Search PubMed⌕ Search

Biomedical subjects

K Uekama

Publications and source records attributed to K Uekama.

At least 145 records · Page 8Linked to original sources
PubMed1982

Cyclodextrin-induced hemolysis and shape changes of human erythrocytes in vitro.

Cyclodextrins (CyDs) at higher concentrations were found to cause hemolysis of human erythrocytes in the order of beta- greater than alpha- greater than gamma-CyD in isotonic solution. Biphasic effects of CyDs were observed for the osmotic and heat-induced hemolysis; i.e. the protection at relatively low CyD concentrations and stimulation at higher CyD concentrations. From the scanning electron microscopic observations, CyDs induced shape changes of membrane internalization type on erythrocytes. CyDs caused the release of cholesterol from erythrocyte membrane in the order of beta- greater than gamma- greater than alpha-CyD. These results clearly indicate that CyD-induced hemolysis is probably a secondary event resulting from the membrane disruption which elicited the removal of membrane components from erythrocytes.

Cyclodextrins↗
PubMed1981

Effects of cyclodextrins on chlorpromazine-induced haemolysis and central nervous system responses.

Cyclodextrins (CyDs) protected the human erythrocytes from haemolysis induced with chlorpromazine (CPZ) in isotonic solution, depending upon the magnitude of the stability constant of CPZ-CyD complexes (beta-greater than-gamma-greater than alpha-CyD). From the observations of CPZ uptake into erythrocytes and changes in surface activity of CPZ, the protective effects of CyDs in vitro appeared to be due to the decrease in effective haemolytic concentration of CPZ through inclusion complex formation rather than the direct interaction of CyDs with the erythrocyte membrane. The effect of beta-CyD on some central nervous system (c.n.s.) actions of CPZ in rats was also investigated to see if there were any advantages in the use of beta-CyD complexes given by injection. The results suggest that beta-CyD does not after the time-course or magnitude of the effects of CPZ on the c.n.s.

Animals↗
PubMed1981

Protective effects of cyclodextrins on drug-induced hemolysis in vitro.

beta-Cyclodextrin (beta-CyD) significantly protected the human erythrocytes from hemolysis and shape changes induced with chlorpromazine and flufenamic acid in isotonic solution. A good correlation between the stability constants of inclusion complexes (beta- greater than gamma- greater than alpha-CyD) and the inhibitory effects on drug-induced hemolysis was found. From the observations of drug uptake into erythrocytes and changes in surface tension, the protective effects of CyDs appeared to be due to the decrease in effective concentration of drug through inclusion complexation rather than the direct interaction of CyDs with erythrocyte membrane.

Chlorpromazine↗
PubMed1981

Enhanced bioavailability of digoxin by gamma-cyclodextrin complexation.

Inclusion complex of digoxin with gamma-cyclodextrin (gamma-CyD) in 1:4 molar ratio was prepared, and its dissolution and absorption behaviors were compared with those of digoxin alone. The dissolution rate of digoxin in water was found to be markedly increased by gamma-CyD complexation. Bioavailability of digoxin following the oral administration of gamma-CyD complex to dogs was 5.4 times as much as that of digoxin alone. The present data did indicate improvement of dissolution and absorption characteristics of digoxin by inclusion complexation, suggesting the decrease in dose in oral digoxin therapy.

Animals↗
PubMed1979

Improvements of dissolution characteristics and chemical stability of 16,16-dimethyl-trans-delta 2-prostaglandin E1 methyl ester by cyclodextrin complexation.

Inclusion complexation of 16,16-dimethyl-trans-delta 2-prostaglandin E1 methyl ester (I), which is effective in early pregnancy termination, with cyclodextrins in water was ascertained by a solubility study. A solid complex of I-beta-cyclodextrin in a 1:2 molar ratio was obtained, and its dissolution behavior and chemical stability were examined. The results indicated that the complex may have great utility as a rapidly dissolving form of I with prolonged storage time.

Biopharmaceutics↗