A pharmacological treatment algorithm for localized neuropathic pain

Is the Capsaicin 179 mg (8% w/w) Cutaneous Patch an Appropriate Treatment Option for Older Patients with Peripheral Neuropathic Pain?

Introduction

Capsaicin 179 mg (8% weight per weight) cutaneous patch ("capsaicin patch") is a recommended topical treatment for peripheral neuropathic pain (PNP). In older patients, topical treatments may be preferred over systemic treatments, but data specific to the older population are scarce.

Methods

We conducted pooled analyses of multiple clinical trials to evaluate efficacy and safety of capsaicin patch in older patients. The analysis of efficacy included four randomized, double-blind, 12-week studies with similar trial design comparing a single treatment of capsaicin 179 mg cutaneous patch vs low-dose control patch in post-herpetic neuralgia. For the safety evaluation, data were pooled from 18 interventional studies in which capsaicin patch was used in PNP with varying etiologies.

Results

Capsaicin patch had similar analgesic efficacy in elderly (n=582) and non-elderly patients (n=545) in terms of change from baseline to 2-12 weeks in the 11-point numeric pain rating scale (NPRS) score for average pain over the previous 24 hours. In both age groups, decrease in NPRS score was significantly greater with capsaicin patch vs control. Older patients treated with capsaicin patch were significantly more likely than those in the control group to achieve responder status (ie mean decrease in NPRS score from baseline to week 2-12 of at least 30% or ≥2 points): 36.1% vs 27.1% (odds ratio [OR] [95% CI] 1.52 [1.06, 2.18]; P=0.0231) and 33.1% vs 20.9% (OR [95% CI] 1.90 [1.30, 2.78]; P=0.0009) for active treatment vs control group, respectively. Similar proportions of non-elderly patients (n=2,311) and elderly patients (n=537) treated with capsaicin patch experienced treatment-emergent adverse events (TEAEs) (81.6% and 78.1%, respectively) and serious TEAEs (8.2% and 7.2%), with application-site reactions the most common TEAEs in both groups.

Conclusion

The capsaicin patch was equally efficacious and well tolerated in older patients as in younger patients.

People's experiences living with peripheral neuropathy: a qualitative study

Introduction

Peripheral neuropathy is a neurological disorder characterised by pain, numbness, or tingling due to nerve damage. Peripheral neuropathy is one of the main health issues in Kuwait and is a rising concern which affects a large proportion of the population, therefore the lived experience needs to be explored to identify areas for improvement in care. This qualitative study explored the experiences of people living with peripheral neuropathy in Kuwait.

Methods

Semi-structured interviews were conducted with 25 participants recruited from the Neurology Outpatient Clinic of the Ibn Sina Hospital in Kuwait. The interview questions explored their experiences and understanding of pain along with the impact on their daily life. The interviews were audio recorded, transcribed and translated into English then coded using NVivo 12. Thematic analysis was conducted to identify patterns and themes in the data.

Results

Three major themes were identified including treatment beliefs (perceived effectiveness of treatment and seeking alternative treatments), the barriers to pain management (medication side effects, relationships with healthcare professionals and lack of information and access to healthcare), and the impact on quality of life (impact on work and social, physical, and psychological consequences). Self-efficacy was a key construct and over-arching theme that was discussed in all aspects, which finds reflection in the protection motivation theory.

Discussion

This paper presents the experiences of people living with peripheral neuropathy and highlights there is scope for improvement of current treatments in Kuwait. Self-management strategies are recommended alongside prescribed medication and healthcare professionals are encouraged to use a patient-centered approach. More importantly, information and support on the condition to promote coping strategies and self-efficacy should be adopted to improve quality of life. These findings can be implemented locally and globally to improve the quality of care provided to people living with peripheral neuropathy.

Treadmill workouts alleviate neuropathic allodynia and scratching behavior in rats following thoracotomy

BACKGROUND

The aim of the experiment was to investigate the effects of treadmill exercise on postthoracotomy pain and the expression of spinal pro-inflammatory and anti-inflammatory cytokines.

METHODS

Animals were randomly distributed into four groups: (a) sham surgery, (b) rats following 60 min thoracotomy and rib retraction (thoracotomy), (c) thoracotomy rats received treadmill training (thoracotomy+treadmill), and (d) sham surgery rats received treadmill training (sham surgery+treadmill). Treadmill workouts were started on postoperative day 10 (POD10) and lasted for 6 weeks (5 days per week). Rats were examined for cold allodynia using acetone and mechanical allodynia using von Frey hairs (in grams) at the surgical site. Spinal pro-inflammatory and anti-inflammatory cytokines were analyzed on PODs 28 and 49.

RESULTS

Both thoracotomy and thoracotomy+treadmill groups exhibited a decrease in mechanical force thresholds (g) and an increase in scratches per min on POD10. Mechanical hypersensitivity and incremental scratches lasted from POD14 and POD49 in the thoracotomy group. Although force thresholds and scratches remained not return to baseline, incremental force thresholds (p < 0.001) and diminutive scratches (p < 0.001) occurred after 6-week treadmill workouts. The rise in spinal interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations or the decline in spinal IL-10 concentration in thoracotomy+treadmill rats was less (p < 0.05) than thoracotomy rats without exercise.

