The Effects of Topical Treatment With Clonidine + Pentoxifylline in Patients With Neuropathic Pain

Summary

Microvascular dysfunction underlies pain in different animal models of neuropathic pain. Pentoxifylline is a phosphodiesterase inhibitor that reduces cyclic adenosine monophosphate (cAMP) hydrolysis, enhances blood flow and reduces platelet aggregation, decreases blood viscosity, and increases the flexibility of red blood cells, all of which relieve microvascular dysfunction. Clonidine is an α2-adrenergic receptor agonist that decreases sympathetic outflow from the brainstem, vascular reactivity and has direct peripheral vasodilatory action. Topical combination of pentoxifylline and clonidine produced significant antiallodynic effects in rat models of neuropathic pain with sciatic nerve injury, painful diabetic neuropathy, and chemotherapy-induced painful neuropathy. In healthy volunteers with an experimentally-induced surrogate for neuropathic pain: post-capsaicin tourniquet exposure, the topical combination reduced areas of dynamic allodynia and mechanical hyperalgesia, in addition to reducing post-capsaicin ischemic pain. This study will investigate if the same topical combination of clonidine + pentoxifylline will relieve pain in patients with neuropathic pain following traumatic injuries of peripheral nerves.

Timeline

Start

2019-02-19

Primary completion

2021-10-12

Completion

2021-10-12

Publications

• Background Ragavendran JV, Laferriere A, Xiao WH, Bennett GJ, Padi SS, Zhang J, Coderre TJ. Topical combinations aimed at treating microvascular dysfunction reduce allodynia in rat models of CRPS-I and neuropathic pain. J Pain. 2013 Jan;14(1):66-78. doi: 10.1016/j.jpain.2012.10.004.
• Background Ragavendran JV, Laferriere A, Bennett GJ, Ware MA, Gandhi W, Bley K, Schweinhardt P, Coderre TJ. Effects of topical combinations of clonidine and pentoxifylline on capsaicin-induced allodynia and postcapsaicin tourniquet-induced pain in healthy volunteers: a double-blind, randomized, controlled study. Pain. 2016 Oct;157(10):2366-2374. doi: 10.1097/j.pain.0000000000000659.
• Background Brown MB, Martin GP, Jones SA, Akomeah FK. Dermal and transdermal drug delivery systems: current and future prospects. Drug Deliv. 2006 May-Jun;13(3):175-87. doi: 10.1080/10717540500455975.
• Background Li C, Sekiyama H, Hayashida M, Takeda K, Sumida T, Sawamura S, Yamada Y, Arita H, Hanaoka K. Effects of topical application of clonidine cream on pain behaviors and spinal Fos protein expression in rat models of neuropathic pain, postoperative pain, and inflammatory pain. Anesthesiology. 2007 Sep;107(3):486-94. doi: 10.1097/01.anes.0000278874.78715.1d.
• Background Palos GR, Mendoza TR, Cantor SB, Aday LA, Cleeland CS. Perceptions of analgesic use and side effects: what the public values in pain management. J Pain Symptom Manage. 2004 Nov;28(5):460-73. doi: 10.1016/j.jpainsymman.2004.02.016.
• Fulas OA, Laferriere A, Ware DMA, Shir Y, Coderre TJ. The effect of a topical combination of clonidine and pentoxifylline on post-traumatic neuropathic pain patients: study protocol for a randomized, double-blind placebo-controlled trial. Trials. 2021 Feb 17;22(1):149. doi: 10.1186/s13063-021-05088-w.

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