What are the topical treatments for neuropathic pain?

From the Guidelines

Topical capsaicin is the most effective topical treatment for neuropathic pain, as evidenced by a recent high-quality study, and can be considered for patients with contraindications to oral pharmacotherapy or who prefer topical treatments. According to the study published in Diabetes Care 1, capsaicin has received FDA approval for treatment of pain in diabetic peripheral neuropathy (DPN) using an 8% patch, with one high-quality study reported. Additionally, a medium-quality study of 0.075% capsaicin cream has been reported, suggesting therapeutic equivalency for capsaicin.

Other topical treatments, such as lidocaine 5% patches, may also be effective for localized neuropathic pain, as they provide numbing relief by blocking sodium channels that transmit pain signals. However, the evidence for these treatments is not as strong as for capsaicin. The American Academy of Neurology update suggested that gabapentinoids, serotonin-norepinephrine reuptake inhibitors (SNRIs), sodium channel blockers, tricyclic antidepressants (TCAs), and SNRI/opioid dual-mechanism agents could all be considered in the treatment of pain in DPN, but these are primarily oral medications 1.

Some key points to consider when using topical treatments for neuropathic pain include:

• Cleaning and drying the skin before application
• Following specific product instructions regarding frequency and duration
• Being aware that some treatments, particularly capsaicin, may take several applications before maximum benefit is achieved
• Considering combination approaches or consulting a healthcare provider if one topical treatment is ineffective after adequate trial. The Mayo Clinic Proceedings study 1 provides a step-wise approach to the pharmacological management of neuropathic pain, but the most recent and highest quality evidence supports the use of topical capsaicin as a first-line treatment for localized neuropathic pain.

From the FDA Drug Label

Directions Adults and children 18 years of age and older: Apply a thin film of cream to affected area and gently rub in until fully absorbed. For best results, apply 3 to 4 times daily. Children under 18 years: ask a doctor

Topical treatments for neuropathy pain include:

• Capsaicin (TOP): Apply a thin film of cream to the affected area 3 to 4 times daily 2
• Lidocaine (TOP): A 4% lidocaine cream is available for topical use, although the provided label does not specify application instructions for neuropathy pain 3
• Gabapentin (TOP): There is no information provided on the topical use of gabapentin for neuropathy pain, as the label only discusses oral administration 4

From the Research

Topical Treatments for Neuropathy Pain

• Topical capsaicin is used to treat peripheral neuropathic pain, with high-concentration (8%) capsaicin patches being more effective than low-concentration creams 5, 6, 7.
• The efficacy of topical capsaicin is supported by multiple studies, with numbers needed to treat (NNT) for pain relief ranging from 6.6 to 12 5, 6, 7.
• Local skin reactions are common with topical capsaicin, but are usually mild and transient, with numbers needed to harm (NNH) ranging from 2.5 to 3.1 5, 6, 7.
• High-concentration topical capsaicin has been shown to be effective in treating postherpetic neuralgia, HIV-neuropathy, and painful diabetic neuropathy, with additional improvements in sleep, fatigue, depression, and quality of life 6, 7.
• Topical lidocaine and capsaicin have been compared to oral standard of care (pregabalin), with the capsaicin 8% patch demonstrating noninferior efficacy and minimal systemic adverse events 8.
• Topical capsaicin has a sensible safety profile and is effective in reducing neuropathic pain, with potential as a first-line treatment option, especially in patients where oral therapy is a concern 8, 9.

Mechanism of Action

• Capsaicin works by activating the transient receptor potential channel vanilloid type 1 (TRPV1) receptor, which is expressed in central and peripheral terminals of sensitive primary nerve cells 9.
• The activation of TRPV1 leads to desensitization of nociceptors, resulting in pain relief 5, 6, 7.

Clinical Implications

• Topical capsaicin may be a useful treatment option for patients with neuropathic pain who have not responded to oral therapies or have concerns about systemic adverse events 8, 9.
• Further research is needed to fully understand the efficacy and safety of topical capsaicin in different patient populations and to determine its place in treatment algorithms for neuropathic pain 5, 6, 7, 8, 9.