含8%辣椒素贴片可缓解臂桡侧瘙痒症

土耳其伊斯坦布尔——欧洲皮肤病与性病学会(EADV)年会上报告的一项初步观察研究显示，含8%辣椒素的贴片，即Quenza，可能是臂桡侧瘙痒症的一种新型有效治疗药物，这种新型治疗策略的一大优势在于患者只需使用贴片而不必每天服药。

德国Müenster大学的Claudia Zeidler医生报告指出，臂桡侧瘙痒症(Brachioradial pruritus，BRP)是一种神经病变性瘙痒，常伴有疼痛、烧灼感和刺痛，病变局限于前臂背外侧，沿着C5或C6皮节分布区分布，在女性中更为多见。患者的影像学检查一般显示椎管狭窄或其他颈椎管病理改变，压迫颈神经根。Zeidler医生及其同事发现，BRP患者病变皮肤与前臂腹侧面的非病变皮肤相比，表皮内神经纤维密度减小。患者一过性受体电位阳离子通道亚家族V成员1(TRPV1)的表达与非病变皮肤相比也减少。TRPV1影响角质细胞分化与增殖间的平衡，因此能够影响表皮屏障功能。

这项研究招募了16例BRP病程平均为91个月、曾尝试联合各种抗惊厥药、抗抑郁药及抗组胺药治疗但均未成功的患者，其中13例为女患者，年龄介于47~69岁。受累皮肤外观正常，只是有12例患者抓痕处有色素沉着，看起来像结节性痒疹。磁共振成像显示16例患者中有15例存在颈神经压迫或退行性改变。瘙痒症缓解一般始于诊室治疗开始的次日。治疗后3周，0~10分视觉模拟量表的平均瘙痒症强度评分从治疗前的5.8降至1.1。平均疼痛强度评分从4.2 降至0.8。皮肤病生活质量指数评分从治疗前的8.9减至4.3，证实生活质量有显著改善。病变皮肤的TRPV1水平在治疗后3周与基线相比显著上升，但病变皮肤的表皮内神经纤维密度没有显著差异。2、3、4个月的患者随访表明瘙痒症和疼痛缓解一般持续5~6周。研究结束以后，在症状复发时，患者会前来接受再治疗。

含8%的辣椒素贴片的副作用为持续20分钟的轻微的局部疼痛和烧灼感，见于14例患者。

14×20 cm的含8%辣椒素的贴片已在欧洲获准用于治疗非糖尿病性神经病变痛，在美国获准用于治疗带状疱疹后神经痛。贴片含179 mg辣椒素。Zeidler医生及合作者们在研究中遵循了该贴片的详细指导说明。

该贴片一定要由医务人员使用，不允许擅自用药。为了促进贴片的粘附，应该使用剪刀去毛而非剃毛。研究者们在直接将贴片置于瘙痒区之前，局部给予2.5%的利多卡因作用1小时，以减少不适感。在1小时后取下贴片，随后立即应用贴片自带的清洁啫喱，持续1分钟，以便于完全清除辣椒素而避免残留。

Zeidler医生计划在BRP患者中进行一项随机对照试验，以证实观察性研究的结果，同时还将观察再治疗的长期效果。该观察研究由安斯泰来制药公司支持，Zeidler医生报告无利益冲突。

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By: BRUCE JANCIN, Clinical Neurology News Digital Network

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 prurigonodularis 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 AstellasPharma. She reported having no financial conflicts.