What is the role of capsaicin cream in managing pain for patients with osteoarthritis (OA)?

Role of Capsaicin Cream in Managing Osteoarthritis Pain

Topical capsaicin is effective for treating knee osteoarthritis pain with a moderate effect size, but is not recommended for hip OA and has mixed recommendations for hand OA. 1

Mechanism of Action and Efficacy

• Capsaicin, derived from chili peppers, works by depleting substance P, a neuropeptide involved in pain pathogenesis and intensity 1
• When applied, capsaicin initially causes pain and burning as it triggers substance P release, but continued use leads to substance P depletion and pain reduction 1
• Evidence supports at least a moderate effect (standard mean difference of 0.44) in reducing moderate knee pain associated with OA 1, 2
• May require continuous use for 2-4 weeks before experiencing therapeutic effects 1

Recommendations by Joint Location

Knee OA

• Conditionally recommended for knee OA by the American College of Rheumatology/Arthritis Foundation guidelines 1
• Evidence from systematic reviews supports its use for moderate knee pain 1, 2
• Concentrations ranging from 0.025% to 0.075% have shown efficacy in randomized controlled trials 2

Hand OA

• Conditionally recommended against use in hand OA by the American College of Rheumatology/Arthritis Foundation 1
• Concerns include lack of direct evidence and potential risk of eye contamination when applied to hands 1
• However, EULAR guidelines suggest topical capsaicin is effective for hand OA with a number needed to treat of 3 (95% CI 2 to 5) in 4 weeks 1

Hip OA

• Not recommended for hip OA due to the depth of the joint beneath the skin surface 1
• Unlikely to provide significant benefit for hip OA 1

Administration and Dosing

• Typical concentrations range from 0.025% to 0.075% 2
• Applied 3-4 times daily for optimal effect 2, 3
• Higher strength formulations (0.25%) may provide more rapid onset of action with twice daily dosing 3
• Even lower concentrations (0.0125%) have shown efficacy with less burning sensation 4

Side Effects and Tolerability

• Most common adverse effect is a burning sensation at the application site, affecting 35-100% of patients 1, 2
• Burning sensation typically peaks during the first week and diminishes over time 2
• No systemic toxicity has been reported 2
• Combination with glyceryl trinitrate may enhance analgesic efficacy and improve tolerability 5

Place in OA Treatment Algorithm

• Local treatments like capsaicin are preferred over systemic treatments for mild to moderate pain when only a few joints are affected 1
• Consider capsaicin after core treatments (exercise, weight loss if needed) have been implemented 1
• For knee OA, consider topical NSAIDs first, then capsaicin as an alternative topical option 1
• For comprehensive pain management, capsaicin may be used as part of a multimodal approach including non-pharmacological interventions 1

Duration of Treatment

• Studies show efficacy for up to 4-12 weeks 2
• Limited data on long-term use beyond 12 weeks, with some studies showing continued or increasing benefit up to 20 weeks 2

Key Considerations for Clinical Use

• Most appropriate for patients with mild to moderate OA pain 1
• Warn patients about initial burning sensation to improve adherence 1, 2
• May be particularly useful for patients who cannot tolerate oral NSAIDs or have contraindications to their use 1
• Should be considered as part of a comprehensive treatment plan that includes non-pharmacological approaches 1