[Analysis of the correlation between hydrophilic-lipophilic balance, coefficient of diffusion and hydrogen ion concentration in a series of nonsteroidal anti-inflammatory drugs].

A thorough investigation on the dependence of rate diffusion constants (Kd) of nonsteroidal antiinflammatory drugs on pH and pKa values was carried out. It is shown that a modified multiparametric curve-fitting technique may constitute an useful tool to describe the rate diffusion pH-profiles of ionogenic substances. A comparison between the Kd values and the corresponding distribution coefficients (log D) shows that these constants identify complementary parameters very useful in the study of structure-activity relationships of ionogenic substances.