Molecular Aspects of BBB

The function of the BBB is dynamically regulated by various cells present at the level of the BBB. This realization implies better understanding of the relationship of at the BBB to drug structure and physicochemical properties. The physical barrier naming BBB is characterized by tight junctions between endothelial cells, by the absence of fenestrations and low occurrence of pinocytic activity 1. Penetration of chemicals to the BBB occurs using a combination of intra and intercellular passages. The main factors that limit the penetration of lipophilic membranes by any molecule are its molecular weight and its ability to form hydrogen bonds and so bind to circulating plasma proteins. Tight junctions regulate the intracellular passage of molecules according to their physico-chemical properties (e.g. lipophilicity, ionization and polarity), where inter cellular penetration is regulated by influx and efflux transporters, endocytosis and passive diffusion.