title: Trypsin as a novel potential absorption enhancer for improving the transdermal delivery of macromolecules.
abstract: OBJECTIVE
  The aim was to assess the effect of trypsin on the transdermal delivery of macromolecules by applying its specific biochemical properties to the stratum corneum of the skin.
  
  
  METHODS
  Fluorescein isothiocyanate (FITC)-labelled dextrans (FDs), with molecular weights of 4 to 250 kDa, and FITC-insulin were used as model macromolecules and a model polypeptide, and the in-vitro transdermal permeation experiments, with or without trypsin (0.1-2.5%), were carried out using rat skin and cultured human epidermis. The mechanism for the enhancement of trypsin was also studied using fluorescence and conventional light microscopy.
  
  
  RESULTS
  Trypsin significantly increased the transdermal permeability of all FDs through the rat skin (2.0- to 10.0-fold). It also markedly enhanced the permeation of FD4 through three-dimensional cultured human epidermis (3.1-fold), which was used to evaluate the transport pathways other than the transfollicular route. Furthermore, the permeation flux of FITC-insulin was increased by 10.0-fold with trypsin pretreatment (from 0.02 +/- 0.00 to 0.20 +/- 0.07 microg/cm(2) per h). Mechanistic studies indicated that trypsin affects both the intercellular pathway and the hair follicular route, and may alter stratum corneum protein structures, thereby affecting skin barrier properties.
  
  
  CONCLUSIONS
  This study suggests that trypsin could be effective as a biochemical enhancer for the transdermal delivery of macromolecules including peptide and protein drugs.
authors.affiliation: Institute for Frontier Medical Science, Kyoto University, Shogoin, Sakyo-ku, Japan.
authors.forename: Ying-Zhe
authors.initials: YZ
authors.lastname: Li
authors.forename: Ying-Shu
authors.initials: YS
authors.lastname: Quan
authors.forename: Lei
authors.initials: L
authors.lastname: Zang
authors.forename: Mei-Na
authors.initials: MN
authors.lastname: Jin
authors.forename: Fumio
authors.initials: F
authors.lastname: Kamiyama
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Katsumi
authors.forename: Sadami
authors.initials: S
authors.lastname: Tsutsumi
authors.forename: Akira
authors.initials: A
authors.lastname: Yamamoto
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D003911:Dextrans / Q000008:administration & dosage / Q000493:pharmacokinetics; D005079:Excipients / Q000737:chemistry*; D016650:Fluorescein-5-isothiocyanate / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D006801:Humans; D066298:In Vitro Techniques; D007328:Insulin / Q000008:administration & dosage / Q000493:pharmacokinetics; D008297:Male; D008856:Microscopy, Fluorescence; D010539:Permeability; D051381:Rats; D017208:Rats, Wistar; D012867:Skin / Q000187:drug effects / Q000378:metabolism; D012869:Skin Absorption; D013552:Swine; D014357:Trypsin / Q000737:chemistry*
chemical_list: D003911:Dextrans; D005079:Excipients; D007328:Insulin; C015219:fluorescein isothiocyanate dextran; D014357:Trypsin; D016650:Fluorescein-5-isothiocyanate