The Sojourn of Polymeric Micelles for Effective Brain Drug Delivery System.

The brain is a delicate organ and targeting neurological diseases with conventional approaches is still a daunting task. This is due to the presence of necessary physiological barriers, mainly the blood-brain barrier, that blocks the entry of dangerous and poisonous substances from the bloodstream, thus helping in maintaining homeostasis. Furthermore, the presence of multidrug resistance transporters which act by prohibiting the entry of drugs across the cell membrane and by channelizing them to the outside environment is another defense mechanism. Despite the advancements in the understanding of disease pathology, only a restricted number of drugs and drug therapies can treat and target neurological diseases. To overcome this shortcoming, the therapeutic approach using amphiphilic block copolymers - using polymeric micelles has gained momentum because of its wide applications like drug targeting, delivery, and imaging. Polymeric micelles are nanocarriers that arise when amphiphilic block copolymers spontaneously assemble in aqueous solutions. The hydrophobic core-hydrophilic shell configuration of these nanoparticles makes it easier to load hydrophobic drugs into the core and as a result, the solubility of these medications is improved. Micelle-based drug delivery carriers can target the brain with reticuloendothelial system uptake and produce a long-circulating effect. PMs can also be combined with targeting ligands that increase their uptake by specific cells and thus decreasing off-target effects. In the present review, we primarily focused on polymeric micelles for brain delivery along with the method of preparation, mechanism of micelle formulation, and the ongoing formulations under clinical trials for brain delivery.