Microdialysis is a catheter-based sampling method that allows for continuous sampling of the unbound drug fraction in a range of different tissues over time. The microdialysis setup consists of a precision pump, a microdialysis catheter with a semipermeable membrane which is placed in the target tissue, and an outlet tube from where vials can be collected. 

The microdialysis method relies on the fact that diffusion across the semipermeable membrane is quantitatively equal in both directions, prompting a fraction of molecules in the target tissue to diffuse over the membrane that can be collected in vials. This fraction is referred to as the relative recovery and is imperative to determine when evaluating total tissue concentrations.  

With microdialysis it is possible to obtain dynamic target site concentration-time profiles which enables evaluation of ect. existing antibiotic and chemotherapy treatment regimes.