Oral drugs administrate to a body with painless and low cost, however, the efficiency of most oral drugs is not high due to the metabolic degradation during adsorption process. In contrast, a skin patch-based transdermal drug delivery is attractive for avoiding the route of metabolic degradation, as well as its painless property. In order to improve the transdermal drug delivery, microneedle array has been of much interest since it can reach inside stratum corneum and enhance the transdermal adsorption of the drugs. Different types of microneedles of the drug-coated, the dissolvable, and the hollowed structure have been applied for skin patches. In the previous study, we have developed porous microneedles (PMN) consisting of glycidyl methacrylate (GMA) by using the porogen method with polyethylene glycol (PEG), which allowed fast water absorption and enough mechanical strength to reach into the skin. Moreover, the GMA-PMN was proved to decrease the transdermal ionic resistance, and thus is expected to enhance the iontophoresis efficiency. However, since the tip of GMA-PMN remained in the body is hard to be metabolized, an adverse effect on the human body could be cased. In this study, we developed PMNs consisting of a biodegradable material, polylactic acid-glycolic acid copolymer (PLGA) (Figure 1A). In order to improve the hydrophilicity and mechanical strength of the PLGA-PMNs, the water-soluble and biodegradable polymer was composited to the PLGA-PMNs.
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