Objective: The aim of this work was to prepare chitosan nanoparticles (CS NPs) using sodium tripolyphosphate (TPP) as crosslinker and to study the effect of chitosan polymeric properties and experimental conditions on the properties and stability of NPs.Methods: CS NPs were prepared by ionic gelation method, using TPP as a crosslinker. The particle size (PS), polydispersity index (PDI), zeta potential (ZP) and the morphologies of the NPs were studied. CS NPs prepared by varying the concentration of TPP, Chitosan molecular weight and its degree of deacetylation, the stirring speed, the rate of TPP addition and the freeze-drying method to study the effect of these variables on the NPs. The stability of the CS NPs was evaluated by storing aqueous suspensions of NPs and comparing the PS, PDI and ZP at the beginning and the end of the experiment.Results: This study shows that the PS, ZP and dispersity of the NPs depend on the chitosan polymeric properties and experimental conditions. The NPs sizes range between 145.73 and 724.23 nm. They all carried positive charges ranging between+4.32 and+43.67 mV. Most of the NPs have the same sizes after freeze-drying, but showed higher monodispersity and ZP, indicating higher stability. After twenty days of studying the stability, the NPs that had low ZP showed a large increment in size in comparison to the highly charged NPs.Conclusion: In conclusion, the polymeric properties and formulation variables in the ionic gelation method have a great influence on the CS NPs formed.
ABSTRACT. Aim of current research was to prepare ibuprofen-poloxamer 407 binary mixtures using fusion method and characterize them for their physicochemical and performance properties. Binary mixtures of ibuprofen and poloxamer were prepared in three different ratios (1:0.25, 1:0.5, and 1:0.75, respectively) using a water-jacketed high shear mixer. In vitro dissolution and saturation solubility studies were carried out for the drug, physical mixtures, and formulations for all ratios in de-ionized water, 0.1 N HCl (pH = 1.2), and phosphate buffer (pH = 7.2). Thermal and physical characterization of samples was done using modulated differential scanning calorimetry (mDSC), X-ray powder diffraction (XRD), and infrared spectroscopy (FTIR). Flow properties were evaluated using a powder rheometer. Maximum solubility enhancement was seen in acidic media for fused formulations where the ratio 1:0.75 had 18-fold increase. In vitro dissolution studies showed dissolution rate enhancement for physical mixtures and the formulations in all three media. The most pronounced effect was seen for formulation (1:0.75) in acidic media where the cumulative drug release was 58.27% while for drug, it was 3.67%. Model independent statistical methods and ANOVA based methods were used to check the significance of difference in the dissolution profiles. Thermograms from mDSC showed a characteristic peak for all formulations with T peak of around 45°C which suggested formation of a eutectic mixture. XRD data displayed that crystalline nature of ibuprofen was intact in the formulations. This work shows the effect of eutectic formation and micellar solubilization between ibuprofen and poloxamer at the given ratios on its solubility and dissolution rate enhancement.
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