Effectiveness of the capsaicin 8% patch in the management of peripheral neuropathic pain in European clinical practice: the ASCEND study

Effect of Cooling Capsaicin Application Site on Reducing Burning Sensation in Neuropathic Pain Patients: A Randomized Controlled Trial

PURPOSE

Treatment of localized neuropathic pain continues to represent an unmet need. The primary objective of the present study was to evaluate the efficacy of cryotherapy to reduce the burning pain induced by capsaicin (8%) patches (QUTENZA) in a neuropathic pain cohort. We also investigated subsequent neuropathic pain during an 8-week follow-up.

DESIGN

The present work resulted from a prospective, randomized, two-center, open-label, interventional French trial.

METHODS

This study aimed to investigate the effects of cooling of the application area of QUTENZA patches. Visual analog scale (VAS) scores were measured 30 and 60 minutes after patch application. Weekly neuropathic VAS scores were then collated for 2 months. Ninety-nine patients were included and randomized into a cryotherapy group (n = 50 [80% women], median age = 51 years old) and a no cryotherapy group (n = 49 [69% women], median age = 48 years old).

RESULTS

Cooling at the application site of the patch resulted in a reduction by 3.20 in burning pain VAS score at 60 minutes, with no cooling VAS 6.99 (95% CI [6.2, 7.77]) versus 3.78 (95% CI [3, 4.56]) for cryotherapy. Neuropathic VAS pain scores over the follow-up period were not statistically different.

CONCLUSIONS

Cryotherapy at the application site significantly reduced the burning pain induced by capsaicin patches but had no effect on neuropathic pain for the 8 weeks following application.

CLINICAL IMPLICATIONS

The use of cooling during capsaicin patch application, by ameliorating the therapeutic alliance, improves the clinical management of neuropathic pain. © 20XX by the American Society for Pain Management Nursing.

Topical treatment of chemotherapy-induced peripheral neuropathy (CIPN) with high-concentration (179 mg) capsaicin patch in breast cancer patients - results of the QUCIP study

Background

Chemotherapy-induced peripheral neuropathy (CIPN) following oral or intravenous chemotherapy often results in neuropathic pain, accompanied by symptoms such tingling, burning and hypersensitivity to stimuli, with a notable decline in quality of life (QoL). Effective therapies for CIPN are lacking, with a high demand for analgesics to address this issue. The QUCIP study aimed to assess the effectiveness of high concentration (179 mg) capsaicin patch (HCCP) in alleviating neuropathic pain and associated symptoms in breast cancer patients with confirmed CIPN.

Methods

QUCIP is a prospective, multi-center observational study spanning 36 weeks with up to three HCCP treatments. Initial treatment (visit V0) was followed by two telephone contacts (T1, T2) and subsequent face-to-face visits every 12 weeks or upon retreatment (visits V1-V3). 73 female patients with painful CIPN post neoadjuvant/adjuvant breast cancer therapy were enrolled. Primary endpoint was the reduction of neuropathic pain symptom score (painDETECT®). Secondary endpoints included improvements in CIPN-specific QoL (QLQ-CIPN20), reductions in pain intensity (numeric pain rating scale, NPRS), and achievement of ≥ 30% and ≥ 50% pain reduction.

Results

Median age was 61 years, with 52.0% of patients experiencing peripheral neuropathic pain for > 1 year (> 2 years: 34.2%). The painDETECT® score significantly decreased from baseline (19.71 ± 4.69) to 15.80 ± 6.20 after initial treatment (p < 0.0001) and continued to decrease at follow-up visits. The NPRS indicated significant pain intensity reduction at each time point, particularly pronounced in patients receiving three HCCP treatments. Clinically significant pain relief of ≥ 30% increased from 25.0% at week 4 (T2) to 36.2%, 43.5%, and 40.0% at weeks 12 (V1), 24 (V2), and 36 (V3), respectively. The percentage of patients achieving pain relief of ≥ 50% increased from 14.7% at T2 to 15.5%, 21.7% and 32.5% at V1, V2 and V3, respectively. Patients further reported a significant improvement in their CIPN-related QoL throughout the study. Adverse drug reactions (ADRs) mainly included application site reactions.

Conclusion

In this study, HCCP shows benefit in managing CIPN in real-world settings. The data demonstrate a sustained and progressive reduction in neuropathic pain and symptomatology, confirming the clinical benefit of repeated treatment observed in former clinical trials. HCCP treatment has also the potential to significantly improve the QoL associated with CIPN. The safety profile of HCCP was confirmed, supporting its use in clinical practice.

Does Topical Capsaicin Affect the Central Nervous System in Neuropathic Pain? A Narrative Review

Research has been conducted investigating the neuronal pathways responsible for the generation of chronic neuropathic pain, including the components of it in conditions such as chronic post-surgical pain, phantom limb pain, and cluster headaches. Forming part of the management of such conditions, capsaicin as a molecule has proven effective. This review has investigated the central nervous system modifications exhibited in such conditions and the pharmacological mechanisms of capsaicin relevant to this. The current paradigm for explaining topical capsaicin-induced analgesia is that TRPV1-mediated calcium ion influx induces calpain, in turn causing axonal ablation and functional defunctionalisation in the PNS (Peripheral Nervous System). Demonstrated through the analysis of existing data, this review demonstrates the changes seen in the CNS (Central Nervous System) in chronic neuropathic pain, as well as some of the evidence for capsaicin modulation on the CNS. Further supporting this, the specific molecular mechanisms of capsaicin-induced analgesia will also be explored, including the action of TRPV1, as well as discussing the further need for clinical research into this area of uncertainty due to the limited specific data with suitable parameters. Further research this review identified as potentially useful in this field included fMRI (functional Magnetic Resonance Imaging) studies, though more specific observational studies of patients who have already been administered capsaicin as a current treatment may prove helpful in studying the modification of the CNS in the long term.

