Search

This review refers to biocompatible microemulsions, which in recent decades have attracted the interest of formulators as nanosystems useful for the skin drug delivery. Microemulsions are homogeneous pseudoternary colloidal dispersions, thermodynamically stable, fluid, transparent, isotropic, consisting of an oil phase and an aqueous phase, stabilized by a mixture of surfactant and cosurfactant and with the droplet diameter of the dispersed phase usually within the range 10-100 nm. To support the potential of biocompatible microemulsions as an innovative topical pharmaceutical form, this paper provides an overview of their type, formulation, structure, composition and characterization, as well as their advantages and disadvantages. Currently, the main purpose of the dermal microemulsion formulation is to obtain optimal drug bioavailability under conditions of minimal skin irritability. Numerous studies carried out in the last two decades have shown the potential of microemulsions to increase the percutaneous penetration of drugs, acting as penetration enhancers due to the following advantageous characteristics: high solubilization capacity of natural and synthetic lipophilic and hydrophilic compounds; the release of a large amount of active ingredient in the skin, followed by an increased dermal distribution and permeation. Ensuring skin tolerance in the presence of large amounts of surfactant and co-surfactant in the formulation of microemulsions can be achieved by selecting clinically accepted excipients for topical preparations and generally recognized as safe (Food and Drug Administration). Therefore, biocompatible dermal microemulsions can be prepared using natural excipients (vegetable oils, non-ionic surfactants, volatile oils), which are biodegradable and have lower skin toxicity and irritant potential than synthetic ones.

To initiate our research into the development of biocompati&icirc, le 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&rsquo, 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&ndash, isopropyl miristate/SE&ndash, 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&ndash, 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.

The objectives of this study are the development and evaluation of modified release multi-particulate drug delivery systems containing a BCS class II drug (meloxicam), formulated as polymer-coated pellets. Inert seeds containing microcrystalline cellulose, lactose monohydrate, and polyvinylpyrrolidone were prepared by extrusion-spheronization. The obtained cores were loaded with meloxicam using the drug layering technique, by spray coating in a fluidized bed with a liquid dispersion of the drug. The resulting drug pellets were film-coated with various polymers (Acryl-EZE&reg, 93O, Eudragit&reg, RS 30-D as well as experimental composite obtained by adding Methocel&trade, E5 Premium LV as pore forming agent to the extended release polymer Eudragit&reg, RS 30-D). All experimental systems were evaluated by scanning electron microscopy and in vitro release testing, in an attempt to investigate the characteristics of the film coatings and their influence on drug release from the multi-particulate systems. The in vitro release study was performed in two stages, using two media with pH values corresponding to the gastric and intestinal environment (HCl 0.1N, pH = 1.2 for the first two hours of the test and phosphate buffer 50 mM, pH 6.8 for the next 4 h). The in vitro release data have highlighted the impact of the formulation factors on the drug release.