Molecular determinants of drug-receptor binding kinetics.

It is increasingly appreciated that the rates at which drugs associate with and dissociate from receptors--the binding kinetics--directly impact drug efficacy and safety. The molecular determinants of drug-receptor binding kinetics remain poorly understood, however, especially when compared with the well-known factors that affect binding affinity. The rational modulation of kinetics during lead optimization thus remains challenging. We review some of the key factors thought to control drug-receptor binding kinetics at the molecular level--molecular size, conformational fluctuations, electrostatic interactions and hydrophobic effects--and discuss several possible approaches for the rational design of drugs with desired binding kinetics.