In Vivo Methods to Estimate Drug Transport to the Brain Across the Blood-Brain Barrier

In this paper, we review the in vivo methods to estimate drug transport to the brain. These vary from invasive ones like the brain uptake index (BUI), multiple pass techniques, brain efflux index (BEI), in situ brain perfusion, CSF (cerebrospinal fluid) sampling (unit impulse response), quantitative autoradiography (QAR), and intracerebral microdialysis to non invasive ones like positron emission tomography (PET), and magnetic resonance techniques (imaging (MRI), spectroscopy (MRS)). The latter two methods can be applied in human also. In addition, in this review an overview is given for which purposes these methods can be applied.