Peptides and the Blood-Brain Barrier: Enhancing Peptide Bioavailability to the Brain

The growth of the biotech industry over the last decade has resulted in an exponential increase in the number of drugs developed to treat neurological disorders. Despite the obvious importance of peptides in modulating physiological function, the number of peptide neuropharmaceuticals remains small. The primary reason for this is the presence of the blood-brain barrier (BBB). The BBB is a unique membranous barrier, which regulates the delivery of substances to the brain. Peptides generally have limited transport across the BBB for a number of reasons, based principally on the biochemical nature of the peptides. Peptides are generally metabolized enzymatically and are taken up avidly by peripheral organs, thus further reducing availability to be transported to the brain. This chapter describes a number of strategies that have proven effective in the experimental delivery of peptides to the central nervous system, which can be utilized for neuropharmaceutical development.