3,4,5-Trihy­droxy­benzoic acid

In the title compound, C7H6O5, the three hy­droxy groups on the ring are oriented in the same direction. There are two intra­molecular O—H⋯O hydrogen bonds in the ring. In the crystal, there are several inter­molecular O—H⋯O hydrogen bonds and a short contact of 2.7150 (18) Å between the O atoms of the para-OH groups of adjacent mol­ecules

Physicochemical and permeation of NSAIDs and H2-antagonist binary system

Prince of Songkla Universit

Thermosensitive Polymer Blend Composed of Poloxamer 407, Poloxamer 188 and Polycarbophil for the Use as Mucoadhesive In Situ Gel

Herein, thermosensitive blends of poloxamer 407 (P407)/poloxamer 188 (P188)/polycarbophil (PCB) were developed in terms of maximized content of PCB (a mucoadhesive polymer) and desired temperature-dependent rheological properties of the blends as in situ gelling matrices. Maximizing PCB content while achieving the preferable rheological characteristics was accomplished through the Box–Behnken design. The quantitative effect of the polymer composition in the blends on the thermosensitive characteristics was evaluated using the fitted design model and the corresponding surface plots. The optimized P407/P188/PCB blend (OPT) was the mixture of 20.000, 7.349 and 0.595% (w/w) of P407, P188, and PCB, respectively. The thermosensitive micellization of OPT was investigated using differential scanning calorimetry which revealed an overlapping double endothermic peak caused by the temperature-induced micellization of pure micelles in co-existence with the micelles with attached PCB. Mixing PCB with the P407/P188 matrix promoted a more intense mucoadhesion of the blend. After incorporating metronidazole, a model hydrophilic drug, into OPT, the temperature-dependent characteristics of the hydrogel did not change. Metronidazole release from OPT was sustained by an anomalous mechanism. This optimal ternary hydrogel benefiting from thermosensitive gelling and mucoadhesive matrix might be used as a viable platform for mucoadhesive in situ gelling drug delivery

Report Synthesis and characterization of biopolymers for local application against helicobacter pylori

Thailand Research Fun

In situ mucoadhesive hydrogel based on methylcellulose/xyloglucan for periodontitis : graphical abstract

Novel hydrogels of 5, 6, and 7% w/v of methylcellulose (5MC, 6MC, and 7MC) with 1.5% w/v of tamarind seed xyloglucan (TSX) were developed via an in situ gel forming process. The MC and MC/TSX solutions formed two gel types: a soft gel and a turbid hard gel respectively upon heating. These samples were characterized using a test-tube-tilting method (TTM), rheological, and turbidity measurements. The interactions and the mechanism of gelation were studied using ATR-FTIR. The release of metronidazole (MTZ) from the hydrogels was also investigated. Based on the TTM results, 6MC/TSX, 7MC, and 7MC/TSX were solution at room temperature but could form gel at body temperature. ATR-FTIR demonstrated stronger hydrophobic associations of MC in the turbid gel than in the soft gel which corresponded to the higher intensity of the C–O band of MC. The peak intensity was greater in the presence of TSX, reflecting the role of TSX to increase hydrophobicity and decrease gelation temperature of MC. SEM revealed a microporous morphology of 6MC/TSX, 7MC, and 7MC/TSX and the pore size of the soft gel was greater than that of the turbid gel. The high relative rheological synergism at 37 °C indicated a high mucoadhesive property of the MC/TSX hydrogels. MC and MC/TSX exhibited a suitable syringeability to ease of administration at 25 °C. MTZ exhibited a more sustained release from 7MC/TSX than from a commercial formulation. Therefore, 7MC/TSX hydrogel could be potentially used for the in situ delivery of MTZ for the treatment of periodontitis

Micro-DSC, rheological and NMR investigations of the gelation of gallic acid and xyloglucan

A novel thermoreversible gelling system consisting of tamarind seed xyloglucan (TSX) and gallic acid (GA) was prepared and investigated. The thermal transition temperatures obtained from both micro-DSC and viscoelastic methods were consistent. The hysteresis was observed for the GA–TSX gelling system. The hydrogen bonding interactions between GA and TSX were detected using 13C nuclear magnetic resonance analyses. The carboxylic acid and the hydroxyl group at the para position of GA are the principal groups that interact with TSX. A low temperature induced intermolecular aggregation of TSX via hydrogen bonds between GA and TSX, leading to the formation of a gel network. The thermal stability of the GA–TSX gel increased with increasing the GA concentration. The viscoelastic behavior of the GA–TSX mixtures depended on the concentration of GA. For the mixture of GA and 1% (w/v) TSX, the critical gel concentration of GA was 0.69% (w/v) at physiological temperature (37 °C) and the sol–gel transition was well described by the scaling law. Moreover, the dried GA–TSX gels exhibited various morphologies that reflected the dependence of the arrangement of the TSX chains on the GA concentration

Characterization of Cimetidine–Piroxicam Coprecipitate Interaction Using Experimental Studies and Molecular Dynamic Simulations

The crystalline states of cimetidine and piroxicam, when coprecipitated from solvents containing 1:1 mole ratio, were transformed to amorphous states as observed using powder X-ray diffraction (PXRD). Amorphous forms of drugs generally exhibit higher water solubility than crystalline forms. It is therefore interesting to investigate the interactions that cause the transformation of both the crystalline drugs. Intermolecular interactions between the drugs were determined using Fourier-transform infrared spectroscopy (FTIR) and solid-state 13C CP/MAS NMR. Molecular dynamic (MD) simulation was performed for the first time for this type of study to indicate the specific groups involved in the interactions based on radial distribution function (RDF) analyses. RDF is a useful tool to describe the average density of atoms at a distance from a specified atom. FTIR spectra revealed a shift of the C≡N stretching band of cimetidine. The 13C CP/MAS NMR spectra indicated downfield shifts of C11, C15 and C7 of piroxicam. RDF analyses indicated that intermolecular interactions occurred between the amide oxygen atom as well as the pyridyl nitrogen of piroxicam and H-N3 of cimetidine. The hydrogen atom (O–H) at C7 interacts with the N1 of cimetidine. Since the MD simulation results are consistent with, and complementary to the experimental analyses, such simulations could provide a novel strategy for investigating specific interacting groups of drugs in coprecipitates, or in amorphous mixtures