-Nanoemulsifying Drug Delivery Systems on In Vitro Solubilisation

Reformulating poorly water-soluble drugs as supersaturated lipid-based formulations achieves higher drug loading and potentially improves solubilisation and bioavailability. However, for the weak base blonanserin, silica solidified supersaturated lipid-based formulations have demonstrated reduced in vitro solubilisation compared to their liquid-state counterparts. Therefore, this study aimed to understand the influence of supersaturated drug load on blonanserin solubilisation from liquid and silica solidified supersaturated self-nanoemulsifying drug delivery systems (super-SNEDDS) during in vitro lipolysis. Stable liquid super-SNEDDS with varying drug loads (90-300% of the equilibrium solubility) were solidified by imbibition into porous silica microparticles (1:1 lipid: silica ratio). In vitro lipolysis revealed greater blonanserin solubilisation from liquid super-SNEDDS compared to solid at equivalent drug saturation levels, owing to strong silica-BLON/lipid interactions, evidenced by a significant decrease in blonanserin solubilisation upon addition of silica to a digesting liquid super-SNEDDS. An increase in solid super-SNEDDS drug loading led to increased solubilisation, owing to the increased drug:silica and drug:lipid ratios. Solidifying SNEDDS with silica enables the fabrication of powdered formulations with higher blonanserin loading and greater stability than liquid super-SNEDDS, however at the expense of drug solubilisation. These competing parameters need careful consideration in designing optimal super-SNEDDS for pre-clinical and clinical application.

The Anti-Obesity Effect of Porous Silica Is Dependent on Pore Nanostructure, Particle Size, and Surface Chemistry in an In Vitro Digestion Model

The potential for porous silica to serve as an effective anti-obesity agent has received growing attention in recent years. However, neither the exact pharmacological mechanism nor the fundamental physicochemical properties of porous silica that drive its weight-lowering effect are well understood. Subsequently, in this study, an advanced in vitro digestion model capable of monitoring lipid and carbohydrate digestion was employed to elucidate the effect of porous silica supplementation on digestive enzyme activities. A suite of porous silica samples with contrasting physicochemical properties was investigated, where it was established that the inhibitory action of porous silica on digestive enzyme functionality was strongly dependent on porous nanostructure, particle size and morphology, and surface chemistry. Insights derived from this study validate the capacity of porous silica to impede the digestive processes mediated by pancreatic lipase and α-amylase within the gastrointestinal tract, while the subtle interplay between porous nanostructure and enzyme inhibition indicates that the anti-obesity effect can be optimized through strategic particle design.