RESEARCH
themselves and are therefore limited to utilisation primarily in the clinic or at home by those who have received special training on correct injection method and safe needle disposal. This has been found to be a major issue in patients who work full time due to the inconvenience of appointment schedules. Patient compliance is further limited by pain and needle- phobia experienced by many. Spread of blood borne pathogens by needle reuse is also a major concern, but specifically more in developing countries. To overcome such drawbacks, it is now hypothesised that an advantageous scenario would involve transdermal delivery of the vaccine by a means that increases vaccine immunogenicity; enhances patient compliance via simple self-administration; permits mass immunisation, and, as such, complete elimination of the use of hypodermic needles and their associated concerns. Therefore, a self-applied painless vaccine patch containing hundreds of micron-sized needles, or more commonly known in research circles as ‘microneedles’ could significantly increase the number of patients receiving vaccinations.
So what actually are microneedles? By definition, they are what they say on the tin: micron-sized needles. Rather than avoiding needles completely, the concept utilises needles of micrometre dimensions in order to exploit powerful delivery capabilities while improving patient compliance and safety. The needles are long enough to deliver almost any drug formulation, but still small enough to avoid pain, fear and the need for expert training to administer. Transdermal microneedles are minimally invasive devices that are applied to the skin and which painlessly bypass the skin’s main barrier to drug absorption (stratum corneum) by creating transient micron-sized pores by utilising the hundreds of micron-sized
projections position on the patch or baseplate. Consequently, they have garnered much interest by researchers within the past two decades as they have demonstrated successful in vivo delivery in rat models of oligonucleotides, reduction of blood glucose level by insulin, and induction of immune responses from protein and DNA vaccines.
A National Institutes of Health- funded study led by a team at the Georgia Institute of Technology and Emory University has shown that an influenza vaccine can produce robust immune responses and administered safely with an experimental patch of dissolving microneedles in a human trial. With further developments in design, it could potentially provide an alternative method to IM immunisation, thus eliminating the discomfort of a hypodermic injection as well as the inconvenience of visiting a flu clinic.
The randomised controlled trial was conducted in the US by Georgia Tech, led by Nadine Rouphael, MD and Mark J Mulligan, MD and published online June 27, 2017 in The Lancet¹. It involved 100 people aged between 18 and 49 years who had not received the vaccination during the 2014-2015 flu season. Patients were divided into four groups and given a single dose of inactivated influenza vaccine by various means. One group received the vaccine delivered via microneedle patch, the second via IM injection, while the third group
received a placebo formulation via microneedle patch. The vaccine in the first three groups was administered by a healthcare professional, whereas the fourth group self administered the vaccine by a microneedle array. The IM injection was administered to the upper arm, while the microneedle patch was applied for 20 minutes on the back of the wrist.
The phase I trial produced promising results for microneedle transdermal technology, as the three microneedle group’s patients produced an acceptability score of between 4.5-4.8 out of 5 after it was administered, compared to the 4.4 acceptability score produced by the hypodermic needle group. After 28 days, 70 per cent of the microneedle patch group said they preferred the painless skin patch to the conventional method of IM vaccination. At the six-month stage, there were no reports of serious side effects nor any cases of influenza in any of the patients.
The device used an adhesive, which helped the array grip to the skin during administration of the influenza vaccine. The vaccine itself was encapsulated within the needles and released simultaneously as the needle tips dissolved, taking only minutes. The remainder of the patch was then peeled away and discarded like a used bandage strip. Due to the fact that the microneedle tips had dissolved, it could not be reused and therefore generated no biohazardous waste compared to that of a traditional
hypodermic needle.
The team is now planning to conduct further clinical trials to pursue the technology’s ultimate availability to patients. Other microneedle vaccination projects in the pipeline from the team include those against measles, rubella and polio.
Perhaps unsurprisingly, researchers directly involved in the study were optimistic about the future.
‘These early findings suggest the emergence of a promising new option for seasonal vaccination,’ they said in a statement, before going on to describe the added benefits of the delivery concept such as patient safety, low cost, and its ‘stability’ for one year stored at 40 degrees Celsius as ‘more exciting’ features of the technology. This, coupled with no disposal requirements and the potential for self application, mean that this vaccination patch could potentially be delivered in the mail and self administered without the need to see the local GP, nurse or pharmacist for the influenza vaccine, and simply dispose the patch with regular waste.
Until then, guidance from the National Institute for Health and Care Excellence (NICE) proposes that people should be offered the flu vaccine at every given opportunity, including when they pick up a prescription, in order to reduce the number of deaths caused by the virus and reduce the burden of hospital admissions. •
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