Microneedle patches could make a flu shot as simple as a Band-Aid
It’s that time of year again – influenza has begun making the rounds, wreaking havoc on our bodies and schedules as it starts its seasonal journey toward hospitalizing hundreds of thousands of us in the U.S. alone.
And while this year’s flu vaccine looks like a good match to protect against this season’s strains, according to the CDC, less than half of Americans typically get vaccinated, thanks in part to the fairly common fear of hypodermic needles and the financial and logistical strain of getting to a clinic to get the shot.
Such inconveniences, however, may soon fall by the way side if a new needle approach out of Georgia Tech proves safe and effective in humans. (So far it’s performing well in mice.) Known as microneedle patches, the technology involves spreading the vaccine dose across 100 tiny, hair-like needles that are applied to the skin much like a Band-Aid. It takes anywhere from 30 seconds to five minutes, is totally painless, and the patch is then simply removed and discarded.
Early testing in mice shows that the microneedle approach isn’t just effective; it could be even more effective than hypodermic needles because the vaccine is delivered directly into the skin instead of muscle. Our skin is rich in immune cells, while our muscles are basically void of those cells – a hypodermic needle requires that the vaccine make its way to the blood and lymph system to encounter the cells that will ultimately offer protection.
The benefits don’t stop at efficacy. Of course, there is the fact that a painless patch is less scary than a big needle (the nasal flu spray, by the way, is limited to 2- to 49-year-olds and comes with several restrictions). It also takes zero training to apply and can be stored at room temperature, so flu patches could be sold in drug stores and self-applied in the comfort of one’s own home, saving money and time.
Microneedles trump regular needles
Microneedle patches don’t stop at vaccine delivery. Researchers around the world are working on using these tiny needles to deliver a wide range of medicines and perform a wide range of tests.
Some of the same researchers at Georgia Tech are working on two approaches for delivering drugs directly into the eye. If that sounds altogether unadvisable, it’s already happening – and with large, hypodermic needles, often while the patient is still conscious.
Post-doctoral fellow Yoo-Chun Kim told me that in patients with an eye injury called corneal neovascularization, topical anesthesia is used, but the patient still has to sit through a large needle approaching and then piercing the eye in order to receive treatment. Using the new tech, a single microneedle could accomplish the same task and in an even more targeted manner.
In a second approach, the researchers at George Tech hope to replace the daily eye drop regimen prescribed to treat glaucoma with a time-release version of the drug that could be administered via one microneedle (again, no patch). It would be more targeted than eye drops and could last for as many as three months.
At the University of Washington, meanwhile, researchers are working to overhaul the current standard test for tuberculosis, which requires a hypodermic needle inserted at a specific angle and depth. Engineering prof Marco Rolandi told me by email that by using a microneedle patch instead, the “depth of delivery of the purified protein derivative is controlled by the length of the microneedles rather than by the angle at which the hypodermic needle penetrates the skin,” rendering the test “less prone to user error.”
But what about delivering the drugs whose molecules are too large to be injected using these tiny needles transdermally, through the skin? Researchers at Purdue are working on a small pump that is activated simply using the heat of one’s finger on the pump, which in turn generates enough force to push its way through the patch. Research is still underway, but the team has already filed for a provisional patent.
Swallow your medicine
At MIT and Massachusetts General Hospital, meanwhile, researchers have teamed up to take microneedles a step further – and have them be ingested orally, in the form of a pill. Testing insulin delivery in animals, they found that their capsule delivered insulin more efficiently than when injected into the skin, and by injecting drugs directly into the stomach’s lining, they get around the issue of the drug being broken down in the stomach before it is fully absorbed.
What’s more, they’re working on a system by which contractions of the digestive tract would squeeze the drug out of the capsule as it makes its way through the tract. They say this approach should even work for vaccines.
But what about swallowing sharp objects, no matter how small? “Part of our study was motivated by the fact that it is known that patients can safely pass sharp objects without complications – for example, razor blades and small pieces of glass can cause no issues,” chemical engineering grad student Carl Schoellhammer assured me by email.
The pill could get even more revolutionary: “In addition to the use of solid metal needles that we demonstrated in this study, one could also formulate needles out of biocompatible, dissolvable polymers with the drug to be delivered loaded in the needle. Then, when the needle lodges in the GI tissue, it could detach from the pill and slowly dissolve, releasing the drug directly into the tissue. This would then pose no danger to the patient.”
Much of the work in the microneedle world is still working its way through labs and animal models, but the success of these and many other studies suggest that tiny needles will some day do the job as well as, if not better than, their larger forebears. Move over, flu shot, the patch may soon be king.
Image copyright Christine Daniloff/MIT, based on images by Carol Schoellhammer and Giovanni Traverso.
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