Estimation and correlation of drug water solubility with pharmacological parameters required for biological activity

A procedure for estimating the molar water solubility (S) for a series of structurally related drug compounds is presented. HPLC methods for the determination of partition coefficients (P) are combined with semiempirical calculations for S. Multidimensional plots are developed with the physical constants S and P along the x and y axes and with a biological response, e.g. IC50 or ED50, along the z axis. Other attributes, e.g. bioavailability or biodistribution, can be added by color coding, shading, or numbering. Since the methods have a high throughput capability, parameters governing the events leading to pharmacological action [i.e. gastrointestinal dissolution (S), absorption (P), blood level (bioavailability), and biological action (IC50, EC50)] can be correlated for drug series comprising large numbers of compounds.