Microneedles

Side comparison of microneedle (350μm in depth) to standard hollow-bore needle[1]

Microneedles (MNs) are medical tools used for microneedling, primarily in drug delivery, disease diagnosis, and collagen induction therapy. Known for their minimally invasive and precise nature, MNs consist of arrays of micro-sized needles ranging from 25μm to 2000μm. Although the concept of microneedling was first introduced in the 1970s, its popularity has surged due to its effectiveness in drug delivery and its cosmetic benefits.

Since the 2000s, there has been discoveries on new fabrication materials of MNs, like silicon, metal and polymer. Alongside with materials, a variety of MNs types (solid, hollow, coated, hydrogel) has also been developed to possess different functions. The research on MNs has led to improvements in different aspects, including instruments and techniques, yet adverse events are possible in MNs users.

Microneedle patches or Microarray patches are micron-scaled medical devices used to administer vaccines, drugs, and other therapeutic agents.[2] While microneedles were initially explored for transdermal drug delivery applications, their use has been extended for the intraocular, vaginal, transungual, cardiac, vascular, gastrointestinal, and intracochlear delivery of drugs.[3][4][5] Microneedles are constructed through various methods, usually involving photolithographic processes or micromolding.[6] These methods involve etching microscopic structure into resin or silicon in order to cast microneedles. Microneedles are made from a variety of material ranging from silicon, titanium, stainless steel, and polymers.[7][1] Some microneedles are made of a drug to be delivered to the body but are shaped into a needle so they will penetrate the skin. The microneedles range in size, shape, and function but are all used as an alternative to other delivery methods like the conventional hypodermic needle or other injection apparatus. Stimuli-responsive microneedles are advanced devices that respond to environmental triggers such as temperature, pH, or light to release therapeutic agents.[8]

Microneedles are usually applied through even single needle or small arrays. The arrays used are a collection of microneedles, ranging from only a few microneedles to several hundred, attached to an applicator, sometimes a patch or other solid stamping device. The arrays are applied to the skin of patients and are given time to allow for the effective administration of drugs. Microneedles are an easier method for physicians as they require less training to apply and because they are not as hazardous as other needles, making the administration of drugs to patients safer and less painful while also avoiding some of the drawbacks of using other forms of drug delivery, such as risk of infection, production of hazardous waste, or cost.[9]

  1. ^ a b McConville A, Hegarty C, Davis J (June 2018). "Mini-Review: Assessing the Potential Impact of Microneedle Technologies on Home Healthcare Applications". Medicines. 5 (2): 50. doi:10.3390/medicines5020050. PMC 6023334. PMID 29890643.
  2. ^ Cite error: The named reference :4a was invoked but never defined (see the help page).
  3. ^ Panda A, Matadh VA, Suresh S, Shivakumar HN, Murthy SN (January 2022). "Non-dermal applications of microneedle drug delivery systems". Drug Delivery and Translational Research. 12 (1): 67–78. doi:10.1007/s13346-021-00922-9. PMID 33629222. S2CID 232047454.
  4. ^ Thakur RR, Tekko IA, Al-Shammari F, Ali AA, McCarthy H, Donnelly RF (December 2016). "Rapidly dissolving polymeric microneedles for minimally invasive intraocular drug delivery". Drug Delivery and Translational Research. 6 (6): 800–815. doi:10.1007/s13346-016-0332-9. PMC 5097091. PMID 27709355.
  5. ^ Peppi M, Marie A, Belline C, Borenstein JT (April 2018). "Intracochlear drug delivery systems: a novel approach whose time has come". Expert Opinion on Drug Delivery. 15 (4): 319–324. doi:10.1080/17425247.2018.1444026. PMID 29480039.
  6. ^ Kim YC, Park JH, Prausnitz MR (November 2012). "Microneedles for drug and vaccine delivery". Advanced Drug Delivery Reviews. 64 (14): 1547–1568. doi:10.1016/j.addr.2012.04.005. PMC 3419303. PMID 22575858.
  7. ^ Park JH, Allen MG, Prausnitz MR (May 2005). "Biodegradable polymer microneedles: fabrication, mechanics and transdermal drug delivery". Journal of Controlled Release. 104 (1): 51–66. doi:10.1016/j.jconrel.2005.02.002. PMID 15866334.
  8. ^ Gowda, B.H. Jaswanth; Ahmed, Mohammed Gulzar; Sahebkar, Amirhossein; Riadi, Yassine; Shukla, Rahul; Kesharwani, Prashant (2022-04-11). "Stimuli-Responsive Microneedles as a Transdermal Drug Delivery System: A Demand-Supply Strategy". Biomacromolecules. 23 (4): 1519–1544. doi:10.1021/acs.biomac.1c01691. ISSN 1525-7797. PMID 35274937.
  9. ^ Donnelly, Ryan F; Woolfson, A David (June 2014). "Patient Safety and Beyond: What Should We Expect From Microneedle Arrays in the Transdermal Delivery Arena?". Therapeutic Delivery. 5 (6): 653–662. doi:10.4155/tde.14.29. ISSN 2041-5990. PMID 25090279.