Dissolving microneedles for transdermal drug administration prepared by stepwise controlled drawing of maltose

Dissolving microneedles, three-dimensional polymer structures with microscale cross-sectional dimensions, have been introduced as a means of safe transdermal drug delivery. Most dissolving microneedles have been fabricated using a traditional micro-casting method that cures biopolymers within three-dimensional mold, nevertheless, repeated molding process may cause damage to encapsulated drugs, a critical hurdle for clinical application. Here, we describe the stepwise controlled drawing technique that can directly fabricate dissolving microneedle from maltose by precise controlling the drawing time and the viscosity of the maltose. Controlled drawing shaped the particular sharp-conical microneedles of 1200 pm length with tip diameter of 60 pm, and dissolved within 20 min in-vivo after inserting to the skin. This technique surpasses the limitations of micro-casting for dissolving microneedle. Furthermore, transdermal delivery of impermeable hydrophilic molecules such as ascorbic acid-2-glucoside and niacinamide was confirmed as inhibition of cutaneous hypermelanosis. We anticipate that controlled drawing technique will be suitable to design dissolving microneedles for use in minimally invasive transcutaneous drug delivery to patients. (C) 2011 Elsevier Ltd. All rights reserved.