Classification of Drugs by CNS Access: An Insight from Quantitative Blood-Brain Transport Characteristics

INTRODUCTION

The ultimate goal of QSAR analysis focusing on blood-brain barrier penetration is the ability to discriminate between CNS active and inactive molecules. The objective of the current study was to establish the relationship between quantitative blood-brain transport parameters and qualitative data indicating whether the compound penetrates into the brain efficiently enough to exhibit action in the central nervous system (CNS).

Two quantitative characteristics were considered: brain/plasma equilibration rate (log [PS • fu,br]), and the extent of brain/plasma partitioning at equilibrium (log BB). Analysis of a diverse data set consisting of >1500 compounds from the World Drug Index (WDI) database with experimentally assigned brain penetration categories revealed that a linear combination of the above mentioned parameters allowed classification of drugs by CNS access with 94% accuracy. Furthermore, the devised classification score correlated well with the unbound brain/plasma partitioning coefficient (log Kp,uu), which is recognized as an unambiguous determinant of brain exposure. The obtained results confirm the validity of the proposed classification approach.