Topical Lidocaine Patch Research Articles

Pharmacological Treatment of Diabetic Neuropathic Pain

Neuropathic pain continues to be a difficult and challenging clinical issue to deal with effectively. Painful diabetic polyneuropathy is a complex pain condition that occurs with reasonable frequency in the population and it may be extremely difficult for clinicians to provide patients with effective analgesia. Chronic neuropathic pain may occur in approximately one of every four diabetic patients. The pain may be described as burning or a deep-seated ache with sporadic paroxysms of lancinating painful exacerbations. The pain is often constant, moderate to severe in intensity, usually primarily involves the feet and generally tends to worsen at night. Treatment may be multimodal but largely involves pharmacological approaches. Pharmacological therapeutic options include antidepressants (tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors), α2δ ligands and topical (5%) lidocaine patch. Other agents may be different antiepileptic drugs (carbamazepine, lamotrigine, topiramate), topical capsaicin, tramadol and other opioids. Progress continues with respect to understanding various mechanisms that may contribute to painful diabetic neuropathy. Agents that may hold some promise include neurotrophic factors, growth factors, immunomodulators, gene therapy and poly (adenosine diphosphate-ribose) polymerase inhibitors. It is hoped that in the future clinicians will be able to assess patient pathophysiology, which may help them to match optimal therapeutic agents to target individual patient aberrant mechanisms.

Carbamazepine

Carbamazepine

EFNS guidelines on the pharmacological treatment of neuropathic pain: 2010 revision

This second European Federation of Neurological Societies Task Force aimed at updating the existing evidence about the pharmacological treatment of neuropathic pain since 2005. Studies were identified using the Cochrane Database and Medline. Trials were classified according to the aetiological condition. All class I and II randomized controlled trials (RCTs) were assessed; lower class studies were considered only in conditions that had no top-level studies. Treatments administered using repeated or single administrations were considered, provided they are feasible in an outpatient setting. Most large RCTs included patients with diabetic polyneuropathies and post-herpetic neuralgia, while an increasing number of smaller studies explored other conditions. Drugs generally have similar efficacy in various conditions, except in trigeminal neuralgia, chronic radiculopathy and HIV neuropathy, with level A evidence in support of tricyclic antidepressants (TCA), pregabalin, gabapentin, tramadol and opioids (in various conditions), duloxetine, venlafaxine, topical lidocaine and capsaicin patches (in restricted conditions). Combination therapy appears useful for TCA-gabapentin and gabapentin-opioids (level A). There are still too few large-scale comparative studies. For future trials, we recommend to assess comorbidities, quality of life, symptoms and signs with standardized tools and attempt to better define responder profiles to specific drug treatments.

Efficacy of a Metered-dose 8% Lidocaine Pump Spray for Patients with Post-herpetic Neuralgia

Topical lidocaine patch is effective in the treatment of post-herpetic neuralgia (PHN), but not suited for paroxysmal pain because of the long latency of analgesia. Here, we examined the efficacy of 8% lidocaine pump spray (Xylocaine pump spray, XPS) for PHN. Twenty-four patients with PHN were recruited into a randomized, double-blind, placebo-controlled, crossover study (study 1), and 100 patients with PHN were recruited into an open-labeled study (study 2). In study 1, patients were randomized to receive either XPS or saline placebo pump spray (PPS) applied to the painful skin areas. Following a 7-day period, patients were crossed over to receive the alternative treatment. In study 2, XPS was prescribed for patients who were advised to use the spray anytime, with a 2-hour gap between applications, for 2 weeks. The pain was assessed with a visual analogue scale (VAS). Details of use were noted in the diary. In study 1, greater decreases in VAS of persistent pain followed application of XPS (baseline: 6.1 +/- 1.7 cm, 15-minute post-spray: 2.3 +/- 2.5 cm, mean +/- SD) than with PPS (6.1 +/- 1.7 cm, 5.7 +/- 1.6 cm, [P < 0.01]). The effect persisted for a median of 4.5 hours (range, 2 to 24 hours) after application. In study 2, 13 of 100 patients discontinued the treatment because of mild local side effects or insufficient effect. In the remaining 87 patients, XPS maintained significant pain relief relative to baseline throughout the 2-week period. Satisfaction with the therapy was reported by 79% of patients. In both studies, XPS provided a significant improvement in PHN due to its prompt analgesia, lack of systemic side effects, and convenience of use.

