Stabilization and Amorphization of Lovastatin Using Different Types of Silica

Candesartan cilexetil formulations in mesoporous silica: preparation, enhanced dissolution in vitro, and oral bioavailability in vivo

Candesartan cilexetil (CC) is one of well-tolerated antihypertensive drugs, while its poor solubility and low bioavailability limit its use. Herein, two mesoporous silica (Syloid XDP 3150 and Syloid AL-1 FP) and the corresponding amino-modified products (N-XDP 3150 and N-AL-1 FP) have been selected as the carriers of Candesartan cilexetil to prepare solid dispersion through solvent immersion, and characterized through using powder X-ray diffraction analysis, infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, and solid-state nuclear magnetic resonance spectroscopy, etc. The state of CC changed from crystalline to amorphous after loading onto the silica carriers, in which no interactions between CC and silica existed. Then, the dissolution behaviors in vitro were studied through using flow-through cell dissolution method. CC-XDP 3150 sample exhibited the most extensive dissolution, and the cumulative release of CC from it was 1.88-fold larger than that of CC. Moreover, the pharmacokinetic results in rats revealed that the relative bioavailability of CC-XDP 3150 and CC-N-XDP 3150 solid dispersions were estimated to be 326 % and 238 % in comparison with CC, respectively. Clearly, pore size, pore volume, and surface properties of silica carrier have remarkable effect on loading, dissolution and bioavailability of CC. In brief, this work will provide valuable information in construction of mesoporous silica-based delivery system toward poorly water-soluble drugs.

Investigating the Influence of Processing Conditions on Dissolution and Physical Stability of Solid Dispersions with Fenofibrate and Mesoporous Silica

The study aimed to enhance the solubility of the poorly water-soluble drug, fenofibrate, by loading it onto mesoporous silica, forming amorphous solid dispersions. Solid dispersions with 30% fenofibrate were prepared using the solvent evaporation method with three solvents (ethyl acetate, acetone, and isopropanol) at different temperatures (40 °C, boiling point temperature). Various characteristics, including solid-state properties, particle morphology, and drug release, were evaluated by different methods and compared to a pure drug and a physical mixture of fenofibrate and silica. Results revealed that higher solvent temperatures facilitated complete amorphization and rapid drug release, with solvent choice having a lesser impact. The optimal conditions for preparation were identified as ethyl acetate at boiling point temperature. Solid dispersions with different fenofibrate amounts (20%, 25%, 35%) were prepared under these conditions. All formulations were fully amorphous, and their dissolution profiles were comparable to the formulation with 30% fenofibrate. Stability assessments after 8 weeks at 40 °C and 75% relative humidity indicated that formulations prepared with ethyl acetate and at 40 °C were physically stable. Interestingly, some formulations showed improved dissolution profiles compared to initial tests. In conclusion, mesoporous silica-based solid dispersions effectively improved fenofibrate dissolution and demonstrated good physical stability if prepared under appropriate conditions.

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.

Design and Optimization of Pioglitazone Hydrochloride Self-Nanoemulsifying Drug Delivery System (SNEDDS) Incorporated into an Orally Disintegrating Tablet

Pioglitazone Hydrochloride (PGZ) suffers from poor aqueous solubility. The aim of this research was to design orally disintegrating tablets with self-nanoemulsifying properties (T-SNEDDS) to improve the Pioglitazone solubility and dissolution rate. Three liquid self-nanoemulsifying systems (L-SNEDDS) were formulated and evaluated for transmittance percentage, emulsification time, particle size, Poly dispersity index (PDI), percentage of content, solubility and stability. The optimum L-SNEDDS formula was converted to a solidified self-nanoemulsifying drug delivery system (S-SNEDDS) by adsorption on Syloid (SYL). Powder characterization tests, such as flowability tests, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), were performed for the selected S-SNEDDS formulation. Orally disintegrating tablets (ODT) were formulated by blending S-SNEDDS with tableting excipients. The ODT tablet batch composed of Prosolv was selected for tablet quality control tests, such as hardness, friability, disintegration time, content uniformity, weight variation, in vitro release, in vivo studies and accelerated stability studies. ODT tablets showed accepted mechanical properties and rapid disintegration time (<30 s). No drug degradation was observed at 3 months into the accelerated stability study. The optimized L-SNEDDS, S-SNEDDS and ODT (T-SNEDDS), showed significant enhancement of PGZ in vitro dissolution profiles compared to the pure drug (p > 0.05). In vivo pharmacokinetic and pharmacodynamic evaluation of ODTs showed better behavior compared to the raw drug suspension and the commercial tablet (p > 0.05). Orally disintegrating tablets revealed a promising potential to improve Pioglitazone poor aqueous solubility, dissolution profile and bioavailability.

