Microneedles: The Tiniest Needles With the Greatest Potential

Many patients around the world suffer from a fear of needles and dread getting vaccinated as a result. Even for those who do not fear it, the process of finding an accessible vein and injection can be uncomfortable. However, nearly invisible needles called microneedles may revolutionize the way in which shots are administered. These tiny needles have numerous benefits for their users and may soon replace normal injections. 

Microneedles are miniscule needles used to inject medications through the skin without needing to locate a vein and use a hypodermic needle. They are typically 50 to 2,000 microns in length and penetrate the epidermis, where they deliver their contents (O’Day, 2020). These tiny needles are attached to a small patch which can be applied easily onto the skin. Microneedles create a path into the body for effective and pain-free drug delivery (Kim et al. 2012, McConville, 2018).

Fig 1. This diagram shows the different layers of skin and how far microneedles are inserted into them compared to a regular needle.

The use of microneedles will alleviate the discomfort of receiving shots by eliminating the need to probe for veins and the use of large, intimidating needles. There are five main types of microneedles: solid, coated, dissolving, hollow, and swelled. Solid needles are pushed into the skin where they create tiny puncture marks from the stratum corneum into the epidermis. The drug or vaccine is then applied onto the surface of the skin, where it can slowly diffuse into the body through the pathway made by microneedles (Kim et al., 2012). When coated needles are used, the needles on the patch are covered in a water-soluble version of the drug. This patch is then attached to the skin and the drug coating is able to dissolve into the body (Kim et al., 2012). Dissolving needles are made out of a biodegradable material containing the drug. When these needles enter the body, they break down and deliver the drug into the epidermis (Kim et al., 2012). Hollow microneedles contain a cavity which stores the medication for delivery into the body. These needles penetrate the skin and open up so the drug can be released into the epidermis (Kim et al., 2012). Lastly, swellable needles are inserted into the skin where they expand, creating a larger path for the drug to enter the body (McConville, 2018).

Fig 2. The figure shows the different methods of delivery by microneedles: solid (A), coated (B), hollow (C), dissolvable (D), and swellable (E).

There are many practical benefits to making the use of microneedles widespread. Microneedles allow individuals with trypanophobia to obtain vital medications and get vaccinated without losing consciousness. Trypanophobia leads people who need medical care to avoid doctors solely due to fear of getting a hypodermic shot (Hamilton,1995). Microneedles provide a less-intimidating route to obtaining necessary medical care, making it useful for people with trypanophobia and children (Jeong, 2017). Another benefit of using microneedles is the reduction in danger produced by waste. Hypodermic needles produce harmful waste, called sharps, in the form of used shots. These used shots must be disposed of by highly trained staff following strict protocols to avoid harm to anyone (Rzhevskiy, 2018). However, microneedles are disposable and are not intended for repeated use. As a result, drug delivery using microneedles reduces the risks associated with sharps and requires minimal training(Rzhevskiy, 2018). Another valuable feature of microneedles is that they can be used by patients at home (O’Day, 2020). Given the current challenges posed by COVID-19, this can be incredibly helpful for patients. 

While there are many benefits to microneedle usage, it also has a few drawbacks. A needle may break inside the patient’s skin. However, scientists remedied this flaw by creating a new type of microneedle – dissolving needles (Rzhevskiy, 2018). Another cause for concern is that microneedle usage may lead to infection through the exposed epidermis or lurking needles. However, the chances of infection from leaking or contaminated needles is very small, and the minute risk is outweighed by the significant benefits of using microneedles (Rzhevskiy 2018). Although there are a few challenges regarding microneedle use, they are largely safe for use and researchers are working to address problems that arise.

Microneedles are transforming the way physicians are able to deliver drugs and vaccines to help their patients in multiple ways. They also have many potential applications outside of doctors’ offices. Researchers are looking into using microneedles as possible vaccine passports. Customs officers would be able to scan anyone entering their country and ensure that visitors are up to date on vaccinations to prevent outbreaks like COVID-19 from spreading (Zeldovich, 2020). Microneedles could also allow for a patient’s data to be stored within their skin, which could help physicians in emergency situations. Knowing a patient’s full history could prevent accidents in the E.R. This would allow people in an emergency situation to help a patient, knowing their full history and preventing accidents from happening (Trafton, 2020). Microneedles may be small in size, but they will have a large impact on the future of medicine.

Edited by Rhea Tumminkatti

References

Hamilton JG, (1995). “Needle Phobia: A Neglected Diagnosis”. Journal of Family Practice. https://cdn.mdedge.com/files/s3fs-public/jfp-archived-issues/1995-volume_40-41/JFP_1995-08_v41_i2_needle-phobia-a-neglected-diagnosis.pdf

Jeong HR, Lee HS, Choi IJ, Park JH (January 2017). “Considerations in the use of microneedles: pain, convenience, anxiety and safety”. Journal of Drug Targeting. https://doi.org/10.1080%2F1061186x.2016.1200589

Kim YC, Park JH, Prausnitz MR (November 2012). “Microneedles for drug and vaccine delivery”. Advanced Drug Delivery Reviews. https://doi.org/10.1016%2Fj.addr.2012.04.005

McConville, A., Hegarty, C., & Davis, J. (2018). Mini-Review: Assessing the Potential Impact of Microneedle Technologies on Home Healthcare Applications. Medicines (Basel, Switzerland), 5(2), 50. https://doi.org/10.3390/medicines5020050

O’Day, E. (2020, November 10). Microneedles could enable painless injections and blood draws. Retrieved February 14, 2021, from https://www.scientificamerican.com/article/microneedles-could-enable-painless-injections-and-blood-draws/

Rzhevskiy AS, Singh TR, Donnelly RF, Anissimov YG (January 2018). “Microneedles as the technique of drug delivery enhancement in diverse organs and tissues”. Journal of Controlled Release. https://doi.org/10.1016%2Fj.jconrel.2017.11.048

Trafton, Anne | MIT News Office. (December 2019). Storing medical information below the skin’s surface. Retrieved February 14, 2021, from https://news.mit.edu/2019/storing-vaccine-history-skin-1218

Zeldovich, L. (2020, June 22). Travel – will travel be safer By 2022? Retrieved February 14, 2021, from http://www.bbc.com/travel/story/20200621-will-travel-be-safer-by-2022

Image References

Fig 1. Tucak A, Sirbubalo M, Hindija L, Rahić O, Hadžiabdić J, Muhamedagić K, Čekić A, Vranić E. Microneedles: Characteristics, Materials, Production Methods and Commercial Development. Micromachines. 2020; 11(11):961. https://doi.org/10.3390/mi11110961

Fig 2. McConville, A., Hegarty, C., & Davis, J. (2018). Mini-Review: Assessing the Potential Impact of Microneedle Technologies on Home Healthcare Applications. Medicines (Basel, Switzerland), 5(2), 50. https://doi.org/10.3390/medicines5020050

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