title: In vitro and in vivo characterization of MEMS microneedles.
abstract: Transdermal drug delivery TDD systems have many advantages but are conventionally limited by the low permeability of skin. The idea of using microneedles to painlessly penetrate the topmost impermeable stratum corneum has previously been put forward. In this paper, the fabrication of solid and hollow silicon microneedles with straight side-walls and with the following dimensions: 20-100 microm in diameter and 100-150 microm in length is described. In vitro tests demonstrate that with prior solid microneedle application, transdermal drug transport is significantly increased by 10-20 times, with the degree of enhancement being related to needle diameter. In vivo tests in diabetic animals, however, were unable to demonstrate any delivery of insulin through the hollow microneedles. It is proposed that two factors, microneedle length and tip sharpness, have to be improved for systemic drug delivery to be seen in vivo.
authors.affiliation: Defence Medical & Environmental Research Institute, Defence Science Organisation, 27 Medical Drive, #12-00, DSO (Kent Ridge) Building, Singapore 117510.
authors.forename: Melissa Ai Ling
authors.initials: MA
authors.lastname: Teo
authors.forename: Christopher
authors.initials: C
authors.lastname: Shearwood
authors.forename: Kian Chye
authors.initials: KC
authors.lastname: Ng
authors.forename: Jia
authors.initials: J
authors.lastname: Lu
authors.forename: Shabbir
authors.initials: S
authors.lastname: Moochhala
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000175:diagnosis / Q000188:drug therapy*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007279:Injections, Subcutaneous / Q000295:instrumentation* / Q000379:methods; D007328:Insulin / Q000008:administration & dosage*; D008297:Male; D008845:Microinjections / Q000295:instrumentation* / Q000379:methods; D008904:Miniaturization / Q000379:methods; D009339:Needles; D051381:Rats; D017207:Rats, Sprague-Dawley; D013311:Streptozocin; D016896:Treatment Outcome
chemical_list: D007328:Insulin; D013311:Streptozocin