Co-spray-dried powders of theophylline and ethylcellulose were prepared using aqueous ethylcellulose dispersion. Co-spray-dried powders were directly compressed into the matrices and the release characteristics of the prepared matrices were investigated. The co-spray-dried powders exhibited good matrix formations with high hardness at rather low compression force. The concentration of ethylcellulose in the matrices was, as expected, the rate-determining factor in controlling the release rate of the drug. Increasing the weight fractions of ethylcellulose resulted in a corresponding decrease in the drug release rates in both 0.1 N HCl and phosphate buffer pH 6.8. However, at the same level of ethylcellulose content, the drug release in acidic conditions was higher than in alkaline medium. To modify release characteristics of the matrices, PVP K30 and lactose were employed as channeling agents. At concentrations of 5 and 10%, PVP K30 was found to slow the drug release when incorporated into the co-spray-dried powder formulations containing 5% ethylcellulose. Lactose at a concentration of 15% provided an increasing effect on drug release when added in the formulations. But an increase in lactose quantity from 15 to 25% did not exert much more influence on release characteristics. Higuchi plots were found to be best applicable to all release data. Scanning electron microscopic examinations on the surface and cross-section of the matrices before and after subjection to release testing revealed the formation of porous networks within the matrices by the ethylcellulose fibers. Such polymeric networks would account for the controlled diffusion of the drug from the matrices.

Oxidative stress can cause several severe ophthalmological diseases. In this study, we developed a thermosensitive gel as a delivery system for two antioxidant substances, namely, quercetin and epigallocatechin gallate. The quercetin was loaded in the PLGA nanoparticles using a solvent displacement method. The physical and chemical stability of the quercetin nanoparticles were evaluated, and the degradation kinetics of the quercetin in the nanoparticles was investigated. The in vitro antioxidant and intracellular reactive oxygen species inhibition of the quercetin nanoparticles, combined with the epigallocatechin gallate (EGCG), were determined using a 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay and a 2,7-dichlorodihydrofluorescein fluorescent probes, respectively. The thermosensitive gel loaded with the quercetin nanoparticles and EGCG was formulated. We confirmed that quercetin nanoparticles displayed the desired physical characteristics, release kinetics, and stability. The combination of quercetin nanoparticles and EGCG suggested the additive effect of antioxidant activity. We also demonstrated the superior intracellular ROS inhibition activity of the quercetin nanoparticles and EGCG with n-acetyl cysteine. The thermosensitive gel showed an appropriate gelation temperature and time for ocular drug delivery. Our results provide promising prospects for applying the thermosensitive gel loaded with quercetin nanoparticles and EGCG as an efficient drug delivery system for antioxidant activity in human corneal epithelial cells.

ABSTRACT:The main objective of this research has been to study the efficiency of chitosan as an ocular drug delivery vehicle for topically applied vancomycin in rabbit eyes. Vancomycin 50 mg/mL was reconstituted in four preparations, namely: in Tears Naturale II TM , in 0.9% w/v aqueous sodium chloride, and in 0.1% and 0.3% w/v chitosan solutions in 1% aqueous L(þ)-lactic acid. Twenty-five microliters of vancomycin (50 mg/mL) were applied into the lower conjunctival eye sac in rabbit eyes. Tear samples were then collected after 0, 30, 60, 90, and 120 min to evaluate the pharmacokinetics of the topically applied vancomycin. Comparison of the results obtained showed that vancomycin 50 mg/mL eye drops in the 0.3% chitosan solution were similar to Tears Naturale II TM in terms of bioavailability. The main conclusion to be drawn from this study is that the 0.3% w/v chitosan solution appears to be a highly promising, cost effective candidate for biomedical use as a vehicle for vancomycin ocular drug delivery.

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SUMMARYThis paper presents a framework of supporting system for a drug formulation. We designed ontology to represent the related knowledge for reusable and sharing purposes. The designed ontology is applied with operation rules to suggest an appropriate generic drug production based on information of original drug. The system also provides a validation module to preliminarily approve a pharmaceutical equivalence of the suggested result. Preliminary testing with four random samples shows potential to reformulate a generic product by returning a satisfactory and acceptable of the system suggestions for all samples.