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In our previous study, the degree of adsorption of 9 representative antimicrobial agents to Toraymyxin ® PMX-F sheets was quantitatively evaluated [1] . As a result, the adsorption rate was 22.1% for Linezolid in the presence of serum. Therefore, we investigated whether two types of antimicrobial agents (Ciprofroxacin and Linezolid) can be better adsorbed on PMX-F sheets. When the number of PMX-F sheets was increased in a step wise manner, specifically 2, 4, 6, 8 and 12, the adsorption rate increased linearly. In addition, the adsorption to polymyxin-B immobilized fiber (Toraymyxin ® PMX-20R) cartridges, widely used to remove endotoxins from circulating blood in the treatment of sepsis, was quantitatively evaluated. As a result, in the presence of serum, Linezolid showed adsorption to PMX-20R, and the adsorption rate after 2 h was 54.5%, and that after 4 h was 65.8%. The results of this study suggest the necessity of monitoring blood antimicrobial concentration during treatment for sepsis with Linezolid, which showed adsorption to PMX-20R in an environment close to a clinical environment.

The influences of various salts and water-soluble polymers on the phase transition temperature of thermo-setting gels prepared by combining methylcellulose (MC)-sodium citrate (SC)-polyethylene glycol (PEG) at appropriate ratios (the MC-SC-PEG system) were investigated. Concerning cations, comparison of the phase transition temperature between SC and tripotassium citrate (PC) showed a rapid increase in the viscosity of SC between 20 degrees C and 25 degrees C and an increase in the viscosity of PC between 30 degrees C and 35 degrees C. Concerning the valency of anions, comparisons among SC, disodium tartrate dihydrate (ST), disodium maleate hemihydrates (SM), and sodium sulfate (SS) showed a rapid increase in the viscosity of trivalent SC between 20 degrees C and 25 degrees C and changes in the viscosity of the three bivalent sodium salts (ST, SM, and SS) ator =30 degrees C. Thus the phase transition temperature decreased with an increase in the valency of anions. Subsequently, the influences of various water-soluble polymers on the gelling temperature were compared. Using polyvinylpyrrolidone (PVP) instead of PEG, the gelling temperature decreased with an increase in the PVP concentration even without the addition of SC. Unlike PVP, the addition of xanthan gum as a viscosity-increasing polysaccharide did not reduce the gelling temperature irrespective of its concentration. Temperature-associated changes in viscosity were observed at a fixed SC concentration with changes in the concentration of PVP or PEG. The gel phase transition temperature increased from 46 degrees C to 50 degrees C in gels not containing PVP or PEG. The viscosity did not differ between the addition of PVP or PEG at a low concentration and its absence. However, the viscosity clearly changed after the addition of each agent at a high concentration.

Drug carrier emulsions were prepared with structured phosphatidylcholine (PC-LM) which has both a long hydrocarbon chain and a medium hydrocarbon chain, and the characteristics of PC-LM as an emulsifier were investigated by measuring the creaming ratio, the surface tension of the emulsion system, and the mean particle size and zeta potential of the oil droplets in emulsions. The emulsion prepared with PC-LM as an emulsifier kept the condition and the ratio of separation was lower than those with purified egg yolk lecithin (PEL). The mean particle size of the emulsion prepared with PC-LM was smaller than that with PEL when using only sonication, approximately 250 nm. When using a high-pressure homogenizer after sonication, the mean emulsion size with PC-LM was also smaller than with PEL, approximately 150 nm. The surface tension of the various emulsions and the zeta potential of the emulsion droplets were measured to investigate the stability of the systems. In emulsions with PC-LM or PEL, the surface tension as an index of stability increased as the pressure of the homogenizer increased. Moreover, the zeta potential of the emulsion droplets prepared with PC-LM also increased with an increase in pressure of the homogenizer. As a result, it was found that the drug carrier emulsion prepared with PC-LM had significant advantages in terms of stability and mean diameter. We considered it could be used for the preparations of nanoparticle dispersion systems in drug delivery systems.

Synthesized saturated phosphatidylcholine (PC) and egg yolk lecithin (EYL) were investigated to explore their influence on particle sizes in emulsions when dispersing various triglycerides (TG). One of four different kinds of synthesized saturated PC (DLPC, DMPC, DPPC and DSPC) or three different kinds of EYL (purified EYL (PEL) and hydrogenated purified EYL with two different iodine values (IV), R-20 and R-5), 2.5% (w/w) glycerol solution and one of four kinds of TG (tricaprylin, tricaprin, trilaurin and trimyristin) were sonicated five times for 1 min with intervals of 0.5 min. When using four kinds of synthesized saturated PCs as emulsifiers, the carbon numbers of each PC had a strong correlation with the mean diameters of the emulsion when analyzed with each of the four kinds of TG used in the study (regression function ranged from 0.811 to 0.915). The carbon numbers of the TG had less correlation with the mean diameters than the PC in simple regression analysis (regression function ranged from 0.236 to 0.875). Multiple regression analysis using the carbon numbers both of the PC and TG as independent variables was remarkably significant in the regression function (2.0 x 10(-14)) and all regression coefficients (2.7 x 10(-13), 5.8 x 10(-7) and 1.9 x 10(-9) for PC, TG and intercept, respectively). Among the regression coefficients, the contribution of the carbon number of the PC was the most significant. These results indicated that a multiple regression function should be useful to estimate the mean diameters of emulsion droplets in any combinations of PC and TG used in this study. In the experiments using three kinds of EYL, the mean diameters also tended to increase according to the order of PEL, R-20 and R-5, which corresponds to the order of degrees of saturation (IV = 75, 20 and 2, respectively). The experimental values for EYL were compared with the estimated values calculated by the multiple regression function derived from synthesized PC data using the arithmetic carbon number, based on the components of each EYL. The estimated mean diameters were at comparable levels to the corresponding experimental mean diameters in the most saturated hydrogenated lecithin (R-5), while those were larger than the experimental mean diameters in two less saturated kinds of lecithin (R-20 and purified EYL). These findings gave useful information on the mean diameters of emulsion droplets when designing an emulsion formulation using a particular combination of a phospholipid and triglyceride.