Pain
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Randomized Controlled Trial Multicenter Study Clinical Trial
Efficacy of lidocaine patch 5% in the treatment of focal peripheral neuropathic pain syndromes: a randomized, double-blind, placebo-controlled study.
Peripheral neuropathic pain syndromes (PNPS) are difficult to treat because commonly used analgesics are often ineffective when, for example, touch-evoked allodynia, hyperalgesia, and pain paroxysms are present. To investigate whether lidocaine patch 5% treatment is also effective in postherpetic neuropathy (PHN) and in other PNPS, 40 patients with various forms and localizations of PNPS completed a prospective, randomized, placebo-controlled, two-way, cross-over study in three medical hospitals. Patients suffering from pain in a localized skin area with intensity above 40 mm visual analog scale (VAS) and a stable consumption of pain medication were included in this study. ⋯ When, after the wash-out period, the pain intensity scores did not return to the pre-treatment values (+/-20%), these patients were excluded from the study. The present study revealed that, as an add-on therapy, the lidocaine patch 5% was clearly effective in reducing ongoing pain (P=0.017) and allodynia (P=0.023) during the first 8 h after application and that the patches also worked well over a period of 7 days (P=0.018) in diverse focal PNPS. Calculation of the numbers needed to treat (NNT) to obtain one patient with more than 50% relief of ongoing pain revealed that the NNT of 4.4 in the present study compared reasonably well with other studies of PHN, such as topically applied capsaicin (NNT: 5.3-infinity) or systemic treatment with gabapentin (NNT: 3.2-5.0).