6. Systemic action

6.1 Tissue biodistribution

When the nanomedicine suspension is administered directly intravenously, the absorption phase is absent, and the particles distribute directly into the tissues accessible from the blood compartment. This distribution depends on the lifetime of the nanodrugs in the blood. This is a function of protein adsorption and, more specifically, of so-called opsonization, which, depending on whether or not it occurs, leads to two types of behavior: rapid elimination by the immune system in the case of strong adsorption, or long circulation in the blood if the nanoparticle surface is designed to repel opsonins.