The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform
Hiraku Onishi - One of the best experts on this subject based on the ideXlab platform.
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development of polyethylene glycol and hard fat based mucoadhesive tablets containing various types of Polyvinyl Alcohols as mucoadhesive polymers for buccal application
Biological & Pharmaceutical Bulletin, 2017Co-Authors: Yuri Ikeuchitakahashi, Ayaka Kobayashi, Hiraku OnishiAbstract:Topical drug application has the advantage of avoiding systemic side effects. We attempted to develop a long-acting matrix-type tablet containing indomethacin (IM) with low physical stimulus and potent mucoadhesive force to treat pain caused by oral aphtha. A mixture of polyethylene glycol (PEG) and hard fat was used as the tablet base. Ethylcellulose was added to the base in an attempt to control drug release. Tablets with PEG as a base were also prepared for comparison. Polyvinyl Alcohols (PVAs) with various degrees of saponification were added to increase the mucoadhesive force. From the optical microscopic observations, formulations using PEG and hard fat exhibit PEG/hard fat dispersions caused by the stabilizing effects of PVA. Although the tablets using PEG and hard fat showed sufficient adhesiveness and sustained drug release, those using PEG as the base did not. Drug release was controlled by the amount of hard fat and the saponification degree of PVA. The drug release rate was most increased in a tablet containing PVA with an intermediate degree of saponification, PEG and hard fat. From differential scanning calorimetry and powder X-ray diffraction, IM was considered to exist in the molecular phase. From the results of buccal administration of tablets to rats, highest tissue concentrations were observed in the tablet containing PVA with the intermediate degree of saponification using PEG and hard fat, and the plasma concentrations were sufficiently low in comparison.
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evaluation of Polyvinyl Alcohols as mucoadhesive polymers for mucoadhesive buccal tablets prepared by direct compression
Drug Development and Industrial Pharmacy, 2017Co-Authors: Yuri Ikeuchitakahashi, Chizuko Ishihara, Hiraku OnishiAbstract:The purpose of the present work was to evaluate Polyvinyl Alcohols (PVAs) as a mucoadhesive polymer for mucoadhesive buccal tablets prepared by direct compression. Various polymerization degree and particle diameter PVAs were investigated for their usability. The tensile strength, in vitro adhesive force, and water absorption properties of the tablets were determined to compare the various PVAs. The highest values of the tensile strength and the in vitro adhesive force were observed for PVAs with a medium viscosity and small particle size. The optimal PVA was identified by a factorial design analysis. Mucoadhesive tablets containing the optimal PVA were compared with carboxyvinyl polymer and hydroxypropyl cellulose formulations. The optimal PVA gives a high adhesive force, has a low viscosity, and resulted in relatively rapid drug release. Formulations containing carboxyvinyl polymer had high tensile strengths but short disintegration times. Higher hydroxypropyl cellulose concentration formulations had good adhesion forces and very long disintegration times. We identified the optimal characteristics of PVA, and the usefulness of mucoadhesive buccal tablets containing this PVA was suggested from their formulation properties.
Yuri Ikeuchitakahashi - One of the best experts on this subject based on the ideXlab platform.
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development of polyethylene glycol and hard fat based mucoadhesive tablets containing various types of Polyvinyl Alcohols as mucoadhesive polymers for buccal application
Biological & Pharmaceutical Bulletin, 2017Co-Authors: Yuri Ikeuchitakahashi, Ayaka Kobayashi, Hiraku OnishiAbstract:Topical drug application has the advantage of avoiding systemic side effects. We attempted to develop a long-acting matrix-type tablet containing indomethacin (IM) with low physical stimulus and potent mucoadhesive force to treat pain caused by oral aphtha. A mixture of polyethylene glycol (PEG) and hard fat was used as the tablet base. Ethylcellulose was added to the base in an attempt to control drug release. Tablets with PEG as a base were also prepared for comparison. Polyvinyl Alcohols (PVAs) with various degrees of saponification were added to increase the mucoadhesive force. From the optical microscopic observations, formulations using PEG and hard fat exhibit PEG/hard fat dispersions caused by the stabilizing effects of PVA. Although the tablets using PEG and hard fat showed sufficient adhesiveness and sustained drug release, those using PEG as the base did not. Drug release was controlled by the amount of hard fat and the saponification degree of PVA. The drug release rate was most increased in a tablet containing PVA with an intermediate degree of saponification, PEG and hard fat. From differential scanning calorimetry and powder X-ray diffraction, IM was considered to exist in the molecular phase. From the results of buccal administration of tablets to rats, highest tissue concentrations were observed in the tablet containing PVA with the intermediate degree of saponification using PEG and hard fat, and the plasma concentrations were sufficiently low in comparison.
