Novel delivery systems for drug targeting to the brain

The development of new drugs is expensive and time-consuming. Most of the potential compounds lack therapeutic efficacy due to their inability to reach the target site. An alternative to developing new drugs is to focus on delivering drugs of potential therapeutic value to the target site. The brain is one of the organs where the targeting of drugs is difficult. Transport of drugs from circulating blood into the central nervous system (CNS) is restricted by the blood-brain barrier (BBB) and blood-cerebrospinal fluid (CSF) barrier, which are formed by tight junctions connecting the cerebral endothelial and epithelial cells of the choroid plexus, respectively. Several strategies have been developed to circumvent the BIBB, of which chemical delivery systems and novel delivery systems are the most important. The objective of this article is to provide updated information on the utilization of known transport systems across the BBB for the development of novel delivery systems that deliver drugs to the brain at a desired rate under various pathological conditions, including cerebral ischemia, brain tumors and Alzheimers disease. The novel delivery systems include microspheres, niosomes, liposomes, nanoparticles, solid lipid nanoparticles, lipid microspheres, polymeric micelles, vector-mediated delivery, noninvasive gene therapy and nasal administration.