Future of the transdermal drug delivery market – have we barely touched the surface?

ABSTRACT

Introduction: Transdermal drug delivery is the movement of drugs across the skin for absorption into the systemic circulation. Transfer of the drug can occur via passive or active means; passive transdermal products do not disrupt the stratum corneum to facilitate delivery whereas active technologies do. Due to the very specific physicochemical properties necessary for successful passive transdermal drug delivery, this sector of the pharmaceutical industry is relatively small. There are many well-documented benefits of this delivery route however, and as a result there is great interest in increasing the number of therapeutic substances that can be delivered transdermally.

Areas Covered: This review discusses the various transdermal products that are currently/have been marketed, and the paths that led to their success, or lack of. Both passive and active transdermal technologies are considered with the advantages and limitations of each highlighted. In addition to marketed products, technologies that are in the investigative stages by various pharmaceutical companies are reviewed.

Expert Opinion: Passive transdermal drug delivery has made limited progress in recent years, however with the ongoing intense research into active technologies, there is great potential for growth within the transdermal delivery market. A number of active technologies have already been translated into marketed products, with other platforms including microneedles, rapidly progressing towards commercialisation.

KEYWORDS:

• Active
• microneedles
• passive
• skin
• transdermal drug delivery

Article highlights.

• Transdermal drug delivery is the movement of drugs across the skin for absorption into the systemic circulation and can be classified as passive or active.

• In order for a molecule to passively traverse the skin, it must fulfill specific physicochemical criteria in terms of molecular weight, lipohilicity, and melting point.

• Only a relatively small number of transdermal drug products have progressed successfully to market.

• A number of active strategies have been investigated to assist with transdermal drug delivery, e.g. iontophoresis, sonophoresis, thermal & electrical ablation, and microneedle technology.

• Simple demonstration of drug delivery will not ensure market success for a transdermal product – factors such as patient safety, usability, and clinical need must also be met.

• There is significant potential, in terms of market value, for novel transdermal products able to satisfy regulatory requirements and patient demand.

This box summarizes key points contained in this article.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.