Hydrophobicity of XXXX protease inhibitors by immobilized artificial membrane chromatography: application and significance to drug transport.

@entity1792 @entity1626 @entity645 @entity3884
PURPOSE: The feasibility of using hydrophobicity measurements as screens for intracellular availability in T-cells or intestinal permeability in Caco-2 cells was examined. METHODS: T-cell experiments: Cells were counted, collected, then incubated with drug solution at 37 degrees C. At selected time intervals, uptake was quenched by transferring a sample into oil, followed by rinsing, lysis of cells, protein precipitation and analysis by HPLC. Caco-2 cell experiments: Cells were grown on plastic dishes for 7-10 d, then rinsed and incubated with drug solution at 37 degrees C. Uptake was quenched, cells were lysed, protein precipitated and drug was analyzed by HPLC. IAM chromatography: Stock solutions were injected onto an IAM column for HPLC. Mobile phase consisted of varying amounts of @entity1626 in buffer (pH 7.4). The capacity factor, k'IAM, was calculated using @entity1792 to measure the void volume and was obtained by extrapolation to pure buffer. RESULTS: Nine @entity645 protease inhibitors were studied for uptake by CEM T-cell suspensions or Caco-2 cell monolayers. Capacity factors (log) between IAM and C-18 columns were positively correlated for this series. Caco-2 uptake rates correlated well with T-cell uptake rates when normalized by protein mass. Single-variable regression using IAM or C-18 columns was acceptable for analysis of T-cell data. Correlation coefficients between T-cell uptake and log k'IAM or log k'C-18 were not improved with multivariable regression. Correlation between Caco-2 uptake and log k'IAM was enhanced when molecular weight and @entity3884 -bonding potential were included in multivariable regression analysis (from r2 of 0.39 to 0.91). Correlations obtained using log k'IAM, log k'C-18 or log distribution coefficient (log D) were comparable when regressed against Caco-2 uptake using this approach. Calculated log partition coefficient (ClogP) provided the poorest correlation in the multivariable analysis (r2=0.57 for T-cell uptake and r2=0.71 for Caco-2 cell uptake). CONCLUSIONS: Uptake of @entity645 protease inhibitors by T-cell suspensions or Caco-2 cell monolayers was positively correlated. Uptake by T-cell suspensions was adequately described by hydrophobicity alone. Description of uptake by Caco-2 cell monolayers required multivariable regression analysis in which molecular weight and @entity3884 bonding were included. Experimental measures of hydrophobicity (log k'IAM, log k'C-18 and log D) were superior to ClogP in the correlation analysis.