Adhesive capsaicin 8% patch for improved control of pain caused by chemotherapy-induced peripheral neuropathy in patients with multiple myeloma: A single-centre, seven-case series

BACKGROUND

Capsaicin is a highly selective agonist of the transient receptor potential vanilloid 1. The adhesive capsaicin patch provides a high capsaicin concentration (8%) directly in the painful area - its efficacy in benign peripheral neuropathic pain (diabetic neuropathy or postherpetic neuralgia) has recently been described in the literature. However, there is scant evidence of its efficacy in chemotherapy-induced peripheral neuropathy (CIPN). This is a concern for patients with multiple myeloma, who suffer from peripheral neuropathic pain induced by first-line treatments (bortezomib or thalidomide).

AIM

To describe improved control of CIPN in patients with multiple myeloma using adhesive capsaicin 8% patch.

METHODS

We opted for a retrospective observational case series. Between October 2017 and October 2020, we collected clinical data from adult multiple myeloma patients affected by CIPN who were administered the capsaicin 8% patch in our palliative care outpatient clinic. We compiled Numerical Pain Rating Scale (NPRS) scores, patients' medication needs and performance status before and after patch application.

RESULTS

Two women and five men with an average age of 62.85 years received bortezomib. Two patients (28.57% of the sample) also received thalidomide. The average NPRS score before patch application was 6.42/10. Five of the seven patients (71.42%) received a mean daily oral morphine dose of 52.85 mg/day, five (71.42%) received gabapentinoids and one (14.28%) received antidepressants. The average NPRS score decreased to 4/10 seven days after patch application, while the mean daily oral morphine dose remained stable. Performance status improved slightly in two patients (28.57%) and remained stable in the rest. One patient (14.28%) required an extra analgesic dose during patch application.

CONCLUSIONS

Capsaicin 8% patch application appears to reduce pain intensity in patients with multiple myeloma suffering from CIPN.

Neuropathic Pain in Aged People: An Unresolved Issue Open to Novel Drug Approaches, Focusing on Painful Diabetic Neuropathy

A majority of older patients suffer from neuropathic pain (NP) that significantly alters their daily activities and imposes a significant burden on health care. Multiple comorbidities and the risk of polypharmacy in the elderly make it challenging to determine the appropriate drug, dosage, and maintenance of therapy. Age-dependent processes play a contributing role in neuropathy given that diabetic neuropathy (DN) is the most common form of neuropathy. This narrative review is mainly focused on the drug treatment approach for neuropathy-associated pain in aged people including both drugs and dietary supplements, considering the latter as add-on mechanism-based treatments to increase the effectiveness of usual treatments by implementing their activity or activating other analgesic pathways. On one hand, the limited clinical studies assessing the effectiveness and the adverse effects of existing pain management options in this age segment of the population (> 65), on the other hand, the expanding global demographics of the elderly contribute to building up an unresolved pain management problem that needs the attention of healthcare providers, researchers, and health authorities as well as the expansion of the current therapeutic options.

Evaluation of 8% Capsaicin Patches in Chemotherapy-Induced Peripheral Neuropathy: A Retrospective Study in a Comprehensive Cancer Center

Introduction: Chemotherapy-induced peripheral neuropathy (CIPN) is often painful and can arise during or after the end of oncological treatments. They are mostly induced by platinum salts, taxanes, and immunotherapies. Their incidence is estimated between 19 and 85%. They can require a chemotherapy dose reduction or early termination. The European Society for Medical Oncology (ESMO) recommends high-concentration capsaicin patch (HCCP) in second line for the treatment of painful CIPN. This treatment induces a significative pain relief but only shown by low-powered studies. The objective of this study was to evaluate efficacy and tolerability of HCCP applications in CIPN. Methods: This monocentric observational retrospective real-world-data study of the CERCAN cohort took place in the Western Cancer Institute's Anaesthesiology and Pain Department at Angers, France. Independent pain physicians completed the CGIC (Clinician Global Impression of Change) for each patient who benefited from HCCP applications for painful CIPN starting from 1 January 2014 to 22 December 2021, based on the collected data after every patch application. Results: A total of 57 patients (80.7% women) was treated with HCCP for painful CIPN, and 184 applications were realized, consisting of 296 sessions. CGIC found an important or complete pain relief for 61 applications (33.2%, corresponding to 43.9% patients). We found less efficacy for platinum-salts-induced CIPN compared to others (p = 0.0238). The efficacy was significatively higher for repeated applications when HCCP was used in second line compared to third line (p = 0.018). The efficacy of HCCP was significatively higher starting the third application (p = 0.0334). HCCPs were mainly responsible for local adverse events found in 66.6% patients (65.1% burning or painful sensation, 21.1% erythema). Conclusion: HCCP applications in painful CIPN induce an important pain relief with a global satisfying tolerability.

A Pan-Global Study of Bacterial Leaf Spot of Chilli Caused by Xanthomonas spp

Bacterial Leaf Spot (BLS) is a serious bacterial disease of chilli (Capsicum spp.) caused by at least four different Xanthomonas biotypes: X. euvesicatoria pv. euvesicatoria, X. euvesicatoria pv. perforans, X. hortorum pv. gardneri, and X. vesicatoria. Symptoms include black lesions and yellow halos on the leaves and fruits, resulting in reports of up to 66% losses due to unsalable and damaged fruits. BLS pathogens are widely distributed in tropical and subtropical regions. Xanthomonas is able to survive in seeds and crop residues for short periods, leading to the infections in subsequent crops. The pathogen can be detected using several techniques, but largely via a combination of traditional and molecular approaches. Conventional detection is based on microscopic and culture observations, while a suite of Polymerase Chain Reaction (PCR) and Loop-Mediated Isothermal Amplification (LAMP) assays are available. Management of BLS is challenging due to the broad genetic diversity of the pathogens, a lack of resilient host resistance, and poor efficacy of chemical control. Some biological control agents have been reported, including bacteriophage deployment. Incorporating stable host resistance is a critical component in ongoing integrated management for BLS. This paper reviews the current status of BLS of chilli, including its distribution, pathogen profiles, diagnostic options, disease management, and the pursuit of plant resistance.

Capsaicin for Weight Control: “Exercise in a Pill” (or Just Another Fad)?

