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Official Journal of the Italian Society of Dermatology and Sexually Transmitted Diseases
Indexed/Abstracted in: EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,014
Unit of Dermatology, Department of Systematic Pathology University of Naples Federico II, Naples, Italy
Various aspects have been established of how a drug or an active principle can cross the barrier of the corneous layer, and how this limiting factor can be influenced to obtain better functional and therapeutical effects. In spite of the wide variety of the methods studied in order to increase transdermal vehiculation to obtain systemic effects, the applicability in this field remains limited. Attention to the problem of overcoming the epidermal barrier has come mostly from dermocosmetic studies. Dermatological research is mainly concerned today with dedicating clinical and experimental studies to methods of intradermal penetration. The cutaneous bioavailability of most commercialized dermatological formulations is low. The strategies to increase delivery can be of a chemical, biochemical or physical order. The chemical enhancers: a) increase the diffusibility of the substance across the barrier; b) increase their solubility in the vehicle; c) improve the partition coefficient. Moreover, the methods able to interfere with the biosynthesis of some lipids by altering the structure of the barrier increase penetration. Of dermatological interest are the physical mechanisms that increase the cutaneous penetration of substances: iontophoresis (that increases the penetration of ionized substances), electroporation (that uses currents to create new ways through the barrier), and sonophoresis, based on ultrasounds ranging from 20 to 25 KHz that induce alterations and overcoming of the horny barrier. This paper reports the recent development of these methods, and stress is laid on the importance and role of vehicles and excipients, that determine effects of partition and diffusion, differences in the entity of the absorption and complex interactions between substance, vehicle and skin, conditioning the specific effects; for which reason useful formulations cannot be established on an extemporaneous basis.
language: English, Italian