title: Desolvation energy: a major determinant of absorption, but not clearance, of peptides in rats.
abstract: The oral delivery of peptidic drugs is problematic because of their degradation in the gastrointestinal tract and low absorption through the intestinal mucosa. Earlier in vitro studies with two series of digestion-resistant, radiolabeled peptides that varied in physical properties (molecular weight, lipophilicity, and hydrogen bonding sites) had suggested that intestinal transport of these peptides was most influenced by the number of hydrogen bonding sites, the major determinant of desolvation energy. To determine whether this correlation could be confirmed in vivo, intestinal absorption was determined by comparing the biliary and urinary recovery of these radiolabeled peptides in rats given intravenous or intraduodenal doses. Absorption was inversely correlated to the number of calculated hydrogen bonding sites for the model peptides, similar to what had been found in vitro. Clearance by liver and kidneys appeared to be unaffected by desolvation energy but was well correlated with lipophilicity.
authors.affiliation: Drug Delivery Systems Research, Upjohn Co., Kalamazoo, Michigan 49001.
authors.forename: M S
authors.initials: MS
authors.lastname: Karls
authors.forename: B D
authors.initials: BD
authors.lastname: Rush
authors.forename: K F
authors.initials: KF
authors.lastname: Wilkinson
authors.forename: T J
authors.initials: TJ
authors.lastname: Vidmar
authors.forename: P S
authors.initials: PS
authors.lastname: Burton
authors.forename: M J
authors.initials: MJ
authors.lastname: Ruwart
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001646:Bile / Q000378:metabolism; D001659:Biliary Tract / Q000378:metabolism; D002250:Carbon Radioisotopes; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004386:Duodenum; D007275:Injections, Intravenous; D007408:Intestinal Absorption; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009842:Oligopeptides / Q000493:pharmacokinetics* / Q000652:urine; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002250:Carbon Radioisotopes; D009842:Oligopeptides