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The use of microneedle patches as a drug delivery platform has received a lot of media buzz of late. The concept of microneedles is actually several decades old. It has taken relatively recent advancements of microfabrication technology and manufacturing techniques to move the concept to reality. Today, this cutting-edge technology is being evaluated—and in some cases already being used—for diagnostic purposes and to deliver drugs, vaccines, and biotherapeutics. Indeed, the use of microneedle patches to deliver vaccines could be a major breakthrough impacting global health.
The question is: Could this novel platform deliver contraceptives? With support from the Bill & Melinda Gates Foundation and the U.S. Agency for International Development, FHI 360 and its partners, the Georgia Institute of Technology and the University of Michigan, are investigating just that.
So, what are microneedle patches and how do they work?
About the size of a quarter, a microneedle patch is covered on one side with hundreds of micron-scale needles. When the patch is applied to the skin, the microneedles penetrate only slightly, resulting in little, if any, pain or bleeding. (Pain is often noted as a concern with subcutaneous or intramuscular contraceptive injections that use much larger needles.) Some describe the applied patch as feeling like a cat’s tongue.
Microneedle patches can be fabricated in different ways. Some contain metal microneedles covered with drug. The drug dissolves off the needles into the skin. The patch is then removed and discarded. Others consist of hollow microneedles that deliver drugs from a reservoir in the patch backing. And some—like the ones we are exploring for contraception—are biodegradable. Once the patch is applied to the skin, the microneedles detach quickly into the skin and dissolve internally. The sharps-free backing is then pulled away and discarded.
Our research efforts are currently following two paths. One idea is to fill the microneedles with microspheres containing a contraceptive agent. The needles would dissolve rapidly upon insertion, leaving behind slowly dissolving microspheres that release a contraceptive hormone over an extended period (up to six months). We are also looking at microneedles made of a material similar to the microspheres. In this case, the microneedles would dissolve slowly over time, releasing the hormone for a shorter period (perhaps three months).
Microneedle patch technology is a refinement of how contraceptives are currently delivered intramuscularly or subcutaneously. Our target product profile includes the following key attributes:
- Less painful injection, because needles are 1/50th the size of a typical syringe needle
- Longer period of effectiveness: the goal is to deliver a contraceptive steroid that provides between three and six months of pregnancy protection (current injectables offer one to three months of protection)
- Less waste; no needle disposal or reuse issues
- Easy to store and ship; no need for refrigeration
Perhaps the two biggest reasons why a contraceptive patch would appeal to women are that it could be used discreetly and be self-administered.
Before we get too far down the product development path, we need to ask potential users their thoughts. What size of patch would be acceptable? Where on the body should the patch be applied? What would be an acceptable length of time to keep the patch on the skin? How often would users be willing to apply it? What kind of side effects would be tolerable? What would be a reasonable price? My colleagues, Rebecca Callahan and Aurélie Brunie, are currently studying potential user preferences for a contraceptive patch among women of reproductive age in India and Nigeria. Their findings, due out this summer, will inform our future efforts. Their research is being funded by the National Institutes of Health and the U.S. Agency for International Development.
It is important to remember that our research is in a pre-clinical stage, with clinical trials still several years away. Commercialization could be an additional five years out. The lessons we learn in our ongoing research will move the science of contraceptive technology forward. Who knows? Someday the same materials science and manufacturing advancements may be applied to developing a contraceptive patch for men. For sure, getting to that point would create an even greater level of buzz!
This blog series is a collaboration with FHI 360 and can also be found on the CTI Exchange.