Recent advances and development in epidermal and dermal drug deposition enhancement technology.

Skin is the largest and easily accessible organ of the body. Increases in incidences of dermatological disorders, demand for drug targeting, and patient compliance have increased the popularity of topical drug delivery amongst the people. However, drug delivery across the skin is still a challenge for researchers because permeation of maximum drugs is hindered by the upper layer of the epidermis (stratum corneum). Several approaches like use of chemical permeation enhancers and physical methods such as sonophoresis, iontophoresis, electroporation, microneedles, etc., have been used to deliver the drugs topically. These methods of topical drug delivery have some limitations and drawbacks. Therefore new techniques based on nano drug delivery system such as ultradeformable liposomes, nanostructured lipid carriers, nanoemulsions, solid lipid nanoparticles, lipospheres, nanoparticles, and ethosomes have been exploited for enhancing epidermal and dermal drug deposition. Development of these nanosytems requires a good understanding of mechanism of drug permeation, physicochemical properties of drug and carriers, and technological advancements in methodology. Therefore, this article covers recent advances in epidermal and dermal drug deposition enhancement approaches, biopharmaceutical challenges with dermal drug delivery, issues in formulation development, and regulatory aspects of nanosystem. This review article also discusses the concern of topical drug delivery in immunization, gene delivery, and cosmeceuticals.