Microneedle:An Advanced Technique in Transdermal Drug Delivery System

Transdermal drug delivery offers an attractive alternative to the conventional drug delivery methods of oral administration and injection. However, the stratum corneum acts as a barrier that limits the penetration of substances through the skin. Recently, the use of micron-scale needles in increasing skin permeability has been proposed and shown to dramatically increase transdermal delivery. Microneedles have been fabricated with a range of sizes, shapes, and materials. Microneedles inserted into the skin of human subjects were reported to be painless. Microneedle is a novel method of drug delivery. The advantage of using microneedle is that it does not pass the stratum corneum. The dosing in microgram quantities can be done by this type of needle. The mechanism of action is based on temporary mechanical disruption of skin. The drug, in bimolecular form, is encapsulated within the microneedles, which are then inserted into the skin, in the same way a drug like nitro-glycerine is released into the bloodstream from a patch. The review covers the various methods of drug delivery like Poke with patch approach, coat and poke approach, biodegradable microneedles, hollow microneedles and dip and scrape. This review presents the main findings concerning the use of microneedles in transdermal drug delivery. It also covers types of microneedles, their advantages and disadvantages, fabrication material, and fabrication process and evaluation of microneedles. The evaluation of microneedle has shown that this technique can be used safely.