Loading of tacrolimus containing lipid based drug delivery systems into mesoporous silica for extended release

Microsponge-Based Gel Loaded with Immunosuppressant as a Simple and Valuable Strategy for Psoriasis Therapy: Determination of Pro-Inflammatory Response through Cytokine IL-2 mRNA Expression

Tacrolimus (TL) is a topical calcineurin inhibitor immunosuppressive drug widely used to manage various skin disorders. Herein, we report a TL-loaded microsphere gel formulation with severe atopic dermatitis effects that are required to manage skin disorders. The current study adopted a modified emulsion solvent evaporation technique to synthesize TL-loaded microspheres, which were further converted into gels for skin use. Characterization of the synthesized formulation was performed by differential dynamic light scattering, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray crystallography, Brunauer-Emmett-Teller (BET) analysis, differential scanning calorimetry, and drug release. A Franz diffusion cell was used to study the diffusion of TL for up to 8 h at pH 6.8 and 5.5. Evaluation of cell viability was determined by MTT assay and showed higher IC50 values compared to the plain drug. RNA extraction, real-time polymerase chain reaction (RT-PCR), and reverse transcription were also performed to determine the expression levels of the anti-inflammatory cytokine IL-2. Particle size determination was performed by a zeta sizer, and the TL microsphere size was 1745 ± 70 nm with a good polydispersity (0.337 ± 0.12). The drug entrapment efficiency was also very good at 60% ± 10, and the drug release was 93.9% ± 3.5 within 8 h. An in vitro diffusion study of the formulation also showed improved permeability at both pH values (4.5 and 5.5). The findings of the hemolytic tests demonstrated that TL-MG at concentrations of 50, 100, and 200 mg/mL did not produce any hemolysis. A dose-dependent pattern of cytotoxicity was found during the cell viability assay, with an IC50 value of 787.55 ± 12.78 µg/mL. There was a significant decrease in the IL-2 level in the TL-MG group compared to the other groups. TL-MG microspheres were nontoxic carriers for tacrolimus delivery, with greater loading capacity, a significant release profile, and enhanced cellular uptake with improved permeability.

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.

Fabrication, In Vitro and In Vivo Evaluation of Non-Ordered Mesoporous Silica-Based Ternary Solid Dispersions for Enhanced Solubility of Flurbiprofen

The aim of this study was to improve the solubility and prevent the ulcerogenic effect of flurbiprofen. Initially, binary and ternary solid dispersions (BSDs and TSDs) of flurbiprofen were prepared by using non-ordered mesoporous silica and gelucire. After preformulation testing (solubility, flow properties, % yield, and entrapment efficiency), four formulations were selected for further detailed studies. Solid-state characterization of optimized formulations (S1, S6, S7, and S12) showed successful drug incorporation in the solid dispersion at the molecular state without any noticeable interactions. The in vitro solubility and release study showed an increase in solubility and 98–100% of drug release in 30–45 min. The in vivo gastro-protective effect of the optimized formulations containing flurbiprofen and silica (1:1) with 25% w/w gelucire (S6 and S12) showed a reduction in the gastric lesion index (GLI) after four days of treatment. Moreover, histological images of the stomach lining (S6 and S12) illustrated normal epithelial cells and a partially protected mucosal membrane. Thus, TSD exhibited a significant increase in solubility and the dissolution rate and reduced the gastric ulceration. Therefore, TSDs are dubbed as efficacious carriers to enhance the bioavailability of flurbiprofen while simultaneously reducing its side effects.

Fundamental Aspects of Lipid-Based Excipients in Lipid-Based Product Development

Poor aqueous solubility of drugs is still a foremost challenge in pharmaceutical product development. The use of lipids in designing formulations provides an opportunity to enhance the aqueous solubility and consequently bioavailability of drugs. Pre-dissolution of drugs in lipids, surfactants, or mixtures of lipid excipients and surfactants eliminate the dissolution/dissolving step, which is likely to be the rate-limiting factor for oral absorption of poorly water-soluble drugs. In this review, we exhaustively summarize the lipids excipients in relation to their classification, absorption mechanisms, and lipid-based product development. Methodologies utilized for the preparation of solid and semi-solid lipid formulations, applications, phase behaviour, and regulatory perspective of lipid excipients are discussed.

