Biomedical subjects

E Yonemochi

Publications and source records attributed to E Yonemochi.

21 records · Page 2Linked to original sources

PubMed1995

[Determination of partial solubility parameters of lactoses and its application to solubility evaluation].

Partial solubility parameters of lactose packed into a glass column were calculated from adsorption energies of n-decane, acetonitrile and ethyl alcohol determined by gas-solid chromatography. Three kinds of crystalline lactoses, alpha-lactose monohydrate, anhydrous alpha-lactose (desiccated) prepared by desiccation with methyl alcohol, and anhydrous alpha-lactose (heated) prepared by heating, were used. It was characterized from the results that the partial solubility parameter, delta p, due to dipole interaction, of anhydrous forms had two-fold value than that of the hydrous form. In addition, it was suggested that the affinity of lactose for water vapor and the solubility of lactose for water were able to be evaluated using the three dimensional plot of partial solubility parameters and the interaction radius calculated from partial solubility parameters. It was shown that the appropriate information for the evaluation of physicochemical properties of active ingredients and excipients in the formulation study could be obtained from the data determined using partial solubility parameters.

Adsorption↗

PubMed1994

Fluorometric study of the molecular states of 2,5-diphenyloxazole in ground mixtures with gamma-cyclodextrin.

Molecular states of 2,5-diphenyloxazole (PPO) were investigated in ground mixtures with gamma-cyclodextrin (gamma-CD). Crystalline PPO gradually became amorphous upon grinding in the presence of gamma-CD. Solid-state fluorescence spectra of the ground mixtures showed that the fluorescence emission peak due to PPO crystals was reduced in intensity with an increasing duration of grinding. A new fluorescence peak attributed to PPO excimer appeared at a longer wave-length. Results of the time-resolved fluorescence study indicated that the cogrinding caused an increase in the portion of PPO excimer in the gamma-CD ground mixture. On the other hand, only a small portion of excimer was formed in ground mixtures with beta-CD, which has a smaller cavity than gamma-CD. These results suggest that cogrinding of PPO with gamma-CD caused two PPO molecules to be included in the gamma-CD cavity, contributing to excimer formation.

Cyclodextrins↗

PubMed1990

Effect of grinding on dehydration of crystal water of theophylline.

The effect of grinding on the dehydration of crystal water of theophylline has been studied. It was observed that the water content of theophylline hydrate decreased with increased grinding time. As the grinding time proceeded, the results of differential scanning calorimetry (DSC) indicated that crystal water of ground theophylline hydrate dehydrated in three steps at ca. 58, 44, and 17 degrees C, respectively. Powder X-ray diffraction study revealed that the crystal lattice of theophylline monohydrate collapsed by grinding, and part of the theophylline molecules subsequently rearranged the collapsed lattice to form theophylline anhydrate. The result of Fourier transformed infrared spectroscopy demonstrated that the hydrogen bonds between crystal water molecules and theophylline molecules were weakened or destroyed to some extent by grinding. It was supposed that crystal water in the ground theophylline hydrate might exist at least in three molecular states of different hydrogen-bonding. From DSC study, it was suggested that the ruptured hydrogen bonds of water molecules in the ground theophylline hydrate were strengthened after storage under 96.5% relative humidity at 30 degrees C.

Calorimetry, Differential Scanning↗