CONCLUSIONS

Mechanical allodynia using von Frey filament testing and cold allodynia by acetone testing were improved in thoracotomy rats after treadmill workouts.. Treadmill exercise restrained excess pro-inflammatory cytokine expression but increased anti-inflammatory cytokine level in a rib retraction model.

Localized peripheral neuropathic pain: topical treatment with lidocaine 700 mg medicated plaster in routine clinical practice

Aim: To provide real-world evidence for the effectiveness and tolerability of lidocaine 700 mg medicated plaster (LMP) in localized peripheral neuropathic pain (l-PNP) treatment compared with first-line oral medications (OM). Patients & methods: This was a noninterventional, retrospective 6-month cohort study in patients refractory to at least one recommended OM, using anonymized medical care data from the German Pain eRegistry. Treatment groups were matched by propensity scoring, considering seven predefined confounding factors. The primary effectiveness end point was the absolute change in average pain intensity index from baseline at weeks 4, 12 and 24 of treatment and over the treatment period. Results: A total of 3081 datasets were retained per treatment group. LMP provided superior pain reductions and significantly greater improvements in pain-related impairments of daily living and quality of life with significantly better tolerability (p < 0.001 for all parameters) than OM. Conclusion: These real-world data confirm the effectiveness and good tolerability of LMP for l-PNP treatment under routine medical care.

New Serotonin-Norepinephrine Reuptake Inhibitors and Their Anesthetic and Analgesic Considerations

Serotonin-norepinephrine reuptake inhibitors (SNRIs) inhibit the presynaptic neuronal uptake of serotonin and norepinephrine and prolong the effects of the monoamines in the synaptic cleft within the central nervous system, leading to increased postsynaptic receptor activation and neuronal activities. Serotonin-norepinephrine reuptake inhibitors can have multiple clinical indications, including as the first-line agents for the management of depression and anxiety, and as analgesics in the treatment of chronic pain. The effects of reuptake inhibition of norepinephrine and serotonin are often dose-dependent and agent-dependent. There are five FDA-approved serotonin-norepinephrine reuptake inhibitors (desvenlafaxine, duloxetine, levomilnacipran, milnacipran and sibutramine) currently being marketed in the United States. As the COVID-19 pandemic significantly increased the incidence and prevalence of anxiety and depression across the country, there are significantly increased prescriptions of these medications perioperatively. Thus, anesthesiologists are more likely than ever to have patients administered with these agents and scheduled for elective or emergency surgical procedures. A thorough understanding of these commonly prescribed serotonin-norepinephrine reuptake inhibitors and their interactions with commonly utilized anesthetic agents is paramount. There are two potentially increased risks related to the continuation of SNRIs through the perioperative period: intraoperative bleeding and serotonin syndrome. SNRIs have some off-label uses, more new indications, and ever-increasing new applications in perioperative practice. This article aims to review the commonly prescribed serotonin-norepinephrine reuptake inhibitors and the current clinical evidence regarding their considerations in perioperative anesthesia and analgesia.

Topical Capsaicin for the Treatment of Neuropathic Pain

BACKGROUND

Neuropathic pain (NP) is an egregious problem worldwide. Due to the side-effects of oral drugs, drugs delivered directly to the affected area of pain are preferred.

OBJECTIVE

Capsaicin, a chemical compound isolated from chili peppers, is used as an analgesic in topical ointments and dermal patches to alleviate pain. Objective of the study is to review the application and functionality of topical capsaicin in treatment of neuropathic pain.

DATA SOURCES

To systematically review capsaicin's functions on NP, we retrieved articles from the PubMed database published in the last ten years.

STUDY ELIGIBILITY CRITERIA

The inclusion criteria were capsaicin and the use of capsaicin for the treatment of NP; on the other hand, articles were excluded according to the mentioned criteria such as abstracts, articles written in any language other than English, incomplete articles, and conference papers.

PARTICIPANTS AND INTERVENTIONS

Out of 265 articles, 108 articles were selected after filtering through the inclusion and exclusion criteria. The data and knowledge currently existing for capsaicin treatment in NP are summarized.

RESULTS

This review indicates that capsaicin effectively improves NP treatment without affecting the motor and large nerve fibres involved in sensory function. Transient receptor potential channel vanilloid type 1 (TRPV1) is the capsaicin receptor expressed in central and peripheral terminals of a sensitive primary nerve cell. Conclusions and implications of key findings: Topical capsaicin has a sensible safety profile and is effective in reducing NP. Therefore, studies over the last decade suggest that capsaicin might be a potential drug for NP treatment.

Localised neuropathic pain in the primary care setting: a cross-sectional study of prevalence, clinical characteristics, treatment patterns, quality of life and sleep performance

BACKGROUND

Localised Neuropathic Pain (LNP) is challenging to diagnose and manage in primary care.

OBJECTIVE

To describe clinical characteristics, treatment patterns, quality of life and sleep performance of patients with LNP and estimate its prevalence in primary care.

METHODS

Cross-sectional study in 4 European countries. Patients were identified using a screening tool for LNP. Patients completed the EQ-5D VAS score and Chronic Pain Sleep Inventory (CPSI).

