(LML) Treatment for neuropathic pain

Leprosy Mailing List – April 24,  2019

Ref.:   (LML) Treatment for neuropathic pain

From:  Pieter Schreuder, Maastricht, the Netherlands

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Dear colleagues,

Ben Naafs sent us the following references regarding the LML letter by Francine Brandão of April 23, 2019. He is not sure if topical capsaicin has ever been tried in leprosy. We ask those who have tried this application in leprosy to send us their experiences.

References topical application of capsaicin:

• P. Anand. Topical capsaicin for pain management: therapeutic potential and mechanisms of action of the new high-concentration capsaicin 8% patch.
• Ganesan Baranidharan, Sangeeta Das, and Arun Bhaskar. A review of the high-concentration capsaicin patch and experience in its use in the management of neuropathic pain

P. Anand. Topical capsaicin for pain management: therapeutic potential and mechanisms of action of the new high-concentration capsaicin 8% patch. British Journal of  Anaesthesia Volume 107, Issue 4 October 2011

Summary: Topical capsaicin formulations are widely used to manage pain. Low-concentration creams, lotions, and patches intended for daily skin application have been available in most countries since the early 1980s. Prescriptions are usually not needed for these self-administered medicines, which often have not been reviewed formally by drug regulatory authorities. The recent approval in the EU and USA of a prescription-strength high-concentration single-administration capsaicin 8% patch (Qutenza™) with a duration of action over many weeks invites an examination of recent advances in the understanding of capsaicin's mechanism and site of action.

Editor's key points

• Topical capsaicin is used in pain management.
• The mechanism of action (MoA) was thought to be by depletion of substance P.
• A more likely MoA is described as 'defunctionalization', and involves alteration of several mechanisms involved in pain.
• A new higher concentration (8%) patch shows promise in pain management.

In this review, which does not cover other naturally occurring or synthetic TRPV1 agonists, we discuss the potential utility of topically administered capsaicin for the management of pain in classical peripheral neuropathies and other hypersensitivity disorders, some of which are currently considered as idiopathic. Furthermore, we seek to elucidate the molecular and cellular basis of capsaicin treatment, and clarify misunderstandings, particularly with respect to the involvement of substance P depletion.

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Ganesan Baranidharan, Sangeeta Das, and Arun Bhaskar. A review of the high-concentration capsaicin patch and experience in its use in the management of neuropathic pain. Ther Adv Neurol Disord. 2013 Sep; 6(5): 287–297. doi: 10.1177/1756285613496862 PMCID: PMC3755533 PMID: 23997814

Abstract: In the European Union, the high-concentration capsaicin patch is licensed for the management of neuropathic pain conditions in nondiabetic patients, including postherpetic neuralgia (PHN) and HIV-associated distal sensory polyneuropathy (HIV-DSP). However, in the USA, the Food and Drug Administration approved its use only in PHN (post herpetic neuralgia) patients. Capsaicin is a transient receptor potential vanilloid-1 agonist, which increases the intracellular calcium ion concentration. This triggers calcium-dependent protease enzymes causing cytoskeletal breakdown and leads to the loss of cellular integrity and 'defunctionalization' of nociceptor fibres. Efficacy and therapeutic effect have been shown in several clinical studies of PHN and HIV-DSP. The high-concentration capsaicin patch and its practical application are different from low-concentration creams; one application can help for up to 3 months.

Neuropathic pain is a major problem among leprosy patients. In  an editorial by Maija Haanpää, Diana N.J. Lockwood and Aki Hietaharju (Leprosy Review (2004) 75, 7-18) the concept, clinical features and diagnosis of neuropathic pain are reviewed. The possible pathophysiological mechanisms, treatment challenges and research needs in this area are discussed. The only topical application mentioned in this review is lidocaine, but not discussed in detail.

It should be stressed  that chronic treatment with steroids, which we see often in practice, is clearly not the solution and should be discouraged. 

Yours sincerely,

Pieter AM Schreuder

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LML - S Deepak, B Naafs, S Noto and P Schreuder

LML blog link: http://leprosymailinglist.blogspot.it/

Contact: Dr Pieter Schreuder << editorlml@gmail.com