Abstract
Background: Curcumin constitutes 80% of the curcuminoids (4 - 5%) of the rhizomes of Curcuma longa L. and saffron. This polyphenol regulates various targets through direct interaction or modulation of gene expression. Despite well documented clinical benefits in colon disorders and safety profile, curcumin has limited pharmaceutical role owing to reduced water solubility, instability in alkaline condition, enzymatic degradation, high metabolism and systemic clearance, hence poor bioavailability (<1%). This demands administration of multiple and larger doses (0.4-8 gm) of curcumin to achieve intended therapeutic benefits. Several strategies have been explored to enhance curcumin delivery to the colonic tissues including microencapsulation using nondigestible polysaccharides developed as bioresponsive drug delivery systems. The aim of the study was to formulate casein-chitosan microparticles of curcumin.
Methods: In Accordance with 32 factorial design, total 9 formulations were prepared to optimize curcumin loaded microparticles using coacervation by polyelectrolyte complexation. Microparticles collected from the slurry were dried at 300C for 6 h and stored in an air tight container. % Drug loading of the formulations was assessed by UV spectroscopy at 425 nm. Average particle size and yield were determined by optical microscopy and gravimetry respectively. % Swelling and release prolfiles in SGF and SIF containing 0.2% tween 80 were plotted. Drug polymer interactions were assessed by FTIR spectroscopy and Differential scanning colorimetry. Morphology of microparticles was recorded by scanning electron microscopy.
Results and Conclusions: Formulation 4 turned out to be the best microparticulate system prepared using 0.5% casein and 0.25% chitosan. This formulation exhibited yield of 98% ± 4.9, average particle size of 251 ± 12µ, drug loading (%) 10.8 ± 2, encapsulation efficiency of 95 ± 3.2% with good color, appearance, texture and flow properties by subjective assessment. This formulation can be scaled up conveniently for industrial production. Release behavior demonstrated that release rate of curcumin at pH 1.2 was relatively more than that in pH 7.4 for formulations 4 & 7. Release profile is in agreement with swelling profile at the two chosen pH. Formulation 4 found to be most optimum with reference to all the parameters tested - yield, particle size, encapsulation efficiency, swelling behavior, sustenance of release, curcumin - polymer compatibility by FTIR and DSC, formation of microcapsules by SEM images. Formulation 4 has released nearly 18% of its pay load in the first two hours at SGF and 25% in SIF at the end of 24 hours implying approximately 75% of curcumin cargo is available for delivery in the colonic region after transit through stomach and small intestine.
Keywords: Curcumin, microparticles, casein, chitosan, controlled delivery, pH progression.
Graphical Abstract
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