RESULTS

There were 1030 LNP patients for analysis. They presented a median pain intensity of 6.0 (IQR 4.0-7.0) with a median duration of 30.9 months (IQR 12.0-75.3), despite 97% receiving pain treatment. Main sites affected were the limbs (62% upper/58% lower) and spine (41%). Main aetiologies were neuropathic low back pain (47%), post-surgical neuropathic pain (17%), and diabetic poly-neuropathy (12%). Thirty percent received a single analgesic (2% topical), while combinations comprised 43% systemic-systemic, 24% topical-systemic, 1% topical-topical. Medications included NSAIDs (45%), anticonvulsants (38%), WHO step 2 opioids (35%), and topical analgesics (27%). In the previous 6 months, 40% had switched treatment. The mean (SD) EQ-5D VAS score was 58 (22.3) and the mean (SD) EQ-5D summary score (UK tariff) was 0.62 (0.25). Patients had a CPSI mean index of 41/100, and sleeping pills were used by 33% of patients. The standardized prevalence of LNP by age and sex was 2.01% in the general population and 43.3% among chronic pain patients.

CONCLUSIONS

Many LNP patients reported pain intensities of six on a ten-point scale in average for durations longer than 2.5 years, with quality of life and sleep performance affected, with frequent treatment combinations and switches, suggesting suboptimal pain management.

Assessment of Pain and Associated Comorbidities: A Survey of Real Life Experiences Among Nurses in Italy

PURPOSE

Pain is a symptom that should be evaluated along with its comorbidities in order to plan an effective holistic treatment strategy involving specific pharmacological interventions, side effect management, psychological support, control of therapeutic effects over time, and dialogue with the patient and their relatives. In this holistic process of caring for patients with pain, nurses play a central role as they deal with suffering patients directly and continuously. The purpose of this study was to evaluate the types of pain identified by nurses in their daily clinical practice and the associated comorbidities (anamnestic history taking) by geographical region and to evaluate the pharmacological strategies used.

METHODS

A cross-sectional survey was performed among 696 registered nurses in Italy. Data were collected using an online questionnaire.

RESULTS

There was a significant difference between geographical regions in terms of reports of acute and chronic pain: acute pain was more frequently reported in the South (63.5%), while chronic pain was more frequent in the Central region (32.3%; p=0.0008). Additionally, chronic oncological pain was more frequent in the Northeast (29.6%), while chronic non-oncological pain was more frequently reported in the Central region (33.9%; p=0.0001). The underlying pain disorders reported were also different between geographical regions; rheumatic pain (21.8%) and neurological pain (18.6%) were more frequent in the Central region, while musculoskeletal pain was significantly more frequent in the South (43.4%; p=0.004). Anxiety, sleep disorders and somatization were found in acute pain (60.82%, 43.56% and 53.12%), while depression and mood disorders were more frequently detected in chronic pain condition (p<0.001).

CONCLUSION

Our study showed differences among Italian regions in pain assessment. Specific education on pain management nursing is essential for nurses. Promotion of optimal nursing care for people affected by pain is the main focus of pain management nursing. Nowadays, nurses should focus on personalized complex care and research in order to improve the patient's quality of life.

Expert Opinion: Exploring the Effectiveness and Tolerability of Capsaicin 179 mg Cutaneous Patch and Pregabalin in the Treatment of Peripheral Neuropathic Pain

Background and Objective

Treatment of peripheral neuropathic pain (PNP) remains a challenge. In the absence of clear predictors of response, clinical decision-making involves trial and error. While many classes of pharmacological agent are used and have shown efficacy, one of the most commonly used first-line treatments is pregabalin. However, in the 60% of PNP cases in which the pain is localized, a local treatment may be more suitable. This article will summarize the evidence for the relative effectiveness and tolerability of the capsaicin 179 mg patch and pregabalin in the treatment of PNP and highlight the expert opinion of the authors based on their own clinical experiences.

Results

When compared in a head-to-head trial in patients with PNP, capsaicin 179 mg patch provided non-inferior pain relief compared with an optimized dose of pregabalin, as well as a reduction in dynamic mechanical allodynia, faster onset of action, fewer systemic side effects, and greater treatment satisfaction. Adverse events associated with capsaicin patch are mainly application site reactions, compared with systemic and central nervous system effects with pregabalin. Studies indicate that capsaicin 179 mg patch is associated with a lower burden of therapy than pregabalin in terms of improved tolerability, lack of a daily pill burden, lack of drug-drug interactions, and increased regimen flexibility.

Conclusion

In localized neuropathic pain, evidence supports a pragmatic approach of using a local treatment before considering a systemic treatment. For treatment selection, the patient profile (eg, concomitant medication use, age) and the treatments' efficacy and tolerability profiles should be considered.

Circ_0005075 targeting miR-151a-3p promotes neuropathic pain in CCI rats via inducing NOTCH2 expression

