Chitosan/Polyethylene Glycol Beads Crosslinked with Tripolyphosphate and Glutaraldehyde for Gastrointestinal Drug Delivery

This study reports on the preparation of chitosan (CS)/polyethylene glycol (PEG) hydrogel beads using sodium diclofenac (DFNa) as a model drug. Following the optimization of the polymer to drug ratio, the chitosan beads were modified by ionic crosslinking with sodium tripolyphosphate (TPP). The CS/PEG/DFNa beads obtained from a (w/w/w) ratio of 1/0.5/0.5 with crosslinking in 10% (w/v) TPP at pH 6.0 for 30 min yielded excellent DFNa encapsulation levels with over 90% loading efficiency. The dissolution profile of DFNa from CS/PEG/DFNa beads demonstrated that this formulation was able to maintain a prolonged drug release for approximately 8 h. Among the formulations tested, the CS/PEG/DFNa (1/0.5/1 (w/w/w)) beads crosslinked with a combination of TPP (10% (w/v) for 30 min) and glutaraldehyde (GD) (5% (w/v)) were able to provide minimal DFNa release in the gastric and duodenal simulated fluids (pH 1.2 and 6.8, respectively) allowing for a principally gradual drug release over 24 h in the intestinal (jejunum and ileum) simulated fluid (pH 7.4). Thus, overall the CS/PEG beads crosslinked with TPP and GD look to be a promising and novel alternative gastrointestinal drug release system.     

A new screening method for flunitrazepam in vodka and tequila by fluorescence spectroscopy

A new screening method for flunitrazepam in colourless alcoholic beverages based on a spectroscopic technique is proposed. Absorption and steady‐state fluorescence of flunitrazepam and its protonated form with various acids were investigated. The redshift of the wavelength of maximum absorption was distinctively observed in protonated flunitrazepam. An emissive fluorescence at 472 nm was detected in colourless spirits (vodka and tequila) at room temperature. 2‐M perchloric acid was the most appropriated proton source. By using electron ionization mass spectrometry and time‐dependent density functional theory calculations, the possible structure of protonated flunitrazepam was identified to be 2‐nitro‐N‐methylacridone, an acridone derivative as opposed to 2‐methylamino‐5‐nitro‐2′‐fluorobenzophenone, a benzophenone derivative. Copyright © 2012 John Wiley & Sons, Ltd.