*2.3. Elimination*

In general, NPs are eliminated from the human body by renal and hepatobiliary routes and need to be done for clinical approval in a reasonable timeframe. Then, drug conjugated NPs must be designed to avoid quick clearance and long period of body maintenance.

As is expected, surface chemistry, shape, and NP size influence elimination. For example, surface chemistry is quite critical in the clearance efficiency -even for small NPs- and polyethylene glycol (PEG) coating promotes more efficient hepatobiliary clearance [27]. Another point is the NP size. The hydrodynamic NP size has a strong influence on the renal clearance, where the glomerular pores are a physical barrier [23,28].
