**1. Introduction**

toxicity, uptake mechanism and in vivo tolerance. Invest. Ophtlamol. Vis. Sci 2006;

[232] Lockman P R, Mumper R J, Khan M A, Allen D D. Nanoparticle technology for drug delivery across the blood–brain barrier. Drug Dev. Ind. Pharm 2002; 28 (1): 1-13. [233] Roney C, Kulkarni P, Arora V, et al. Targeted nanoparticles for drug delivery through the blood–brain barrier for Alzheimer's disease. Journal of Controlled Re‐

[234] Kreuter J. Nanoparticulate systems for brain delivery of drugs. Adv. Drug Deliv. Rev

[235] Wong H, Chattopadhyay N, Wu X, Bendayan R. Nanotechnology applications for improved delivery of antiretroviral drugs to the brain. Advanced Drug Delivery Re‐

[236] Pardridge W M. Drug and gene targeting to the brain with molecular trojan horses.

[237] Dutta T, Jain N K. Targeting potential and anti-HIV activity of lamivudine loaded mannosylated poly(propyleneimine) dendrimer, Biochim. Biophys. Acta 2007;

[238] Ring K, Walz C M, Sabel B A. Nanoparticle drug delivery to the brain. Eocyclopedia

47: 1416–1425.

192 Application of Nanotechnology in Drug Delivery

lease 2005; 108: 193–214.

views 2010; 62: 503–517.

Nat Rev Drug Discov 2002; 1(2):131-139.

of Nanoscience and Nanotechnology. 2004; 7: 91-104.

2001; 47 (1): 65–81.

1770:681–686.

The term "nanoscale" refers to particle size range from ~ 1 to 100 nm [1], but for the purpose of drug delivery, nanoparticles in the range of 50 – 500 nm are acceptable depending on the route of administration. The method by which a drug is delivered can have a significant effect on its efficacy. Some drugs have an optimum concentration range within which maximum benefit is derived and concentrations above or below this range can be toxic or produce no therapeutic benefit. The slow progress in the efficacy of the treatment of several diseases has suggested a growing need for a multidisciplinary approach to the delivery of therapeutics to target tissues [2]. Transdermal drug delivery systems (TDDS) or patches are controlled-release devices that contain the drug either for localized treatment of tissues underlying the skin or for systemic therapy after topical application to the skin surface [3]. TDDS are available for a number of drugs, although the formulation matrices of these delivery systems differ. They differ from conventional topical formulations in the following ways:


© 2014 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Topical or transdermal drug delivery is challenging because the skin acts as a natural and protective barrier. TDDS were introduced into the US market in the late 1970s [5], but trans‐ dermal delivery of drugs had been used for a very long time. There have been previous reports about the use of mustard plasters to alleviate chest congestion and belladonna plasters as analgesics. The mustard plasters were homemade as well as available commercially where mustard seeds were ground and mixed with water to form a paste, which was in turn used to form a dispersion type of delivery system. Several methods have been examined to increase the permeation of therapeutic molecules into and through the skin and one such approach is use of nanoparticulate delivery system.

The skin has been an important route for drug delivery when topical, regional, or systemic effects are desired. Nevertheless, skin constitutes an excellent barrier and presents difficulties for the transdermal delivery of therapeutic agents, since few drugs possess the characteristics required to permeate across the stratum corneum in sufficient quantities to reach a therapeutic concentration in the blood [6]. In order to enhance drug transdermal absorption, different methodologies have been investigated, developed, and patented. Improvement in physical permeation-enhancement technologies has led to renewed interest in transdermal drug delivery. Some of these novel advanced transdermal permeation-enhancement technologies include iontophoresis, electroporation, ultrasound, microneedles to open up the skin, and more recently the use of transdermal nanocarriers.