Neuropathic pain is a most challenging diseases worldwide, caused by the injury of nerve system. CircularRNAs (circRNAs) are revealed to be involved in various diseases, includingneuropathic pain. However, the waycircRNAsparticipate in the progress ofneuropathic painstill needs further study. Identifyingthe possible circRNAexpression patterns of neuropathic painis of great significance to understand its underlying mechanism. Previously, circ_0005075 has been regarded as an important oncogene in multiple cancers and it has been characterized as an inflammation‑associated circRNA in various processes. Nevertheless, the functional role of circ_0005075 in neuropathic pain development is still poorly known. In our present study, we observed circ_0005075 was obviously increased in CCI rat models. Knockdown of circ_0005075 repressed thebehaviors of neuropathic pain including mechanical and thermal hyperalgesia. Moreover, loss of circ_0005075 could repress the neuroinflammation via targeting COX-2, IL-6 and TNF-α whereas inducing IL-10 in vivo. Additionally, we predicted miR-151a-3p as the potential target of circ_0005075 using bioinformatics analysis. We displayed that miR-151a-3p was greatly reduced in CCI rats and circ_0005075 reversed the repressive effect of miR-151a-3p on neuropathic pain. For another, NOTCH2 has been shown to induce a variety of intracellular responses correlated withneuropathic pain. Here, we found NOTCH2 expression was strongly induced in CCI rats and miR-151a-3p. In addition, circ_0005075 significantly rescued NOTCH2 expression, which could be repressed by miR-151a-3p. To sum up, we indicated that loss ofcirc_0005075relieved neuropathic pain progression by inducement of miR-151a-3p and inactivation of NOTCH2 signaling.

Topical Treatment of Localized Neuropathic Pain in the Elderly

The prevalence of neuropathic pain in the older population has been reported to be very high and is most commonly localized to a circumscribed area. Treatment failure is frequent in neuropathic pain and is accompanied by central side effects with recommended oral drugs acting on the central nervous system. A number of topical pharmaceuticals are available on prescription and also sold over the counter. This review in persons aged older than 60 years shows the efficacy of lidocaine 5% and capsaicin 8% for localized neuropathic pain while results with other pharmaceuticals are rather inconsistent. Local application of drugs has a very limited systemic effect and the pharmacological advantages of local over systemic treatment are particularly interesting in older persons who often have comorbidities and take multiple medications. However, more information is needed on the efficacy and safety of lidocaine 5% and capsaicin 8% in older old persons and on the long-term effects of these pharmaceuticals. These studies should also pave the way for research and development in the field of topical analgesics with a satisfactory level of evidence-based medicine.

Challenges of neuropathic pain: focus on diabetic neuropathy

Neuropathic pain is a frequent condition caused by a lesion or disease of the central or peripheral somatosensory nervous system. A frequent cause of peripheral neuropathic pain is diabetic neuropathy. Its complex pathophysiology is not yet fully elucidated, which contributes to underassessment and undertreatment. A mechanism-based treatment of painful diabetic neuropathy is challenging but phenotype-based stratification might be a way to develop individualized therapeutic concepts. Our goal is to review current knowledge of the pathophysiology of peripheral neuropathic pain, particularly painful diabetic neuropathy. We discuss state-of-the-art clinical assessment, validity of diagnostic and screening tools, and recommendations for the management of diabetic neuropathic pain including approaches towards personalized pain management. We also propose a research agenda for translational research including patient stratification for clinical trials and improved preclinical models in relation to current knowledge of underlying mechanisms.

Novel insights on the management of pain: highlights from the ‘Science of Relief’ meeting

The ‘Science of Relief’ event, held in Milan on 10–11 May 2019, was aimed at promoting dialog between different stakeholders among scientific associations, pharma industry, healthcare services and related institutions. The goal was to renew interest and attention on the management of pain, sharing new solutions in order to bring the patients and their quality of life to the center of attention. An international group of scientists and clinicians presented and discussed new and known evidence in the field of chronic pain, from physiopathology and diagnosis to the choice of appropriate and timely pharmacological treatments. This paper reports the highlights of those presentations.

[Update in the pharmacological treatment of neuropathic pain]

We provide an updated review of the pharmacological treatment of neuropathic pain, with emphasis on the latest evidence-based recommendations. Drugs proposed as first line include tricyclic antidepressants (particularly amitriptyline), serotonin-noradrenaline reuptake inhibitors (particularly duloxetine), pregabalin and gabapentin. Second-line treatments include 5% lidocaine medicated plasters and capsaicin 8% patches, only for peripheral neuropathic pain and tramadol; whereas potent opioids and botulinum toxin A (for peripheral neuropathic pain) are considered third-line treatments. Future perspectives include the development of new drugs and a more personalised therapeutic approach, which is made possible by recent progress in the assessment and understanding of neuropathic pain.

Assessment of Pharmacology, Safety, and Metabolic activity of Capsaicin Feeding in Mice

Capsaicin (CAP) activates transient receptor potential vanilloid subfamily 1 (TRPV1) to counter high-fat diet (HFD)-induced obesity. Several studies suggest that CAP induces the browning of white adipocytes in vitro or inguinal white adipose tissue (iWAT) in vivo. However, there is a lack of data on the dose-response for CAP to inhibit HFD-induced obesity. Therefore, we first performed experiments to correlate the effect of various doses of CAP to prevent HFD-induced weight gain in wild-type (WT) mice. Next, we performed a subchronic safety study in WT mice fed a normal chow diet (NCD ± CAP, 0.01% in NCD) or HFD ± CAP (0.01% in HFD) for eight months. We analyzed the expression of adipogenic and thermogenic genes and proteins in the iWAT from these mice, conducted histological studies of vital organs, measured the inflammatory cytokines in plasma and iWAT, and evaluated liver and kidney functions. The dose-response study showed that CAP, at doses above 0.001% in HFD, countered HFD-induced obesity in mice. However, no difference in the anti-obesity effect of CAP was observed at doses above 0.003% in HFD. Also, CAP, above 0.001%, enhanced the expression of sirtuin-1 and thermogenic uncoupling protein 1 (UCP-1) in the iWAT. Safety analyses suggest that CAP did not cause inflammation. However, HFD elevated plasma alanine aminotransferase and creatinine, caused iWAT hypertrophy and hepatic steatosis, and CAP reversed these. Our data suggest that CAP antagonizes HFD-induced metabolic stress and inflammation, while it does not cause any systemic toxicities and is well tolerated by mice.

