Chapter 4: Transdermal Drug Delivery
Published:04 May 2022
Q. K. Anjani, A. H. Bin Sabri, S. Henke, and R. F. Donnelly, in Specialised Pharmaceutical Formulation: The Science and Technology of Dosage Forms, ed. G. D. Tovey, The Royal Society of Chemistry, 2022, ch. 4, pp. 94-120.
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Being the largest and most accessible organ, the skin is an attractive target for drug delivery. However, the efficient barrier function of the stratum corneum presents a considerable challenge to the delivery of therapeutic into and across the skin. Nevertheless, years of research in the area of skin permeation culminated with the regulatory approval of the first transdermal patch for the delivery of the antiemetic drug scopolamine in 1979. Since then, the delivery of therapeutics across the skin has progressed considerably with the development of various innovative drug delivery strategies, with microneedles being one of them. Since the first microneedle patent was filed in the 1950s, microneedle research has gained considerable momentum. Microneedle-based delivery strategy offers a minimally invasive drug delivery approach while obviating first-pass hepatic metabolism. Judicious selection in formulation designs coupled with advancement in the microfabrication techniques have led to the development of novel microneedle systems. The first part of this chapter aims to provide a general outline of the anatomy of the skin along with strategies that have been explored in delivering drugs into and across the skin. The second part of this chapter covers the development, classification, and manufacturing methods of manufacture microneedles along with a discussion with regards to commercialising such technology.