title: Paracellular permeation-enhancing effect of AT1002 C-terminal amidation in nasal delivery.
abstract: BACKGROUND
  The identification of permeation enhancers has gained interest in the development of drug delivery systems. A six-mer peptide, H-FCIGRL-OH (AT1002), is a tight junction modulator with promising permeation-enhancing activity. AT1002 enhances the transport of molecular weight markers or agents with low bioavailability with no cytotoxicity. However, AT1002 is not stable in neutral pH or after incubation under physiological conditions, which is necessary to fully uncover its permeation-enhancing effect. Thus, we increased the stability or mitigated the instability of AT1002 by modifying its terminal amino acids and evaluated its subsequent biological activity.
  
  
  METHODS
  C-terminal-amidated (FCIGRL-NH2, Pep1) and N-terminal-acetylated (Ac-FCIGRL, Pep2) peptides were analyzed by liquid chromatography-mass spectrometry. We further assessed cytotoxicity on cell monolayers, as well as the permeation-enhancing activity following nasal administration of the paracellular marker mannitol.
  
  
  RESULTS
  Pep1 was nontoxic to cell monolayers and showed a relatively low decrease in peak area compared to AT1002. In addition, administration of mannitol with Pep1 resulted in significant increases in the area under the plasma concentration-time curve and peak plasma concentration at 3.63-fold and 2.68-fold, respectively, compared to mannitol alone. In contrast, no increase in mannitol concentration was shown with mannitol/AT1002 or mannitol/Pep2 compared to the control. Thus, Pep1 increased the stability or possibly reduced the instability of AT1002, which resulted in an increased permeation-enhancing effect of AT1002.
  
  
  CONCLUSIONS
  These results suggest the potential usefulness of C-terminal-amidated AT1002 in enhancing nasal drug delivery, which may lead to the development of a practical drug delivery technology for drugs with low bioavailability.
authors.affiliation: Department of Pharmaceutical Engineering, Soonchunhyang University, Asan, Republic of Korea.
authors.forename: Keon-Hyoung
authors.initials: KH
authors.lastname: Song
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea.
authors.forename: Sang-Bum
authors.initials: SB
authors.lastname: Kim
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea.
authors.forename: Chang-Koo
authors.initials: CK
authors.lastname: Shim
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea.
authors.forename: Suk-Jae
authors.initials: SJ
authors.lastname: Chung
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea.
authors.forename: Dae-Duk
authors.initials: DD
authors.lastname: Kim
authors.affiliation: Department of Pharmaceutical Engineering, Soonchunhyang University, Asan, Republic of Korea.
authors.forename: Sang-Ki
authors.initials: SK
authors.lastname: Rhee
authors.affiliation: Department of Pharmaceutical Engineering, Soonchunhyang University, Asan, Republic of Korea.
authors.forename: Guang J
authors.initials: GJ
authors.lastname: Choi
authors.affiliation: Department of Sports Medicine, Soonchunhyang University, Asan, Republic of Korea.
authors.forename: Chul-Hyun
authors.initials: CH
authors.lastname: Kim
authors.affiliation: Department of Medical Biotechnology, Soonchunhyang University, Asan, Republic of Korea.
authors.forename: Kiyoung
authors.initials: K
authors.lastname: Kim
mesh_terms: D000281:Administration, Intranasal; D000577:Amides / Q000737:chemistry*; D000818:Animals; D001682:Biological Availability; D018938:Caco-2 Cells; D016503:Drug Delivery Systems; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D009297:Nasal Mucosa / Q000187:drug effects; D009842:Oligopeptides / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C530561:AT1002; D000577:Amides; D009842:Oligopeptides
keywords: N-terminal acetylation; permeation enhancer; stability
references.citation: Int J Pharm. 2008 Mar 3;351(1-2):8-14
references.pmid: 17954018
references.citation: Eur J Pharm Biopharm. 2001 Sep;52(2):145-50
references.pmid: 11522479
references.citation: Expert Opin Drug Discov. 2014 Apr;9(4):367-81
references.pmid: 24558958
references.citation: Pharm Res. 2002 Nov;19(11):1680-8
references.pmid: 12458674
references.citation: J Pharm Sci. 1998 Nov;87(11):1351-6
references.pmid: 9811489
references.citation: Trends Biotechnol. 1998 Apr;16(4):152-7
references.pmid: 9586237
references.citation: J Clin Invest. 1997 Mar 15;99(6):1158-64
references.pmid: 9077522
references.citation: Int J Pharm. 2009 Jan 5;365(1-2):121-30
references.pmid: 18832018
references.citation: J Pharm Pharmacol. 2012 Jan;64(1):30-9
references.pmid: 22150669
references.citation: Eur J Pharm Biopharm. 2008 May;69(1):231-7
references.pmid: 18039562
references.citation: Mol Genet Metab. 1998 May;64(1):12-8
references.pmid: 9682213
references.citation: Arch Pharm Res. 2012 Feb;35(2):359-66
references.pmid: 22370791
references.citation: Clin Pharmacokinet. 2003;42(13):1107-28
references.pmid: 14531723
references.citation: J Clin Invest. 1995 Aug;96(2):710-20
references.pmid: 7635964
references.citation: J Neurochem. 2000 Jan;74(1):320-6
references.pmid: 10617135
references.citation: Gastroenterology. 1997 Mar;112(3):839-46
references.pmid: 9041245
references.citation: Pharm Res. 1993 Jul;10(7):933-44
references.pmid: 8378255
references.citation: Arch Pharm Res. 2012 May;35(5):937-43
references.pmid: 22644862
references.citation: Pharm Biotechnol. 1996;9:141-80
references.pmid: 8914191
references.citation: Pharm Res. 1994 Jul;11(7):936-44
references.pmid: 7937552
references.citation: Proc Natl Acad Sci U S A. 1993 Feb 1;90(3):838-42
references.pmid: 8430094
references.citation: Int J Pharm. 2003 Jan 30;251(1-2):113-21
references.pmid: 12527181
references.citation: Biochemistry. 1993 Jan 19;32(2):421-5
references.pmid: 8422351
references.citation: Int J Pharm. 1999 Aug 20;185(2):129-88
references.pmid: 10460913