“…The choroid"s plexus behaves as a physical, immunological and enzymatic barrier which assists the drug transport, metabolism and signaling functions and restricts transport into the CSF as well [23][24][25][26]. The choroid plexus vigorously regulates the concentration of molecules in the CSF and the various transfer and secretion channels operative in the choroid plexus epithelial cells, make them suitable to control the molecular and cellular composition J o u r n a l P r e -p r o o f brain fluid and CSF and with the arachnoid membrane, performs between the blood and CSF at the barriers [25,27,28]. Thus therapeutic organic acids are actively taken out from the CSF [29,30].…”