The Analgesic Effect of a Metered-Dose 8% Lidocaine Pump Spray In Posttraumatic Peripheral Neuropathy: A Pilot Study

A topical lidocaine patch is effective in the treatment of posttraumatic peripheral neuropathy (PTPN), but it is not suited for breakthrough pain because of difficulty with an additional application. Here, we examined the effect of 8% lidocaine pump spray (Xylocaine pump spray, XPS) on peripheral neuropathic pain caused by surgery or injury. Thirty-one patients with PTPN were randomized to receive either XPS or saline placebo pump spray applied to painful skin areas. The optimal dose of up to 30 sprays (0.1 mL/single spray, 30 times) was individually determined as the dose which completely covered the painful site. After a 7-day period, the patients were crossed over to receive the optimal dose of the alternative spray. Pain was assessed with a visual analog scale. XPS, but not placebo pump spray, significantly decreased the visual analog scale for continuing pain and tactile allodynia. The effect persisted for a median of 5 h (range, 2-60 h) after application. Mild side effects were reported in three patients with XPS consisting of local irritation (n = 3) and local flare (n = 1). All adverse events disappeared without medication within a few hours. The present study suggests that XPS provides a significant improvement in PTPN due to its prompt analgesia, lack of systemic side effects and convenience.

(212) Topical Lidocaine Patch Produces a Significant Improvement in Quality of Life Indicators in Treated PHN Patients: Results of a Multicenter Open-Label Trial

Aim: To assess quality of life (QOL) treatment effects on postherpetic neuralgia (PHN) patients treated with lidocaine patch 5% (Lidoderm®). Methods: An open-label, non-randomized, multi-center study evaluated the efficacy of lidocaine patch 5% using quality of life indicators over a 28 day treatment period in 333 subjects with postherpetic neuralgia (PHN). A maximum of 3 patches was applied to cover the area of greatest pain during a 12-hour period each day for 28 days. The Brief Pain Inventory (BPI- Short Form) was completed at baseline, day 7, day 14 and day 28. Patients reported distinct aspects of QOL using a 0 (does not interfere) to 10 (completely interferes) categorical scale. Results: Lidocaine patch 5% significantly (p = 0.0001) reduced the impact of pain on all quality of life indicators at all time points [Table 1; Figure 1]. Conclusion: This large multi-center study further demonstrates that lidocaine patch 5% produces a significantly positive impact on all measured quality of life indicators in the 333 PHN patients studied. The support of Endo Pharmaceuticals Inc. for this research project is gratefully acknowledged. Table 1. Change in Impact of Pain on Quality Of Life Indicators (N = 333) Baseline to Day 7 Baseline to Day 14 Baseline to Final Mean Change SD Pvalue Mean Change SD Pvalue Mean Change SD Pvalue General Activity 1.6 3.6 0.0001 2.1 3.0 0.0001 2.1 3.3 0.0001 Mood 2.0 3.1 0.0001 2.4 3.1 0.0001 2.3 3.3 0.0001 Walk 1.1 2.8 0.0001 1.4 3.0 0.0001 1.3 3.0 0.0001 Work 1.7 2.7 0.0001 1.8 3.0 0.0001 2.0 3.2 0.0001 Relationships w/Others 1.5 2.9 0.0001 1.7 3.2 0.0001 1.8 3.3 0.0001 Sleep 1.7 3.1 0.0001 1.9 3.2 0.0001 2.0 3.4 0.0001 Enjoy Life 1.8 3.1 0.0001 2.2 3.0 0.0001 2.3 3.2 0.0001

Insufficient evidence to recommend topical lidocaine as first-line treatment for postherpetic neuralgia

