Models to explain dose-response relationships that exhibit a downturn phase.

Over a broad dose (or concentration) range, dose-response relationships frequently display a bell-shaped form. Mechanisms leading to this phenomenon may be manifold, but so far they have not been adequately identified. In this article, Vladimir Pliska discusses two models that are based on multiple-state cell-signaling pathways and enable an estimate of generally applicable descriptors. These can be used for expression of drug potency and for similar purposes.