Short-Term Effects of 10% Lidocaine Ointment on Allodynia in Cancer Pain: A Randomized, Double-Blind, Placebo-Controlled Crossover Study

Background: There is currently no established therapy for allodynia, which is a type of neuropathic pain. However, high concentrations of topical anesthetics can anesthetize the skin and increase the sensory threshold to tactile stimulation. Objective: We aimed to evaluate the short-term effects and safety of 10% lidocaine ointment for treating allodynia in cancer pain. Design: This was a randomized double-blind crossover study comparing the efficacies of 10% lidocaine ointment and placebo ointment for the treatment of static allodynia and spontaneous pain within 24 hours after ointment application, using a numerical rating scale (NRS). Setting/Subjects: The subjects were 25 cancer patients with current pain rating of ≥4 on NRS of static allodynia in cancer pain. Results: The NRS scores for static allodynia were significantly lower in the lidocaine group than in the placebo group at two to eight hours after initial ointment application. A total of 56% of patients (95% confidence interval 35%-77%) had NRS improvements of ≥50% at eight hours after lidocaine ointment application compared with 20% (3%-37%) after placebo ointment application. There was no interaction between time and group in terms of NRS values for spontaneous pain (p = 0.835), but a significant main effect of group was found, with NRS scores being significantly lower in the lidocaine group than in the placebo group (p = 0.027). There were no adverse events associated with lidocaine use. Conclusions: Lidocaine ointment 10% can alleviate allodynia for two to eight hours after application.

MicroRNA-7a ameliorates neuropathic pain in a rat model of spinal nerve ligation via the neurofilament light polypeptide-dependent signal transducer and activator of transcription signaling pathway

Neuropathic pain is a type of chronic pain induced by either central or peripheral nerve injury. MicroRNAs have been recently linked to many diseases, including neuropathic pain. However, the role of miR-7a in neuropathic pain still remains elusive. Thus, we aim to investigate the effects of miR-7a on neuropathic pain based on the spinal nerve ligation rat model. After establishment of spinal nerve ligation rat models, rats were infected with adeno-associated virus-neurofilament light polypeptide, adeno-associated virus-miR-7a or treated with metformin. The paw withdrawal threshold and paw withdrawal latency were assessed afterward, and the expression of miR-7a and neurofilament light polypeptide as well as their interaction was determined. Subsequently, miR-7a was overexpressed or silenced in dorsal root ganglion cells to investigate the role of miR-7a in neuropathic pain. Furthermore, the regulatory effect of neurofilament light polypeptide on neuropathic pain was detected using plasmid overexpressing neurofilament light polypeptide. Spinal nerve ligation rat model exhibited upregulation of neurofilament light polypeptide but downregulation of miR-7a. In addition, neurofilament light polypeptide accumulation or miR-7a inhibition decreased paw withdrawal threshold and paw withdrawal latency. Then, neurofilament light polypeptide accumulation or miR-7a inhibition was observed to increase the phosphorylation level of signal transducer and activator of transcription. miR-7a was found to directly target neurofilament light polypeptide and downregulate neurofilament light polypeptide. In addition, inhibiting the signal transducer and activator of transcription signaling pathway was also revealed to increase paw withdrawal threshold and paw withdrawal latency. Collectively, our study demonstrated that miR-7a ameliorated neuropathic pain via blocking the signal transducer and activator of transcription signaling pathway by repressing neurofilament light polypeptide. These findings, if taken further, can be of important clinical significance in treating patients with neuropathic pain.

Topical drug therapeutics for neuropathic pain

INTRODUCTION

Neuropathic pain (NP) is a particularly severe and intractable chronic condition that is not well treated by commonly recommended systemic pharmacological therapies, partly due to dose-limiting side effects or adverse events. The use of topical therapeutics for NP is growing and benefits from the reduced potential for adverse effects, as well as the ability to directly target peripheral pathological processes.

AREAS COVERED

The current review defines and describes the limitations of various commonly prescribed systemic pharmacological therapies for NP. It also provides a justification for increased research aimed at developing topical therapeutics for NP, particularly localized and peripheral NP. The review discusses the various classes of topical treatments used for NP, including agents that: block sensory inputs; activate inhibitory systems; provide mechanism-based therapeutics; are used in mucosal tissues; and include combinations that produce multimodal therapeutic effects.

EXPERT OPINION

There are arguments that the current topical therapeutics for NP rely too heavily on the use of local anesthetics and capsaicinoids, and more research is certainly needed on topical therapies that are multimodal and/or are targeted at the peripheral sources of pathology. The potential for novel topical therapeutics may be enhanced by further research on topical co-drugs, drug-drug salts, co-crystals and hydrates, and ionic liquids.

Local Application of Ultrasound Attenuates Neuropathic Allodynia and Proinflammatory Cytokines in Rats After Thoracotomy

BACKGROUND AND OBJECTIVES

We aimed to investigate the effect of therapeutic ultrasound (TU) on pain sensitivity and the concentration inflammatory cytokines in a thoracotomy rat model.

