Transdermal Magazine with technical articles and manufacturer links

Saturday, July 31, 2010

Industry Update

Current Issue

Transdermal is the only magazine published exclusively for the delivery of pharmaceuticals through the skin

Cover photo courtesy of Mikolaj Milewski, graduate student, University of Kentucky College of Pharmacy, Lexington, Kentucky, USA

Complete table of contents

				This Month's Focus: In-Vitro Testing
		Human Skin Equivalents (HSEs) as Alternatives for Transdermal Permeation, Phototoxicity, and Cytotoxicity Studies (Free) The development of HSEs is important because of a shortage of available human skin and because of growing concerns regarding the ban on use of animal testing by various countries throughout the world. HSEs are in the developmental stage and could provide a good alternative to human skin in testing of compounds for transdermal permeability. They are also an effective tool for measuring tissue based cytotoxicity and phototoxicity and can take researchers a step further in predicting the response of human skin to chemicals versus results from cell-based assays. API Heterogeneity in a Multilayered Transdermal Patch (Free) This article addresses how Raman Chemical Imaging (RCI) can improve characterization of pharmaceutical products that use multilayer polymer systems, such as transdermal patches. RCI uses noninvasive imaging through polymer layers at submicron spatial resolution with no sample preparation. The author investigated the heterogeneity of the API in the reservoir of transdermal patches. Understanding particle size distribution (PSD) as well as particle morphology can provide insight into the drug release rate in multilayered systems. General Features Chemical Enhancements of Transdermal Drug Delivery Systems: Advantages and Challenges—Part 1 (Free) The unique bio-architecture of the skin limits delivery of large molecules by the transdermal route. Extensive research during the past two decades has revealed the feasibility of using several classes of Chemical Penetration Enhancers (CPEs) to penetrate the skin, including fatty acids, fatty esters, alcohols, terpenes, pyrrolidones, sulfoxides, and surfactants. Despite their fairly satisfactory performance in enhancing the permeation of drugs across the skin, CPEs have faced a big challenge in successfully delivering drugs at therapeutic rates without causing irritation or damage. Part 1 of this article summarizes the mechanisms that the most popular CPEs use and identifies the safety issues for and adverse effects of these CPEs. Part 2, to be published in May, will discuss new chemical permeation enhancers, the lipid vesicular system and synergistic penetration enhancement, and considerations in selecting CPEs. Chemical Enhancements of Transdermal Drug Delivery Systems: Advantages and Challenges—Part 2 (Free) The unique bio-architecture of the skin limits delivery of large molecules by the transdermal route. Extensive research during the past two decades has revealed the feasibility of using several classes of Chemical Penetration Enhancers (CPEs) to penetrate the skin, including fatty acids, fatty esters, alcohols, terpenes, pyrrolidones, sulfoxides, and surfactants. Despite their fairly satisfactory performance in enhancing the permeation of drugs across the skin, CPEs have faced a big challenge in successfully delivering drugs at therapeutic rates without causing irritation or damage. Part 1 of this article, published in March 2010, summarized the mechanisms that the most popular CPEs use and identifies the safety issues for and adverse effects of these CPEs. Part 2 discusses new chemical permeation enhancers, the lipid vesicular system and synergistic penetration enhancement, and considerations in selecting CPEs. The Follicular Route for Drug Delivery (Free) The stratum corneum provides a relatively impermeable covering at the skin surface and limits the penetration of substances applied to the skin. Scientists have long recognized the possibility of bypassing this barrier by diffusion through sweat ducts or hair follicles; however, because these openings represent a very small fraction (10-3) of the total skin area, these potential shunt pathways have received relatively little attention. The purpose of this article is to review briefly some of the recent studies on the follicular pathway.