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evaluation of Polyvinyl Alcohols as mucoadhesive polymers for mucoadhesive buccal tablets prepared by direct compression
Drug Development and Industrial Pharmacy, 2017Co-Authors: Yuri Ikeuchitakahashi, Chizuko Ishihara, Hiraku OnishiAbstract:The purpose of the present work was to evaluate Polyvinyl Alcohols (PVAs) as a mucoadhesive polymer for mucoadhesive buccal tablets prepared by direct compression. Various polymerization degree and particle diameter PVAs were investigated for their usability. The tensile strength, in vitro adhesive force, and water absorption properties of the tablets were determined to compare the various PVAs. The highest values of the tensile strength and the in vitro adhesive force were observed for PVAs with a medium viscosity and small particle size. The optimal PVA was identified by a factorial design analysis. Mucoadhesive tablets containing the optimal PVA were compared with carboxyvinyl polymer and hydroxypropyl cellulose formulations. The optimal PVA gives a high adhesive force, has a low viscosity, and resulted in relatively rapid drug release. Formulations containing carboxyvinyl polymer had high tensile strengths but short disintegration times. Higher hydroxypropyl cellulose concentration formulations had good adhesion forces and very long disintegration times. We identified the optimal characteristics of PVA, and the usefulness of mucoadhesive buccal tablets containing this PVA was suggested from their formulation properties.
Manfred Grote - One of the best experts on this subject based on the ideXlab platform.
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synthesis and complexing properties of resins containing aminocarboxylic acid as functional groups from diethylenetriaminepentaacetic acid bisanhydride and Polyvinyl Alcohols
Reactive & Functional Polymers, 1999Co-Authors: Veronique Montembault, Jeanclaude Soutif, Jeanclaude Brosse, Manfred GroteAbstract:The one-step reaction of diethylenetriaminepentaacetic acid bisanhydride with Polyvinyl Alcohols of different molecular weights produces chelating resins containing aminocarboxylic acids as functional groups. Metal sorption in different hydrochloric acid concentrations media and desorption studies were carried out and the results compared according to the density of complexing groups. The resins show a great sorption affinity towards Au(III). The desorption of Au(III) from the resins carried out by applying perchloric acid or thiourea as eluting agents led to the assumption that gold is strongly complexed indicating a particular mechanism of metal sorption.
John F Robyt - One of the best experts on this subject based on the ideXlab platform.
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activation and stabilization of 10 starch degrading enzymes by triton x 100 polyethylene glycols and Polyvinyl Alcohols
Enzyme and Microbial Technology, 2005Co-Authors: Seungheon Yoon, John F RobytAbstract:Abstract A dilute solution (0.01–0.1 unit/mL) of porcine pancreatic α-amylase (PPA) at pH 6.5, 24 °C, and 1 mM CaCl 2 was found to lose 98% of its activity on standing for 2 h. Addition of 0.02% (w/v) Triton X-100 gave 41% activation and stabilization for 3 h. Because Triton X-100 has a polyethylene glycol side chain, seven polyethylene glycols (PEGs), ranging in MWs of 400–8000 Da and two Polyvinyl Alcohols (PVAs) of MWs of 10,000 and 50,000 Da were tested as activators and stabilizers of 10 starch-degrading enzymes: PPA, human salivary α-amylase (HSA), Aspergillus oryzae α-amylase (AOA), Bacillus amyloliquefaciens α-amylase (BAA), Bacillus licheniformis α-amylase (BLA), Aspergillus niger glucoamylase (GA), barley β-amylase (β-A), Pseudomonas amylodermosa isoamylase (IA), Bacillus acidopullulyticus pullulanase (PUL), and Bacillus macerans cyclomaltodextrin glucanyltransferase (CGTase). Although nearly all of the additives gave activation and stabilization of the 10 enzymes, there was one specific additive and concentration for each enzyme that gave a maximum degree of activation: 0.02% (w/v) PEG 1500 Da gave 77% activation for β-A; 0.04% PEG 1500 Da gave 70% for PPA; 0.04% PEG 2000 Da gave 58% for IA; 0.04% PEG 1500 Da gave 53% for AOA; 0.04% PVA 50,000 Da gave 48% for GA; 0.04% PEG 4500 Da gave 46% for BLA; 0.02% Triton X-100 gave 45% for HSA; 0.04% PEG 1000 Da gave 42% for BAA; 0.02% Triton X-100 gave 27% for PUL; and 0.02% PEG 1500 Da gave 20% for CGTase. The mechanism of activation and stabilization is postulated to be the binding of the additives to the enzyme-proteins to give a single tertiary structure that results in a maximum enzyme activity, whereas without the additive the enzymes have several tertiary structures in equilibrium, each with a specific activity that results in an average lower activity.
D Debrouwer - One of the best experts on this subject based on the ideXlab platform.
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rna rna in situ hybridization using digoxigenin labeled probes the use of high molecular weight Polyvinyl alcohol in the alkaline phosphatase indoxyl nitroblue tetrazolium reaction
Analytical Biochemistry, 1993Co-Authors: M Deblock, D DebrouwerAbstract:Abstract A nonradioactive RNA-RNA in situ hybridization method using digoxigenin-labeled probes is described. The visualization of hybrids is done using the indoxyl-nitro blue tetrazolium alkaline phosphatase reaction. The addition of Polyvinyl Alcohols of high molecular weight (40-100 kDa) to the reaction medium enhances the alkaline phosphatase reaction and prevents diffusion of reaction intermediates, resulting in a 20-fold increase in sensitivity without increasing the background. Due to the more localized precipitation of the formazan, the site of hybridization can be determined more precisely.