Medical management of obesity represents a large unmet clinical need. Animal experiments suggest a therapeutic potential for dietary capsaicin, the pungent ingredient in hot chili peppers, to lose weight. This is an attractive theory since capsaicin has been a culinary staple for thousands of years and is generally deemed safe when consumed in hedonically acceptable, restaurant-like doses. This review critically evaluates the available experimental and clinical evidence for and against capsaicin as a weight control agent and comes to the conclusion that capsaicin is not a magic “exercise in a pill”, although there is emerging evidence that it may help restore a healthy gut microbiota.

The role of the capsaicin 8% patch in the treatment of painful diabetic peripheral neuropathy

Treatment of painful diabetic peripheral neuropathy (PDPN) is challenging and often limited by drug tolerability and adverse effects. This review article focuses on the high-dose (8%) capsaicin patch that allows for improved efficacy and reduced application frequency in comparison to low-dose capsaicin formulations. Systemic absorption is minimal resulting in fewer systemic side effects than first-line oral medications. There is evidence that capsaicin patch treatment is well-tolerated, safe and provides effective pain relief maintained for several weeks; well-powered studies are needed to confirm these findings. The capsaicin 8% patch may benefit patients at high risk for adverse effects from oral medication, polypharmacy or inadequate pain relief from first-line therapies.

Capsaicin 8% Patch and Chronic Postsurgical Neuropathic Pain

(1) Background: Surgery is a frequent cause of persistent pain, defined chronic post-surgical pain (CPSP). The capsaicin 8% patch (Qutenza^®) is approved for the treatment of postherpetic neuralgia (PHN) and for diabetic peripheral neuropathy (DPN) of the feet. We propose a review of the literature on use of the capsaicin 8% patch to treat neuropathic pain associated with surgery; (2) Methods: We identified the articles by searching electronic databases using a combination of such terms as “capsaicin 8% patch”, “Qutenza^®”, and “chronic postsurgical pain”; (3) Results: We identified 14 selected studies reporting on a total of 632 CPSP cases treated with capsaicin 8% patch. Treatment with the capsaicin 8% patch significantly reduced the average pain intensity. Only 5 studies reported adverse events (AEs) after the patch application. The most common AEs were erythema, burning sensation and pain; (4) Conclusions: Our review indicate that capsaicin 8% patch treatment for CPSP is effective, safe and well tolerated, but randomized controlled trials on efficacy, safety and tolerability should be conducted.

Capsaicin 179-mg cutaneous patch in the treatment of post-surgical neuropathic pain: a scoping review of current evidence and place in therapy

INTRODUCTION

The use of topical agents has been suggested for post-surgical neuropathic pain. A high-concentration capsaicin 179-mg cutaneous patch (Qutenza™) is licensed in adults for chronic neuropathic pain in the EU, and neuropathic pain with post-herpetic neuralgia and neuropathic pain with diabetic peripheral neuropathy in the USA. This article aims to describe the use of a topical capsaicin 179-mg cutaneous patch in the treatment of PSNP.

AREA COVERED

This narrative review presents the relevant clinical aspects of the use of a topical capsaicin 179-mg cutaneous patch for the treatment of post-surgical neuropathic pain (PSNP). Randomized control trials, observational studies, case series, and reports investigating the clinical use of the capsaicin patch were searched through MEDLINE, EMBASE, AMED, Cochrane Library, CINAHL, Web of Science, and ROAD databases. Trials from citation lists of reviewed articles and hand-searching were added. The search concluded in September 2020. 10/20 articles were considered.

EXPERT OPINION

Some clinical studies demonstrated the efficacy of the capsaicin 179-mg patch in PSNP as monotherapy and concomitant treatment with oral treatments. This topical treatment of PSNP is better tolerated and accepted compared with systemic treatments. To maximize the effectiveness of the treatment, correct administration recommendations should be followed.

Treatment Strategies for Generator Pocket Pain

OBJECTIVE

Generator site pain is a relatively common phenomenon in patients undergoing spinal cord stimulation (SCS) that complicates management and effective pain relief. This pain may be managed conservatively, with repositioning of the battery and, in some cases, with explant. Here we explore our experience with management of generator site pain ("pocket pain") in a large single-center study.

METHODS

All SCS permanent implants and implantable pulse generator (IPG) placements over 9 years were reviewed. Of 785 cases, we identified 43 patients with pocket pain (5.5%). Demographics and treatments of the pocket pain cohort were analyzed.

RESULTS

The mean age (± SEM) of the pocket pain cohort was 46.86 ± 1.06, and there were 10/33 males/females. Females were overrepresented in pocket pain cohort (76.7%) when compared with the total SCS cohort (59.0%) (X2 = 5.93, P = 0.015). Diagnosis included failed back surgery syndrome (51.2%), complex regional pain syndrome (23.3%), and chronic neuropathic pain (25.5%). No patients improved with conservative therapy. All patients either went on to revision (n = 23) or explant (n = 20). Time from initial surgery to development of pocket pain was 7.5 months (range: 0.3-88) and from pocket pain to revision surgery was 4.5 months (range: 0.4-26). In addition, significantly more pocket pain patients (65.1%) had workers' compensation (WC) insurance compared with patients without pocket pain (24.9%) (X2 = 33.3, P < 0.001).

CONCLUSION

In our institutional experience, pocket pain was inadequately managed with conservative treatments. Being female and having SCS filed under WC increased risk of pocket pain. Future work will explore the nuances in device placement based on body shape and manual activity responsibilities.

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.

Progressive Response to Repeat Application of Capsaicin 179 mg (8% w/w) Cutaneous Patch in Peripheral Neuropathic Pain: Comprehensive New Analysis and Clinical Implications

Objective

To investigate the efficacy of repeated application of capsaicin 179 mg cutaneous patch in nonresponders to the first application.

Design

Post hoc, as-treated analysis of two prospective trials (STRIDE and PACE) with 52-week follow-up.

Blinding

Open-label.

Setting

Multicenter clinical trial.

Subjects

STRIDE: nondiabetic neuropathic pain; PACE: painful diabetic peripheral neuropathy.

Methods

Patients were divided according to number of applications needed before attainment of a ≥30% reduction in average pain intensity (question 5 of the Brief Pain Inventory [BPI-Q5]). We assessed the change from baseline in average pain intensity (BPI-Q5), mean “interference with sleep” score, Patient Global Impression of Change, quality of life (QOL) via the EuroQol 5-dimension, and Self-Assessment of Treatment.

