Preparation and Evaluation of Sorbitan Monopalmitate and Sunflower Oil Based Biphasic Formulation as Matrices for Controlled Delivery

Abstract

The flexible properties of the gels make them superior candidates for the delivery of bioactive agents in cosmetics, medicine, biomaterials and food technologies. The aim of the present study was to develop bigels from the oleogel of sunflower oil and sorbitan monopalmitate for the delivery of metronidazole. The bigels were prepared by mixing oleogel with the polymer solution. Natural (proteins and polysaccharides) and synthetic polymers were used to alter properties of the bigels. Fluorescence microscope was used to study the microstructure of the bigels. The molecular interactions amongst the components of the bigels were studied by FTIR spectroscopy. The mechanical behavior of the bigels was determined using viscometer and static mechanical tester. Gel disintegration studies were carried out at pH 7.4. The thermal and electrical properties of the bigels were analysed using differential scanning calorimeter (DSC) and phase-sensitive multimeter, respectively. Goat blood and HaCaT cells were used to test the hemocompatibility and the cytocompatibility of the bigels, respectively. The antimicrobial efficacy of the drug (metronidazole) loaded bigels was studied against E. coli. The efficiency of the bigels as controlled delivery formulations was evaluated in vitro. Iontophoretic delivery of the drugs was carried out by injecting an AC current (peak current of 96.44 μA). The micrographs suggested the formation of an oleogel-in-hydrogel type of bigels. The particle size of the bigels containing proteins was smaller (4-5 μm) than the bigels containing natural polysaccharides and synthetic polymers. Hydrogen bonding was the major driving force in the formation of the bigels. The mechanical properties of the polysaccharide based bigels were better as compared to the other bigels. The firmness of starch bigels and maltodextrin bigels was found to be highest 729.4421 ± 3.1471 g and 1000.7623 ± 1.8211 g, respectively. All the bigels exhibited pseudoplastic flow and were viscoelastic in nature. The disintegration time of the bigels was dependent on the property of the polymer used. The melting endotherm of the bigels was ~46 °C. The bigels were biocompatible in nature. The drug loaded bigels showed equivalent inhibitory zones against E. coli as compared to the marketed formulations. The application of AC current increased the in vitro drug release. In conclusion the results of the study suggested that the release of metronidazole was controlled by various types of polymers and also greatly influenced by the physical and mechanical properties of the bigels.