The Cochrane Pain, Palliative and Supportive Care Group Trials Register, Cochrane Central Register of Controlled Trials, Medline, Embase, LILACS (Latin American and Caribbean Health Sciences), SIGLE (System for Information on Grey Literature in Europe)(for conference proceedings) and Science Citation Index were searched, along with the reference lists of all eligible trials, key textbooks and previous systematic reviews. Authors of all identified trials were contacted. Studies of interest were randomised controlled trials (RCT) or quasi-RCT comparing all topical applications of lidocaine, including gels and patches in people of all ages suffering from postherpetic neuralgia (PHN; pain persisting at the site of shingles at least 1 month after the onset of the acute rash). Data were extracted independently by two authors with disputes resolved by a third reviewer. A meta-analysis was conducted using a fixed-effect approach. Three trials were included, giving a total of 182 individuals who used topical lidocaine and 132 controls. Two trials provided data on pain relief, and the remaining study provided data on secondary outcome measures. The largest trial published as an abstract compared a topical lidocaine patch to a placebo patch and accounted for 150 of the 314 patients (48%). A meta-analysis combining two of the three studies identified a significant difference between the topical lidocaine and control groups for the primary outcome measure: a mean improvement in pain relief according to a pain relief scale. Topical lidocaine relieved pain better than placebo (P 0.003). There was a statistical difference between the groups for the secondary outcome measure of mean score-reduction on a visual analogue scale (P 0.030), but this was only for a single small trial. There were a similar number of adverse skin reactions in both treatment and placebo groups. There is insufficient evidence to recommend topical lidocaine as a first-line agent in the treatment of PHN with allodynia. Further research should be undertaken on the efficacy of topical lidocaine for other chronic neuropathic pain disorders, and also to compare different classes of drugs (eg, topical anaesthetics versus anti-epileptics).

A role for peripheral afferents in the pathophysiology and treatment of at-level neuropathic pain in spinal cord injury? A case report

At-level neuropathic pain is a frequent symptom following spinal cord injury, but the underlying pathophysiology is not completely understood. We report a patient suffering from treatment-resistant at-level pain characterized by ongoing pain and mechanical allodynia for three years after an incomplete spinal lesion. Quantitative sensory testing revealed severe thermosensory deficits in the neuropathic pain area. However, topical application of capsaicin in the neuropathic pain area induced a burning pain sensation, a marked decrease in heat pain threshold and an increase in mechanical allodynia. Treatment with topical lidocaine patches (5%) led to considerable pain relief. These results indicate a functional connection between peripheral, spinal and supraspinal nociceptive pathways and that peripheral afferents may contribute to at-level neuropathic pain after spinal cord injury in this patient. Lesioned peripheral afferents in combination with central neuronal hyperexcitability are discussed as a likely underlying pain mechanism.

(834): Topical sterile lidocaine patch to reduce postoperative pain and decrease need for oral analgesics after inguinal herniorrhaphy

