[Molecular interaction in pharmaceutical solution, solubilization, partition, and stability of drugs]

The pharmaceutical studies carried out by the author during 40 years were reviewed from the viewpoint of molecular interaction. Included subjects are: electrostatic interaction between drug ions, ion pair formation and its partition to organic phase, drug solubilization by adjuvants, partition of drugs between aqueous and micellar phases, cyclodextrin inclusions, human serum albumin binding and drug stability related to the esterase-like activity of the albumin, and oral liposome preparation of vitamin K1. The drug stabilities related to those molecular interactions were emphasized.