METHODS

Rats were distributed randomly into 4 groups: (1) sham operated, (2) thoracotomy and rib retraction (TRR), (3) TRR rats that received TU (TRR + TU-1), and (4) TRR rats that received TU with the ultrasound turned off (TRR + TU-0). Ultrasound was set at 1-MHz frequency (1.0-W/cm intensity and 100% duty cycle for 5 minutes), began on postoperative day (POD) 10, and then continued once per day, 5 days a week for 3 weeks.

RESULTS

The TRR and TRR + TU-0 rats encountered tactile hypersensitivity from PODs 10 to 28. Mechanical withdrawal thresholds were increased (all P < 0.05) following 5 days of TU, but thresholds remained significantly lower than baseline values. Therapeutic ultrasound increased the subcutaneous, but not body temperature. All groups receiving TRR demonstrated an increase in concentration of interleukin 1β and tumor necrosis factor α (TNF-α) on POD 14; however, the rise in TNF-α concentration was less in the TU-treated group than in the others. The decrease in concentration was greatest in the TRR + TU-1 group and similar between the TRR and TRR + TU-0 groups.

CONCLUSIONS

Mechanical allodynia was partially resolved with TU. Tissue temperature increased with ultrasound, while TU restricted the up-regulation of interleukin 1β and TNF-α around the injured intercostal nerve.

Localized neuropathic pain: an expert consensus on local treatments

BACKGROUND

Pain localization is one of the hallmarks for the choice of first-line treatment in neuropathic pain. This literature review has been conducted to provide an overview of the current knowledge regarding the etiology and pathophysiology of localized neuropathic pain (LNP), its assessment and the existing topical pharmacological treatments.

MATERIALS AND METHODS

Literature review was performed using Medline from 2010 to December 2016, and all studies involving LNP and treatments were examined. A multidisciplinary expert panel of five pain specialists in this article reports a consensus on topical approaches that may be recommended to alleviate LNP and on their advantages in clinical practice.

RESULTS

Successive international recommendations have included topical 5% lidocaine and 8% capsaicin for LNP treatment. The expert panel considers that these compounds can be a first-line treatment for LNP, especially in elderly patients and patients with comorbidities and polypharmacy. Regulatory LNP indications should cover the whole range of LNP and not be restricted to specific etiologies or sites. Precautions for the use of plasters must be followed cautiously.

CONCLUSION

Although there is a real need for more randomized controlled trials for both drugs, publications clearly demonstrate excellent risk/benefit ratios, safety, tolerance and continued efficacy throughout long-term treatment. A major advantage of both plasters is that they have proven efficacy and may reduce the risk of adverse events such as cognitive impairment, confusion, somnolence, dizziness and constipation that are often associated with systemic neuropathic pain treatment and reduce the quality of life. Topical modalities also may be used in combination with other drugs and analgesics with limited drug-drug interactions.

Characteristics, resource utilization and safety profile of patients prescribed with neuropathic pain treatments: a real-world evidence study on general practices in Europe - the role of the lidocaine 5% medicated plaster

OBJECTIVES

To identify characteristics, resource utilization, and safety profile of patients prescribed with lidocaine 5% medicated plaster, pregabalin, gabapentin, amitriptyline and duloxetine when experiencing pain in the real-world setting of general practitioners (GPs) in Europe.

METHODS

Retrospective analysis on real world data from IMS Health Longitudinal Patient Database. Patients with at least one prescription of the drugs of interest during 2014 were selected and those with a non-neuropathic pain-related diagnosis were excluded. Patients' demographic and clinical characteristics, resource utilization data and adverse drug reactions (ADRs) as described in the leaflet were extracted. The association between treatments and ADR occurrence was evaluated applying multivariate logistic models.

RESULTS

A total of 70,515 patients were selected from Italy, Germany, the UK, Spain and Belgium. Lidocaine 5% medicated plaster patients were the oldest in Italy, the UK and Spain and the most health impaired in Italy, Spain and Belgium. No relevant differences in the number of co-prescriptions, specialist visits, examinations and hospitalizations were found. Significantly less lidocaine 5% plasters patients experienced ADRs, with odds ratios in favor of lidocaine 5% medicated plasters ranging from 3.41 (p = .036) to 52.33 (p < .001).

CONCLUSIONS

Evidence from daily clinical practice in GP settings agrees with the findings from more controlled clinical-trial settings, with lidocaine 5% medicated plaster patients showing a better safety profile, but also a comparable level of resource utilization. A possible re-evaluation of the scientific value coming from this retrospective study in building up a diagnostic as well as a therapeutic algorithm is suggested.

