[Evaluation of biological activity of organic substances by measuring the physico-chemical parameters (author's transl)].

For a particular form (amorphous phase) of physical acting substances the water solubility, in conditions very close to the in vivo ones, has been compared with corresponding biological activities. The reciprocal of the above parameter shows a good correlation with various physico-chemical, biochemical and pharmacological parameters of xanthinic compounds, analgesic alkaloids, barbiturates, sulphonamides. The solubility of the crystalline phase cannot be correlated with the biological activity: the ratio between these two solubilities shows this inability.