Abstract
Binding of drugs to serum protein is an adsorption phenomena. Adsorption equilibrium and velocity of drugs influence their dialysance. We measured adsorption equilibrium and velocity with four cephem antibiotics and human serum albumin. CAZ, CDZM and CTRX had the adsorption isotherms that were obedient to Langmuir equation, but CTX did not. The difference of adsorption mechanism caused this difference. Protein-binding ratio changed with whole concentration of antibiotics, and they depended on antibiotics. The order of adsorption velocity was CDZM or CTRX, CTX and CAZ. Desorption amount of CAZ can be ignored while blood runs in a dialyzer, that of CTX cannot. Adsorption equilibrium of CDZM and CTRX forms anywhere in a dialyzer. It is important to examine the effect of adsorption equilibrium and velocity of drugs on their dialysance. We designed a mass transfer model of protein-binding drugs in a dialyzer. Based on this model, we calculated distribution of antibiotics concentration in a dialyzer. Distribution of free drug concentration and adsorption amount was dependent on their adsorption velocity, that of the whole concentration in blood side were not.
