**4. Case example: Toxicokinetics and central nervous system (CNS) toxicity**

This case example (described below) will highlight an investigation into CNS toxicity where the lead drug candidate displayed CNS toxicity in the monkey and a backup molecule needed to be identified. This example highlights utilization of the efflux transporter, Pglycoprotein (Pgp), to limit the tissue distribution of the backup drug candidate to the CNS in order to limit CNS toxicity potential.
