Sucrose ester-based biocompatible microemulsions as vehicles for aceclofenac as a model drug: formulation approach using D-optimal mixture design

Exploring Microemulsion Systems for the Incorporation of Glucocorticoids into Bacterial Cellulose: A Novel Approach for Anti-Inflammatory Wound Dressings

The effective pharmacological treatment of inflamed wounds such as pyoderma gangraenosum remains challenging, as the systemic application of suitable drugs such as glucocorticoids is compromised by severe side effects and the inherent difficulties of wounds as drug targets. Furthermore, conventional semi-solid formulations are not suitable for direct application to open wounds. Thus, the treatment of inflamed wounds could considerably benefit from the development of active wound dressings for the topical administration of anti-inflammatory drugs. Although bacterial cellulose appears to be an ideal candidate for this purpose due to its known suitability for advanced wound care and as a drug delivery system, the incorporation of poorly water-soluble compounds into the hydrophilic material still poses a problem. The use of microemulsions could solve that open issue. The present study therefore explores their use as a novel approach to incorporate poorly water-soluble glucocorticoids into bacterial cellulose. Five microemulsion formulations were loaded with hydrocortisone or dexamethasone and characterized in detail, demonstrating their regular microstructure, biocompatibility and shelf-life stability. Bacterial cellulose was successfully loaded with the formulations as confirmed by transmission electron microscopy and surprisingly showed homogenous incorporation, even of w/o type microemulsions. High and controllable drug permeation through Strat-M® membranes was observed, and the anti-inflammatory activity for permeated glucocorticoids was confirmed in vitro. This study presents a novel approach for the development of anti-inflammatory wound dressings using bacterial cellulose in combination with microemulsions.

A Cosmeceutical Topical Water-in-Oil Nanoemulsion of Natural Bioactives: Design of Experiment, in vitro Characterization, and in vivo Skin Performance Against UVB Irradiation-Induced Skin Damages

Introduction

Damage to human skin occurs either chronologically or through repetitive exposure to ultraviolet (UV) radiation, where collagen photodegradation leads to the formation of wrinkles and skin imperfections. Consequently, cosmeceutical products containing natural bioactives to restore or regenerate collagen have gained a remarkable attention as an ameliorative remedy.

Methods

This study aimed to develop and optimize collagen-loaded water-in-oil nanoemulsion (W/O NE) through a D-optimal mixture design to achieve an ideal multifunctional nanosystem containing active constituents. Vit E was included as a constituent of the formulation for its antioxidant properties to minimize the destructive impact of UV radiation. The formulated systems were characterized in terms of their globule size, optical clarity, and viscosity. An optimized system was selected and evaluated for its physical stability, in vitro wound healing properties, and in vivo permeation and protection against UV radiation. In addition, the effect of collagen-loaded NE was compared to Vit C-loaded NE and collagen-/Vit C-loaded NEs mixture as Vit C is known to enhance collagen production within the skin.

Results

The optimized NE was formulated with 25% oils (Vit E: safflower oil, 1:3), 54.635% surfactant/cosurfactant (Span 80: Kolliphor EL: Arlasolve, 1:1:1), and 20.365% water. The optimized NE loaded with either collagen or Vit C exhibited a skin-friendly appearance with boosted permeability, and improved cell viability and wound healing properties on fibroblast cell lines. Moreover, the in vivo study and histopathological investigations confirmed the efficacy of the developed system to protect the skin against UV damage. The results revealed that the effect of collagen-/Vit C-loaded NEs mixture was more pronounced, as both drugs reduced the skin damage to an extent that it was free from any detectable alterations.

Conclusion

NE formulated using Vit E and containing collagen and/or Vit C could be a promising ameliorative remedy for skin protection against UVB irradiation.

