Derry Sheena, Lloyd Rosalind, Moore R Andrew, McQuay Henry J
Pain Research and Nuffield Department of Anaesthetics, University of Oxford, West Wing (Level 6), John Radcliffe Hospital, Oxford, Oxfordshire, UK, OX3 9DU.
Cochrane Database Syst Rev. 2009 Oct 7(4):CD007393. doi: 10.1002/14651858.CD007393.pub2.
Topical creams with capsaicin are used to treat pain from a wide range of chronic conditions including neuropathic pain. Following application to the skin capsaicin causes enhanced sensitivity to noxious stimuli, followed by a period with reduced sensitivity and, after repeated applications, persistent desensitisation. There is uncertainty about the efficacy and tolerability of capsaicin for treating painful chronic neuropathies.
To review the evidence from controlled trials on the efficacy and tolerability of topically applied capsaicin in chronic neuropathic pain in adults.
Cochrane CENTRAL, MEDLINE, EMBASE and Oxford Pain Relief Database, searched in May 2009.
Randomised, double blind, placebo controlled studies of at least six weeks' duration, using topical capsaicin to treat neuropathic pain.
Two review authors independently assessed trial quality and validity, and extracted data. Information was extracted on numbers of participants with pain relief (clinical improvement) after at least six weeks, and with local skin reactions, and used to calculate relative risk and numbers needed to treat to benefit (NNT) and harm (NNH). Details of definition of pain relief and specific adverse events were sought.
Six studies (389 participants in total) compared regular application of low dose (0.075%) capsaicin cream with placebo cream; the NNT for any pain relief over six to eight weeks was 6.6 (4.1 to 17). Two studies (709 participants in total) compared a single application of high dose (8%) capsaicin patch with placebo patch; the NNT for >/= 30% pain relief over twelve weeks was 12 (6.4 to 70). Local skin reactions were more common with capsaicin, usually tolerable, and attenuated with time; the NNH for repeated low dose application was 2.5 (2.1 to 3.1). There were insufficient data to analyse either data set by condition or outcome definition. All studies satisfied minimum criteria for quality and validity, but maintenance of blinding remains a potential problem.
AUTHORS' CONCLUSIONS: Capsaicin, either as repeated application of a low dose (0.075%) cream, or a single application of a high dose (8%) patch may provide a degree of pain relief to some patients with painful neuropathic conditions. Local skin irritation, which is often mild and transient but may lead to withdrawal, is common. Systemic adverse effects are rare. Estimates of benefit and harm are not robust due to limited amounts of data for different neuropathic conditions and inconsistent outcome definition.
含辣椒素的外用乳膏用于治疗多种慢性疾病引起的疼痛，包括神经性疼痛。涂抹于皮肤后，辣椒素会使机体对有害刺激的敏感性增强，随后会经历一段敏感性降低的时期，反复涂抹后则会出现持续的脱敏现象。辣椒素治疗慢性疼痛性神经病变的疗效和耐受性尚不确定。
综述关于外用辣椒素治疗成人慢性神经性疼痛的疗效和耐受性的对照试验证据。
2009年5月检索Cochrane中心对照试验注册库、医学索引在线数据库、荷兰医学文摘数据库和牛津疼痛缓解数据库。
随机、双盲、安慰剂对照研究，疗程至少六周，使用外用辣椒素治疗神经性疼痛。
两名综述作者独立评估试验质量和有效性，并提取数据。提取至少六周后疼痛缓解（临床改善）的参与者人数以及出现局部皮肤反应的参与者人数的信息，用于计算相对危险度以及获益所需治疗人数（NNT）和伤害所需治疗人数（NNH）。查找疼痛缓解的定义及特定不良事件的详细信息。
六项研究（共389名参与者）比较了低剂量（0.075%）辣椒素乳膏与安慰剂乳膏的常规应用；六至八周内出现任何疼痛缓解的NNT为6.6（4.1至17）。两项研究（共709名参与者）比较了高剂量（8%）辣椒素贴剂与安慰剂贴剂的单次应用；十二周内疼痛缓解≥30%的NNT为12（6.4至70）。辣椒素组局部皮肤反应更常见，通常可耐受，且会随时间减轻；反复低剂量应用的NNH为2.5（2.1至3.1）。没有足够的数据按病情或结局定义对任何一组数据集进行分析。所有研究均符合质量和有效性的最低标准，但维持盲法仍是一个潜在问题。
辣椒素，无论是反复应用低剂量（0.075%）乳膏还是单次应用高剂量（8%）贴剂，都可能为一些患有疼痛性神经病变的患者提供一定程度的疼痛缓解。局部皮肤刺激很常见，通常轻微且短暂，但可能导致停药。全身不良反应罕见。由于针对不同神经病变的数据量有限且结局定义不一致，获益和伤害的估计并不可靠。
