Influence of different parameters on drug release from hydrogel systems to a biomembrane model. Evaluation by differential scanning calorimetry technique.
ABSTRACT A comparative study on the drug release capacity of four water swellable polymeric systems was carried out by differential scanning calorimetry (DSC). The polymeric systems chosen were alpha,beta-polyaspartahydrazide (PAHy) crosslinked by glutaraldehyde (GLU) (PAHy-GLU) or by ethyleneglycoldiglycidylether (EGDGE), (PAHy-EGDGE), polyvinylalcohol (PVA) crosslinked by glutaraldehyde (PVA-GLU) and alpha,beta-poly(N-hydroxyethyl)-DL-aspartamide (PHEA) by gamma irradiation (PHEA-gamma matrices). The degree of crosslinking for PAHy-GLU, PAHy-EGDGE and PVA-GLU samples was about 0.4 and 0.8. These hydrogels were characterized as free of drugs and were loaded with diflunisal (DFN) (approximately 2.5% w/w). Diflunisal, a non-steroidal anti-inflammatory drug, has been chosen as a model drug to be incorporated into polymeric matrices to follow the release processes of a drug from these hydrogels to a model membrane made by unilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC). Differential scanning calorimetry appears to be a suitable technique to follow the transfer kinetics of the drug from the controlled release system to the biomembrane model. The drug releases from all the considered polymeric hydrogels, were compared with the release observed from the drug solid form by examining the effects on the thermotropic behaviour of DPPC unilamellar vesicles. The release kinetics of the drug from hydrogels were followed at 25, 37 and 50 degrees C to evidence the influence of temperature on the drug release and on the successive transfer to biological membrane model. Particularly, it appears evident that the total amount of drug transferred and the release rate are affected by the polymer crosslinking degree (it increases with crosslinking decrease) as well as by the nature of crosslinking agent. In fact, the drug release profiles from PAHy-GLU samples are more differentiated than those from PAHy-EGDGE. The effect of parameters correlating with the properties of starting polymer, such as water-affinity, crystallinity, glass-to-rubber transition temperature and affinity towards drug molecules, has been also evaluated.
- Journal of The American College of Cardiology - J AMER COLL CARDIOL. 01/2011; 57(14).
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ABSTRACT: The aim of the present work was to develop and characterize mucoadhesive film of cellulose (methyl cellulose and hydroxy propyl methyl cellulose) and polymethacrylate (Eudragit RSPO) polymers for buccal delivery of carvedilol. Drug and polymers were found to be compatible as revealed by FTIR and DSC analysis. Mucoadhesive films were prepared by solvent casting technique. Swelling studies up to 4h did not show erosion of film, which was further confirmed by SEM analysis. New, simple and precise instrumental methods were established for the evaluation of mucoadhesive strength (33.8±0.37-38.4±0.24g) and film strength (331.2±0.73-369.0±1.00g) of developed films. Mucoadhesive film F5 showed 88±1.15% in vitro drug release and 80±2.30% ex vivo drug permeation through goat buccal mucosa in 12h. Drug release and permeation followed Higuchi's model and mechanism was found to be Fickian type diffusion controlled.Carbohydrate Polymers 07/2013; 96(1):172-180. · 3.92 Impact Factor
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ABSTRACT: Thermosensitive hydrogels were prepared by free radical polymerization in aqueous solution from N-isopropylacrylamide (NIPA) monomer and N,N-methylenebis(acrylamide) (MBAAm) crosslinker. The swelling equilibrium of the hydrogels in deionized water was investigated as a function of temperature and MBAAm content. The results indicated that the swelling behavior and temperature sensitivity of the hydrogels were affected by the amount of MBAAm content. The average molecular mass between crosslinks and polymer–solvent interaction parameter (χ) of the hydrogels were determined from equilibrium swelling values. The swelling variations were explained according to swelling theory based on the hydrogel chemical structure. The swelling equilibrium of the hydrogels was also investigated as a function of temperature in aqueous solutions of the anionic surfactant sodium dodecyl sulfate (SDS) and the cationic surfactant dodecyltrimethylammonium bromide (DTAB). In deionized water, the hydrogels showed a discontinuous volume phase transition at 32°C. In SDS and DTAB solutions, the equilibrium swelling ratio and the volume phase transition temperature (lower critical solution temperature) of the hydrogels increased, which is ascribed to the conversion of nonionic PNIPA hydrogel into polyelectrolyte hydrogels because of binding of surfactant molecules through the hydrophobic interaction. Additionally, the amount of free SDS and DTAB ions was measured at different temperatures by a conductometric method; it was found that the electric conductivity of the PNIPA–surfactant systems depended strongly on both the type and concentration of surfactant solutions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1756–1762, 2006Journal of Applied Polymer Science 08/2006; 101(3):1756 - 1762. · 1.40 Impact Factor