“…With the increasing pH, simulating the physiological medium, a lower maximum swelling degree of 990% was found in phosphate buffer pH = 7.4. Similar pH-dependent swelling behavior of CS based hydrogels was also reported in a previous study [28].…”
The objective of this study was to prepare and characterize physically crosslinked gel formulations of chitosan (CS)-graft-poly(N-isopropyl acrylamide) (PNIPAAm) and polyvinyl alcohol (PVA) for smart delivery of an antifungal drug, Voriconazole, for mucosal applications. For this purpose, cryogels of CS-g-PNIPAAm/PVA and CS/PVA were tested by means of texture profile analysis and rheology to determine optimal matrix properties for topical application. The ratio of 75/25 v/v % CS-g-PNIPAAm/PVA was selected to be used for formulation since it gave low compressibility and hardness (1.2 and 0.6 N) as well as high adhesion properties and non-Newtonian flow behavior. The cryogels and formulations were further characterized by means of FTIR spectroscopy, swelling behavior, texture analysis, scanning electron microscopy (SEM), thermal (differential scanning calorimetry (DSC) and TGA), and rheological behavior. The drug loading capacity and in vitro release profile of the drug, storage stability, and cytotoxicity tests were also performed for the gel formulation. The FTIR, DSC, and TGA results verified the successful formation of cryogels. Swelling studies revealed a pH-dependent swelling ability with a maximum swelling degree of 1200% in acid and 990% in phosphate buffer (pH = 7.4). Thermal studies showed that CS-g-PNIPAAm/PVA 75/25 had higher thermal stability proving the structural complexity of the polymer. The loading capacity of Voriconazole was found to be 70% (w/w). The in vitro release profiles of Voriconazole showed Fickian release behavior for CS-g-PNIPAAm/PVA 75/25 gel with an approximate delivery of 38% within 8 h, slower than matrices containing unmodified chitosan. The storage stability test exhibited that the gel formulation was still stable even after aging for two months. Moreover, the cell culture assays revealed a non-toxic character of the polymeric matrix. Overall results showed that the CS-g-PNIPAAm/PVA 75/25 hydrogel has the potential to be used as a smart polymeric vehicle for topical applications.
“…With the increasing pH, simulating the physiological medium, a lower maximum swelling degree of 990% was found in phosphate buffer pH = 7.4. Similar pH-dependent swelling behavior of CS based hydrogels was also reported in a previous study [28].…”
The objective of this study was to prepare and characterize physically crosslinked gel formulations of chitosan (CS)-graft-poly(N-isopropyl acrylamide) (PNIPAAm) and polyvinyl alcohol (PVA) for smart delivery of an antifungal drug, Voriconazole, for mucosal applications. For this purpose, cryogels of CS-g-PNIPAAm/PVA and CS/PVA were tested by means of texture profile analysis and rheology to determine optimal matrix properties for topical application. The ratio of 75/25 v/v % CS-g-PNIPAAm/PVA was selected to be used for formulation since it gave low compressibility and hardness (1.2 and 0.6 N) as well as high adhesion properties and non-Newtonian flow behavior. The cryogels and formulations were further characterized by means of FTIR spectroscopy, swelling behavior, texture analysis, scanning electron microscopy (SEM), thermal (differential scanning calorimetry (DSC) and TGA), and rheological behavior. The drug loading capacity and in vitro release profile of the drug, storage stability, and cytotoxicity tests were also performed for the gel formulation. The FTIR, DSC, and TGA results verified the successful formation of cryogels. Swelling studies revealed a pH-dependent swelling ability with a maximum swelling degree of 1200% in acid and 990% in phosphate buffer (pH = 7.4). Thermal studies showed that CS-g-PNIPAAm/PVA 75/25 had higher thermal stability proving the structural complexity of the polymer. The loading capacity of Voriconazole was found to be 70% (w/w). The in vitro release profiles of Voriconazole showed Fickian release behavior for CS-g-PNIPAAm/PVA 75/25 gel with an approximate delivery of 38% within 8 h, slower than matrices containing unmodified chitosan. The storage stability test exhibited that the gel formulation was still stable even after aging for two months. Moreover, the cell culture assays revealed a non-toxic character of the polymeric matrix. Overall results showed that the CS-g-PNIPAAm/PVA 75/25 hydrogel has the potential to be used as a smart polymeric vehicle for topical applications.
“…9a). The release profile does not conform to a simple diffusion model which indicates that the complex nature of interactions between the drug and clay lattice dictate the release behaviour [3, 22]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Recent studies have indicated that the incorporation of smectite clays in multicomponent theophylline formulations can provide sustained release which affords the potential to reduce both dosing frequency and adverse effects [3, 9]. The principal objective of the present study was to determine whether the intercalation of theophylline in smectite clay is able to protect the drug from the acidic gastric environment and to enable its controlled release in the small intestine.…”
On the basis of their large specific surface areas, high adsorption and cation exchange capacities, swelling potential and low toxicity, natural smectite clays are attractive substrates for the gastric protection of neutral and cationic drugs. Theophylline is an amphoteric xanthine derivative that is widely used as a bronchodilator in the treatment of asthma and chronic obstructive pulmonary disease. This study considers the in vitro uptake and release characteristics of the binary theophylline-smectite system. The cationic form of theophylline was readily ion exchanged into smectite clay at pH 1.2 with a maximum uptake of 67 ± 2 mg g −1. Characterisation of the drug-clay hybrid system by powder X-ray diffraction analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy confirmed that the theophylline had been exclusively intercalated into the clay system in an amorphous form. The drug remained bound within the clay under simulated gastric conditions at pH 1.2; and the prolonged release of approximately 40% of the drug was observed in simulated intestinal fluid at pH 6.8 and 7.4 within a 2-h timeframe. The incomplete reversibility of the intercalation process was attributed to chemisorption of the drug within the clay lattice. These findings indicate that smectite clay is a potentially suitable vehicle for the safe passage of theophylline into the duodenum. Protection from absorption in the stomach and subsequent prolonged release in the small intestine are advantageous in reducing fluctuations in serum concentration which may impact therapeutic effect and toxicity.
“…The obtained results are supported by other studies. [30][31][32] The graphs from Figure 7 present a comparison of % cell viability among control, NYS and NYS-loaded formulations. Untreated cells were used as control.…”
Interpolymeric complexes (IPCs) have the advantage of combined properties of their constituent polymers. They are easy to prepare under mild conditions and do not require high processing costs. The interpolymeric complexes of alginate, chitosan and Nystatin, as antifungal drug systems, represent an alternative for mucosal illness treatment. The composition of the two polymers is a key parameter in obtaining the desired properties for pharmaceutical formulations. IPCs of sodium alginate (SA) and chitosan (CS) were prepared via solution mixing method with various compositions, followed by coacervation in 2-propanol. The outcome obtained from rheological measurements was that the complex SA/CS 60/40 (v/v %) fulfilled the requirements of a semi-solid formulation, e.g. pseudoplasticity. Nystatin showed very good compatibility with the polymeric system. The drug loaded gels showed better rheological, textural and mechanical properties (e.g. pseudoelasticity, spreadability, surface adhesion etc.). The final gel formulations showed no cytotoxic effects in the cell culture assay.
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