The metabolism of a series of ester pro-drugs by NCTC 2544 cells, skin homogenate and LDE testskin.

The metabolism of a series of substituted pyrazolopyridine ester pro-drugs was investigated using NCTC 2544 cells, human skin homogenate and LDE Testskin as model systems. The compounds were incubated in each system and the disappearance of drug and the production of the major hydrolysis product was observed with time and quantitated using HPLC. The toxicity of the ester pro-drugs and the metabolites was examined in NCTC 2544 cells using a cell viability assay procedure. Hydrolytic activity was slightly higher in the cell culture model than in skin homogenate solution but the rank order of activity for each pro-drug was similar. The metabolic activity of LDE Testskin was much reduced compared with the other systems, but again the overall pattern of metabolism was not dissimilar. These findings indicate that NCTC 2544 cells provide a reasonable model for human skin ester hydrolysis both in terms of rate and in terms of substrate specificity.