Transdermal Pain Medication

Chronic pain is a common, complex, and distressing problem that profoundly impacts individuals and society. While frequently presenting as a result of an injury or accident, it is actually a rather a separate condition in its own right, with its own medical definition, taxonomy, and treatment modalities 1. In the United States, an estimated 50 million adults experience chronic pain, defined as pain lasting three or more months, impacting the nation’s health care costs and productivity. In 2021, an estimated 21% of American adults experienced chronic pain, with nearly 7% experiencing high-impact chronic pain, or chronic pain that results in substantial restriction to daily activities 2. Acute pain due to injury, surgery, and neuropathy is also important, with links to chronic pain and the opioid crisis. Treating pain effectively therefore remains an extremely important priority in American health care. Innovation, rather than refinement of existing approaches, is critical – one direction that researchers are exploring is transdermal pain medication.

The skin is an appealing route for drug delivery in general because it allows drugs to go directly to the site of pain in many cases, bypassing the entire gastrointestinal tract. This is beneficial because oral delivery requires a much larger dose. Transdermal drug delivery therefore offers an attractive alternative to conventional drug delivery modalities 3.

However, delivering drugs through the skin is challenging because the tough outer layer of the skin prevents most small molecules from passing through. Research advances have led to a prototype wearable patch that can painlessly deliver drugs through the skin in a swift and efficient way.

Ultrasound exposure enhances the skin’s permeability to small-molecule drugs, but most techniques today require bulky equipment. A team from the Massachusetts Institute of Technology (MIT) sought to find a way to perform this type of transdermal drug delivery using a lightweight, wearable patch, making it easier to use for a variety of applications 4. The patch developed is made of a silicone-based polymer that can stick to the skin without tape. In short, by leveraging ultrasonic waves that propel drug molecules into and through the thick layer of the skin, the patch efficiently delivers medications locally.

The device was tested using a niacinamide, an ingredient in many sunscreens and moisturizers. Using pig skin, the team showed that when they delivered niacinamide using the ultrasound patch, the amount of drug that penetrated the skin was up to 26 times greater than the amount that could penetrate the skin without ultrasonic assistance. The researchers then further compared the results from their new device to microneedling, another method used for transdermal drug delivery, revealing that their patch was able to deliver the same amount of niacinamide in 30 minutes that could be delivered with microneedles over a 6-hour period 5.

After researchers characterize the drug penetration profiles for drugs with different chemical and physical properties, the transdermal patch may be applicable to the delivery of important drugs like hormones, insulin, and pain medications, in order to provide an alternative for individuals who are currently bound to self-administer daily injections, for example.

With further miniaturization of the transducer and the electronics module, the researchers envision the device providing a game-changing alternative to oral and needle-based delivery of intramuscular small-molecule drugs as well 5.

References

1. Mills, S. E. E., Nicolson, K. P. & Smith, B. H. Chronic pain: a review of its epidemiology and associated factors in population-based studies. BJA Br. J. Anaesth. 123, e273 (2019). doi: 10.1016/j.bja.2019.03.023.

2. Rikard, S. M., Strahan, A. E., Schmit, K. M. & Guy, G. P. Chronic Pain Among Adults — United States, 2019–2021. MMWR. Morb. Mortal. Wkly. Rep. 72, 379–385 (2023). doi: 10.15585/mmwr.mm7215a1.

3. Venkatesh, N. Transdermal drug delivery system: An overview Light-controlled Organic semiconductor implants for improved regeneration after Traumatic Brain Injury View project Transdermal drug delivery system: An overview. Welf. Pharmascope Found. | Int. J. Res. Pharm. Sci. 3, 234–241 (2012).

4. Yu, C. C. et al. A Conformable Ultrasound Patch for Cavitation-Enhanced Transdermal Cosmeceutical Delivery. Adv. Mater. (2023). doi:10.1002/adma.202300066

5. Wearable patch can painlessly deliver drugs through the skin | MIT News | Massachusetts Institute of Technology. Available at: https://news.mit.edu/2023/wearable-patch-can-painlessly-deliver-drugs-through-skin-0419. (Accessed: 2nd October 2023)