Percutaneous Penetration Enhancers PDF

Preface

It has been ten years since the first edition of Percutaneous Penetration Enhancers was published. At that time we expected to see an explosion in the number of chemical enhancers researched and developed for commercial formulations. Surprisingly, this has not been the case; at this point there are still only a handful of chemical entities that are close to realizing this goal. In the first edition we suggested that the full impact of penetration enhancer species on transdermal delivery may not become evident simply because of the costs associated with regulatory registration formalities. It now appears that this suggestion may have held more validity than we initially believed. This theory may be corroborated by the evidence of dramatic growth and innovation in the field of physical (rather than chemical) penetration enhancement systems. Several commercial units utilizing physical enhancement mechanisms, spanning the full spectrum from iontophoresis to microneedle devices, are in the final stages of development and testing. On the other hand, there is some renewed interest in transdermal penetration retardation to limit the absorption of chemicals through the skin. These retardation systems are based on the biochemical groundwork established by enhancer studies in the past. To assist with all these research efforts, our analytical, bioengineering, and predictive systems continue to become ever more sophisticated to the point that much laboratory wet-work can now be replaced by computer-assisted systems. The field is clearly evolving and redefining itself, and it is therefore timely to attempt to summarize our current knowledge. To this end we have assembled a list of researchers who are authorities in their respective disciplines - this volume is an elegant summary of their recent research efforts in the ever-broadening fields of topical penetration, enhancement, and retardation. We are thankful to each author for their individual contributions to this volume. We hope that readers will find these chapters useful in establishing the broad framework for the topic and a stimulant for continued research in the diverse areas of percutaneous penetration enhancement.