title: Microneedle-based drug delivery: studies on delivery parameters and biocompatibility.
abstract: There is a significant interest in the application of microneedles in intradermal drug delivery systems. Previous studies have demonstrated that skin permeation of drugs can be increased by orders of magnitude with microneedle insertion. In this study, emphasis is placed on the development of low cost, painless intradermal microneedle systems that can enhance the percutaneous drug permeation. Microneedles of octagonal pyramidal shape with the length of 150 mum were employed, and the capabilities of skin permeation enhancement under different delivery conditions were examined. The delivery parameters taken into account included the insertion time and the area of insertion. It was found that when solid microneedle arrays of 150 mum in length were pierced into human dermatomed skin for 5 to 60 s, microconduits with the depth of 50 to 80 mum were created to facilitate the percutaneous permeation of drugs. In percutaneous tests, it was demonstrated that the permeability coefficient of calcein (MW = 622.55) was significantly increased by 10(4) to 10(5) times compared to that on intact skin. In terms of biocompatibility, biological evaluation indicated a broad spectrum of safety for the microneedle system. These results suggest that the octagonal pyramidal microneedles can be an effective tool in developing novel intradermal drug delivery system.
authors.affiliation: Laboratory of Organic Optoelectronic Functional Materials and Molecular Engineering, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100080, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Qiu
authors.forename: Suohui
authors.initials: S
authors.lastname: Zhang
authors.forename: Guangjiong
authors.initials: G
authors.lastname: Qin
authors.forename: Yunhua
authors.initials: Y
authors.lastname: Gao
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D004333:Drug Administration Routes; D016503:Drug Delivery Systems / Q000009:adverse effects / Q000295:instrumentation*; D005452:Fluoresceins / Q000737:chemistry / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007279:Injections, Subcutaneous / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D008297:Male; D008845:Microinjections / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D008970:Molecular Weight; D009339:Needles; D010539:Permeability; D004364:Pharmaceutical Preparations / Q000008:administration & dosage* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000378:metabolism; D012869:Skin Absorption; D013678:Technology, Pharmaceutical / Q000295:instrumentation* / Q000379:methods
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; D004364:Pharmaceutical Preparations; C007740:fluorexon