**13. Dermal and transdermal formulations on the market**

studies for pharmaceutical products intended for use in humans as described according to are the requirements of the United States, Japan, and Europe because these areas represent the largest pharmaceutical markets in the world today. These requirements have been developed at the International Conference on Harmonization to provide uniformity among the three regions [153]. Phases I, II, and III refer to the different phases of human clinical trials. Phase I refers to the initial trials, limited to one or a few doses to determine absorption, pharmacoki‐ netics, and an initial estimate of safety. Phase II refers to larger scale studies to establish safety and to get an initial estimate of clinical efficacy. Phase III refers to the final, large-scale,

The Food and drug agency (FDA) paradigm for regulation of new products is based on the concepts of risk management, which includes identification, analysis and control of risk [154]. The regulation and approval by the FDA is on a ''product by product'' basis, with the overall regulation process falling into three stages: premarket approval, premarket acceptance and

Premarket approval: Prior to market introduction of any new pharmaceuticals, high-risk medical devices, food additives, colors, and biologicals, FDA approval is required. The producer/sponsor of the product is responsible for identifying and assessing the risks pre‐ sented by the product. This party will also be responsible for indicating means to minimize

Premarket acceptance: This category refers to products that are often copies of similar products that were approved previously or are products prepared according to approved specifications. For these products, the FDA receives and reviews some form of notice that the products will be marketed and the products undergo a more rapid review process than premarket approval.

Postmarket surveillance: In this category, FDA manages the risks of GRAS products like foods, cosmetics, radiation emitting electronic products and materials such as food additives and food packaging. For products in this category, market entry, and distribution are at the discretion of the manufacturer/producer. These products are generally regulated by the application of good manufacturing practices. FDA takes regulatory action if adverse events

The FDA coordinates policies within itself and with other government agencies. As and when new toxicological risks that derive from the new materials and/or new conformations of

The FDA regulations are for products, not technologies. In addition, the FDA regulates only the claims made by the product sponsor. If the manufacturer makes no nanotechnology claims regarding the manufacture or performance of the product, the FDA may be unaware at the time that the product under review employed nanotechnology. Finally, the FDA has only limited authority over some potentially high-risk products, such as cosmetics. Many products are regulated only if they cause adverse health-related events in use. To date there have been

multicenter trials aimed at establishing efficacy.

post-market surveillance.

220 Application of Nanotechnology in Drug Delivery

the risks in a product application.

that threaten public or individual health occur.

existing materials are identified, the FDA will require new tests.

few resources available to assess the risks of these products.

A lot of dermal and transdermal drug delivery systems have been licensed for manufacture after passing through the regulatory approval and trials as specified by different countries example FDA (United States of America). Some of the drugs currently available on the market are presented in Table 3.



Application of vesicular encapsulation holds great promise in the development and use of phytomedicines considering the difficulties of their formulation into stable dosage forms. Certain physicochemical properties of many herbal extracts make their formulation difficult due to stability and processing challenges. By using appropriate techniques, vesicular products of herbal extracts with enhanced stability and efficacy have been produced. A new drug delivery device known as phytosome, composed of phosphatidylcholine, has been developed to overcome the poor absorption of flavonoids, a challenge due mainly to their large molecular sizes and poor miscibility with the lipid contents of cell membrane linings [159]. Phytosomes

Nanoparticles for Dermal and Transdermal Drug Delivery

http://dx.doi.org/10.5772/58672

223

Evaluations of phytosomes indicate that a bond is formed between a flavonoid and a phos‐ phatidylcholine molecule to form a hybrid that is highly lipid-miscible. The development and applications of a variety of novel vesicular herbal formulations such as liposomes, phytosomes, transfersomes and ethosomes have been reported [160,161]. Ethosomes, by virtue of their special characteristics, may circumvent the hindrances to successful delivery of phytomedi‐ cines. Both soluble and insoluble phytomedines can be encapsulated in ethosomes. Ethosomes also offer protection from premature degradation and increased biodistribution, which would make for improved bioavailability and more beneficial therapeutic outcome for TDDS.

From the myriad published studies involving nanoparticles, it is clear that nanoparticles have the potential to effectively deliver drugs across the skin barrier. Conventional liposomes, flexible liposomes, ethosomes, niosomes and ultradeformable liposomes, etc offer potential value as dermal and transdermal drug delivery systems in addition to other lipid

Drug Delivery Research Unit, Department of Pharmaceutics, University of Nigeria, Nsukka,

[1] Hatto P (2011) ISO concensus definitions relevant to nanomaterials and nanotechnol‐ ogies. 4th Annual Nano Safety for Success Dialogue. ISO TC 229and BSI NTI/1 Nano‐

Okoro Uchechi, John D. N. Ogbonna and Anthony A. Attama\*

\*Address all correspondence to: anthony.attama@unn.edu.ng

are well absorbed when taken orally.

**15. Conclusion**

nanoparticles.

**Author details**

Enugu State, Nigeria

**References**

**Table 3.** Currently available medications for transdermal delivery [155,156].