Results

In STRIDE and PACE, respectively, n = 306 and n = 313 received the capsaicin patch; n = 60 and n = 96 had a response after the first application, n = 33 and n = 68 after the second, and n = 11 and n = 43 after the third. Among patients without a ≥30% reduction in pain intensity at 3 months, in STRIDE and PACE, respectively, 23.3% and 28.1% achieved a ≥30% reduction at 6 months, increasing to 33.9% and 45.7% at 12 months. Similar results were obtained when a decrease of ≥50% was used as the responder definition. Progressive improvements in pain intensity in slower responders reached levels similar to those in early responders at month 12 and were accompanied by improvements in sleep, QOL, and patient satisfaction.

Conclusions

Although some patients with peripheral neuropathic pain experience rapid improvements with a single treatment of capsaicin 179 mg patch, some may require two or three treatments before an initial response is observed. Similar benefits for pain, sleep, and QOL can be achieved in early and late responders.

Post Laparoscopy Neuropathic Pain Treated by Capsaicin 8% Dermal Patch

We report a case of chronic left flank neuropathic pain after a renal cyst removal in a 54-year old female. The patient was treated with a single application of capsaicin 8% dermal patch, with satisfactory results at an eight week follow up visit. Capsaicin 8% dermal patch could be a suitable alternative in the conservative management of post laparoscopy neuropathic pain, as it can be effective and has a well-tolerated safety profile.

Capsaicin 8% patch Qutenza and other current treatments for neuropathic pain in chemotherapy-induced peripheral neuropathy (CIPN)

PURPOSE OF REVIEW

Current oral treatments for neuropathic pain associated with chemotherapy-induced peripheral neuropathy (CIPN) have limited clinical efficacy, and undesirable side-effects. Topically delivered treatments have the advantage of avoiding CNS side-effects, while relieving pain. We have reviewed treatments of neuropathic pain associated with CIPN, focusing on the Capsaicin 8% patch, which can provide pain relief for up to 3 months or longer after a single 30-60-min application.

RECENT FINDINGS

Capsaicin 8% patch is a licensed treatment in the EU/UK for neuropathic pain and shown to be safe and effective in providing pain relief for patients with CIPN. Repeated daily oral or topical administrations are not required, as with other current treatments. The side-effects are transient and restricted to the time around patch application. New evidence suggests the Capsaicin 8% patch can promote the regeneration and restoration of skin nerve fibres in CIPN, in addition to the pain relief.

SUMMARY

The Capsaicin 8% patch is now often a preferred a treatment option for localised neuropathic pain conditions, including the feet and hands in patients with CIPN. Capsaicin 8% patch can be repeated three-monthly, if needed, for a year. In addition to pain relief, it may have a disease-modifying effect.

Chemotherapy-induced peripheral neuropathy (CIPN): current therapies and topical treatment option with high-concentration capsaicin

Cancer diagnosis and treatment are drastic events for patients and their families. Besides psychological aspects of the disease, patients are often affected by severe side effects related to the cancer itself or as a result of therapeutic interventions. Particularly, chemotherapy-induced peripheral neuropathy (CIPN) is the most prevalent neurological complication of oral or intravenous chemotherapy. The disorder may require dose reduction of chemotherapy and is accompanied by multiple symptoms with long-term functional impairment affecting quality of life (QoL), e.g., sensory and functional deteriorations as well as severe pain. Although CIPN may reverse or improve after termination of the causative chemotherapy, approximately 30–40% of patients are faced with chronicity of the symptoms. Due to the advantages in cancer diagnosis and treatments, survival rates of cancer patients rise and CIPN may occur even more frequently in the future. In this review, we summarize current recommendations of leading national and international societies regarding prevention and treatment options in CIPN. A special focus will be placed on current evidence for topical treatment of CIPN with high-dose capsaicin. Finally, an algorithm for CIPN treatment in clinical practice is provided, including both pharmacologic and non-pharmacologic modalities based on the clinical presentation.

Herbal Medicine for Pain Management: Efficacy and Drug Interactions

Complementary and alternative medicines such as herbal medicines are not currently part of the conventional medical system. As the popularity of and global market for herbal medicine grows among all age groups, with supporting scientific data and clinical trials, specific alternative treatments such as herbal medicine can be reclassified as a practice of conventional medicine. One of the most common conditions for which adults use herbal medicine is pain. However, herbal medicines carry safety concerns and may impact the efficacy of conventional therapies. Unfortunately, mechanisms of action are poorly understood, and their use is unregulated and often underreported to medical professionals. This review aims to compile common and available herbal medicines which can be used as an alternative to or in combination with conventional pain management approaches. Efficacy and safety are assessed through clinical studies on pain relief. Ensuing herb–drug interactions such as cytochrome modulation, additive and synergistic effects, and contraindications are discussed. While self-management has been recognized as part of the overall treatment strategy for patients suffering from chronic pain, it is important for practitioners to be able to also optimize and integrate herbal medicine and, if warranted, other complementary and alternative medicines into their care.

A critical review of the capsaicin 8% patch for the treatment of neuropathic pain associated with diabetic peripheral neuropathy of the feet in adults

INTRODUCTION

Diabetes is an increasingly prevalent disorder affecting nearly 1-in-5 adults, of which half will experience diabetic peripheral neuropathy (DPN) and a quarter will suffer from diabetic peripheral nerve pain (DPNP), severely impacting quality of life. The currently approved treatment options are typically centrally acting agents whose use is limited by systemic effects and drug interactions. The capsaicin 8% dermal patch was recently approved by the U.S. FDA for the treatment of DPNP.

AREAS COVERED

The authors review the available literature regarding the use of high-concentration capsaicin 8% patch for the treatment of diabetic peripheral neuropathy and neuropathic pain and discuss implementing its use in clinical practice.

EXPERT OPINION

The high-concentration capsaicin 8% patch is an effective and well-tolerated treatment option for treating DPNP. Capsaicin 8% patch may be used alone or in combination with other oral therapies and can provide rapid and sustained neuropathic pain relief following a single application and is safe and effective when used long term.

