Structural and probing dynamics of Brij-35-based microemulsion for fluoroquinolone antibiotics

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.

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.

Microemulsion-Based Polymer Gels with Ketoprofen and Menthol: Physicochemical Properties and Drug Release Studies

Ketoprofen is a non-steroidal, anti-inflammatory drug frequently incorporated in topical dosage forms which are an interesting alternatives for oral formulations. However, due to the physiological barrier function of skin, topical formulations may require some approaches to improve drug permeation across the skin. In this study, ketoprofen-loaded microemulsion-based gels with the addition of menthol, commonly known for absorption-enhancing activity in dermal products, were investigated. The main objective of this study was to analyze the physicochemical properties of the obtained gels in terms of topical application and to investigate the correlation between the gel composition and its mechanical properties and the drug release process. Microemulsion composition was selected with the use of a pseudoternary plot and the selected systems were tested for electrical conductivity, viscosity, pH, and particle diameter. The polymer gels obtained with Carbopol® EZ-3 were subjected to rheological and textural studies, as well as the drug release experiment. The obtained results indicate that the presence of ketoprofen slightly decreased yield stress values. A stronger effect was exerted by menthol presence, even though it was independent of menthol concentration. A similar tendency was seen for hardness and adhesiveness, as tested in texture profile analysis. Sample cohesiveness and the drug release rate were independent of the gel composition.

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.

Brij® integrated bilosomes for improving the transdermal delivery of niflumic acid for effective treatment of osteoarthritis: In vitro characterization, ex vivo permeability assessment, and in vivo study

Bilosomes are innovative vesicular carriers containing bile salt with a non-ionic surfactant. Being highly flexible, bilosomes can squeeze themselves through the skin carrying the drug to the action site and improving its skin penetration. The objective of this research was to encapsulate niflumic acid (NA), a non-steroidal anti-inflammatory drug into Brij® integrated bilosomes (BIBs) for effective treatment of osteoarthritis through transdermal delivery. BIBs were formulated using 100 mg of Span 20 with different amounts of sodium cholate (NaC), sodium taurocholate (NaTC), or sodium glycocholate (NaGC) as bile salt, with the addition of 5 mg of Brij-93 or Brij-35. BIBs were prepared utilizing ethanol injection method with the application of (3¹×2²) complete factorial design using Design-Expert® software. The optimal BIBs formulation determined was (B5) which contains 5 mg of NaTC used as bile salt and 5 mg of Brij-93. B5 exhibited entrapment efficiency% = 95.21 ± 0.00%, particle size = 373.05 ± 0.07 nm, polydispersity index = 0.27 ± 0.01, and zeta potential = -32.00 ± 0.00 mV. It also had a high elasticity with a spherical shape. B5 gel displayed a sustained release profile with a significantly 2.3 folds' higher drug permeation percent across rat skin than that permeated from NA gel. Moreover, in vivo anti-osteoarthritic and histopathological studies assured the efficacy and safety of B5 gel and its superiority over NA gel. Generally, the outcomes confirmed the great efficacy of NA loaded BIBs for the topical treatment of osteoarthritis.

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.