Albumin, distribution coefficient

Figure 5. Predicted and observed distribution coefficients for albumin and lysozyme.

Concerning the distribution of a drug, models have been published for log BB blood/brain partition coefficient) for CNS-active drugs (CNS, central nervous system) crossing the blood-brain barrier (BBB) [38-45] and binding to human serum albumin (HSA) [46]. 

Referring once more to the effect of the aqueous medium composition upon the relative hydrophobicity of biological solutes, the correlation relationship establish-ecj io3,u6) between the effects of the medium ionic composition on the relative hydrophobicity of serum albumins of various origin and on that of erythrocytes from the same species should be noted. The ionic strength value of the medium in the aqueous ficoll-dextran biphasic system has been used as a quantitative index of the ionic composition of the system, and the ionic composition was varied from 0.11 M phosphate buffer to 0.15 M NaCl in 0.01 M buffer at pH 7.4 116). Partition coefficients of cells in an aqueous polymeric biphasic system are determined as the ratio of a number of the cells in the phase to that of the cells present at the interphase 90). Specific features of the partition behavior of cells in aqueous biphasic systems are discussed in detail elsewhere (see, e.g., Ref. 90 91). It has been established 116) that erythrocytes of different species are distributed in the aqueous ficoll-dextran biphasic system according to the following equation ... 

Ballard, P. et al., Prediction of in vivo tissue distribution from in vitro data. 2. Influence of albumin diffusion from tissue pieces during an in vitro incubation on estimated tissue-to-unbound plasma partition coefficients (Kpu), Pharm. Res., 20(6), 857, 2003. 

Addition of salts (e.g. potassium phosphate dibasic ) partitions an aqueous system containing 202 w/v polyethylene glycol < PEG) into two liquid phases a PEG enriched phase and a salt enriched phase. Proteins and polymers (e.g. DNA, albumin, immunoglobulins, alpha-1 antitrypsin, and PEG) distribute unevenly between the two phases. Partition coefficients (concentration in PEG phase / concentration in salt phase = K) are influenced by physical parameters, such as salt composition and concentration, pH (ion ratios) and temperature. Specific proteins (e.g. alpha-1 antitrypsin) exhibit low K values in a wide range of conditions. 

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