Injectable Capsaicin for the Management of Pain Due to Osteoarthritis

Capsaicin is a potent agonist of the TRPV1 channel, a transduction channel that is highly expressed in nociceptive fibers (pain fibers) throughout the peripheral nervous system. Given the importance of TRPV1 as one of several transduction channels in nociceptive fibers, much research has been focused on the potential therapeutic benefits of using TRPV1 antagonists for the management of pain. However, an antagonist has two limitations. First, an antagonist in principle generally only affects one receptor. Secondly, most antagonists must have an ongoing presence on the receptor to have an effect. Capsaicin overcomes both liabilities by disrupting peripheral terminals of nociceptive fibers that express TRPV1, and thereby affects all of the potential means of activating that pain fiber (not just TRPV1 function). This disruptive effect is dependent on the dose and can occur within minutes. Thus, unlike a typical receptor antagonist, continued bioavailability at the level of the receptor is not necessary. By disrupting the entire terminal of the TRPV1-expressing nociceptive fiber, capsaicin blocks all the activation mechanisms within that fiber, and not just TRPV1 function. Topical capsaicin, an FDA approved treatment for neuropathic pain, addresses pain from abnormal nociceptor activity in the superficial layers of the skin. Effects after a single administration are evident over a period of weeks to months, but in time are fully reversible. This review focuses on the rationale for using capsaicin by injection for painful conditions such as osteoarthritis (OA) and provides an update on studies completed to date.

The efficacy and safety profile of capsaicin 8% patch versus 5% Lidocaine patch in patients with diabetic peripheral neuropathic pain: a randomized, placebo-controlled study of south Asian male patients

Aims

Diabetic peripheral neuropathy affects up to 60% of individuals and often leads to foot ulceration and eventual amputation. When oral therapy has failed to achieve pain relief, the first line local treatment is the 5% lidocaine-medicated plaster which provides local relief. Capsaicin 8% patch is considered a promising topical treatment for diabetic peripheral neuropathy. The present study investigated the efficacy, safety and tolerability of capsaicin 8% patch vs 5% lidocaine patch treatments over 24 weeks in South Asian male diabetic patients with established peripheral diabetic neuropathy.

Methods

Analgesic effectiveness was assessed by observing any change in the Numeric Pain Rating Scale (NPRS) score, Brief Pain Inventory (BPI) for painful diabetic peripheral neuropathy (BPI-DPN question 4) and Patient Global Impression of Change (PGIC). All patients received 4% lidocaine gel/cream for 60 min prior to patch application. The trial was probably underpowered, taking into account the smaller than expected number of participants from the calculated 350 sample size required for the whole study. Two hundred ninety-one individuals were divided into three groups based on treatment regimen; Group LL (Lidocaine + Lidocaine), Group LP (Lidocaine + Placebo), Group LC (Lidocaine + Capsaicin). The treatment procedure was conducted once initially and then repeated once at 12 weeks. The patients were followed up on alternate weeks till 24 weeks after the initial treatment.

Results

Group LC experienced a more significant reduction in the average pain intensity (p < 0.05) during the last twenty-four hours. Group LC showed more significant reduction of pain compared to control (p < 0.01), a baseline score of 5.4 ± 1.2 dropped to 3.2 ± 1.5 by week 24 of treatment. The change in mean daily pain intensity was - 2.2 ± 1.5 [95% CI: -2.45, -1.5]. Group LL and LC experienced a significant overall improvement (slightly, much or very much) in the health status during the study. After the second week of the treatment, patient satisfaction scores were 2.1 ± 1.1 in Group LL which increased to 3.2 ± 1.2 by week 24 of treatment. The capsaicin 8% patch appears to be reasonably well tolerated since there were no discontinuations because of serious drug-related treatment emergent adverse event (TEAEs).

Conclusions

The aim of the present study was to assess the efficacy, safety and tolerability of the 8% capsaicin patch in patients with established painful diabetic neuropathy. There was a sustained treatment response to the initial and repeat treatment of the capsaicin 8% patch over the 24 weeks. The study population was very specific so further studies are required to investigate the generalizability of the results for patients experiencing painful diabetic neuropathy. The patch could be considered as an effective long-term treatment option in individuals with painful diabetic neuropathy, particularly those experiencing inadequate pain relief or side effects from systemic therapies.

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.

Baicalin relieves neuropathic pain by regulating α2-adrenoceptor levels in rats following spinal nerve injury

In the present study, the ability of baicalin to relieve neuropathic pain due to spinal nerve ligation in rats was explored, and the relationship between baicalin and α₂-adrenoceptors (α₂-AR) was determined. The neuropathic pain model was established by ligating the L5-L6 spinal nerves in Sprague-Dawley rats. Several α₂-AR antagonists were injected into the intramedullary sheath to evaluate the role of baicalin in neuropathic pain. The antagonists included nonselective α₂-AR antagonist idazoxan, α_2a-AR antagonist BRL 44408, α_2b-AR antagonist ARC 239 and α_2c-AR antagonist JP 1302. The rats were divided into an untreated control group, saline group, baicalin group and baicalin + α₂-AR antagonist groups. Paw withdrawal threshold (PWT) was tested to assess the level of pain felt by the rats. The levels of α₂-AR mRNA were tested by reverse transcription-quantitative PCR. Inflammatory factors, including tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-17 and IL-1β, were analyzed by ELISA. The histopathological changes were assessed by hematoxylin and eosin staining. Flow cytometry was used to examine the percentage of CD4⁺ peripheral blood mononuclear cells (PBMCs). Compared with the saline group, the PWT value increased after treating with baicalin. However, intrathecal injection of α₂-AR antagonist reversed the antinociceptive effects of baicalin. Compared with the saline group, the expression of α_2a-AR and α_2c-AR mRNA was upregulated significantly in the baicalin group (P<0.05). Levels of α₂-AR mRNA were also decreased in the baicalin + idazoxan group compared with the baicalin group (P<0.05). The levels of TNF-α, IL-6, IL-17 and IL-1β were raised after treatment with baicalin. In addition, baicalin treatment ameliorated the histological damage in the spinal cord. The percentage of CD4⁺ PBMCs was increased in the saline group compared with the control group (P<0.05). Compared with the baicalin group, the percentage of CD4+ PBMCs was raised after treatment with the α₂-AR antagonists. In conclusion, intrathecal injection of baicalin produced an antiallodynic effect in a spinal nerve ligation-induced neuropathic pain model. The mechanism may be related to the regulation of a₂-AR expression.