Synthesis of poly(lactide-co-glycerol) as a biodegradable and biocompatible polymer with high loading capacity for dermal drug delivery

Due to the low cutaneous bioavailability of tacrolimus (TAC), penetration enhancers are used to improve its penetration into the skin. However, poor loading capacity, non-biodegradability, toxicity, and in some cases inefficient skin penetration are challenging issues that hamper their applications for the dermal TAC delivery. Here we present poly(lactide-co-glycerol) (PLG) as a water soluble, biodegradable, and biocompatible TAC-carrier with high loading capacity (14.5% w/w for TAC) and high drug delivery efficiencies into the skin. PLG was synthesized by cationic ring-opening copolymerization of a mixture of glycidol and lactide and showed 35 nm and 300 nm average sizes in aqueous solutions before and after loading of TAC, respectively. Delivery experiments on human skin, quantified by fluorescence microscopy and LC-MS/MS, showed a high ability for PLG to deposit Nile red and TAC into the stratum corneum and viable epidermis of skin in comparison with Protopic® (0.03% w/w, TAC ointment). The cutaneous distribution profile of delivered TAC proved that 80%, 16%, and 4% of the cutaneous drug level was deposited in the stratum corneum, viable epidermis, and upper dermis, respectively. TAC delivered by PLG was able to efficiently decrease the IL-2 and TSLP expressions in human skin models. Taking advantage of the excellent physicochemical and biological properties of PLG, it can be used for efficient dermal TAC delivery and potential treatment of inflammatory skin diseases.

Extended tacrolimus release via the combination of lipid-based solid dispersion and HPMC hydrogel matrix tablets

The objective of this study is to evaluate the feasibility of obtaining extended release of tacrolimus by a novel combination of lipid-based solid dispersion and matrix-type extended release tablet techniques. Tacrolimus solid dispersion was prepared using glycerylbehenate (Compritol^® ATO888) and Pluronic F127 as the carrier materials with hot-melt method, which was then blended with hydrogel matrix materials, such as HPMC and lactose, the powders were directly compressed into tablets. In vitro drug release tests were carried out to evaluate the performance of the solid dispersions and the tablets. The dissolution rate of tacrolimus was significantly improved by the lipid-based solid dispersion, and the incorporation of HPC into the solid dispersion obviously improved its stability after storage. Extended release tablets loaded with tacrolimus solid dispersion showed prolonged drug release patterns over 24 h, the release patterns of the tablets can be tailored by the compositions of the matrix materials, including the types and content of HPMCs. A modified processing method that directly mixed the melted solid dispersion with HPMC powders improved the uniformity of the solid dispersion inside the tablet matrix and release profile. The release data of the extended release tablet fitted well to the Korsmeyer–Peppas model with n value of 0.85, which suggested diffusion- and erosion-controlled release mechanism. The combination of lipid-based solid dispersion and HPMC hydrogel matrix may find wide applications in the extended release dosage forms of high potent, water-insoluble drugs.

Evaluation of mesoporous silica particles as drug carriers in hydrogels

Mesoporous silica particles have recently been used in the preparation of solid oral as well as dermal pharmaceutical formulations. In this work, the use of mesoporous silica of different particle size, pore size and pore volume as carrier for curcumin in hydrogels for dermal use was investigated. Oil absorption capacity of the silica, in vitro release of curcumin from formulations and chemical stability of curcumin during three months storage were evaluated. It was found that the silica particles did not alter in vitro release of curcumin compared to an emulsion. Furthermore, curcumin was found to exhibit similar or inferior stability in hydrogels containing mesoporous silica opposed to emulsions.

Poly(NIPAM-co-MPS)-grafted multimodal porous silica nanoparticles as reverse thermoresponsive drug delivery system

Hybrid drug delivery systems (DDS) have been prepared by grafting poly(NIPAM-co-MPS) chains on multimodal porous silica nanoparticles having an inner mesoporous structure and an outer thin layer of micropores. The hybrid thermoresponsive DDS were fully characterized and loaded with a model drug. The in vitro drug release tests are carried out at below and above the lower critical solution temperature (LCST) of the copolymer. The results have revealed that due to the presence of small diameter (~1.3 nm) micropores at the periphery of the particles, the collapsed globules of the thermoresponsive copolymer above its LCST hinders the complete release of the drug which resulted in a reverse thermoresponsive drug release profile by the hybrid DDS.