Letters to the Editor

Lidocaine Patch for Treatment of Postherpetic Neuralgia?



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Am Fam Physician. 2006 Aug 1;74(3):378-381.

to the editor: Although the article “Herpes Zoster and Postherpetic Neuralgia: Prevention and Managment”1 in the September 15, 2005, issue of American Family Physician was generally well done and informative, it did not describe sources or selection criteria for articles to be used in generating evidence-based recommendations. We are concerned about the strength of evidence of the single citation2 provided to support the use of the 5% lidocaine patch (Lidoderm) in the treatment of postherpetic neuralgia. The citation reported benefit in a neuropathic pain scale score in 96 patients participating in a randomized placebo-controlled trial.2 In contrast to the authors' reviews1 of other conventional pharmacotherapies for postherpetic neuralgia (tricyclic antidepressants, gabapentin [Neurontin], opiates, and capsaicin [Zostrix]), there is no discussion of methodology, numbers needed to treat, or side effects for the lidocaine patch.

We conducted a systematic review of treatments for postherpetic neuralgia3 and found insufficient published data to support the use of the lidocaine patch; however, at that time, it was the only drug that the U.S. Food and Drug Administration (FDA) had indicated for treatment of postherpetic neuralgia. We searched the publicly available information on the new drug application for the lidocaine patch.4 The original trial (still unpublished) had 150 patients and found a large placebo response in pain scores throughout the three- to four-week trial duration that was not significantly different from that demonstrated with the lidocaine patch.

Three findings from this trial were used to argue for FDA approval, but the relevance of these findings is unclear. A significant difference was reported in pain relief at the final visit (2.6 versus 2.1 on a 0 to 5 scale). Allodynia was improved at the beginning of the trial in patients receiving lidocaine, but this was based on investigators' sensory skin testing and was not evaluated in relation to patient disability. Finally, on trial exit, the increase in pain scores was greater among those receiving lidocaine.

The FDA denied approval and required “one additional efficacy study” demonstrating benefit before approval. Efficacy was then demonstrated in a placebo-controlled trial in 32 participants who were selected based on prolonged successful use of lidocaine patches.5 This finding met the technical requirement for FDA approval but has not been substantiated in unselected patients.

We encourage the article's authors and the readership of American Family Physician to adopt a more critical view of the lidocaine patch for the treatment of postherpetic neuralgia.

REFERENCES

1. Mounsey AL, Matthew LG, Slawson DC. Herpes zoster and postherpetic neuralgia: prevention and management. Am Fam Physician. 2005;72:1075–80.

2. Galer BS, Jensen MP, Ma T, Davies PS, Rowbotham MC. The lidocaine patch 5% effectively treats all neuropathic pain qualities: results of a randomized, double-blind, vehicle-controlled, 3-week efficacy study with use of the neuropathic pain scale. Clin J Pain. 2002;18:297–301.

3. Alper BS, Lewis PR. Treatment of postherpetic neuralgia: a systematic review of the literature. J Fam Pract. 2002;51:121–8.

4. Lidoderm (lidocaine) patch. Center for Drug Evaluation and Research application number. Application no. NDA 20-612. Medical reviews. Washington, D.C.: U.S. Food and Drug Administration, Center for Drug Evaluation and Research. Submitted June 11, 1996. Accessed October 8, 2005, at: http://www.fda.gov/cder/foi/nda/99/20612_medr_P1.pdf.

5. Galer BS, Rowbotham MC, Perander J, Friedman E. Topical lidocaine patch relieves postherpetic neuralgia more effectively than a vehicle topical patch: results of an enriched enrollment study. Pain. 1999;80:533–8.

in reply: I would like to thank Drs. Alper and Lewis for their comments on our article.1 The criteria for a level B Strength of Recommendation Taxonomy (SORT) recommendation are: inconsistent or limited-quality patient-oriented evidence. The outcome examined in the Galer study2 is pain. We did not think that the evidence from this study2 was strong enough to assign an evidence level of A (consistent, good-quality patient-oriented evidence), but because it was a randomized controlled trial, it certainly warranted a higher evidence level than C (consensus, disease-oriented evidence, usual practice, expert opinion, or case series). We agree with Drs. Alper and Lewis that the evidence for lidocaine patches in the treatment of postherpetic neuralgia is “inconsistent and of limited quality,” which, according to the SORT criteria,3 would give it a recommendation level of B.

ANNE MOUNSEY M.D.

Dept. of Family Medicine

P.O. Box 800729

University of Virginia

Charlottesville, VA 29903

REFERENCES

1. Mounsey AL, Matthew LG, Slawson DC. Herpes zoster and postherpetic neuralgia: prevention and management. Am Fam Physician. 2005;72:1075–80.

2. Galer BS, Jensen MP, Ma T, Davies PS, Rowbotham MC. The lidocaine patch 5% effectively treats all neuropathic pain qualities: results of a randomized, double-blind, vehicle-controlled, 3-week efficacy study with use of the neuropathic pain scale. Clin J Pain. 2002;18:297–301.

3. Ebell MH, Siwek J, Weiss BD, Woolf SH, Susman J, Ewigman B, et al. Strength of Recommendation Taxonomy (SORT): a patient-centered approach to grading evidence in the medical literature. Am Fam Physician. 2004;69:549–57.

Send letters to Kenneth W. Lin, MD, MPH, Associate Deputy Editor for AFP Online, e-mail: afplet@aafp.org, or 11400 Tomahawk Creek Pkwy., Leawood, KS 66211-2680.

Please include your complete address, e-mail address, and telephone number. Letters should be fewer than 400 words and limited to six references, one table or figure, and three authors.

Letters submitted for publication in AFP must not be submitted to any other publication. Possible conflicts of interest must be disclosed at time of submission. Submission of a letter will be construed as granting the American Academy of Family Physicians permission to publish the letter in any of its publications in any form. The editors may edit letters to meet style and space requirements.



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