Microdialysis is a unique technique for monitoring the chemistry of the extracellular space in living tissue. In basic research it is mainly used to determine in vivo changes in endogenous compounds, drug delivery, PK/PD, bioavailability and bioequivalence.

Microdialysis probes are designed to mimic a capillary blood sample and have a semi-permeable membrane that, when infused with physiological saline, allows an exchange of compounds from an area of high concentration to an area of low concentration. A representative proportion of the molecules coming from the extracellular fluid is then brought to the probe outlet for collection and analysis.