We designed a sterile lidocaine patch for application to a closed wound to reduce pain and systemic analgesic use after inguinal herniorrhaphy. We conducted a double-blind placebo(P)controlled parallel, dose-response study comparing the daily application of a 3.5% lidocaine patch to a 10% lidocaine patch for 48 hours after surgery. 221 subjects who underwent unilateral herniorrhaphy using a tension-free mesh were randomized to one of three patches. Anesthesia was general or spinal and no local anesthetic was injected at closure to determine the time of onset of the lidocaine in the patch. Rescue medication was oral methimazole, a short-acting analgesic. Pain intensity (PI) was assessed at time points for up to 48 hours. The AUC for PI from 2-48 hours was P 109, 3.5% 102, and 10% 89,(p=0.05). The AUC for PI from 2-24 hours was P 63, 3.5% 60, and 10% 52 (p= 0.045) and from 24-48 hours was P 47, 3.5% 42, and 10% 34 (p= 0.03). The pain reduction for 10% vs. P from 2 to 48 hours was 19%, from 2-24 hrs was 18% and from 24-48 hours was 27%. The number of rescue analgesic doses over the 48 hours was P 101, 3.5% 81, 10% 65 (p= 0.01), a reduction of 36%(10% patch vs. placebo). The lesser magnitude of AUC in the first 24 hours indicates the onset of the lidocaine patch is 2 to 3 hours. The safety of a 10% lidocaine patch was demonstrated by a single wound infection and no effect on wound healing. A 10% sterile lidocaine patch applied daily over the wound was shown to be safe and effective in reducing post operative pain after inguinal herniorrhaphy. Most importantly, a decrease in the use of oral rescue analgesic after surgery, thereby reducing post-operative side effects. We designed a sterile lidocaine patch for application to a closed wound to reduce pain and systemic analgesic use after inguinal herniorrhaphy. We conducted a double-blind placebo(P)controlled parallel, dose-response study comparing the daily application of a 3.5% lidocaine patch to a 10% lidocaine patch for 48 hours after surgery. 221 subjects who underwent unilateral herniorrhaphy using a tension-free mesh were randomized to one of three patches. Anesthesia was general or spinal and no local anesthetic was injected at closure to determine the time of onset of the lidocaine in the patch. Rescue medication was oral methimazole, a short-acting analgesic. Pain intensity (PI) was assessed at time points for up to 48 hours. The AUC for PI from 2-48 hours was P 109, 3.5% 102, and 10% 89,(p=0.05). The AUC for PI from 2-24 hours was P 63, 3.5% 60, and 10% 52 (p= 0.045) and from 24-48 hours was P 47, 3.5% 42, and 10% 34 (p= 0.03). The pain reduction for 10% vs. P from 2 to 48 hours was 19%, from 2-24 hrs was 18% and from 24-48 hours was 27%. The number of rescue analgesic doses over the 48 hours was P 101, 3.5% 81, 10% 65 (p= 0.01), a reduction of 36%(10% patch vs. placebo). The lesser magnitude of AUC in the first 24 hours indicates the onset of the lidocaine patch is 2 to 3 hours. The safety of a 10% lidocaine patch was demonstrated by a single wound infection and no effect on wound healing. A 10% sterile lidocaine patch applied daily over the wound was shown to be safe and effective in reducing post operative pain after inguinal herniorrhaphy. Most importantly, a decrease in the use of oral rescue analgesic after surgery, thereby reducing post-operative side effects.

Review of lidocaine patch 5% studies in the treatment of postherpetic neuralgia.

Postherpetic neuralgia (PHN) is a chronic pain syndrome that disproportionately affects the elderly; its incidence is anticipated to increase as the population ages. PHN presents as pain (continuous burning or intense paroxysmal), most often with tactile allodynia, which may be severe and disabling, resulting in poor quality of life and depression. Traditional treatments have included tricyclic antidepressants, anticonvulsants and opioids; however, adverse systemic effects associated with these agents have led to the development of a newer and potentially safer agent, the topical lidocaine patch 5% (Lidoderm), a targeted peripheral analgesic. This article reviews the clinical pharmacology of the lidocaine patch 5% for the treatment of PHN and summarises data from clinical trials of its safety, tolerability and efficacy. The Medline search terms "lidocaine" and "patch" were used to search for English-language articles on the pharmacokinetics of the lidocaine patch 5% and its clinical use for the treatment of PHN. Additional published studies not identified by the database search but performed by the authors or their colleagues were also included in the review. The systemic absorption of lidocaine from the patch was minimal in healthy adults when four patches were applied for up to 24 hours/day, and lidocaine absorption was even lower among PHN patients than healthy adults at the currently recommended dose. Vehicle-controlled and open-label trials found the lidocaine patch 5%, either alone or in combination with other agents, to be effective in the treatment of PHN. Most adverse events were at patch application sites; no clinically significant systemic adverse effects were noted, including when used long term or in an elderly population.In patients with PHN, the lidocaine patch 5% has demonstrated relief of pain and tactile allodynia with a minimal risk of systemic adverse effects or drug-drug interactions. Because of its proven efficacy and safety profile, the lidocaine patch 5% has been recommended as a first-line therapy for the treatment of the neuropathic pain of PHN.

