title: Possibility and effectiveness of drug delivery to skin by needle-free injector.
abstract: We evaluated a needle-free injector (NFI), which has been studied as an administration device to the subcutaneous tissue, as a device to deliver drugs into skin tissues. ShimaJet used for self-injection of insulin was selected as a spring-powered NFI in this study. Weak (NFI-w) and strong (NFI-s) injectors were evaluated. Rhodamine 6G, as a model compound, was injected onto the skin surface of hairless rats and the skin distribution and amount released from the skin of the compound were followed. A modified nozzle (able to inject at an angle of 45 degrees ) was prepared in addition to the conventional dedicated nozzle. The spring constants, nozzle shapes and penetration enhancer, 1-[2-(decylthio)ethyl] azacyclopentane-2-one (HPE-101), affected not only the skin distribution, but also the release profiles of rhodamine 6G. In addition, the release profiles of rhodamine 6G after injection using NFI-w or NFI-s obeyed diffusion-controlled or membrane-controlled kinetics, respectively. This difference was probably due to the skin site (depth) of rhodamine 6G delivered by the NFI. Furthermore, HPE-101 increased the retention time of rhodamine 6G in the epidermis. The present results suggested that an NFI can be a useful tool for enhanced drug delivery into skin.
authors.affiliation: Department of Pharmacy Services, Saitama Medical School, Medical Center, 1981 Kamoda, Kawagoe, Saitama 350-8550, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Inoue
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Todo
authors.forename: Dai
authors.initials: D
authors.lastname: Iidaka
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Tokudome
authors.forename: Fumie
authors.initials: F
authors.lastname: Hashimoto
authors.forename: Tohru
authors.initials: T
authors.lastname: Kishino
authors.forename: Kenji
authors.initials: K
authors.lastname: Sugibayashi
mesh_terms: D000818:Animals; D016503:Drug Delivery Systems / Q000295:instrumentation* / Q000379:methods*; D004817:Epidermis / Q000378:metabolism; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D007277:Injections, Jet / Q000295:instrumentation* / Q000379:methods*; D007700:Kinetics; D011758:Pyrroles / Q000494:pharmacology; D051381:Rats; D054772:Rats, Hairless; D012235:Rhodamines / Q000493:pharmacokinetics; D012869:Skin Absorption / Q000187:drug effects*
chemical_list: D005456:Fluorescent Dyes; D011758:Pyrroles; D012235:Rhodamines; C026188:rhodamine 6G; C075725:1-(2-(decylthio)ethyl)azacyclopentane-2-one