A case series of trigeminal nerve injuries caused by periapical lesions of mandibular teeth

Aims Periapical lesions have been implicated in mandibular trigeminal sensory neuropathy. This study aimed to report on a case series of consecutive patients presenting with mandibular division trigeminal nerve injuries (TNI) caused by periapical lesions. Common presenting characteristics and possible strategies for management were also investigated.Materials and methods A retrospective study of 22 patients with TNI caused by periapical lesions. Data were extracted from patient records and analysed using Microsoft Excel and SPSS. Factors associated with TNI resolution were assessed using Student's t-Tests and one-way Analysis of Variance (ANOVA), where P <0.05 indicated statistical significance.Results Twenty-one patients had inferior alveolar nerve injuries (IANI) and one had a lingual nerve injury (LNI). The most commonly affected teeth were the first molars (11 patients; 50%). TNI symptoms included numbness, pain and/or paraesthesia. IANI resolved completely among five patients within a mean time of 4.7 months (range 1.5-12 months). Patients who showed complete resolution had the affected teeth extracted or primary endodontic treatment with antibiotics.Conclusions Patients with TNI caused by periapical lesions can suffer significantly from combined numbness, pain and paraesthesia. Resolution of these injuries may be maximised upon early diagnosis and treatment of the periapical lesion by tooth extraction or primary endodontic treatment.

Lidocaine 5% medicated plaster for localized neuropathic pain in thoracic surgical patients

CONTEXT

Neuropathic pain is a common and distressing symptom in thoracic surgical patients. When it consistently presents with measurable sensory changes in a circumscribed area, neuropathic pain can be diagnosed as localized neuropathic pain (LNP).

OBJECTIVE

The purpose of this study was to report the efficacy of lidocaine 5% medicated plaster (Lido5%P) in the treatment of LNP in thoracic surgical patients.

METHODS

We retrospectively reviewed the records of sixteen cancer and noncancer thoracic patients treated with Lido5%P for LNP. Patients had been assessed before and during treatment with standardized forms and questionnaires for pain intensity, sleep quality, drug dosages and adverse events.

RESULTS

Treatment with Lido5%P yielded a significant and lasting improvement in pain symptomatology. In oncological patients as an add-on therapy, Lido5%P improved pain intensity and sleep quality, and delayed opioid dose escalation. In non-oncological patients as monotherapy or in association with antineuropathic drugs, Lido5%P attenuated LNP. No local or systemic adverse events were recorded.

CONCLUSIONS

Lido5%P was effective in relieving thoracic LNP, and was well tolerated.

Treatment of postherpetic neuralgia with 5% lidocaine medicated plaster in elderly patients - subgroup analyses from three European clinical trials

OBJECTIVE

To investigate short- and long-term effectiveness and safety of the 5% lidocaine medicated plaster in the treatment of postherpetic neuralgia (PHN) in elderly patients (≥70 years of age).

METHODS

Data from three European clinical trials was compared after stratification according to age (<70 years and ≥70 years). Length of study phase investigated was 4 weeks for study 1, 8 weeks for study 2, and up to 12 months for study 3. Effectiveness outcome measures were pain intensity, pain relief, allodynia severity, Clinical Global Impression of Change, and Patient Global Impression of Change. Safety was assessed by adverse event documentation.

RESULTS

Mean average pain intensity improved in the elderly by -2.1 (SD 2.1) vs. -2.5 (SD 2.0) for <70 year old patients after 4 weeks, by -1.4 (SD 1.8) vs. -1.7 (SD 1.3) after 8 weeks, and by -1.5 (SD 1.9) vs. -2.7 (SD 2.2) after 12 months. Most patients presented with allodynia (>85% of elderly, >78% of younger patients) which was described by >51% as painful or extremely painful. Allodynia severity was markedly reduced in both groups during all three trials. Drug-related adverse events occurred in <20% of elderly and <15% of <70 year old patients and were mainly skin related.

CONCLUSIONS

The 5% lidocaine medicated plaster provided pain relief and marked reductions in allodynia severity in elderly PHN patients with an excellent safety profile under short- and long-term treatment supporting the addition of the plaster to the treatment armamentarium for this age group.

STUDY LIMITATIONS

All analyzed study phases were open-label and lacking a placebo control group.

Topical Treatment of Peripheral Neuropathic Pain: Applying the Evidence

CONTEXT

Patients with peripheral neuropathic pain (NP) may only achieve partial pain relief with currently recommended first-line oral treatments, which are also associated with systemic adverse events. Topical treatments are currently considered second- or third-line options, but a recent pharmacologic treatment algorithm has called for broader first-line use of these agents. This has highlighted a need to communicate the benefits associated with topical agents, in particular around the efficacy, targeted local action, and limited systemic availability resulting in minimal systemic adverse events and drug-drug interactions.

OBJECTIVES

This review aims to evaluate the evidence base for topical therapies currently used to treat peripheral NP, discuss the evidence comparing these treatments head-to-head with oral standard of care, and evaluate how they fit into treatment regimens in the "real world."

METHODS

This is a narrative review.

RESULTS

Two topical treatments are currently licensed: lidocaine 5% medicated plaster (post-herpetic neuralgia) and the capsaicin 8% patch (peripheral NP). When compared head to head with the oral standard of care (pregabalin), the lidocaine 5% medicated plaster provided similar relief of pain associated with post-herpetic neuralgia but did not meet the primary predefined criteria for noninferiority. The capsaicin 8% patch, however, demonstrated noninferior efficacy when compared head-to-head with pregabalin across a wide range of peripheral NP etiologies. Importantly, both treatments demonstrated effective pain relief without the systemic adverse events associated with oral therapies.

CONCLUSION

First-line use of topical agents may be of particular benefit in patients where the safety and tolerability of oral therapy is a concern.