The use of high dose topical capsaicin in the management of peripheral neuropathy: narrative review and local experience

Capsaicin, derived from the chilli pepper plant, is available in high concentration (8%) patches to provide topical therapy for neuropathic pain. Its analgesic effects relate to defunctionalisation and nerve terminal retraction of predominantly C fibres in the dermis and epidermis. Systematic reviews and meta-analysis support its use for the management of post-herpetic neuralgia and HIV neuropathy with some evidence for use in painful peripheral diabetic neuropathy. The article concludes with advice on the practicalities of running a topical 8% capsaicin clinic for peripheral neuropathic pain.

In vitro characterization of the thermoneutral transient receptor potential vanilloid-1 (TRPV1) inhibitor GRTE16523

The TRPV1 ion channel is a neuronal sensor that plays an important role in nociception and neuropathic as well as inflammatory pain. In clinical trials, hyperthermia and thermo-hypoaesthesia turned out as major side effects of TRPV1 antagonists, preventing successful development of such molecules as analgesics. In vitro studies demonstrated that the TRPV1 ion channel is a polymodal sensor integrating stimuli from molecular modulators with temperature, pH and transmembrane potential. Temperature dependent gating is suggested to constitute the molecular basis for its role in heat sensation and body temperature regulation. Drug discovery scientists since many years seek to obtain "thermoneutral" TRPV1 inhibitors, blocking the channels sensitivity for painful stimuli while keeping its temperature mode of activation unaffected. Aiming for a screening rational for the identification of thermoneutral TRPV1 antagonists, we broadly characterized the prototypic small molecule TRPV1 inhibitors GRT12360V and GRTE16523. In vitro, GRT12360V demonstrated pan-modality inhibition on human, cynomolgus and rodent TRPV1, whereas GRTE16523 selectively bypassed the channels temperature mode on human and cynomolgus TRPV1 and revealed partial agonism on rodent channels. Strikingly, in vivo, GRT12360V induced hyperthermia in all species tested whereas GRTE16523 proved thermoneutral in cynomolgus monkeys and induced hypothermia in rodents. Hence, working out the different in vitro to in vivo correlations of two compounds, we suggest temperature dependent voltage gating as key parameter when screening for thermoneutral TRPV1 inhibitors. We highlight a species difference of molecular TRPV1 pharmacology between primates and rodents and provide a methodological breakthrough to engineer thermoneutral TRPV1 antagonists with improved therapeutic safety.

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.

[Long-term effectiveness of topical analgesics]

BACKGROUND

Neuropathic pain consistently presents a significant therapeutic challenge. Topically applied analgesics have the advantage of showing low systemic side effects, but data on long-term effectiveness are lacking. Consequently, interviews were carried out with all patients being treated with topical analgesics in hospital.

METHODS

Ethics 16-5690, German Clinical Trials Register (DRKS) 00011877. Between 2008 and 2017 a total of 265 patients were treated at least once with either capsaicin 8% (C), lidocaine 5% (L) and/or perineural botulinum toxin type A (B). From this sample, 205 patients (77%) were interviewed by telephone for feedback on pain reduction (first/last treatment: low/moderate/very good), the possible reduction of analgesic prescription and if applicable the reasons for discontinuation of use (time of interview C: 26 ± 19 months, L: 61 ± 23 months, B: 11 ± 6 months after start). Further pretreatment data and diagnoses were obtained from the in-house documentation system. Responders or long-term responders were defined as patients with at least one moderate pain reduction after the first or last treatment, as long as the effect was adequately maintained.

RESULTS

In all treatment groups (56 ± 13 years, 62% male, C: 80, L: 84, B: 58 patients) patients with a long history of pain (C: 60 ± 73 months, L: 59 ± 66 months, B: 67 ± 71 months) and high pain intensity (numeric rating scale, NRS, C: 7 ± 2, L: 7 ± 2, B: 6 ± 2), were predominant. The highest primary and long-term responder rates were exhibited by L (57%/60%, B: 52%/37%, C: 23%/15%). With B, long-term responders were most frequently able to reduce analgesic use (74%, C: 58%, L: 38%).

DISCUSSION

Despite the long duration of the disease, the most used off-label topical drugs L and B demonstrated a high primary response rate (in contrast to C), with most benefiting from long-term treatment.

Capsaicin: Physicochemical properties, cutaneous reactions and potential applications in painful and inflammatory conditions

Capsaicin is a natural protoalkaloid recognized as the main pungent component in hot peppers (Capsicum annuum L.). The capsaicin receptor is highly expressed in the unmyelinated type C nerve fibers originating from small diameter sensory neurons in dorsal root ganglia and cranial nerve ganglia correspondents. Capsaicin and related vanilloids have a variety of effects on primary sensory neurons function, from sensory neuron excitation characterized by local burning sensation and neurogenic inflammation, followed by conduction blockage accompanied by reversible ultrastructural changes of peripheral nociceptive endings (desensitization), going as far as irreversible degenerative changes (neurotoxicity). The main role in capsaicin-induced neurogenic inflammation relies on the capsaicin sensitive, small diameter primary sensory neurons, therefore its evaluation could be used as a diagnostic instrument in functional alterations of cutaneous sensory nerve fibers. Moreover, capsaicin-induced desensitization and neurotoxicity explain the analgesic/anti-nociceptive and anti-inflammatory effects of topical capsaicin and its potential use in the management of painful and inflammatory conditions. In this study, we describe the effects of capsaicin on neurogenic inflammation and nociception, as well as its potential diagnostic value and therapeutic impact in various conditions involving impairment of sensory nerve fibers.

