ISTANBUL, TURKEY – The capsaicin 8% patch known as Qutenza appears to be a novel and effective treatment for patients with brachioradial pruritus, according to a preliminary observational study.
"The big advantage of this new treatment strategy is the patient only needs one application of the patch instead of taking drugs daily. Most patients experience relief for 5-6 weeks afterward," Dr. Claudia Zeidler said at the annual congress of the European Academy of Dermatology and Venereology.
Brachioradial pruritus (BRP) is a neuropathic itch often accompanied by pain, burning, and stinging. The condition is localized to the dorsolateral forearms along the distribution of the C-5 or C-6 dermatomes. The condition is more common in women. Imaging studies of patients typically show spinal stenosis or other cervical spinal pathology entailing cervical nerve root compression, according to Dr. Zeidler of the University of Müenster, Germany.
She and her colleagues found that patients with BRP have significantly reduced intraepidermal nerve fiber density in lesional skin, compared with nonlesional skin on the ventral forearm. Patients also have reduced expression of transient receptor potential cation channel subfamily V, member 1 (TRPV1) in lesional skin, compared with nonlesional skin. TRPV1 affects the balance between keratinocyte differentiation and proliferation, and thus can influence epidermal barrier function.
Dr. Zeidler’s study enrolled 16 patients with an average BRP duration of 91 months who had undergone unsuccessful treatment attempts with various combinations of anticonvulsants, antidepressants, and antihistamines. Thirteen of the 16 patients were women, and ranged in age from 47 to 69 years. Affected skin areas were normal in appearance, aside from hyperpigmented scratch lesions that looked like prurigo nodularis in 12 patients. Magnetic resonance imaging showed 15 of the 16 patients had cervical nerve compression or degenerative changes.
Itching relief typically began the day after the in-office Qutenza treatment session. Three weeks post treatment, mean pruritus intensity scores on a 0-10 visual analog scale had dropped from 5.8 pretreatment to 1.1. Mean pain intensity scores fell from 4.2 to 0.8. Significant improvement in quality of life was documented via a reduction in Dermatology Life Quality Index scores from 8.9 pretreatment to 4.3. Levels of TRPV1 in lesional skin were significantly increased 3 weeks post treatment compared with baseline; however, intraepithelial nerve fiber density in lesional skin was not significantly different.
Side effects of the capsaicin 8% patch consisted of mild localized pain and burning lasting for 20 minutes to 2 days in 14 patients.
Additional patient follow-up at 2, 3, and 4 months indicated that the pruritus and pain relief typically lasted 5-6 weeks. Since the conclusion of the study, when symptoms return, patients come in for retreatment.
The 14-by-20-cm capsaicin 8% patch is approved in Europe for the treatment of nondiabetic neuropathic pain and in the United States for management of neuropathic pain associated with postherpetic neuralgia. The patch contains 179 mg of capsaicin. Dr. Zeidler and coworkers were careful to follow the detailed labeling instructions for the patch’s use.
The patch has to be administered by a physician or another health care professional. Self-treatment is not permitted. Removal of hair to promote patch adherence should be accomplished with the use of scissors, not by shaving. To reduce discomfort, the researchers applied topical lidocaine 2.5% for 1 hour prior to putting the patch directly on the itchy area. Upon removing the patch after 1 hour, a cleansing gel that comes with the patch was applied for 1 minute to remove any residual capsaicin.
Dr. Zeidler plans to conduct a randomized controlled trial in patients with BRP to confirm the observational study findings, and also to look at the long-term effects of repeated treatments. Her observational study was supported by Astellas Pharma. She reported having no financial conflicts.