Application of commercially available mesoporous silica for drug dissolution enhancement in oral drug delivery

Due to the high number of poorly water-soluble active pharmaceutical ingredients, oral drug delivery development has become challenging. One of the strategies to enhance drug solubility and to achieve high oral bioavailability is to formulate such compounds into amorphous solid dispersions. In recent years, porous materials have been investigated as possible carriers into which a drug can be adsorbed, such as mesoporous silica, in particular. Unlike the ordered mesoporous network of silica, non-ordered silica already has a "generally regarded as safe" status, and is already used as an excipient in pharmaceutical and cosmetic products. Thus, it is reasonable to expect that products that contain solid dispersions with non-ordered carriers will reach the market sooner and more easily than those with ordered mesoporous carriers. The emphasis of this review is therefore on non-ordered commercially available mesoporous silica and the progress that has been made in development of the use of these materials for improved dissolution rates in oral drug delivery. First, a thorough categorisation of the drug loading methods is presented, followed by discussion on the most important characteristics of solid dispersions (i.e., physical state, stability, drug release). Finally, manufacturability and production of a final solid dosage form are considered.

Solid self nano-emulsifying system for the enhancement of dissolution and bioavailability of Prasugrel HCl: in vitro and in vivo studies

Prasugrel Hydrochloride (PHCl) is an antiplatelet drug. It is a class II drug with variable bioavailability. The objective of this work was to enhance the solubility and hence the bioavailability and efficacy of PHCl. A Self Nano-Emulsifying Drug Delivery System (SNEDDS) was prepared using Kolliphor El, Maisine 35-1, and Transcutol P as surfactant, oil, and co-surfactant, respectively in a ratio 10:72:18 v/v%. The SNEDDS was converted into solid by adsorption onto Neusilin. In vitro release of the drug from SNEDDS in (pH = 4) at 37 °C and 75 rpm for 45 min was studied. The results were compared to those from the unprocessed PHCl and Lexar^® (the commercial drug). In-vivo studies (platelet Aggregation and bleeding time) were conducted using rats as animal models. It was found that the particle size of the SNEDDS ranged between 80 and 155 nm and EE% was in the range of 90.2% ± 0.4. The release from SNEDDS was about 84% compared to around 25% from unprocessed PHCl and 65% from Lexar^® after 15 min. The platelet aggregation of the formula was lower than the PHCl, and Lexar^® indicating higher bioavailability. In conclusion, SNEDDS with high EE% was prepared and was successful in enhancing the solubility, dissolution rate, and the bioavailability.

Preparation and characterization of co-processed starch/MCC/chitin hydrophilic polymers onto magnesium silicate

It was aimed to investigate the compressibility, compactibility, powder flow and tablet disintegration of a new excipient comprising magnesium (Mg) silicate co-processed (5%-85% w/w) onto chitin, microcrystalline cellulose (MCC) and starch as the hydrophilic polymers of interest. Initially, the mechanism of tablet disintegration was studied by measuring water infiltration rate, moisture sorption, swelling capacity and hydration ability. Moreover, the powders compression behavior was carried out by applying Kawakita model of compression analysis in addition to porosity and radial tensile strength measurements. In vitro drug release of compacts made of 400 mg ibuprofen and 300 mg of the hydrophilic polymers containing 30% w/w Mg silicate co-precipitate was investigated in phosphate buffer (pH 7.8). This work demonstrated that the incorporation of Mg silicate to the hydrophilic polymers lead to the improvement of powder flowability, compactibility, stability (with regard to storage conditions), compacts crushing strength, and disintegration time in addition to faster drug release. The overall findings are practically advantageous in the context of finding a low cost and multifunctional co-processed excipient of natural origins.

