Structural dynamics of tween-based microemulsions for antimuscarinic drug mirabegron

Formation of alginate gel stabilized silica nanoparticles for encapsulation and topical delivery of minoxidil

Silica nanoparticles-embedded smart-gels are efficient drug carrier systems due to their structural flexibility, high porosity, and ease of formulation development. Herein, the extent of interaction of minoxidil (MXD), a potent vasodilator prodrug, with silica nanoparticles (SiNPs) and alginate (ALG) was investigated. The SiNPs were prepared by extracting silica from rice husk ash, and these SiNPs were further used to prepare MXD-loaded-SiNPs (MXD-SiNPs) by loading them with an appropriate amount of MXD. The as-prepared MXD-SiNPs were encapsulated in ALG polymer by freeze-gelation method and evaluated by various characterization techniques. The amorphous nature of the SiNPs was confirmed by XRD examination, while the nature of physical interaction and encapsulation of the drug in the SiNPs and ALG gel was examined by FTIR analysis. TEM analysis revealed that the MXD-SiNPs had a monodisperse collection of spherical nanoparticles, while the particle size (∼150 nm) of as-prepared formulation was determined from DLS studies. The drug entrapment efficiency was 86 % and the loading efficiency was 22 %. The as-developed MXD-SiNPs@ALG gel formulation exhibited sustained release over 12 h compared to pure MXD and MXD-SiNPs. These results suggest that the newly developed formulation has several advantageous properties that make it suitable for cutaneous administration of the drug.

An Eco-Friendly and Sensitive Microwave-Aided Spectrofluorophotometric Characterization of Mirabegron-Loaded Nanocarriers by Amalgamation of Design of Experiments and White Analytical Chemistry

Mirabegron, a drug for treatment of overactive bladder, has low water solubility and bioavailability. Researchers used quality by design to develop and characterize second-generation lipid nanocarriers for mirabegron, aiming to provide spatially and temporally sustained drug release. Numerous analytical methodologies for assessing mirabegron in pharmaceutical and biological fluids use chemical solvents in the mobile phase, potentially impacting aquatic ecosystems and the environment. The issue was addressed with a microwave-assisted spectrofluorimetric technique, environmentally benign solvents, and a fluorescent probe known as 4-chloro-7-nitrobenzofuran. Researchers used screening design and response-surface methodology to minimize organic waste. The suggested technique satisfied ICH Q2 (R2) and M10 validation standards. This approach described the in vivo pharmacokinetics and in vitro drug release of mirabegron-loaded lipid nano-carriers. We anticipated the chemical reaction pathways that derivatized mirabegron with 4-chloro-7-nitrobenzofuran by the analysis of mass spectra. We assessed the proposed method's environmental effect and sustainability compared to current methods using the RGB model, an analytical greenness calculator, and green analytical process index software. The proposed mirabegron estimate method was user-friendly for analysts, cost-effective, sensitive, robust, and environmentally sustainable, adhering to sustainable analytical practices and reducing ecological consequences.

Formulation of Microemulsion-Based Gels for Enhanced Topical Administration of Nonsteroidal Anti-Inflammatory Drugs

Nonsteroidal anti-inflammatory drugs are commonly administered orally to manage pain and inflammation, but they can have negative gastrointestinal side effects. Topical delivery is an alternative, and microemulsions (μEs) have been shown to be effective in facilitating, but they suffer from a liquid nature and low long-term retention on the skin. Hence, microemulsified gels (μEGs) have been developed, and in this study, we explored certain μEGs with diclofenac sodium (DF-Na) and naproxen sodium (NP-Na) with the hypothesis to ensure a slower and more sustained delivery of NSAIDs through the skin. The μEGs comprised castor oil (∼8%), water (∼12%), Tween-20 (∼72%), Span-20 (∼8%), poloxamer 407, and DF-Na or NP-Na. Optical microscopy was used to study the microstructures in the μEs and μEGs, and phase transitions from water-in-oil (w/o) to oil-in-water (o/w) with continuous networks were observed. Based on studies with dynamic light scattering and analyses of electron micrographs, it was observed that the μEs and μEGs loaded with DF-Na and NP-Na comprised monomodal nanodroplets. The average sizes of the droplets were (∼35 nm) and (∼60 nm) for the μEGs, without and with drugs. Fluorescence spectroscopy was used to ensure that the drugs were more likely to be present in the hydrophobic microenvironment of the formulations. Moreover, ex vivo permeation studies were conducted at pH values of 5.5 and 7.4 across rabbit skin. The release rates of DF-Na (>99 ± 1.5%, P < 0.07) and NP-Na (>89 ± 1.1%, P < 0.01) were slower for the μEGs within 8-10 h than for the μEs at the low pH, which is of relevance to the optimal pH of the skin. It was observed that μEGs with high viscosities are effective and may have potential for use in topical drug delivery applications.