Topical Lidocaine Patch Therapy for Myofascial Pain

An open label study of topical lidocaine 5% patches was conducted for myofascial pain management based on the hypothesis that electrical dysfunction is a component of myofascial pain and therefore sodium channel blockade may be useful in managing myofascial pain. The efficacy of topical lidocaine patch therapy for myofascial pain impact of the therapy on associated quality of life were investigated in the one-month trial. Principal outcome measures were Brief Pain Inventory-Short Form for pain intensity and quality of life score changes. Twenty-seven patients with moderate-severe myofascial pain were enrolled. Eighteen had low back pain. Two patients reported complete pain relief and 3 reported a lot of relief. Mean improvements for average pain intensity (7, 14, and 28 days), general activity (7 and 28 days), mood and sleep (7, 14, and 28 days), walking (14 and 28 days), ability to work, relationships, and enjoyment of life (28 days) were significant (P < 0.05). These results suggest lidocaine patches may be useful in the management of myofascial pain.

Management of herpes zoster (shingles) and postherpetic neuralgia

Herpes zoster (HZ) results from recrudescence of varicella zoster virus latent since primary infection (varicella). The overall incidence of HZ is ∼ 3/1000 of the population per year rising to 10/1000 per year by 80 years of age. Approximately 50% of individuals reaching 90 years of age will have had HZ. In ∼ 6%, a second attack may occur (usually several decades after the first). Patients with HZ can transmit the virus to a non-immune individual causing varicella. HZ is not contracted from individuals with varicella or HZ. Reduced cell-mediated immunity to HZ occurs with ageing, explaining the increased incidence in the elderly and from other causes such as tumours, HIV and immunosuppressant drugs. Diagnosis is usually clinical from typical unilateral dermatomal pain and rash. Prodromal symptoms, pain, itching and malaise, are common. The most common complication of HZ is postherpetic neuralgia (PHN), defined as significant pain or dysaesthesia present ≥ 3 months after HZ. PHN results from damage and secondary changes within components of the nervous system subserving pain. Some motor deficit is common; severe and long-lasting paresis may rarely accompany HZ. More than 5% of elderly patients have PHN at 1 year after acute HZ. Predictors of PHN are, greater age, acute pain and rash severity, prodromal pain, the presence of virus in peripheral blood as well as adverse psychosocial factors. Therapy for acute HZ is intended to reduce acute pain, hasten rash healing and reduce the risk of PHN and other complications. Antiviral drugs are close to achieving these aims but do not entirely remove risk of PHN. Oral steroids show no protective effect against PHN. Adequate analgesia during the acute phase may require strong opioid drugs. Nerve blocks and tricyclic antidepressants (TCAs) may reduce the risk of PHN although firm evidence is lacking. PHN requires thorough evaluation and development of a management strategy for each individual patient. Initial therapy is with TCAs (e.g., nortriptyline) or the anticonvulsant gabapentin. Topical lidocaine patches frequently reduce allodynia. Strong opioids are sometimes required. Topical capsaicin cream is beneficial for a small proportion of patients but is poorly tolerated. NMDA antagonists have not proved beneficial with the exception of ketamine. Transcutaneous Electrical Nerve Stimulation (TENS) may be effective in some cases. HZ is a common condition. Severe complications such as stroke, encephalitis and myelitis are relatively rare whereas sight threatening complications of ophthalmic HZ are more common. PHN is common, distressing and often intractable. Good management improves outcome.

(212) Topical Lidocaine Patch Produces a Significant Improvement in Quality of Life Indicators in Treated PHN Patients: Results of a Multicenter Open-Label Trial

(212) Topical Lidocaine Patch Produces a Significant Improvement in Quality of Life Indicators in Treated PHN Patients: Results of a Multicenter Open-Label Trial

