Formulation and characterization of pH induced in situ gels containing sulfacetamide sodium for ocular drug delivery: A combination of Carbopol^®/HPMC polymer

© 2019, Association of Pharmaceutical Teachers of India. All rights reserved. Introduction: Topical delivery of eye drops which currently accounts to 90% of available ocular dosage forms are ideal for the treatment of eye diseases but having limitations of poor therapeutic response and low bioavailability. Objectives: The objectives of present research was to develop and characterize sustained release in situ ocular gels containing sufacetamide sodium using pH induced gelling polymers for improved therapeutic response and patient compliance. Methods: In situ gel formulations prepared by dispersion method using Carbopol® 940/Carbopol® 934 alone or in combination with hydroxypropyl methylcellulose (HPMC E4M). Formultaions were evaluated for appearance, pH, viscosity, gelling capacity, drug content and in vitro drug release. The optimized formulation was assessed for sterility and antimicrobial efficacy using disk diffusion technique in comparison to commercial eye drops (Albucid®10%). Results: The appearance of in situ gels were clear and free flowing in nature however, a viscous clear solution with no flow was produced for formulations consisting of 0.8% w/v Carbopol® 940/Carbopol® 934 and 2% w/v HPMC E4M. pH of all the formulations was within the range of 5.9 to 6.7. In situ gels with Carbopol® 940 demonstrated higher viscosity compared to Carbopol® 934 and drug release was sustained over a period of 8 hr. The selected formulation containing 0.8% w/v Carbopol® 940 and 1.5% w/v HPMC E4M passed sterility test and demonstrated similar antimicrobial efficiency compared to commercial product. Conclusion: Carbopol®/HPMC-based in situ gels have potential to improve patient’s compliance by reducing the dosing frequency and could be a viable alternative to commercial product

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

Dielectric properties of aluminum-epoxy composites

Dielectric properties of Al-epoxy composites were characterized as a function of composition, frequency, and temperature. The dielectric constant increased smoothly with an increase in the concentration of aluminum. An increase in dielectric constant was also observed with an increase in temperature as well as with a decrease in frequency. In general, dissipation factor values for composites with higher concentrations of aluminum were greater than those with lower volume content of aluminum. Also, the dissipation factor showed an increase both with a decrease in frequency and an increase in temperature. The increase in values of dielectric constant and dissipation factor with an increase in concentration of aluminum was attributed to interfacial polarization. The absence of any discontinuity in the plot of dielectric constant versus composition was ascribed to the absence of continuous aluminum chains in the composition range investigated. The increase in dielectric constant with a rise in temperature was attributed to the segmental mobility of the polymer molecules. (C) 2003

VIBRATIONAL-MODES IN ELECTRODEPOSITED AMORPHOUS-SILICON - FT-IR ANALYSIS

Infrared spectra of 13 samples of amorphous silicon bonded with hydrogen, fluorine and carbon, prepared by electrodeposition using a mixture of ethylene glycol and fluosilicic acid were analysed in the wave number region 4000-400 cm-1 with a Fourier transform infrared spectrometer. Strong absorption peaks were observed at 1000 cm-1 due to the SiF(x) stretching mode. Small peaks were seen around 2300 and 640 cm-1 due to SiH stretching and wagging modes of absorption. The number of bonded hydrogen atoms in the film deposited at 0.05 M, 50 mA cm-2 was calculated to be 6.2579 x 10(21) and 1.2302 x 10(20) atm cm-3 using integrated absorption of the CH and SiH stretching modes, respectively. The absorption coefficient around the SiF(x) stretch region was found to vary from 1300-2500 cm-1 as the molarity of the electrolyte was increased. Binding energy shifts in X-ray photoelectron spectrum were used as a cross check to confirm the silicon bonding with carbon, hydrogen, oxygen and fluorine atoms. The absence of columnar growth in SEM photographs indicates no polysilane formation in the films

STRUCTURAL AND MORPHOLOGICAL-STUDIES OF ELECTRODEPOSITED AMORPHOUS-SILICON THIN-FILMS

Amorphous silicon thin films obtained from hydrofluosilicic acid using the electrodeposition method are analysed for structure and morphology. The chemical nature of the films is discussed using the data from IR spectroscopy. The electrical resistivity of these films is very high, of the order of 10(12)-10(13) OMEGA cm, under the present experimental conditions. X-ray diffraction spectra revealed that the films are not crystalline in nature. At low concentrations of the electrolyte, scanning electron microscopy photographs exhibited some microstructure with crystalline order of about 100 angstrom, At high concentrations, the structure of the films changed widely to be homogeneous