Capsaicin 8% Dermal Patch: A Review in Peripheral Neuropathic Pain

The adhesive capsaicin dermal patch (Qutenza^®) delivers a high concentration (8% w/w) of synthetic capsaicin, a highly selective agonist of transient receptor potential vanilloid-1 (TRPV-1), directly to the site of pain. The capsaicin 8% dermal patch is indicated in the EU for the treatment of peripheral neuropathic pain (PNP) in adults, either alone or in combination with other medicinal products for pain. In patients with painful diabetic peripheral neuropathy, a single 30-min application of the capsaicin 8% dermal patch provided 12 weeks of pain relief and improved sleep quality compared with placebo. Repeat treatment with the capsaicin 8% dermal patch plus standard of care over 52 weeks provided sustained pain relief, with no negative neurological effects compared with standard of care alone. The capsaicin 8% dermal patch was non-inferior to oral pregabalin in relieving pain in patients with non-diabetic PNP, with a faster onset of action and greater treatment satisfaction. A single 60-min application of the capsaicin 8% dermal patch provided rapid and sustained pain relief in patients with postherpetic neuralgia. Results in patients with HIV-associated neuropathy were equivocal, with a significant improvement in pain intensity observed in one trial, but not in the other. The capsaicin 8% dermal patch was generally well tolerated; transient application-site reactions were the most common adverse events. In conclusion, the capsaicin 8% dermal patch is a useful addition to the treatment options currently available for patients with PNP.

Herbal medicinal products or preparations for neuropathic pain

BACKGROUND

Neuropathic pain is a consequence of damage to the central nervous system (CNS), for example, cerebrovascular accident, multiple sclerosis or spinal cord injury, or peripheral nervous system (PNS), for example, painful diabetic neuropathy (PDN), postherpetic neuralgia (PHN), or surgery. Evidence suggests that people suffering from neuropathic pain are likely to seek alternative modes of pain relief such as herbal medicinal products due to adverse events brought about by current pharmacological agents used to treat neuropathic pain. This review includes studies in which participants were treated with herbal medicinal products (topically or ingested) who had experienced neuropathic pain for at least three months.

OBJECTIVES

To assess the analgesic efficacy and effectiveness of herbal medicinal products or preparations for neuropathic pain, and the adverse events associated with their use.

SEARCH METHODS

We searched CENTRAL and the Cochrane Database of Systematic Reviews, MEDLINE, Embase, CINAHL and AMED to March 2018. We identified additional studies from the reference lists of the retrieved papers. We also searched trials registries for ongoing trials and we contacted experts in the field for relevant data in terms of published, unpublished or ongoing studies.

SELECTION CRITERIA

We included randomised controlled trials (including cross-over designs) of double-blind design, assessing efficacy of herbal treatments for neuropathic pain compared to placebo, no intervention or any other active comparator. Participants were 18 years and above and had been suffering from one or more neuropathic pain conditions, for three months or more.We applied no restrictions to language or gender. We excluded studies monitoring effects of isolated, single chemicals derived from the plant or synthetic chemicals based on constituents of the plant, if they were not administered at a concentration naturally present within the plant.We excluded studies monitoring the effects of traditional Asian medicine and Cannabinoids as well as studies looking at headache or migraine as these treatments and conditions are addressed in distinct reviews.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently considered trials for inclusion, assessed risk of bias, and extracted data. We calculated the risk ratio (RR) and number needed to treat for an additional beneficial outcome (NNTB). The primary outcomes were participant-reported pain relief of 30%, or 50%, or greater, and participant-reported global impression of clinical change (PGIC). We also collected information on adverse events. We assessed evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included two studies (128 participants). Both diabetic neuropathy and non-diabetic neuropathic pain conditions were investigated across these two studies.Two herbal medicinal products, namely nutmeg (applied topically as a 125 mL spray for four weeks, containing mace oil 2%, nutmeg oil 14%, methyl salicylate 6%, menthol 6%, coconut oil and alcohol) and St John's wort (taken in capsule form containing 900 μg total hypericin each, taken three times daily, giving a total concentration of 2700 mg for five weeks). Both studies allowed the use of concurrent analgesia.Both reported at least one pain-related outcome but we could not carry out meta-analysis of effectiveness due to heterogeneity between the primary outcomes and could not draw any conclusions of effect. Other outcomes included PGIC, adverse events and withdrawals. There were no data for participant-reported pain relief of 50% or greater or PGIC (moderate and substantial) outcomes.When looking at participant-reported pain relief of 30% or greater over baseline, we observed no evidence of a difference (P = 0.64) in response to nutmeg versus placebo (RR 1.12, 95% confidence interval (CI) 0.69 to 1.85; 48.6% vs 43.2%). We downgraded the evidence for this outcome to very low quality.We observed no change between placebo and nutmeg treatment when looking at secondary pain outcomes. Visual analogue scale (VAS) scores for pain reduction (0 to 100, where 0 = no pain reduction), were 44 for both nutmeg and placebo with standard deviations of 21.5 and 26.5 respectively. There was no evidence of a difference (P = 0.09 to 0.33) in total pain score in response to St John's wort compared to placebo, as there was only a reduction of 1 point when looking at median differences in change from baseline on a 0 to 10-point numeric rating scale.There was a total of five withdrawals out of 91 participants (5%) in the treatment groups compared to six of 91 (6.5%) in the placebo groups, whilst adverse events were the same for both the treatment and placebo groups.We judged neither study as having a low risk of bias. We attributed risk of bias to small study size and incomplete outcome data leading to attrition bias. We downgraded the evidence to very low quality for all primary and secondary outcomes reported in this review. We downgraded the quality of the evidence twice due to very serious limitations in study quality (due to small study size and attrition bias) and downgraded a further level due to indirectness as the included studies only measured outcomes at short-term time points. The results from this review should be treated with scepticism as we have very little confidence in the effect estimate.

AUTHORS' CONCLUSIONS

There was insufficient evidence to determine whether nutmeg or St John's wort has any meaningful efficacy in neuropathic pain conditions.The quality of the current evidence raises serious uncertainties about the estimates of effect observed, therefore, we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect.

Patients' Global Impression of Change in the management of peripheral neuropathic pain: Clinical relevance and correlations in daily practice

BACKGROUND

Patient-Reported Outcome (PRO) instruments have been developed to evaluate pain management in daily practice; the Patients' Global Impression of Change (PGIC) is particularly recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials. The prospective non-interventional multicenter PRO-QURE study aimed at assessing correlations between PGIC and pain measurements and treatment effects in patients followed in French pain centres.