Advances in the Diagnosis and Management of Peripheral Nerve Disease

Much progress has been made in the assessment and management of neuropathic pain over the past 5 years. Assessment has improved with the Neuropathic Pain Scale, a new, easily administered, diagnostic tool. Mechanistically, recent studies indicate that peripheral neuropathic pain is generated through a focal inflammatory process rather than axonal destruction. This process also appears to involve mRNA regulation of fast sodium channels, which produce ectopic discharges and are presumably responsible for pain generation. In addition the entire neuraxis undergoes neuroplastic changes as a result of peripheral nerve injury. The available clinical trial data indicate that newer antiepileptic drugs (AEDs), most notably gabapentin, are better alternatives to older medications such as carbamazepine or phenytoin in the treatment of neuropathic pain. Gabapentin is at least as good with respect to actual pain relief as the antidepressants, including amitriptyline, but has a much better safety profile with minimal drug-drug interactions and side effects. Mexiletine is a reasonable alternative agent in patients who have not had a satisfactory response to, or cannot tolerate, the AEDs or antidepressants. Long-acting opioids should be considered in patients refractory to these adjunctive agents. With the advent of the topical lidocaine patch, the first drug with an FDA-approved indication for postherpetic neuralgia, a revolutionary new agent is now available for the treatment of neuropathic pain that does not have any systemic side effects.

Neurology (61)

Treatment of postherpetic neuralgia: an update. (University of Rochester School of Medicine and Dentistry, Rochester, NY) Drugs 2000;59:1113–1126.This article provided an update on recent developments in the treatment of postherpetic neuralgia (PHN). In clinical trials, the topical lidocaine patch, gabapentin, and controlled release oxycodone have been shown to provide superior pain relief in patients with PHN when compared with placebo. It has also been demonstrated that the tricyclic antidepressant nortriptyline provides equivalent analgesic benefit when compared with amitriptyline, but is better tolerated. Based on these results, nortriptyline can now be considered the preferred antidepressant for treatment of PHN. The topical lidocaine patch, gabapentin, and controlled release oxycodone all appear to be as effective as tricycline antidepressants in the treatment of patients with PHN, and the results of these recent studies suggest that each of these treatments should be considered early in the course of treatment. Additional controlled trials are needed to compare the efficacy and tolerability of these 4 treatments for patients with PHN.

Topical lidocaine patch relieves a variety of neuropathic pain conditions: an open‐label study. (Department of Pain Medicine and Palliative Care, Beth Lsrael Medical Center, New York, NY) Clin J Pain 2000;16:205–208.

Our goal was to perform a pilot, open‐label, prospective study to access the effectiveness and tolerability of a topical lidocaine patch (Lidoderm) for the treatment of peripheral neuropathic pain conditions other than postherpetic neuralgia. Sixteen patients with refractory peripheral neruopathic pain conditions who had reported intolerable side effects or inadequate pain relief with antidepressant, anticonvulsant, antiarrhythmic, and opioid medications participated in this study. Diagnoses included postthoracotomy pain, stump neuroma pain, intercostal neuralgia, diabetic polyneuropathy, meralgia paresthetica, complex regional pain syndrome, radiculopathy, and postmastectomy pain. A 6‐item Pain Relief Scale was used. Moderate or better pain relief was reported by 13 of the 16 participants (81%). One patient stopped treatment after 4 days due to lack of relief. The remaining 15 patients had a mean duration of patch use of 6.2 weeks with continued relief. Only 1 patient reported a side effect, a mild skin irritation. Conclude the Lidoderm patch provides clinically meaningful pain relief in most of these refractory neuropathic pain patients without side effects. Controlled trials need to be performed to confirm these preliminary findings.Comment by Tat‐Leang Lee, M.D. This is an interesting study that highlighted a simple, efficacious method for the treatment of resistant neuropathic pain. As this was a pilot study using an open‐label method, and treating a heterogenous group of neuropathic pain conditions, caution should be adopted in the interpretation of the results. What remains unanswered is the reason for the success of the lidocaine patch, particularly when previous studies have documented the failure of EMLA in the treatment of neuropathic pain. Indeed, several patients who participated in this study had used EMLA unsuccessfully before, although no details on its administration was reported. Both the lidocaine patch and EMLA contain 5% lidocaine, which presumably would result in greater penetration by the EMLA cream. Therefore, a placebo‐controlled randomized trial is needed to confirm the findings of this pilot study. Nevertheless, this is a promising treatment that is convenient, lacks systemic effect, easily added‐on to existing treatment, and with only minor side effects, that is worth considering for our patients.

