[Strategy of molecular drug design: activity and druggability].

Intrinsic activity and druggability represent two essences of innovative drugs. Activity is the fundamental and core virtue of a drug, whereas druggability is essential to translate activity to therapeutic usefulness. Activity and druggability are interconnected natures residing in molecular structure. The pharmaceutical, pharmacokinetic and pharmacodynamic phases in vivo can be conceived as an overall exhibition of activity and druggability. Druggability actually involves all properties, except for intrinsic activity, of a drug. It embraces physico-chemical, bio-chemical, pharmacokinetic and toxicological characteristics, which are intertwined properties determining the attributes and behaviors of a drug in different aspects. Activity and druggability of a drug are endowed in the chemical structure and reflected in the microscopic structure and macroscopic property of a drug molecule. The lead optimization implicates molecular manipulation in multidimensional space covering activity, physicochemistry, biochemistry, pharmacokinetics and safety, and embodies abundant contents of medicinal chemistry.