Table 1.

Considerations for the use of microdialysis for neuro-pharmacokinetic studies in patients with brain tumors.

Advantages	Disadvantages
Near real-time measurement of unbound drug near site of action in the brain; distinction between extracellular space and other compartments	Invasive technique
Simultaneous measurement of drug pharmacokinetics in brain and plasma contributes to decreased interpatient variability	Requires hospitalization
CNS concentration–time profiles of drugs can be determined using a relatively small number of patients	Expensive, particularly if hospitalization is prolonged beyond clinically indicated durations (i.e., prolonged dialysate collections)
Serial sample collections can be done while patients are awake and in the course of standard clinical care	Catheter calibration is needed to estimate the true drug concentration in tissue
Safe with low rates of bleeding or infections (comparable to other intracerebral monitoring techniques)	Sensitive analytical methods are needed to detect drug concentrations in the dialysate samples
More than one catheter can be placed at one time, enabling concurrent measurement in tumor core, peritumoral tissue and normal brain	In vitro testing is required to determine if the drug of interest is a candidate for microdialysis; many new targeted therapies and large proteins will not be good candidates
Accuracy of catheter placement can be confirmed with imaging studies	Accurate placement of catheter into regions of tumor is challenging

The major advantages and limitations of the microdialysis technique for clinical translational studies in neuro-oncology.