Inexpensive Micro-Needle Array for Drug Delivery, Biological Sensing

Procter & Gamble

The human skin is a tough protective barrier. It has evolved over millions of years to resist the incursion of foreign chemicals, mechanical impact, and microorganisms. There are three major layers to the skin. The top dry layer (the stratum corneum) is only 10-15 microns thick. The second layer (the epidermis) is about 80 microns. The third layer (the dermis) contains the capillaries and nerve endings and is several millimeters thick.

The combination of tough stratum corneum layer and live epidermis makes it extremely difficult for external substances to penetrate skin. Traditionally, only small water-soluble molecules are able to diffuse slowly into the skin. Conventional approaches to dermal delivery of drugs include special topical product formulations that can chemically reduce skin barrier properties and/or occlusive skin patches that reduce the barrier by skin hydration. Current topical delivery is typically limited to relatively small water-soluble molecules.

Procter & Gamble scientists have developed a process to make inexpensive, flexible arrays of microscopic needles from plastic. The needles make tiny holes through the two top layers of the skin, bypassing the body´s difficult perimeter defenses, to deliver a wider variety of actives or drugs directly to the body. Conversely these microchannels can be used to extract skin fluids for the purpose of sensing or sampling. The micro-needles have the ability to deliver drugs and sample fluids bloodlessly and painlessly because they are short enough to avoid capillaries and nerve endings that located in the dermis.

By modifying the skin surface, the micro-needle array makes it possible to transdermally deliver skin actives and drugs:

• In greater quantities,
• At greater speed,
• Over larger surface areas,
• With larger molecular sizes,
• In a wider variety of chemical structures, and
• To specific areas and layers of the skin structure where such drugs are most effective.

Additionally, the micro-needle arrays can be used as biological sensors or sampling devices for chemical and electrical changes in the skin´s interstitial fluid.

A platform technology with wide applications

During testing, the micro-needle arrays were 3-4 orders of magnitude more effective at delivering drugs than are conventional patch technologies. Further, they delivered much larger molecules, including proteins and peptides.

The delivery efficacy and large-size molecules that can be introduced to the skin permit applications such as vaccinations, with the vaccine delivered right to the dermal/epidermal boundary where the body is most sensitive to triggering antibodies.

The micro-needle arrays may be used in combination with iontophoresis (electric drug delivery), to offer very precise delivery and sampling profiles. This can be achieved using low voltage power sources (<1 V).

As biological sensors, micro-needle arrays have detected glucose in the interstitial fluid of the skin.

Inexpensive, manufacturable, disposable, safe

The Procter & Gamble micro-needle array technology has produced high-quality, high volume products at low cost. Arrays can be manufactured at pennies per square centimeter. The nature of the manufacturing processes used allows virtually unlimited size and geometry of both the needles and patch areas. Plastic needles allow single use for convenience and disposability. Safety testing has confirmed the micro-needles do not cause irritation to the skin.

Deal structure

Procter & Gamble is currently in the process of soliciting proposals for business deals that lead to the commercialization of the micro-needle technology in a variety of fields with a multitude of customers. Interested parties should request an introduction for more information.

Download this Tech of the Week as a PDF

You can download this Tech of the Week as a PDF file that you can share with co-workers. When viewed on a computer with an Internet connection, the PDF includes live links back to yet2.com and the technology listing.