Yasuo Yoshihashi

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The initial dissolution rates of amorphous, partial crystalline and crystalline samples of terfenadine polymorphs (forms I and II) were measured by the rotating disk method. The heats of fusion due to crystalline fraction of samples were obtained by the differential scanning calorimetry (DSC) data taking into account the heat of crystallization and the heat(More)
The lack of protocols to predict the physical stability has been one of the most important issues in the use of amorphous solid dispersions. In this paper, the crystallization behaviors of pharmaceutical glasses, which have large variations in their crystallization tendencies, have been investigated. Although each compound appears to have a wide variation(More)
Raman spectroscopy is potentially an extremely useful tool for the understanding of drug-polymer interactions in solid dispersions. This is examined and demonstrated for the case of solid dispersions of nifedipine in a polymeric substrate. Solid dispersions consisting of nifedipine and polyvinyl caprolactam - polyvinyl acetate - polyethylene glycol graft(More)
Purpose. The aim of this study is to estimate the initialdissolution rate of drug substances by isothermal microcalorimetry. A theorywas presented on the basis of Gibbs free energy and the Noyes—Whitneyequation. Methods. Polymorphic forms and quenched glass ofindomethacin, and some different crystallinity samples of terfenadine wereused. The heats of(More)
Purpose. The aim of this study was to clarify the quantitativerelationship between solubility, initial dissolution rate and heat of solution ofracemic compound and its enantiomers. Methods. Propranolol, propranolol HCl, tyrosine, and tryptophan wereused as typical chiral drugs. The heat of solution of chiral drug wasmeasured by an isothermal(More)
As psicose cannot be spray dried because of its low glass transition temperature (T(g)), additives have been used to manufacture spray-dried particles. Its thermodynamic miscibility with each additive was evaluated by thermal analysis and C solid-state nuclear magnetic resonance. Aspartame was miscible with psicose at all ratios, and spray-dried particles(More)
The purpose of this study was to elucidate the effect of solute miscibility in frozen solutions on their micro- and macroscopic structural integrity during freeze-drying. Thermal analysis of frozen solutions containing poly(vinylpyrrolidone) (PVP) and dextran showed single or multiple thermal transitions (T'g: glass transition temperature of maximally(More)
Fragility is a measure of the departure from non-Arrhenius behavior for supercooled liquids and glasses, and various simple methods are available for its quantification. However, the obtained values usually do not agree with each other. One of the purposes of this study was to compare the fragility values obtained by different methodologies. Thermodynamic(More)
Although acyclovir is one of the most important antiviral drugs used today, there are several problems with its physical properties. The aim of this study is to prepare cocrystals or amorphous complex of acyclovir using drug-excipient interactions to improve the physical properties of the drug, especially its dissolution rate and transdermal absorption.(More)
A rapidly disintegration tablet in the oral cavity was prepared using a glycine as a disintegrant. Effect of disintegrant on the disintegration behavior of the tablet in the oral cavity was evaluated. Wetting time prepared from carboxymethylcellulose (NS-300) having the hardness of 4 kg was 3 s. Tablet containing NS-300 showed fastest disintegration(More)