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Accounting for one in four GP consultations, musculoskeletal conditions “have the worst impact on quality of life of many chronic diseases,” says Professor Anthony Woolf of the Duke of Cornwall department of rheumatology, Royal Cornwall Hospital, Truro. Pain is the most prominent symptom and is usually associated with some limitation in function. Effective pain management, therefore, can improve function and quality of life.
For patients, topical treatments that act at the site of pain make intuitive sense. For pharmacists, they are a valuable addition to their treatment choice, says Roger Knaggs, associate professor in clinical pharmacy practice at the University of Nottingham and the Royal Pharmaceutical Society’s pain spokesperson: “Topicals are used for those conditions that have an inflammatory component to their pain, such as osteoarthritis or acute musculoskeletal injuries.”
Patients largely use topical treatments as adjunctive therapy, he says, unless they are unable to take oral medications. Where the pain is localised, topicals can be as effective as oral treatments but with fewer side-effects – which can be highly motivating for patients.
A survey for Mentholatum found that concerns over addiction and side-effects (including gastrointestinal and cardiovascular effects seen with oral NSAIDs) were the commonest reason for using topical treatments over oral options.
Nitin Makadia, condition category manager at LloydsPharmacy, recommends topicals for targeted relief where pain is localised to a small area. This may also help with adherence, he says. “Sometimes oral pain relief needs to be taken up to four times a day and antiinflammatories are taken with or after food. This is not the case for a gel that may only need to be used twice a day.”
Improved adherence may also depend on the site of pain, says Roger Knaggs. For superficial joints with easy access, such as the hand, adherence may be easier than for larger, deeper joints, such as the hip.
Patient confusion regarding the wide array of topical products and formats available can also hinder usage. “Consumers want help and reassurance when it comes to self-treating,” says Jill Watt, director of marketing and new product development for Mentholatum. “They do not understand the difference between various types of topical – hot, cold and non-steroidal anti-inflammatory drugs – or how to use them.”
Topical OTC treatments broadly divide into those with active ingredients and those that are drug-free. Formats available include gels, creams, ointments, sprays, patches and wraps.
OTC options are suitable for treating acute musculoskeletal problems, such as soft tissue injuries (e.g. sprains, which are an injury to the ligament, or strains – an injury to the muscle fibres). The estimated 22 million sporting injuries that occur each year are ideal for topical treatment, says Nitin Makadia.
“I would recommend a topical for localised pain relief, such as tennis elbow or tendon problems. They can be used when they are needed and they don’t expose patients to side-effects.”
OTC treatments can also be used in chronic conditions such as persistent back pain and osteoarthritis (OA).
For patients, topical treatments that act at the site of pain make intuitive sense
Efficacy of the various topical OTC treatments varies depending on the condition, but Roger Knaggs advises taking into account patient beliefs when discussing products. For example, Cochrane data and the BNF state that rubefacients are ineffective, but if a patient requests such a treatment and it doesn’t cause harm, then it is acceptable for the pharmacist to supply it. “The placebo response to any analgesic is so large that this contributes an awful lot to the positive outcome. Experience has shown me that if a patient believes a treatment provides a benefit and there is minimal risk, then I am more inclined to go along with it.”
NSAIDs, such as ibuprofen and diclofenac, act by inhibiting the cyclo-oxygenase enzyme to reduce prostaglandin production. These are usually available as gels, creams or sprays, but the amount of NSAID found in plasma is usually less than 5 per cent. Cochrane data conclude that topical NSAIDs provide good pain relief, while avoiding the adverse effects of oral NSAIDs, when used for acute musculoskeletal problems.
In terms of efficacy, one study found a topical ibuprofen gel was as effective as maximum dose oral ibuprofen in relieving sprains and strains when used for seven days. According to advice from NICE, topical NSAIDs can be used as a first-line choice for sprains and strains and OA of the hand and knee.
Rubefacients (also known as counter-irritants) cause the blood vessels to dilate and redden and irritate sensory nerve endings to alter or offset pain in the underlying muscles or joints served by the same nerves.