New, Biocompatible, Chitosan-Gelled Microemulsions Based on Essential Oils and Sucrose Esters as Nanocarriers for Topical Delivery of Fluconazole

Biocompatible gel microemulsions containing natural origin excipients are promising nanocarrier systems for the safe and effective topical application of hydrophobic drugs, including antifungals. Recently, to improve fluconazole skin permeation, tolerability and therapeutic efficacy, we developed topical biocompatible microemulsions based on cinnamon, oregano or clove essential oil (CIN, ORG or CLV) as the oil phase and sucrose laurate (D1216) or sucrose palmitate (D1616) as surfactants, excipients also possessing intrinsic antifungal activity. To follow up this research, this study aimed to improve the adhesiveness of respective fluconazole microemulsions using chitosan (a biopolymer with intrinsic antifungal activity) as gellator and to evaluate the formulation variables' effect (composition and concentration of essential oil, sucrose ester structure) on the gel microemulsions' (MEGELs) properties. All MEGELs were evaluated for drug content, pH, rheological behavior, viscosity, spreadability, in vitro drug release and skin permeation and antifungal activity. The results showed that formulation variables determined distinctive changes in the MEGELs' properties, which were nevertheless in accordance with official requirements for semisolid preparations. The highest flux and release rate values and large diameters of the fungal growth inhibition zone were produced by formulations MEGEL-FZ-D1616-CIN 10%, MEGEL-FZ-D1216-CIN 10% and MEGEL-FZ-D1616-ORG 10%. In conclusion, these MEGELs were demonstrated to be effective platforms for fluconazole topical delivery.

Topical Biocompatible Fluconazole-Loaded Microemulsions Based on Essential Oils and Sucrose Esters: Formulation Design Based on Pseudo-Ternary Phase Diagrams and Physicochemical Characterization

To initiate our research into the development of biocompatiîle gelled-microemulsions based on essential oils (EOs) and sucrose esters (SEs) for the topical delivery of fluconazole, this formulation study investigated the usefulness of two relatively harmless natural non-ionic surfactants from the group of SEs (sucrose laurate and stearate) to form, in the presence of antifungal EOs, stable, isotropic microemulsions effective on fluconazole solubilization. Fluconazole’s solubility in EO significantly depended on their chemical composition, showing higher values for cinnamon, oregano and clove essential oils, further selected as oil phase components for microemulsion formulations. The phase behavior of several EO–isopropyl miristate/SE–isopropanol/water systems was assessed through pseudo-ternary phase diagrams constructed by microplate dilution technique. The hydrocarbon chain length of the SE and EO type strongly influenced the size of the microemulsion region in the pseudo-ternary phase diagrams. Ten microemulsion formulations containing 2% fluconazole, 6% or 10% oil mixture of EO–isopropyl myristate in 1:1 ratio, 45% SE-isopropanol mixture and water, were selected and evaluated for physicochemical properties (droplet size, polydispersity, viscosity, refractive index, zeta potential and pH). All formulations were physicochemically acceptable, but viscosity enhancement and further in vitro and in vivo tests are required for the development of biocompatible, clinically safe and effective fluconazole topical preparations.

Microemulsions as nano-reactors for the solubilization, separation, purification and encapsulation of bioactive compounds

Bioactive components possess various functionalities and are most interested for different food, nutraceutical and pharmaceutical formulations. The current review will discuss the preparation methods and fabrication techniques to design microemulsions (MEs) for the solubilization, separation, encapsulation and purification of various agro-food bioactive compounds. ME systems have shown suitable potential in enhancing oil recovery, protein extraction, and isolation of bioactive compounds. Moreover, the capability of ME based systems as drug and nutraceutical delivery cargos, and synthesis of various organic and inorganic nanoparticles, especially using biopolymers, will be investigated. ME liquid membranes are also developed as nano-extractor/nano-reactor vehicles, capable of simultaneous extraction, encapsulation or even synthesis of hydrophilic and lipophilic bioactive compounds for food, nutraceutical and drug applications.