The 5% Lidocaine-Medicated Plaster: Its Inclusion in International Treatment Guidelines for Treating Localized Neuropathic Pain, and Clinical Evidence Supporting its Use

When peripheral neuropathic pain affects a specific, clearly demarcated area of the body, it may be described as localized neuropathic pain (LNP). Examples include postherpetic neuralgia and painful diabetic neuropathy, as well as post-surgical and post-traumatic pain. These conditions may respond to topical treatment, i.e., pharmaceutical agents acting locally on the peripheral nervous system, and the topical route offers advantages over systemic administration. Notably, only a small fraction of the dose reaches the systemic circulation, thereby reducing the risk of systemic adverse effects, drug–drug interactions and overdose. From the patient’s perspective, the analgesic agent is easily applied to the most painful area(s). The 5% lidocaine-medicated plaster has been used for several years to treat LNP and is registered in approximately 50 countries. Many clinical guidelines recommend this treatment modality as a first-line option for treating LNP, particularly in frail and/or elderly patients and those receiving multiple medications, because the benefit-to-risk ratios are far better than those of systemic analgesics. However, some guidelines make only a weak recommendation for its use. This paper considers the positioning of the 5% lidocaine-medicated plaster in international treatment guidelines and how they may be influenced by the specific criteria used in developing them, such as the methodology employed by randomized, placebo-controlled trials. It then examines the body of evidence supporting use of the plaster in some prevalent LNP conditions. Common themes that emerge from clinical studies are: (1) the excellent tolerability and safety of the plaster, which can increase patients’ adherence to treatment, (2) continued efficacy over long-term treatment, and (3) significant reduction in the size of the painful area. On this basis, it is felt that the 5% lidocaine-medicated plaster should be more strongly recommended for treating LNP, either as one component of a multimodal approach or as monotherapy.

5% Lidocaine-medicated plaster for the treatment of chronic peripheral neuropathic pain: complex regional pain syndrome and other neuropathic conditions

Objectives

Chronic neuropathic pain and chronic complex regional pain syndrome (CRPS), in particular, are debilitating and difficult-to-treat conditions that have a strong impact on patient’s quality of life. The aim of this study was to evaluate the effectiveness of 5% lidocaine-medicated plaster as add-on therapy in patients with chronic peripheral neuropathic pain conditions, including CRPS.

Patients and methods

This was a single-center, prospective, observational study set in a specialized pain unit of a tertiary hospital in Spain. A total of 56 patients with long-standing peripheral neuropathic pain, ten of them with CRPS, received 5% lidocaine-medicated plaster as add-on analgesic therapy for 6 months.

Results

After 6 months of treatment, a ≥50% reduction in pain intensity was attained by 75% of patients, as measured by numeric rating scale (NRS) for pain. The average NRS score was reduced by 61% (4.7 points), from a baseline mean score of 7.8 to an end point mean score of 3.1. Marked improvements were also observed in the CRPS group: six out of ten patients achieved a ≥50% reduction in NRS score, and the average NRS score for patients with CRPS was reduced by 51% (4.0 points), from a baseline mean score of 7.9 to an end point mean score of 3.9. The improvements in pain intensity were partially translated into a decrease in disability index and in anxiety levels.

Conclusion

5% Lidocaine-medicated plaster may be useful as add-on therapy for a number of peripheral neuropathic pain conditions, including CRPS.

Psychological Treatments and Psychotherapies in the Neurorehabilitation of Pain: Evidences and Recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation

BACKGROUND

It is increasingly recognized that treating pain is crucial for effective care within neurological rehabilitation in the setting of the neurological rehabilitation. The Italian Consensus Conference on Pain in Neurorehabilitation was constituted with the purpose identifying best practices for us in this context. Along with drug therapies and physical interventions, psychological treatments have been proven to be some of the most valuable tools that can be used within a multidisciplinary approach for fostering a reduction in pain intensity. However, there is a need to elucidate what forms of psychotherapy could be effectively matched with the specific pathologies that are typically addressed by neurorehabilitation teams.

OBJECTIVES

To extensively assess the available evidence which supports the use of psychological therapies for pain reduction in neurological diseases.

METHODS

A systematic review of the studies evaluating the effect of psychotherapies on pain intensity in neurological disorders was performed through an electronic search using PUBMED, EMBASE, and the Cochrane Database of Systematic Reviews. Based on the level of evidence of the included studies, recommendations were outlined separately for the different conditions.

RESULTS

The literature search yielded 2352 results and the final database included 400 articles. The overall strength of the recommendations was medium/low. The different forms of psychological interventions, including Cognitive-Behavioral Therapy, cognitive or behavioral techniques, Mindfulness, hypnosis, Acceptance and Commitment Therapy (ACT), Brief Interpersonal Therapy, virtual reality interventions, various forms of biofeedback and mirror therapy were found to be effective for pain reduction in pathologies such as musculoskeletal pain, fibromyalgia, Complex Regional Pain Syndrome, Central Post-Stroke pain, Phantom Limb Pain, pain secondary to Spinal Cord Injury, multiple sclerosis and other debilitating syndromes, diabetic neuropathy, Medically Unexplained Symptoms, migraine and headache.

CONCLUSIONS

Psychological interventions and psychotherapies are safe and effective treatments that can be used within an integrated approach for patients undergoing neurological rehabilitation for pain. The different interventions can be specifically selected depending on the disease being treated. A table of evidence and recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation is also provided in the final part of the paper.