Ultrasonic Processing Technique as a Green Preparation Approach for Diacerein-Loaded Niosomes
In this study, the feasibility of ultrasonic processing (UP) technique as green preparation method for production of poorly soluble model drug substance, diacerein, loaded niosomes was demonstrated. Also, the effects of different surfactant systems on niosomes’ characteristics were analyzed. Niosomes were prepared using both the green UP technique and traditional thin-film hydration (TFH) technique, which requires the use of environmentally hazardous organic solvents. The studied surfactant systems were Span 20, Pluronic L64, and their mixture (Span 20 and Pluronic L64). Both the production techniques produced well-defined spherical vesicles, but the UP technique produced smaller and more monodisperse niosomes than TFH. The entrapment efficiencies with the UP method were lower than with TFH, but still at a feasible level. All the niosomal formulations released diacerein faster than pure drug, and the drug release rates from the niosomes produced by the UP method were higher than those from the TFH-produced niosomes. With UP technique, the optimum process conditions for small niosomal products with low PDI values and high entrapment efficiencies were obtained when 70% amplitude and 45-min sonication time were used. The overall results demonstrated the potency of UP technique as an alternative fast, cost-effective, and green preparation approach for production of niosomes, which can be utilized as drug carrier systems for poorly soluble drug materials.
Surfactants and fatty alcohol based novel nanovesicles for resveratrol: Process optimization, characterization and evaluation of functional properties in RAW 264.7 macrophage cells
Abstract Resveratrol, a natural polyphenol widely applauded for its cardio-protective and anti-cancer activity, has limited application due to its poor solubility and low bioavailability. Hence, an attempt was made to optimize the preparation of biocompatible resveratrol loaded niosomes (R-niosomes) using non-ionic surfactants and fatty alcohol as stabilizer employing the novel and green method of sonication. R-Niosomes exhibited mean particle size of 108 nm with narrow size distribution (PDI = 0.24) and high zeta potential (−56.8 mV). The niosomes had >80% of resveratrol encapsulated into the vesicles and exhibited controlled release under simulated gastro-intestinal conditions. FTIR, XRD and DSC analyses confirmed successful encapsulation of resveratrol into the vesicles. Assays in macrophage RAW264.7 cell lines showed that R-niosomes had lower cytotoxicity and higher intracellular ROS scavenging activity when compared to resveratrol in its free form. This study demonstrated that nanoencapsulation of resveratrol through niosomes using non-ionic surfactant and fatty alcohol has dramatically improved its solubility and functionality.
Phase diagram of tyioxapol and water — I
Abstract Tyloxapol, a nonionic liquid polymer of the alkyi aryl polyether alcohol type, described as freely soluble in water, is widely used in pharmacy. At room temperature and above, tyloxapol does not dissolve immediately in water but forms liquid crystalline structures in the contact zone with water resulting among others in the slow formation of aqueous one-phase systems. Macroscopically isotropic aqueous systems with a concentration-dependent viscosity are formed below 35 wt% tyloxapol. Around 35 wt% there is a narrow two-phase coexistence region. From 37.5 to 65 wt% textures of lyotropic liquid crystalline hexagonal phases are observed in the polarizing microscope. Solubilization tests indicate a hexagonal phase. This phase exists in a broad concentration and temperature range as derived from hot-stage polarizing microscopy and differential scanning calorimetry. The hexagonal phase exhibits the highest transition temperature (59°C) and the highest transition heats (0.5 J/g) around 50 wt%. Transmission electron microscopy (TEM) observations indicate a supramolecular arrangement consisting of parallel cylinders of non-uniform length resulting in two-dimensional order. In a narrow concentration range around 70 wt% and below 30°C, there is a stiff lyotropic liquid crystalline cubic phase with a transition heat of 1.3 J/g. Between 74 and 80 wt% at room temperature there is a liquid crystalline lamellar phase with low viscosity exhibiting no measurable transition heats. TEM observations indicate a supramolecular arrangement consisting of extended stacked lamellae exhibiting only one-dimensional order. The retransformation of the cubic phase from the melt is highly retarded. In contrast, the liquid crystalline hexagonal phase and lamellar phase are immediately formed on cooling of the melts to room temperature. Above 80 wt% the systems represent crystal dispersions.