The CNS as a target for peptides and peptide-based drugs.
Peptides hold great potential as CNS drugs, but their delivery to the CNS is problematic. However, actual roadblocks to peptide delivery are different from those often perceived. Many peptides cross the blood-brain barrier by saturable and non-saturable mechanisms, and accumulate in brain in amounts sufficient to produce physiological effects. Peripheral factors (e.g., short half-life in blood) can be dominant factors limiting therapeutic use. Production of therapeutics that are enzymatically resistant and have long circulation times, even when the blood-brain barrier penetration is low, can result in substances with significant CNS accumulation. Surprisingly low amounts of peptide in brain can result in CNS effects, and so the dose needed for brain delivery is generally much smaller than for peripheral tissues. Brain-to-blood transporters can greatly limit CNS accumulation of a potential therapeutic. Finally, intranasal and intrathecal routes may be especially useful for substances that are rapidly degraded in blood or are large and hydrophobic, respectively.
Banks
William A
WA
Veterans Affairs Medical Center - St. Louis and Saint Louis University School of Medicine, Geriatric Research, Education and Clinical Center, Division of Geriatrics, Department of Internal Medicine, St. Louis, MO 63106, USA. bankswa@slu.edu
D000281:Administration, Intranasal; D000818:Animals; D001812:Blood-Brain Barrier / Q000378:metabolism*; D002493:Central Nervous System Diseases / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D007278:Injections, Spinal; D010455:Peptides / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use
D010455:Peptides