Curcumin-loaded low-energy nanoemulsions as a prototype of multifunctional vehicles for different administration routes: Physicochemical and in vitro peculiarities important for dermal application

The objective of this work was to investigate and profoundly characterize low-energy nanoemulsions as multifunctional carriers, with slight reference to dermal administration. An evidence-based approach was offered for deepening the knowledge on their formation via spontaneous emulsification. Curcumin, a compound of natural origin, potentially powerful therapeutic, was chosen as a model API. Due to curcumin's demanding properties (instability, poor solubility, low permeability), its potentials remain unreached. Low-energy nanoemulsions were considered carriers capable of overcoming imposed obstacles. Formulation consisting of Polysorbate 80 and soybean lecithin as stabilizers (9:1, 10%), medium-chain triglycerides as the oil phase (10%) and ultrapure water was selected for curcumin incorporation in 3 different concentrations (1, 2 and 3 mg/mL). Physicochemical stability was demonstrated during 3 months of monitoring (mean droplet size: 111.3-146.8 nm; PDI < 0.2; pH: 4.73-5.73). Curcumin's release from developed vehicles followed Higuchi's kinetics. DPPH (IC50 = 0.1187 mg/mL) and FRAP (1.19 ± 0.02 mmol/g) assays confirmed that curcumin acts as a potent antioxidant through different mechanisms, with no alterations after incorporation in the formulation. High biocompatibility in line with antigenotoxic activity of curcumin-loaded formulations (protective and reparative) was estimated through Comet assay. A multidisciplinary approach is needed to fully characterize developed systems, directing them to more concrete application possibilities.

Alkyl polyglucoside vs. ethoxylated surfactant-based microemulsions as vehicles for two poorly water-soluble drugs: physicochemical characterization and in vivo skin performance

Two types of biocompatible surfactants were evaluated for their capability to formulate skin-friendly/non-irritant microemulsions as vehicles for two poorly water-soluble model drugs differing in properties and concentrations: alkyl polyglucosides (decyl glucoside and caprylyl/capryl glucoside) and ethoxylated surfactants (glycereth-7-caprylate/ caprate and polysorbate 80). Phase behavior, structural inversion and microemulsion solubilization potential for sertaconazole nitrate and adapalene were found to be highly dependent on the surfactants structure and HLB value. Performed characterization (polarized light microscopy, pH, electrical conductivity, rheological, FTIR and DSC measurements) indicated a formulation containing glycereth- 7-caprylate/caprate as suitable for incorporation of both drugs, whereas alkyl polyglucoside-based systems did not exhibit satisfying solubilization capacity for sertaconazole nitrate. Further, monitored parameters were strongly affected by sertaconazole nitrate incorporation, while they remained almost unchanged in adapalene-loaded vehicles. In addition, results of the in vivo skin performance study supported acceptable tolerability for all investigated formulations, suggesting selected microemulsions as promising carriers worth exploring further for effective skin delivery of model drugs.

Sucrose esters as biocompatible surfactants for penetration enhancement: An insight into the mechanism of penetration enhancement studied using stratumcorneum model lipids and Langmuir monolayers

Up to now, the molecular mechanism of the penetration enhancing effect of sucrose esters (SEs) on stratumcorneum (SC) has not been explained in details. In this study, variety of surface sensitive techniques, including surface pressure-area (π-A) isotherms, infrared reflection-absorption spectroscopy (IRRAS), and Brewster angle microscopy (BAM), have been used to investigate interactions between SEs and SC intercellular lipids. A monolayer of the mixture of ceramide AS C18:18, stearic acid and cholesterol in the molar ratio of 1:1:0.7 on an aqueous subphase is a good model to mimic a single layer of intercellular SC lipids. The π-A isotherms of mixed monolayers and parameters derived from the curves demonstrated the interaction between nonionic surfactants such as SEs and SC lipids. With increasing SE concentration, the resultant monolayer films became more fluid and better compressible. IRRAS measurements showed that SEs disordered the acyl chains of SC lipids, and the BAM images demonstrated the modification of the domain structures in SC monolayers. Longer chain-SE has a stronger disordering effect and is better miscible with ceramides in comparison to SE with a shorter hydrophobic part. In conclusion, this study demonstrates the disordering effect of SEs on the biomimetic SC model, pointing out that small changes in the structure of surfactant may have a strong influence on a penetration enhancement of lipophilic drugs through intercellular lipids of skin.