TREATMENT OF POSTHERPETIC NEURALGIA—AN UPDATE

Postherpetic neuralgia (PHN) is a chronic pain syndrome that is often refractory to treatment and can last for years, causing physical and social disability, psychological distress, and increased use of the healthcare system. In this paper we provide an update on recent developments in the treatment of PHN. We emphasize the results of recent studies that provide an evidence‐based approach for treating PHN that was not available until very recently. In randomised, controlled clinical trials, the topical lidocaine patch, gabapentin, and controlled release oxycodone have been shown to provide superior pain relief in patients with PHN when compared with placebo. It has also recently been demonstrated that the tricyclic antidepressant nortriptyline provides equivalent analgesic benefit when compared with amitriptyline, but is better tolerated. Based on these results, nortriptyline can now be considered the preferred antidepressant for the treatment of PHN, although desipramine may be used if the patient experiences unacceptable sedation from nortriptyline. The topical lidocaine patch, gabapentin and controlled release oxycodone all appear to be as effective as tricyclic antidepressants in the treatment of patients with PHN, and the results of these recent studies suggest that each of these treatments should be considered early in the course of treatment. Additional controlled trials are needed to compare the efficacy and tolerability of these 4 treatments—tricyclic antidepressants, gabapentin, the topical lidocaine patch and controlled release opioid analgesics—used singly and in various combinations in the treatment of patients with PHN.

Treatment of postherpetic neuralgia: an update.

Postherpetic neuralgia (PHN) is a chronic pain syndrome that is often refractory to treatment and can last for years, causing physical and social disability, psychological distress, and increased use of the healthcare system. In this paper we provide an update on recent developments in the treatment of PHN. We emphasise the results of recent studies that provide an evidence-based approach for treating PHN that was not available until very recently. In randomised, controlled clinical trials, the topical lidocaine patch, gabapentin, and controlled release oxycodone have been shown to provide superior pain relief in patients with PHN when compared with placebo. It has also recently been demonstrated that the tricyclic antidepressant nortriptyline provides equivalent analgesic benefit when compared with amitriptyline, but is better tolerated. Based on these results, nortriptyline can now be considered the preferred antidepressant for the treatment of PHN, although desipramine may be used if the patient experiences unacceptable sedation from nortriptyline. The topical lidocaine patch, gabapentin and controlled release oxycodone all appear to be as effective as tricyclic antidepressants in the treatment of patients with PHN, and the results of these recent studies suggest that each of these treatments should be considered early in the course of treatment. Additional controlled trials are needed to compare the efficacy and tolerability of these 4 treatments- tricyclic antidepressants, gabapentin, the topical lidocaine patch and controlled release opioid analgesics--used singly and in various combinations in the treatment of patients with PHN.

Topical lidocaine patch relieves postherpetic neuralgia more effectively than a vehicle topical patch: results of an enriched enrollment study

This study compared the efficacy of topical lidocaine patches versus vehicle (placebo) patches applied directly to the painful skin of subjects with postherpetic neuralgia (PHN) utilizing an `enriched enrollment' study design. All subjects had been successfully treated with topical lidocaine patches on a regular basis for at least 1 month prior to study enrollment. Subjects were enrolled in a randomized, two-treatment period, vehicle-controlled, cross-over study. The primary efficacy variable was `time to exit'; subjects were allowed to exit either treatment period if their pain relief score decreased by 2 or more categories on a 6-item Pain Relief Scale for any 2 consecutive days. The median time to exit with the lidocaine patch phase was greater than 14 days, whereas the vehicle patch exit time was 3.8 days ( P<0.001). At study completion, 25/32 (78.1%) of subjects preferred the lidocaine patch treatment phase as compared with 3/32 (9.4%) the placebo patch phase ( P<0.001). No statistical difference was noted between the active and placebo treatments with regards to side effects. Thus, topical lidocaine patch provides significantly more pain relief for PHN than does a vehicle patch. Topical lidocaine patch is a novel therapy for PHN that is effective, does not cause systemic side effects, and is simple to use.