Comparison of Reliability of log P Values for Drugs Calculated by Several Methods.

The values of log P (partition coefficient in octanol/water) for 22 drugs selected by Rekker et al. Quant. Struct.-Act. Relat., 12, 152 (1993) were calculated by the simple method of Moriguchi et al. Chem. Pharm. Bull., 40, 127 (1992); M using only 7 parameters, and compared with those obtained from the procedures of Rekker (R), Hansch and Leo (H), and Suzuki and Kudo (S). The descending order of the reliability was M, H, R, and S in the standard error of estimate, R, H, M, and S in the averaged absolute residual-sums, and M, R, H, and S in the regression coefficients between observed and estimated log P values. Serious errors of estimate beyond 2.0 in the absolute residual were seen in R, H, and S, but not in M. These results showed that the method of Moriguchi et al. is not only simple and convenient but also reliable in the application to drugs with complex structures.