Blood–brain barrier permeability considerations for CNS-targeted compound library design

A further refinement of the concept of drug-likeness is required for compound libraries intended for central nervous system (CNS) targets to account for the limitations imposed by blood–brain barrier permeability. This review describes criteria and processes that can be applied in the de novo design and assembly of libraries to increase the odds of compounds residing within CNS-accessible chemical space. A number of published examples where CNS activity and/or penetration characteristics have been a factor in library design are discussed.