Review of Microneedle based Transdermal Drug Delivery Systems

Transdermal drug delivery (TDD) provides an attractive and alternative drug delivery when compared to oral and other drug delivery as the former route offers several advantages like avoiding pre-systemic first pass metabolism of administered drugs, patient compliance, and avoiding gastric irritation. However, stratum corneum (SC), the upper most layer of skin, limits the permeation of number of drugs because of its barrier property. To breach or bypass this barrier, two approaches namely: chemical and physical are generally used. Physical approaches seem to be better as it does not involve the use of chemicals in the formulations, which could interact, with other component of formulations and more importantly may cause reversible damage to the skin. Microneedle technique is one of the most advanced physical techniques, which can easily by-pass, the SC and allow the drug to reach viable epidermis directly. The needles used in microneedle techniques are in hundreds of micron length range and when applied on skin generally produce little or no pain. The objective of this review is mainly focused on types of microneedles, various materials and fabrication techniques used in the preparation of microneedles. Furthermore, various techniques used in the application of microneedles and mechanism of action are described. In addition, this review also describes commercial products, patents on microneedle technology and recent works carried out on microneedles research and safety aspects of microneedles.