How vaccines can be delivered through a plaster
They look like simple plasters, but these micropatches can deliver medication without you having to visit a GP, writes Eleanor Steafel
‘You hear a snap, then the microneedles dissolve within the skin, along with the vaccine’
The sight of a needle heading for your upper arm is enough to make those of us with the sturdiest of constitutions suffer what is medically known as “a funny turn”.
Just the thought of an injection can be sufficiently anxiety-inducing that many of us avoid them at all costs. Last winter, fewer than 50 per cent of pregnant women went for a flu jab, despite being classed as an at-risk group by the NHS.
So could a new skin patch bring an end to painful jabs altogether?
Last month, a single-dose flu vaccine delivered via a skin patch was shown for the first time to be as effective as a conventional jab at inoculating patients – and far less traumatising.
The plaster, which resembles a nicotine patch, is embedded with tiny microscopic needles that enter the outermost epidermal layer, which is just a fraction of a millimetre thick. Applying the patch feels like pressing Velcro against your skin. “You hear an audible snap when the microneedles penetrate the skin,” says Dr Mark Prausnitz, a professor of chemical and biomolecular engineering at Georgia Tech, in Atlanta, which spearheaded the technology.
“After a few minutes, we remove the patch. By then, those microneedles will be completely dissolved within the skin, along with the vaccine.”
As well as being as effective a way to generate immunity as an injection, the flu patch is also cheaper, and could eventually be picked up at the chemist or even posted to your home, meaning there would be no need to take the morning off work for a GP appointment.
“Despite the recommendation of universal flu vaccination, influenza continues to be a major cause of illness leading to significant morbidity and mortality,” says Dr Nadine Rouphael, associate professor of medicine at Emory University School of Medicine, in Atlanta, and principal investigator of the clinical trial. “Having the option of a flu vaccine that can be easily and painlessly self-administered could increase coverage and protection by this important vaccine.”
Researchers also say they are developing patches for the measles, rubella and polio vaccines, which could go a long way towards wiping out these diseases in countries where they are still prevalent, as administering the patch wouldn’t require a highly trained medical professional. The patches also travel much better than hypodermic needles as they don’t have to be kept refrigerated, meaning they could easily be taken to hard-to-reach places. But it isn’t just vaccinations that could be revolutionised by the microneedle patch – there are all manner of medicines that could be administered just as efficiently this way.
“The real value in the microneedle patch is in taking some kind of medicine that is not easy for people to administer to themselves, that has to be given by injection, which is a real barrier in many cases,” says Dr Prausnitz. “There is, however, one limitation, which is that the microneedle patch by design is small. If you need very large doses of the drug, they don’t fit into the microneedle patches so well.
“But that leaves many drugs including vaccines and immunotherapies as possibilities.”
How, then, might a microneedle patch one day change your life?
Hay fever and other allergies
With summer well under way, chronic hay fever sufferers will by now have given up trying to acclimatise to the local pollen with spoonfuls of artisan honey. Experts say a microneedle patch worn before the hay fever season starts, to administer small doses of the allergen, could be a more effective way to lessen the sufferer’s symptoms. Dr Prausnitz says: “Small amounts of pollen given to patients will get their bodies used to the
allergen so that when a larger exposure occurs during the hay fever season, the body does not react with an allergic attack.”
Should the sufferer experience a sneezing-and-itching attack, the most efficient way to administer antihistamine into the bloodstream remains by oral medication, rather than micropatch. So it seems hay fever sufferers will have to keep taking the tablets.
However, those with nut allergies, for instance, might find a micropatch beneficial. Again, it couldn’t replace the Epipen, which delivers an immediate ‘hit’ of adrenaline, but it could be a very effective way of administering a slow-release dose of allergy-preventing therapies that will “train” the immune system to tolerate substances that can cause anaphylaxis.
Diabetes
Anyone who suffers from diabetes will know that, when it comes to insulin, it’s all in the timing.
If you inject and then rush into a meeting, forgetting to eat beforehand, you are likely to have a hypoglycemic episode within the hour. This is where micropatches could come in.
Dr Prausnitz explains that, while an insulin injection can take up to an hour to become effective, the patch method would mean it takes just 30 minutes to kick in. “This offers some advantages in terms of having a more rapid feedback from the insulin,” says Dr Prausnitz. “But there’s also the convenience of being able to put on a patch, rather than having to deal with needles.”
Already in use is a skin-worn sensor that has changed how diabetics test their glucose levels. Applied like a plaster to the upper arm, the Freestyle Libre (£57.95, freestylelibre.co.uk/libre) inserts a thin, sterile fibre under the patient’s skin. It then transmits blood sugar data to a receiver, allowing glucose levels to be monitored without the need for routine pricks and tests.
Scientists are currently developing a “smart” micropatch that can not only monitor the body’s blood glucose levels, but also release a shot
of insulin automatically when levels climb too high.
Pain relief
Say you were suffering from back pain. Rather than take an oral painkiller, you could stick a microneedle patch on the affected area and administer a low but efficient dose of localised analgesia.
Such a patch could also work well for anyone suffering from discomfort that needed a constant slow-release dose of pain relief over time – notably lumbago and sciatica sufferers.
“When you’re taking in medicine by mouth, usually there is suddenly a very high concentration in your bloodstream and then that slowly decays down,” says Dr Prausnitz. “At the point when the concentration is very high, it’s really more than you need and maybe more that you want, so if you can just keep it down at the lower level, you can avoid having those peaks that are an excess of the drug. “Often, that is what you want, rather than getting a lot of it all of a sudden and then later in the day needing more.”
Contraception/hrt
Patches to administer contraception and HRT have been in use for a while, but as the delivered dose is so low, it can be absorbed on the surface of the skin. But the micropatch could one day be used for more sophisticated treatments for fertility or the menopause.
Dr Prausnitz explains: “The skin doesn’t let much in, and that’s good – skin is a barrier, it shouldn’t let much in. However, certain potent drugs can be absorbed a little. “What the microneedle does is crosses the stratum corneum, the very outer layer of your skin that’s a fraction of a millimetre thick.”
Cancer treatment
One of the most promising new drugs in the treatment of cancer is pembrolizumab, an immunotherapy reported to have reversed former US president Jimmy Carter’s brain cancer. President Carter’s doctors found four small spots of melanoma in 2014 after an operation to remove a tumour from his liver. It sounded like a fatal diagnosis at the time, but after immunotherapy, the melanoma disappeared.
Much like with allergy treatments, Dr Prausnitz explains that the microneedle patch could be an effective way to easily administer this kind of drug.
“Any time you’re dealing with the immune system, a little bit goes a long way, so just like a little bit of vaccine kicks the immune system into gear and gives you a protective immune response, in immunotherapies that are activating the immune system to attack the cancer, a little bit goes a long way.
“There is a lot of hope and expectation that the microneedle patch will be especially effective at delivering those kinds of immunotherapies to treat cancer.”