Measurement of the pharmacokinetics and pharmacodynamics of neuroactive compounds.

The need to discover and develop safe and effective new medicines is greatest for disorders of the CNS. A core requirement for an effective neurotherapeutic agent is an ability to cross the blood-brain barrier and remain in the brain interstitial fluid (ISF) for a sufficient duration and concentration to evoke the desired therapeutic effect. Measuring the free concentration of a neuroactive compound in brain ISF is therefore an essential step in the critical path towards the development of a CNS medicine. In vivo microdialysis provides a powerful method for the measurement of endogenous and exogenous substances in the ISF surrounding the probe and so it represents an important tool in CNS drug discovery. It can also be used to measure the pharmacodynamic response of neuroactive compounds by measuring neurotransmitters and second messengers. Another approach to measure both pharmacokinetics and the pharmacodynamics of neuroactive compounds is the measurement of receptor occupancy, which has the advantage of being applicable to the study of humans as well as experimental animals. Measurement of the pharmacokinetics and pharmacodynamics of neuroactive compounds clearly improve understanding of the efficacy and safety of drug candidates, which improves both the efficiency and the effectiveness of CNS medicines research.