Synergistic stabilization of a menthol Pickering emulsion by zein nanoparticles and starch nanocrystals: Preparation, structural characterization, and functional properties

A Pickering emulsion was synergistically stabilised with zein nanoparticles (ZNPs) and starch nanocrystals (SNCs) to prepare it for menthol loading. After response surface optimisation of the emulsion preparation conditions, a Pickering emulsion prepared with a ZNPs:SNCs ratio of 1:1, a particle concentration of 2 wt% and a water:oil ratio of 1:1 provided the highest menthol encapsulation rate of the emulsions tested (83%) with good storage stability within 30 days. We examined the bilayer interface structure of the emulsion by optical microscopy, scanning electron microscopy, and confocal laser scanning microscopy. The results of simulated digestion experiments showed that the release rate of free fatty acid was 75.06 ± 1.23%, which ensured bioavailability. At the same time, the emulsions facilitated the slow release of menthol. Bacteriostatic studies revealed that the Pickering emulsion had a protective effect on menthol, with the most significant inhibitory effects on Escherichia coli and Staphylococcus aureus under the same conditions. Overall, this study proposes a novel approach for the application and development of l-menthol by combining it with Pickering emulsion.

Encapsulation of Indicaxanthin-Rich Opuntia Green Extracts by Double Emulsions for Improved Stability and Bioaccessibility

Opuntia ficus-indica var. Colorada fruit is an important source of indicaxanthin, a betalain with antioxidant, anti-inflammatory, and neuromodulatory potential, proven in both in vitro and in vivo models. Other betalains and phenolic compounds with bioactive activities have also been identified in Colorada fruit extracts. These compounds may degrade by their exposure to different environmental factors, so in the present research, two double emulsion systems (W1/O/W2) were elaborated using Tween 20 (TW) and sodium caseinate (SC) as surfactants to encapsulate Colorada fruit pulp extracts, with the aim of enhancing their stability during storage. Encapsulation efficiencies of up to 97.3 ± 2.7%, particle sizes between 236 ± 4 and 3373 ± 64 nm, and zeta potential values of up to ∣46.2∣ ± 0.3 mV were obtained. In addition, the evaluation of the in vitro gastro-intestinal stability and bioaccessibility of the main individual bioactives was carried out by standardized INFOGEST© protocol, obtaining the highest values for the encapsulated extract bioactives in comparison with the non-encapsulated extract (control). Especially, TW double emulsion showed bioaccessibility values of up to 82.8 ± 1.5% for the main bioactives (indicaxanthin, piscidic acid, and isorhamnetin glucoxyl-rhamnosyl-pentoside 2 (IG2)), indicating a promising potential for its use as a functional natural colorant ingredient.

Microemulsified Gel Formulations for Topical Delivery of Clotrimazole: Structural and In Vitro Evaluation

Microemulsified gels (μEGs) with fascinating functions have become indispensable as topical drug delivery systems due to their structural flexibility, high stability, and facile manufacturing process. Topical administration is an attractive alternative to traditional methods because of advantages such as noninvasive administration, bypassing first-pass metabolism, and improving patient compliance. In this article, we report on the new formulations of microemulsion-based gels suitable for topical pharmaceutical applications using biocompatible and ecological ingredients. For this, two biocompatible μE formulations comprising clove oil/Brij-35/water/ethanol (formulation A) and clove oil/Brij-35/water/1-propanol (formulation B) were developed to encapsulate and improve the load of an antimycotic drug, Clotrimazole (CTZ), and further gelatinized to control the release of CTZ through skin barriers. By delimiting the pseudo-ternary phase diagram, optimum μE formulations with clove oil (∼15%) and Brij-35 (∼30%) were developed, keeping constant surfactant/co-surfactant ratio (1:1), to upheld 2.0 wt % CTZ. The as-developed formulations were further converted into smart gels by adding 2.0 wt % carboxymethyl cellulose (CMC) as a cross-linker to adhere to the controlled release of CTZ through complex skin barriers. Electron micrographs show a fine, monodispersed collection of CTZ-μE nanodroplets (∼60 nm), which did not coalesce even after gelation, forming spherical CTZ-μEG (∼90 nm). However, the maturity of CTZ nanodroplets observed by dynamic light scattering suggests the affinity of CTZ for the nonpolar microenvironment, which was further supported by the peak-to-peak correlation of Fourier transform infrared (FTIR) analysis and fluorescence measurement. In addition, HPLC analysis showed that the in vitro permeation release of CTZ-μEG from rabbit skin in the ethanolic phosphate buffer (pH = 7.4) was significantly increased by >98% within 6.0 h. This indicates the sustained release of CTZ in μEBG and the improvement in transdermal therapeutic efficacy of CTZ over its traditional topical formulations.

Lipophilic Vitamin E Diffusion through Bicontinuous Microemulsions

We studied the diffusion properties of lipophilic vitamin E (VE) through bicontinuous microemulsions (BME) using both electrochemical and fluorescence correlation spectroscopy (FCS) measurements. We investigated the effect of different composition ratios of micro-water and micro-oil phases in BMEs (W/O_BME). When we employed the BME with a lower W/O_BME value of 40/60 (oil-rich BME) as an electrolyte solution, we obtained a larger current response from VE at a fluorinated nanocarbon film electrode. Further voltammetric studies revealed that a higher VE diffusion coefficient was observed in the oil-rich BME. The FCS results also exhibited faster diffusion through the oil-rich BME, which played a significant role in accelerating the VE diffusion probably due to the widening of the micro-oil phase pathway in the BME. Moreover, the effect of increasing the VE diffusion was pronounced at the interface between the electrode surface and the BME solution. These results indicate that controlling the conditions of the BME as the measurement electrolyte is very effective for achieving superior electrochemical measurements in a BME.