A Cochrane review of salicylate rubefacients concluded that the evidence did not support their use for acute injuries and that in chronic conditions efficacy was poor compared with topical NSAIDs. There is little evidence for other topical rubefacient ingredients and NICE advises against their use in OA.
Superficial cold therapy (e.g. ice, cold gels, sprays, patches) is used to reduce inflammation, pain and oedema. NICE guidance recommends cold therapy in addition to core non-pharmacological options for OA and it forms a core element of the PRICE treatment approach to sprains and strains.
Superficial heat therapy (e.g. heat patches, hot water bottles) works by increasing the temperature of the skin and underlying tissue, increasing blood flow to promote healing of the affected muscle or joint and stopping pain signals from reaching the brain.
A Cochrane review says there is moderate evidence in a small number of trials that heat can reduce pain and disability in those with acute and sub-acute low back pain in the short-term, although it is not included in NICE’s low back pain guidance.
NICE’s OA guidance recommends heat therapy in addition to core non-pharmacological options. It should be noted that heat should be avoided for the first 72 hours after an acute soft tissue injury. Nitin Makadia says a useful tip on when to recommend either heat or cold therapy is that “if there is heat and inflammation, use the opposite to cool them. If there is stiffness, then use heat”.
Arnica and comfrey are said to inhibit the cyclo-oxygenase enzyme, with a Cochrane review concluding that arnica gel was probably as effective as oral NSAIDs in relieving pain and improving function, while comfrey extract gel may be more effective than placebo in easing pain.
The latest OTC option for pain associated with OA is a drug-free gel that replaces the depleted phospholipids in the degraded OA cartilage. The gel contains phospholipids in nanostructures (Sequessome vesicles) that are said to penetrate the skin and reach the synovial fluid of OA-affected joints, coating the cartilage and lubricating the joint.
Pro Bono Bio’s medical director Dr Sam Yurdakul comments: “If you take a normal topical cream and put a NSAID into the drug, the substance is taken up by the microvasculature in the skin and ends up in the systemic system. Here the phospholipid vesicles are too large to be taken up by the microvasculature and so reach the joint.”
NICE recommends the following for managing musculoskeletal conditions:
Back pain and OA are the commonest chronic musculoskeletal complaints. Back pain affects an estimated 18 per cent of the population at any one time. The majority of sufferers will experience acute back pain, recovering within six weeks, with just 7 per cent developing a chronic problem that persists for more than 12 weeks.
OA, one of over 200 types of arthritis, is estimated to affect 8.5m people in the UK. Around a third of OA sufferers do not consult a GP, putting the pharmacist in the position of providing effective management. Even among those who are diagnosed, a quarter supplement their prescription medication with OTC treatments.
Dr John Dickson, co-founder of the Primary Care Rheumatology Society, comments: “It is well recognised that effectively managing chronic pain, particularly in patients with other conditions and risk factors, is a massive challenge that GPs and patients face on a daily basis.”
One of the reasons for this is that chronic pain is more complex. “All types of chronic pain are essentially a hypersensitive nervous system,” says Roger Knaggs. “Even predominantly inflammatory pain, like OA, over time may develop the signs and symptoms of neuropathic pain.”
A mixed bag of neuropathic and inflammatory pain is very common with OA and back pain, he adds. In addition to using OTC options to alleviate the pain, there are a number of topical prescription therapies that can help tackle this type of pain.
Capsaicin – the active compound present in chilli peppers – binds to the pain receptors. It interferes with the movement of sodium and calcium ions across the cell membrane, resulting in depolarisation.
In the UK, a low dose cream is licensed as a prescription medicine for hand and knee OA, with higher strength creams and patches used to treat neuropathic pain. NICE’s OA guidance recommends that capsaicin is considered as an adjunct to non-pharmacological treatments for hand and knee OA.
Opioids work by targeting the spinal and supraspinal opioid receptors. Transdermal opioids administered for OA have been found in a Cochrane review to have a small-to-moderate benefit in easing pain and improving function in OA patients.