With a wide choice of active ingredients and formulations, Steve Titmarsh considers who might find topical analgesics helpful and looks at some of the market trends…

For a number of painful conditions, topical analgesics provide an effective treatment and one that may be potentially better tolerated than oral formulations.

Their relative ease of application and the potential for reduced systemic side effects compared with oral analgesics makes topical analgesics an increasingly popular choice for pain relief. Our ageing population and the growing participation in sport and exercise among people of all ages are also helping to drive sales.

In the UK the OTC analgesics market is valued at around £0.75bn and is predicted to grow by around 3.29% a year until 2028. There is also a trend for increasing demand for natural and herbal remedies.¹

According to some analysts the pandemic gave a boost to the OTC medicines market with people being more focused on personal health. Add to that the rise in the number of people experiencing chronic pain globally – around 20% of the population according to some estimates – these are just some of the factors behind analgesics being one of the OTC categories that has grown.²

Why topical?

Topical analgesics are chosen for a variety of situations: acute conditions such as strains or sprains, tendinopathy, or muscle aches. They are also beneficial for some chronic conditions such as osteoarthritis of the hand or knee, or neuropathic pain.

The Scottish Intercollegiate Guidelines Network (SIGN), for example, recommends topical analgesics for certain scenarios for people with chronic pain:³

• Topical NSAIDs should be considered in the treatment of patients with chronic pain from musculoskeletal conditions, particularly in patients who cannot tolerate oral NSAIDs.
• Topical capsaicin patches (8%) should be considered in the treatment of patients with peripheral neuropathic pain when first-line pharmacological therapies have been ineffective or not tolerated.
• Topical lidocaine should be considered for the treatment of patients with postherpetic neuralgia if first-line pharmacological therapies have been ineffective.
• Topical rubefacients should be considered for the treatment of pain in patients with musculoskeletal conditions if other pharmacological therapies have been ineffective.

A Cochrane review of reviews concluded that diclofenac Emulgel, ketoprofen gel, piroxicam gel and diclofenac plaster work reasonably well for strains and sprains. For hand and knee osteoarthritis, topical diclofenac and topical ketoprofen rubbed on the skin for at least 6 to 12 weeks help reduce pain by at least half.

For postherpetic neuralgia (pain following shingles), topical high‐concentration capsaicin can reduce pain by at least half for some people, according to authors of the analysis.⁴

An advantage of topical formulations is that they exert their effects close to where they are applied and there should be limited systemic uptake or distribution.

For example, plasma drug levels of non-steroidal anti-inflammatory drugs after topical application are much lower (typically less than 5%) than those seen after the same drug taken orally. That should also be reflected in a lower incidence of adverse reactions associated with topical delivery compared with oral drugs.

And that is another reason for the increase in use of topical formulations as patients and doctors look for alternatives to systemic drugs in a bid to reduce the chance of side-effects.⁴

Topical analgesics may a be a popular choice for older patients who tend to be treated with polypharmacy as they can have a number of comorbid conditions, because the likelihood of drug-drug interactions is also reduced when using topical formulations.⁵

Athletes may find topical analgesia preferable to oral medication according to a recent meta-analysis of published randomised controlled studies of athletes (elite or recreational) who used topical analgesic medicines compared with those who used oral formulations or placebo. The researchers found 13 articles that met their search criteria.

The analysis suggested that ‘topical analgesics were more effective compared with a placebo in reducing pain in an athletic population suffering from musculoskeletal injuries’. Whereas the analysis showed that ‘oral analgesic medications were not effective in reducing pain in injured athletes compared with a placebo’.

The researchers say their results may differ from other studies that show oral medication is effective for athletes because they looked studies of athletes with actual musculoskeletal injuries rather than experimentally induced pain models that other studies included.⁶

To some extent the convenience of topical formulations and their potential for fewer side-effects may also be beneficial in terms of medication adherence.⁷

Which formulation?

Topical analgesics are available in a wide range of formulations. For example, OTC formulations include: gels, sprays, patches, plasters, creams, lotions, rubs, wraps and even a belt.

Active ingredients include: non-steroidal anti-inflammatory drugs such as ibuprofen and diclofenac; salicylic acid (methyl and ethyl esters); lidocaine; belladonna alkaloids, and other ingredients such as camphor, levomenthol, capsaicin, eucalyptus oil, turpentine oil, cajuput oil and clove oil.⁸.

Choice of formulation is mainly a case of personal preference. Allergies may play a part in influencing choice of formulation, as can previous experience and likes and dislikes associated with scent and texture, for example.

However, creams and gels or spray may be preferable to a patch or plaster for an area that is constantly moving such as a knee or elbow – patches or plasters are usually best suited to flat areas of skin such as the back.⁹

A spray may be easiest for some people to apply to a hard-to-reach area. Of course, some active ingredients may not be available in all types of formulation, so the choice maybe more limited if someone prefers a particular active substance or drug.

Conclusion

With a wide range of formulations and choice of active ingredients – both drug and non-drug – topical analgesics offer a useful option for people trying to manage certain painful conditions.

They can be recommended in some cases where oral medicines have not worked or cannot be tolerated, as well as for those who prefer to avoid oral treatments.¹⁰

References 

1. Analgesics – United Kingdom (www.statista.com/outlook/hmo/otc-pharmaceuticals/analgesics/united-kingdom#revenue; accessed February 2024).
2. yahoo!finance. Over-the-counter (OTC) Analgesics Market Analysis & Growth Trends Report 2023-2028: Rising Trend of Self-Medication and Growing Demand for Topical Analgesics Drives Expansion (https://uk.finance.yahoo.com/news/over-counter-otc-analgesics-market-070300514.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_sig=AQAAAFtF4J97g1Z7NfhQ544pKCd83HATlmPrPpNUequBFyfWqKS7C5qsCQy08UnST_f4tjn0aBEYw6fjXFw7ZvhEr2PsbpAg8KmEaALUxvj1301lH-3YT6kP1qQ8CY0D3mWY0jzyqvrFQDAAoz2GkaVREBsx8PejOHJV6iI2LYux8D38; accessed February 2024)
3. SIGN 136. Management of chronic pain (www.sign.ac.uk/assets/sign136.pdf; accessed February 2024).
4. Derry S, Wiffen PJ, Kalso EA, et al. Topical analgesics for acute and chronic pain in adults – an overview of Cochrane Reviews. Cochrane Database Syst Rev 2017;5(5):CD008609.
5. Choi E, Nahm FS, Han WK, et al. Topical agents: a thoughtful choice for multimodal analgesia. Korean J Anesthesiol 2020;73(5):384–93.
6. Nudo S, Jimenez-Garcia JA, Dover G. Efficacy of topical versus oral analgesic medication compared to a placebo in injured athletes: A systematic review with meta-analysis. Scand J Med Sci Sports 2023;33(10):1884–1900.
7. Pickering G, Martin E, Tiberghien F, et al. Localized neuropathic pain: an expert consensus on local treatments. Drug Des Devel Ther 2017;11:2709–18.
8. PAGB. OTC Directory online (www.otcdirectory.co.uk/list/search/Analgesics?page=1; accessed February 2024).
9. Cleveland Clinic. Topical pain relief: what is it and how does it work? (https://health.clevelandclinic.org/topical-pain-relief-what-is-it-and-how-does-it-work; accessed February 2024)
10. Clinical Knowledge Summaries. Neuropathic pain – drug treatment: Capsaicin cream (https://cks.nice.org.uk/topics/neuropathic-pain-drug-treatment/prescribing-information/capsaicin-cream; accessed February 2024).