Fall 2020 Newsletter
By Catherine Jensen, Doctor of Pharmacy Candidate, and Lisa C. Hutchison, PharmD, MPH, BCPS, BCGP
University of Arkansas for Medical Sciences (UAMS) College of Pharmacy
Osteoarthritis is the most common form of arthritis and is the leading cause of disability in adults.1 Roughly 40% of adults in the United States will develop this disease in at least one hand by 85 years of age2. Non-pharmacological therapies recommended for osteoarthritis include weight loss and resistance exercises, but these treatments are seldom enough. According to the American College of Rheumatology (ACR) osteoarthritis guidelines, topical NSAIDs like diclofenac should be considered before other topical agents and oral NSAIDs. This is due to the lower risk of systemic exposure and superior efficacy noted through clinical trials3,4.
Ingredients of topical arthritis pain medications with example products are listed in Table 1. Topical lidocaine is also available for neuropathic or burn pain, but is not recommended for arthritis pain.
|Table 1: Over The Counter Topical Medications for Arthritis Pain1,5,6,9|
|Ingredients||Brand Name Examples||Advantages||Disadvantages||Usual Area of Use|
|Menthol, camphor||Icy Hot Gel, Biofreeze, Tigerbalm||Cooling sensation with immediate effect||Does not treat inflammation or pain||Hand, knee, back|
|Salicylates||Bengay, Aspercreme, Myoflex||Cooling sensationSlight anti-inflammatory effectScented/unscented||Avoid with aspirin allergy||Knee, hand, foot|
|Capsaicin||Capzasin-HP creamZostrix, Capsiderm||Treatment of pain Potential adjunct agent when other therapies not tolerated||Skin irritation Poorly absorbed, Difficult adherence||Knee, hands|
|Diclofenac (NSAID) 1% gel||Voltaren Gel||Treatment of painGI & renal effects of oral NSAIDs unlikely||Skin irritation, Delayed pain relief, Difficult adherence||Knee, hand, foot|
Until recently, diclofenac 1% gel (Voltaren) was only available by prescription5. This product provides both analgesic and anti-inflammatory actions to the affected joints. Safety and efficacy of diclofenac 1% gel on knee osteoarthritis was proven in three randomized double-blind multicenter trials3. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) assessed pain (scale 0-20) and physical function (0-68) after 12 weeks. Patients 65 years and older showed significant improvement in pain (-5.3 vs. -4.1 p=0.02) and physical function (-15.5 vs -11, p=0.004) from baseline compared to placebo. There was also a significant decrease in pain on movement in the diclofenac group (-33.7 vs. -26.4, p=0.02).3 Study participants had over 90% adherence despite using a medication that requires application four times daily. Patients should be counseled on the importance of adherence and to not expect immediate relief.
Capsaicin is derived from chili peppers and acts as a counterirritant to pain. The agent is also useful for neuropathic pain. Capsaicin causes a depletion of substance P from sensory neurons, resulting in a numbing effect6. Capsaicin also requires application 3-4 times a day however, it requires a longer time to absorb into the skin before washing6,7. A meta-analysis of 28 randomized-controlled trials explored the efficacy of capsaicin in osteoarthritis pain. Capsaicin trials were evaluated as low quality, but did show superiority to placebo when used at recommended doses (0.41, CI 0.17-0.64)7. Use of capsaicin on the hands is difficult, given the need to avoid touching the face or eyes after application to avoid burning. There is also concern for long-lasting nerve desensitization with chronic capsaicin use6,8. The low quality evidence and adverse effects limit the use of capsaicin topical products for osteoarthritis to second line therapy after topical diclofenac. This meta-analysis also evaluated topical NSAIDs and found them overall superior to placebo based on effect size (0.30, CI 0.19-0.41).
Ingredients like camphor, menthol, and salicylates provide a distraction from pain through a cooling or warming sensation on the skin. These agents may provide an immediate feeling of relief but overall studies have shown mixed efficacy4,9. Despite having been available for many years, there is limited data on their use.4 Menthol, camphor, and salicylate products are not currently recommended by the ACR guidelines for osteoarthritis pain management4. However, side effects with menthol and camphor products are few when used topically except to note that salicylates as a derivative of salicylic acid should not be used in patients with an aspirin allergy.9
Use of topical agents must be carefully guided in a geriatric population due increased absorption potential with the thinning of the skin in older adults and if heat is applied to the affected joint before or after topical application. Increased permeability may increase the risk of systemic side effects like that seen in oral NSAID medications. Topical agents are an important option because of easy application for patients suffering from mild to moderate osteoarthritis pain. The introduction of topical diclofenac to store shelves increases the availability of a therapy with evidence of providing significant pain reduction and improved physical function in patients with osteoarthritis.
- Osteoarthritis (2020). Centers for Disease Control and Prevention. Retrieved from https://www.cdc.gov/arthritis/basics/osteoarthritis.htm
- Arthritis By The Numbers: Book of Trusted Facts & Figures (2019). Arthritis Foundation. Section Two: OA Facts (p17-27). Retrieved from https://www.arthritis.org/getmedia/e1256607-fa87-4593-aa8a-8db4f291072a/2019-abtn-final-march-2019.pdf
- Baraf, H. S., Gloth, F. M., Barthel, H. R., Gold, M. S., & Altman, R. D. (2011). Safety and efficacy of topical diclofenac sodium gel for knee osteoarthritis in elderly and younger patients: pooled data from three randomized, double-blind, parallel-group, placebo-controlled, multicentre trials. Drugs & aging, 28(1), 27–40. https://doi.org/10.2165/11584880-000000000-00000
- Kolasinski S., Neogi T., Hochberg M.,et. al. (2020). 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee. American College of Rheumatology. Vol. 72, No. 2, February 2020, pp 149–162 DOI 10.1002/acr.24131
- FDA Approves Three Drugs for Nonprescription Use Through Rx-to-OTC Switch Process (2020). S. Drug & Food Administration. Retrieved from https://www.fda.gov/news-events/press-announcements/fda-approves-three-drugs-nonprescription-use-through-rx-otc-switch-process.
- Altman, R. D., Barthel, H. R. (2011). Topical therapies for osteoarthritis. Drugs, 71(10), 1259-1279.
- Persson, M., Stocks, J., Walsh, D. A., Doherty, M., & Zhang, W. (2018). The relative efficacy of topical non-steroidal anti-inflammatory drugs and capsaicin in osteoarthritis: a network meta-analysis of randomised controlled trials. Osteoarthritis and cartilage, 26(12), 1575–1582. https://doi.org/10.1016/j.joca.2018.08.008
- van Laar, M., Pergolizzi, J. V., Jr, Mellinghoff, H. U., et al. (2012). Pain treatment in arthritis-related pain: beyond NSAIDs. The open rheumatology journal, 6, 320–330. https://doi.org/10.2174/1874312901206010320
- Rubbing It In (2019). Harvard Health Publishing. Retrieved from https://www.health.harvard.edu/pain/rubbing_it_in