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

We assessed the functionality of sucrose esters (sucrose laurate, myristate, palmitate, and stearate), relatively innocuous nonionic surfactants, in formulation of biocompatible microemulsions. The putative influence of surfactant structure on the extension of microemulsion region was explored through the construction of the pseudo-ternary phase diagrams for the isopropyl myristate/sucrose ester-isopropyl alcohol/water system, using the titration method and mixture experimental approach. Minor changes in surfactant tail length strongly affected the microemulsion area boundaries. D-optimal mixture design proved to be highly applicable in detecting the microemulsion regions. Examination of conductivity, rheology, and thermal behavior of the selected sucrose laurate and sucrose myristate-based microemulsions, upon dilution with water, indicated existence of percolation threshold and suggested the phase inversion from water-in-oil to oil-in-water via a bicontinuous structure. Atomic force micrographs confirmed the suggested type of microemulsions and were valuable in further exploring their inner structure. The solubilization capacity of aceclofenac as a model drug has decreased as the water volume fraction in microemulsion increased. High surfactant concentration and the measured solubility of aceclofenac in microemulsion components suggested that the interfacial film may mostly contribute to aceclofenac solubilization

Resveratrol loaded liposomes produced by different techniques

Several different methods for production of liposomes incorporating resveratrol were investigated and compared from the aspect of size distribution, surface charge, entrapment efficiency, phase behavior and stability. Thin film method and proliposome method provided high entrapment efficiency (92.9% and 97.4%, respectively). Extrusion and sonication techniques were applied to obtain particles of the average diameter between 120 and 270 nm. The sonicated liposomes incorporated resveratrol (44-56%) fewer than extruded vesicles (92-96%). Antioxidative activity of resveratrol was retained upon encapsulation. Differential scanning calorimetry was performed in order to study the interaction of liposomal membranes with resveratrol, and their physical state. The release studies performed in Franz diffusion cell showed that liposomes impart slow diffusion of resveratrol, where diffusion resistance derived from liposomal membrane ranged from 5.90 . 10(5) to 9.55 . 10(5) s/m depending on the size of particles. Cytotoxicity of the formulations was evaluated via morphological changes of keratinocytes treated by liposomes. Industrial Relevance: Resveratrol displays many health-beneficial properties and possesses a remarkably strong antioxidant activity. Although often consumed in food, the positive effects of resveratrol are restricted because it is prone to oxidation, poorly absorbed when orally administrated, and cytotoxic in higher total dosages (though relatively high local concentrations are required for an effect). Encapsulation is one way to improve bioavailability and stability of resveratrol; herein the main challenge is to find a suitable solution, as resveratrol is weakly water soluble. This has motivated us to design new formulations based on liposomes for delivering of resveratrol. In the food sector, liposomes have been investigated for delivering proteins, enzymes, antioxidants, flavors and vitamins. The mean advantage of liposomes over other encapsulation technologies (spray-drying, extrusion, and fluidized beds) is the stability that liposomes impart to water-soluble compounds in aqueous surroundings. Liposomes are able to stabilize the encapsulated materials against a range of environmental and chemical changes. Another important characteristic of liposomes is that, unlike many other existing encapsulants, they can be utilized in the entrapment, delivery, and release of poorly water soluble compounds, such as resveratrol, and they are also convenient for water-soluble, lipid-soluble, and amphiphilic compounds. As liposomes could be produced from naturally occurring components, regulatory issues that may prevent the application in food systems are potentially diminished, and new formulations could be quickly implemented. Despite benefits described here, up to date little use of liposomes in food systems has been made, as current manufacturing processes are mainly time consuming, often consisting of several steps with high costs of raw materials. Another problem is that devices available commercially which are utilized for production of liposomes are able to process only small quantities. Therefore, our research is devoted to the development of the process for liposome production which is easy to scale up, and at the same time, is effective as the common way based on thin film hydration process. The process elaborated in our study utilizes a commercial lipid mixture. The method used called proliposome method is based on replacement of ethanol solvent by aqueous media. For liposome downsizing, sonication (which can be easily modified to increase sample volume capability) is tested versus membrane extrusion (equipment for small-large batches is readily available). The goal of this article is to provide evidence for food manufacturers and food scientists to make broader use of resveratrol-loaded liposomes that can add value and improve the quality of existing food products

Encapsulation of natural antioxidant resveratrol in liposomes

Liposomes have been shown to be suitable systems for encapsulation and preserving the health-beneficial properties of a wide range of biological active ingredients such as resveratrol (RSV). The aim of this study was to encapsulate RSV in liposomes, with a goal to achieve the extended release and improved stability of RSV. Multilameral liposomes were prepared by means of two different methods: thin film method (TF) and proliposome method (PRO). In both methods, the ratio between added RSV and phospolipon 90G (P90G) was 1:20 w/w. Extrusion and sonication were applied in order to obtain unilameral liposomes. Both methods were efficient in capturing RSV within the microparticles, thus encapsulation efficiency had high values (92,9% in case of TF and 97,4% in case of PRO). The size reduction of liposomes resulted with particles of the average diameter ranged between 120 and 270 nm. Antioxidative activity was retained at a high level (approximately 95%). Franz diffusion cell was used for release studies and diffusion of RSV was monitored for 6h. According to the results, liposomes appeared to be suitable vehicles for encapsulation of resveratrol where PRO is particularly useful for encapsulation of antioxidants

Biocompatible microemulsions of a model NSAID for skin delivery: A decisive role of surfactants in skin penetration/irritation profiles and pharmacokinetic performance

To elaborate the decisive role of surfactants in promotion of aceclofenac' skin absorption, potentially avoiding irritation, we developed non-ionic microemulsions varying natural or synthetic surfactants: sucrose esters (laurate or myristate) vs. polysorbate 80. A comprehensive physicochemical characterization indicated no significant influence of the solubilized nonsteroidal anti-inflammatory drug on the bicontinuous structure of blank formulations. To evaluate skin tolerability of isopropyl alcohol, a sucrose ester-based microemulsion containing transcutol P as a cosurfactant was also developed. The measured skin parameters strongly depended on the (co)surfactant type, showing higher compatibility of the microemulsions containing sucrose ester and isopropyl alcohol. In vitro release results, in vivo tape stripping and pharmacokinetics in rats confirmed superiority of the sucrose ester-over polysorbate-based microemulsions (total amounts of aceclofenac penetrated 60.81 +/- 5.97 and 60.86 +/- 3.67 vs. 27.00 +/- 5.09 mu g/cm(2), and its maximum plasma concentrations 275.57 +/- 109.49 and 281.31 +/- 76.76 vs. 150.23 +/- 69.74 ng/ml for sucrose laurate- and myristate- vs. polysorbate 80-based microemulsions, respectively). Hence, sugar-based excipients increased delivery of aceclofenac through stratum corneum by increasing its fluidity, showing overall more satisfying safety profiles. In conclusion, sucrose ester-based microemulsions proved to be promising carriers for dermal/transdermal aceclofenac delivery