Correlation of Contraceptive Activity of Norethisterone and Levonorgestrel Esters with VR(w) Values and Hydrolysis Rates

Abstract

The relationships between contraceptive activity, hydrophobic character and alkaline hydrolysis rates were studied in three homologous series of norethister one and levonorgestrel esters. Hydrophobic character was expressed by the high-performance liquid chromatographic retention term, VR(w) or retention volume at 100% aqueous mobile phase. A parabolic and bilinear relationship was shown between log VR(w) and log biological response. No correlation between second-order alkaline hydrolysis rates, k2, measured in 70% (v/v) aqueous dioxan and contraceptive activity was established. © 1989, The Pharmaceutical Society of Japan. All rights reserved.