title: Estimation of skin concentrations of topically applied lidocaine at each depth profile.
abstract: Skin concentrations of topically administered compounds need to be considered in order to evaluate their efficacies and toxicities. This study investigated the relationship between the skin permeation and concentrations of compounds, and also predicted the skin concentrations of these compounds using their permeation parameters. Full-thickness skin or stripped skin from pig ears was set on a vertical-type diffusion cell, and lidocaine (LID) solution was applied to the stratum corneum (SC) in order to determine in vitro skin permeability. Permeation parameters were obtained based on Fick's second law of diffusion. LID concentrations at each depth of the SC were measured using tape-stripping. Concentration-depth profiles were obtained from viable epidermis and dermis (VED) by analyzing horizontal sections. The corresponding skin concentration at each depth was calculated based on Fick's law using permeation parameters and then compared with the observed value. The steady state LID concentrations decreased linearly as the site became deeper in SC or VED. The calculated concentration-depth profiles of the SC and VED were almost identical to the observed profiles. The compound concentration at each depth could be easily predicted in the skin using diffusion equations and skin permeation data. Thus, this method was considered to be useful for promoting the efficient preparation of topically applied drugs and cosmetics.
authors.affiliation: Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Oshizaka
authors.affiliation: Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kikuchi
authors.affiliation: Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan.
authors.forename: Wesam R
authors.initials: WR
authors.lastname: Kadhum
authors.affiliation: Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Todo
authors.affiliation: Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan; Tokai University Institute of Innovative Science and Technology, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Hatanaka
authors.affiliation: Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan.
authors.forename: Konstanty
authors.initials: K
authors.lastname: Wierzba
authors.affiliation: Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan. Electronic address: sugib@josai.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sugibayashi
mesh_terms: D000287:Administration, Topical; D000818:Animals; D020405:Dermis / Q000378:metabolism*; D004058:Diffusion; D004817:Epidermis / Q000378:metabolism*; D008012:Lidocaine / Q000737:chemistry* / Q000378:metabolism*; D010539:Permeability; D012869:Skin Absorption; D012996:Solutions / Q000737:chemistry / Q000378:metabolism; D013552:Swine
chemical_list: D012996:Solutions; D008012:Lidocaine
keywords: Concentration-distance profile; Lidocaine (PubChem CID: 3676); Lidocaine hydrochloride monohydrate (PubChem CID: 16219577); Permeation parameter; Skin concentration; Skin permeation