Physical properties of gelatin based solid emulsions: Effects on drug release in the GI tract
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Oral administration of pharmaceuticals is a convenient and simple route for drug delivery. Due to challenges concerning patient compliance and bioavailability, there has been exerted a great effort the last couple of years to optimize different types of oral delivery vehicles. Gelled emulsion-based systems have shown great promise as delivery system. They are chewable, thereby increasing patient compliance, and they are able to trap drugs, either in the gelled or dispersed phase, and thus provide a controlled and prolonged release of the drug, which reduce the possibility of the drug being inactivated in the stomach.The purpose of this study was to investigate how gelatin type and strength, as well as oil content, influences the physical properties of gelatin-based solid emulsions.Filled gel emulsions stabilized by 160 g or 260 g Bloom gelatin type A or B were prepared with varying amounts of corn oil (0, 10, 20, 40 and 50 wt.%) and subjected to rheological characterization. The obtained results showed an increase in storage modulus, gelling and melting temperatures and viscosity with increasing amount of dispersed phase. The increases were more pronounced for both 160 g and 260 g gelatin type A, than for either types of gelatin B. Gelled emulsions were investigated using longitudinal deformation and there was a clear increase in Young s modulus for gelatin A when the oil content was raised. For 260 g Bloom gelatin A and B, there was also a clear trend towards a decrease in force and strain at break with increasing oil content, but again, this was more pronounced in gelatin type A. In vitro dissolution studies in a near gastric environment were performed on a filled gel emulsion (40 wt.% corn oil) stabilised by either gelatin type A or B (260 g Bloom). Here there was also seen a clear correlation between the rheological characteristics of the filled gel emulsions and dissolution time, where gelatin type A had a prolonged dissolution profile compared to gelatin type B. According to these results, there is a possibility to use different gelatin types and oil content to modify the properties of filled gel emulsions for a variety of pharmaceutical applications.