METHODS

Respectively, 495 and 379 patients with peripheral neuropathic pain initiating treatment with capsaicin 8% cutaneous patch(es) (female, 62.6%; mean age, 54.0 ± 14.8 years; post-surgical or traumatic pain, 52.7%; mean pain duration, 42.2 ± 54.1 months; DN4 score >4, 92.9%) completed the PGIC and several other PRO instruments before (baseline) and 3 months (M3) after treatment application.

RESULTS

At M3, improvement ("much improved" or "very much improved") was observed in 23.0% of patients, associated with decreases of -3.0 ± 2.2, -2.5 ± 2.4, and -23.1 ± 19.7 in BPI pain intensity, BPI pain interference and NPSI total scores, respectively. The highest Spearman's rank correlation coefficients with PGIC were found for pain intensity (BPI: r = -0.479, p < 0.001), satisfaction with current state (Patient Acceptable Symptomatic State: r = 0.455, p < 0.001), and treatment effectiveness (TSQM: r = 0.431, p < 0.001); correlation coefficients were lower for all NPSI scores, BPI pain interference score, HAD scores and EQ-5D-3L index.

CONCLUSIONS

In daily clinical practice, significant improvement in peripheral neuropathic pain, as assessed by PGIC scores, significantly correlated with changes in well-established measures of pain intensity, pain interference with activities of daily living, mood and quality of life, confirming its clinical interest as PRO measure in real-world conditions.

SIGNIFICANCE

Clinically important improvement in peripheral neuropathic pain, as assessed by PGIC scores, significantly correlated with well-established measures of pain intensity, pain interference in daily life and treatment efficacy. This result, associated with the ease of administration and scoring, encourages the widespread use of the PGIC in daily practice.

Potential Phytopharmacy and Food Applications of Capsicum spp.: A Comprehensive Review

Capsicum genus (Solanaceae) is native to the Americas. Today, it is an important agricultural crop cultivated around the world, not only due to its economic importance, but also for the nutritional value of the fruits. Among their phytochemical constituents, capsaicinoids are characteristic and responsible of the pungency of sharp-tasting cultivars. Moreover, Capsicum and capsaicinoids (mainly, capsaicin) have been largely studied because of their health benefits. Thus, this study reviews the scientific knowledge about Capsicum spp. and their phytochemicals against cancer, diabetes, gastrointestinal diseases, pain, and metabolic syndrome, as well as their antioxidant and antimicrobial activity. These bioactivities can be the basis of the formulation of functional ingredients and natural preservatives containing Capsicum extracts or isolated compounds.

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.

High-concentration topical capsaicin in the management of refractory neuropathic pain in patients with neurofibromatosis type 1: a case series

AIM

The aim of this case series was to report the use of 8% topical capsaicin patch (marketed under the trade name Qutenza^®) ^a in the management of refractory neuropathic pain (NP) in adult patients with type 1 neurofibromatosis (NF1).

METHODS

Capsaicin has been suggested for NF1 patients suffering from refractory peripheral NP despite several years of analgesic treatments. The patch was applied for 60 minutes on the painful area, with tolerability control (blood pressure, intensity of pain and dermal reaction). The evaluation was done at the beginning of treatment and during the 2 months following the first treatment (phone calls at weeks 1, 2, 4 and 8). The primary efficacy criterion was the response rate: a patient was considered to be responding if he or she reported an average relief ≥30% at the time of the follow-up calls. The secondary criteria were: interference scores (QCD), Patient Global Impression of Change (PGIC) and overall treatment satisfaction, self-reported by the patient.

RESULTS

Eight patients (5 females/3 males, 41.8 ± 8.2 years of age) received a first treatment with capsaicin. Patients had pre-existing pain for 6.6 years (±6.0) and were currently receiving an average of 6.1 (±3.9) different analgesics. The response rate was 37.5%. The three responders felt globally improved and satisfied, with the improvement in overall condition as interference scores decreased. Apart from the expected local reactions, the treatment was not accompanied by systemic side effects.

CONCLUSIONS

As suggested in this case series, capsaicin provided pain relief in certain NF1 patients with resistant NP. The response rate is that expected in multi-line refractory NP. A significant benefit on the overall condition of some patients was observed. In addition, this topical treatment is administered every 3 months without systemic effects. This study is limited by the small number of patients, but was intended to describe a new and well tolerated alternative treatment.

Pain-relieving effectiveness, quality of life and tolerability of repeated capsaicin 8% patch treatment of peripheral neuropathic pain in Scandinavian clinical practice

Context

Clinical trials have demonstrated the efficacy and safety of the capsaicin 8% patch in patients with peripheral neuropathic pain (PNP); however, few studies have assessed this treatment in a clinical practice.

Objective

To determine whether treatment and re‐treatment with the capsaicin 8% patch reduce PNP intensity in clinical practice.

Methods

Three non‐interventional, observational studies were concurrently conducted in Denmark, Norway and Sweden. Patients with probable or definite PNP received one or two treatments with the capsaicin 8% patch according to usual clinical practice. All analyses were performed on combined data.

Results

Overall, 382 and 181 patients received treatment and re‐treatment, respectively, with the capsaicin 8% patch. At the group level, a significant reduction in mean level of ‘usual pain’ intensity (Numerical Pain Rating Scale) over the last 24 h’ score was observed from baseline to Weeks 2 through 8 [−1.05 (95% confidence interval: −1.27, 0.82); p < 0.001] with 28% and 31% of patients reporting a ≥30% reduction in pain after first treatment and re‐treatment, respectively. Improvements in health‐related quality of life (EQ‐5D‐3L index) and overall health status (Patient Global Impression of Change) were observed early (Week 1) and throughout the treatment periods. Most application site reactions subsided within a week after treatment. Following treatment and re‐treatment, 57% and 71% of patients, respectively, were willing to undergo further treatment with the capsaicin 8% patch.

Conclusion

In Scandinavian clinical practice, capsaicin 8% patch treatment was associated with significant reductions in pain intensity and was well tolerated with over half of patients willing to undergo re‐treatment.