RP‐HPLC Determination of Lipophilicity of 22 Penicillins, Their Correlation with Reported Values and Establishment of Quantitative Structure‐log Kw Relationships

Lipophilicity parameters were determined for a series of 22 penicillins by the reversed phase high-performance liquid chromatography (RP-HPLC). First, the capacity factors were determined for each drug at different concentrations of the organic modifier (methanol) at a constant flow rate, using an octadecylsilane column. The capacity factors were then extrapolated to zero methanol concentration to determine lipophilicity parameter, log k w . The resultant log k w values were correlated to previously reported lipophilicity parameters and good relationships were observed. Correlations were also established between log k w values and various structural parameters using CODESSA software. Excellent correlations, free from chance correlations and high predictive power, were obtained.