ABSTRACT
Brain and central nervous system (CNS) disorders are major causes of disability. Despite extensive research, clinical treatment options are still limited for the majority of CNS diseases, and therapeutic outcomes are sometimes disappointing. The blood-brain barrier (BBB) presents a formidable obstacle to effective drug delivery to the CNS. Although biologically intended to protect the brain and spinal cord and provide a very stable fluid environment, the presence of a BBB makes treatment of many CNS diseases difficult to achieve, as required therapies cannot be delivered across the barrier in sufficient quantities or at all (1). Moreover, CNS-active agents must pass through the BBB, and overcome drug efflux mechanisms in order to reach the brain and exert therapeutic effects. Therefore, an understanding of the physiology and cell biology of the BBB, rational drug design, and optimized drug structure and physiochemical properties are necessary in order to achieve efficient drug delivery to CNS (2). For some existing CNS medications, advanced formulation and drug delivery strategies can be utilized to improve delivery efficiency and drug therapy.
