Asira Fuongfuchat

Optimization and evaluation of thermoresponsive diclofenac sodium ophthalmic in situ gels

This work was conducted to optimize and evaluate Pluronic F127-based thermoresponsive diclofenac sodium ophthalmic in situ gels (DS in situ gel). They were prepared by cold method and investigated their physicochemical properties i.e., pH, flow ability, sol-gel transition temperature, gelling capacity and rheological properties. An optimized formulation was selected and investigated its physicochemical properties before and after autoclaving, eye irritation potency in SIRC cells and rabbits. In vivo ophthalmic absorption was performed in rabbits. It was found that physicochemical properties of DS in situ gels were affected by formulation compositions. Increment of Pluronic F127 content decreased sol-gel transition temperature of the products while increase in Pluronic F68 concentration tended to increase sol-gel transition temperature. In this study, Carbopol 940 did not affect sol-gel transition temperature but it affected transparency, pH, and gelling capacity of the products. The optimized formulation exhibited sol-gel transition at 32.6 ± 1.1 °C with pseudoplastic flow behavior. It was lost diclofenac sodium content during autoclaving. However, it was accepted as safe for ophthalmic use and could increase diclofenac sodium bioavailability in aqueous humor significantly. In conclusion, the optimized DS in situ gel had potential for using as an alternative to the conventional diclofenac sodium eye drop. However, autoclaving was not a suitable sterilization method for this product.

Effect of cross-linking on physicochemical properties of tapioca starch and its application in soup product

Physicochemical properties of cross-linked tapioca starch (CLTS) with different cross-linking levels and their application as a thickening agent in soups were studied. The CLTS was prepared by cross-linking native tapioca starch suspended in alkaline solution (41.67% (w/w), pH 11) using a mixture (99:1 (w/w) ratio) of sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) at different concentrations ranged from 0.25% to 6.0% (w/w of starch) at 45°C for 3h. Starch paste clarity decreased with increasing concentration of STMP/STPP mixture. Variations of swelling power, solubility, pasting, gelatinization, and rheological properties of the CLTS were found. Thermogravimetric analysis exhibited higher thermal stability for the CLTS granules compared to the native one. Among the samples, the CLTS prepared using 1.0% STMP/STPP (1.0%-CLTS) and soup containing the 1.0%-CLTS exhibited the strongest gel characteristic and the greatest shear resistant properties. The 1.0%-CLTS improved the textural properties and sensory quality of soups.

Modification of tapioca starch by non-chemical route using jet atmospheric argon plasma

Non-chemical modification of tapioca starch was investigated using jet atmospheric argon plasma treatment. Two forms of starch slurry, i.e. granular starch (G) and cooked starch (C), were jet-treated by argon plasma generated by supplying input power of 50 W (denoted as G50 and C50 samples) and 100 W (denoted as G100 and C100 samples) for 5 min. Physical, rheological, and structural characteristics of the modified starch were investigated. The G50 and C100 samples had lower paste clarity but higher thermal stability and performed stronger gels (G50 only) compared to their control counterparts. On the other hand, the analyzed properties of the G100 and C50 samples showed the opposite trend. FTIR and (1)H NMR results revealed that the relative areas of COC and OH peaks were changed after the treatment. Cross-linking reaction seemed to predominantly take place for the G50 and C100 samples, whereas depolymerization predominated for the G100 and C50 samples.

Physicochemical Properties and Anti-Propionibacterium acnes Activity of Film-Forming Solutions Containing Alpha-Mangostin-Rich Extract

The objective of this study was to study the effect of formulation compositions on physicochemical properties and anti-Propionibacterium acnes activity of film-forming solutions containing alpha-mangostin-rich extract (AM). Film-forming solution bases and film-forming solutions containing AM were prepared by using Eudragit RL PO or Klucel LF or combinations of them as film-forming polymers. Rheological properties, pH values of the solutions, and mechanical properties of the dry films were investigated. An optimized formulation was selected and evaluated for the film surface, in vitro AM release, an anti-P. acnes activity, and potential for being a skin irritant. It was found that mechanical properties of the dry films were affected by total polymer contents, ratios of Klucel LF/Eudragit RL PO, AM, and contents of triethyl citrate. The film-forming solutions containing AM had pH values around 7.0. Their flow curves exhibited Newtonian flow behaviors. The optimized formulation provided films possessing smooth and nonporous surfaces. These films showed greater anti-P. acnes activity than their base films without toxicity to skin fibroblasts. Furthermore, AM released from the film matrix obeyed Higuchis equation. In conclusion, the film-forming solutions containing AM had potential for treatment of acne vulgaris caused by P. acnes. However, further in vivo study is necessary to determine their efficacy and safety for using in patients suffering from acne vulgaris.

Gamma sterilization of diclofenac sodium loaded- N-trimethyl chitosan nanoparticles for ophthalmic use

This study was conducted to investigate the effect of gamma irradiation on physicochemical properties of N-trimethyl chitosan (TMC), diclofenac sodium (DC) and diclofenac sodium loaded N-trimethylchitosan nanoparticles (DC-TMCNs), and to determine suitable doses of gamma rays for sterilization of DC-TMCNs. Physicochemical properties of TMC, DC and DC-TMCNs before and after exposure to gamma rays at various doses were investigated. It was found that gamma irradiation at doses of 5-25kGy did not cause any significant changes in physical and chemical properties of TMC, DC and DC-TMCNs. The bioburden of DC-TMCNs was 1.5×106 CFU/vial. The initial contaminating bacteria were radiosensitive bacteria. A number of microorganisms was reduced to 10-6 after exposure to 9.9kGy of gamma rays. Therefore, DC-TMCNs could be sterilized by gamma irradiation at a dose of 10kGy, which did not alter their physicochemical properties and did not produce any substances toxic to the eye.

Effect of Freezing Rate and Starch Granular Morphology on Ice Formation and Non-Freezable Water Content of Flour and Starch Gels

Ice formation and non-freezable water (WNFW) of rice flour and tapioca starch gels were studied at two different freezing rates (–10 and –100°C/min) using differential scanning calorimetry. Ice crystal growth was observed in the slow freezing but not in the fast one. Ice melting enthalpies, however, were similar since more ice formed in holding and reheating steps. Melting enthalpy of fully gelatinized systems with water contents ~ 0.50–0.66 was associated to starch composition and granule morphology. Highly swollen tapioca starch gave the lowest enthalpy and the highest WNFW (0.40 g/g dry starch versus 0.32 and 0.38 g/g dry starch of normal and waxy rice flours, respectively). The further studies revealed that the WNFW values were associated to swelling power, solubility, and granule morphology.