A Drug Release Model Constructed by Factorial Design to Investigate the Interaction Between Host Mesoporous Silica Carriers and Drug Molecules

A drug release model based on mesocellular foam silica (MCF) for Biopharmaceutics Classification System (BCS) II drugs was conducted. A three-level two-factorial factorial design was carried out for the exploration of the influence of the pore size of MCF (X₁) and drug-loading degree (X₂) for drug release behaviors. Cumulative release in 1 h (Y₁), cumulative release in 24 h (Y₂), and rate constant k (Y₃) were selected as dependent response variables. A series of MCFs (7MCF, 12MCF, and 17MCF) with arithmetic increased pore diameters was synthesized as drug carriers. The morphologies and structures of MCFs and pore size distributions were detected by scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption analysis. With celecoxib as a model drug, nine drug-loaded samples were prepared and further characterized by differential scanning calorimetry and X-ray diffraction analyses. The release behavior was examined by in vitro dissolution. Factorial design results demonstrated that cumulative release in 1 h and the rate constant k were mainly affected by X₂, while cumulative release in 24 h was influenced by both X₁ and X₂. Furthermore, quadratic equations of Y₁, Y₂, and Y₃ were conducted, respectively. This work was expected to provide some scientific references for designing specific drug delivery models with mesoporous silica carrier.

Lipophilicity and hydrophobicity considerations in bio-enabling oral formulations approaches – a PEARRL review

Objectives

This review highlights aspects of drug hydrophobicity and lipophilicity as determinants of different oral formulation approaches with specific focus on enabling formulation technologies. An overview is provided on appropriate formulation selection by focussing on the physicochemical properties of the drug.

Key findings

Crystal lattice energy and the octanol–water partitioning behaviour of a poorly soluble drug are conventionally viewed as characteristics of hydrophobicity and lipophilicity, which matter particularly for any dissolution process during manufacturing and regarding drug release in the gastrointestinal tract. Different oral formulation strategies are discussed in the present review, including lipid-based delivery, amorphous solid dispersions, mesoporous silica, nanosuspensions and cyclodextrin formulations.

Summary

Current literature suggests that selection of formulation approaches in pharmaceutics is still highly dependent on the availability of technological expertise in a company or research group. Encouraging is that, recent advancements point to more structured and scientifically based development approaches. More research is still needed to better link physicochemical drug properties to pharmaceutical formulation design.

Risk Assessment Integrated QbD Approach for Development of Optimized Bicontinuous Mucoadhesive Limicubes for Oral Delivery of Rosuvastatin

Statins are widely prescribed for hyperlipidemia, cancer, and Alzheimer's disease but are facing some inherent challenges such as low solubility and drug loading, higher hepatic metabolism, as well as instability at gastric pH. So, relatively higher circulating dose, required for exerting the therapeutic benefits, leads to dose-mediated severe toxicity. Furthermore, due to low biocompatibility, high toxicity, and other regulatory caveats such as product conformity, reproducibility, and stability of conventional formulations as well as preferentially higher bioabsorption of lipids in their favorable cuboidal geometry, enhancement in in vivo biopharmaceutical performance of Rosuvastatin could be well manifested in Quality by Design (QbD) integrated cuboidal-shaped mucoadhesive microcrystalline delivery systems (Limicubes). Here, quality-target-product-profile (QTPPs), critical quality attributes (CQAs), Ishikawa fishbone diagram, and integration of risk management through risk assessment matrix for failure mode and effects analysis (FMEA) followed by processing of Plackett-Burman design matrix using different statistical test for the first time established an approach to substantiate the claims that controlling levels of only these three screened out independent process variables, i.e., Monoolein (B = 800-1100 μL), Poloxamer (C = 150-200 mg), and stirring speed (F = 700-1000 rpm) were statistically significant to modulate and improve the biopharmaceutical performance affecting key attributes, viz., average particle size (Y₁ = 1.40-2.70 μ), entrapment efficiency (Y₂ = 62.60-88.80%), and drug loading (Y₃ = 0.817-1.15%), in QbD-enabled process. The optimal performance of developed Limicubes exhibited an average particle size of 1.8 ± 0.2 μ, entrapment efficiency 80.32 ± 2.88%, and drug loading 0.93 ± 0.08% at the level of 1100 μL (+ 1), 200 mg (+ 1), and 700 rpm (- 1) for Monoolein, Poloxamer, and stirring speed, respectively.