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.

Investigational Drugs for the Treatment of Postherpetic Neuralgia: Systematic Review of Randomized Controlled Trials.

The pharmacological treatment of postherpetic neuralgia (PHN) is unsatisfactory, and there is a clinical need for new approaches. Several drugs under advanced clinical development are addressed in this review. A systematic literature search was conducted in three electronic databases (Medline, Web of Science, Scopus) and in the ClinicalTrials.gov register from 1 January 2016 to 1 June 2023 to identify Phase II, III and IV clinical trials evaluating drugs for the treatment of PHN. A total of 18 clinical trials were selected evaluating 15 molecules with pharmacological actions on nine different molecular targets: Angiotensin Type 2 Receptor (AT2R) antagonism (olodanrigan), Voltage-Gated Calcium Channel (VGCC) α2δ subunit inhibition (crisugabalin, mirogabalin and pregabalin), Voltage-Gated Sodium Channel (VGSC) blockade (funapide and lidocaine), Cyclooxygenase-1 (COX-1) inhibition (TRK-700), Adaptor-Associated Kinase 1 (AAK1) inhibition (LX9211), Lanthionine Synthetase C-Like Protein (LANCL) activation (LAT8881), N-Methyl-D-Aspartate (NMDA) receptor antagonism (esketamine), mu opioid receptor agonism (tramadol, oxycodone and hydromorphone) and Nerve Growth Factor (NGF) inhibition (fulranumab). In brief, there are several drugs in advanced clinical development for treating PHN with some of them reporting promising results. AT2R antagonism, AAK1 inhibition, LANCL activation and NGF inhibition are considered first-in-class analgesics. Hopefully, these trials will result in a better clinical management of PHN.

Update on Interventional Management of Neuropathic Pain: A Delphi Consensus of the Spanish Pain Society Neuropathic Pain Task Force.

Background and Objectives: Interventional management of neuropathic pain (NP) is available to the patients who do not obtain satisfactory pain relief with pharmacotherapy. Evidence supporting this is sparse and fragmented. We attempted to summarize and critically appraise the existing data to identify strategies that yield the greatest benefit, guide clinicians, and identify areas that merit further investigation. Material and Methods: A two-round Delphi survey that involved pain clinic specialists with experience in the research and management of NP was done over an ad hoc 26-item questionnaire made by the authors. Consensus on each statement was defined as either at least 80% endorsement or rejection after the 2nd round. Results: Thirty-five and 29 panelists participated in the 1st and 2nd round, respectively. Consensus was reached in 20 out of 26 statements. There is sufficient basis to treat postherpetic neuralgias and complex regional pain syndromes with progressive levels of invasiveness and failed back surgery syndrome with neuromodulation. Radiculopathies and localized NP can be treated with peripheral blocks, neuromodulation, or pulsed radiofrequency. Non-ablative radiofrequency and non-paresthetic neuromodulation are efficacious and better tolerated than ablative and suprathreshold procedures. Conclusions: A graded approach, from least to most invasive interventions has the potential to improve outcomes in many patients with common refractory NP conditions. Preliminary promising data warrant further research on new indications, and technical advances might enhance the safety and efficacy of current and future therapies.

Combination Therapy for Neuropathic Pain: A Review of Recent Evidence.

Pharmacological treatment is not very effective for neuropathic pain (NP). A progressive decrease in the estimated effect of NP drugs has been reported, giving rise to an increase in the use of the multimodal analgesic approach. We performed a new independent review to assess whether more and better-quality evidence has become available since the last systematic review. We evaluated the efficacy, tolerability, and safety of double-blinded randomized controlled trials involving only adult participants and comparing combination therapy (CT: ≥2 drugs) with a placebo and/or at least one other comparator with an NP indication. The primary outcome assessed was the proportion of participants reporting ≥50% pain reductions from baseline. The secondary outcome assessed was the proportion of drop-outs due to treatment-emergent adverse events. After removing duplicates, 2323 citations were screened, with 164 articles assessed for eligibility, from which 16 were included for qualitative analysis. From the latter, only five lasted for at least 12 weeks and only six complied with the required data for complete analysis. CT has been adopted for years without robust evidence. Efforts have been made to achieve better-quality evidence, but the quality has not improved over the years. In this regard, guidelines for NP should attempt to make recommendations about CT research, prioritizing which combinations to analyze.

Neuropathic Pain due to Neurofibromatosis Treated With Transcutaneous Electrical Nerve Stimulation in a Pregnant Patient: A Case Report.

A patient with neurofibromatosis type 1 presented to the pain clinic with neuropathic pain. Thoracolumbar magnetic resonance imagining revealed meningocele T12-L2 with cauda equina distortion. After becoming pregnant, the patient interrupted opioid treatment, refusing pharmacological treatment until the pain became unbearable. Transcutaneous electrical nerve stimulation (TENS) was proposed. The patient used this treatment from the first trimester until month 6 postpartum, achieving good analgesia without any adverse effects for the mother or child. TENS may be a viable treatment for neuropathic pain (NP) during pregnancy. However, more data are needed due to the difficulty of conducting clinical trials in this population.

Aclaraciones sobre el artículo "Recomendaciones basadas en la evidencia para el manejo del dolor neuropático (revisión de la literatura)" / Explanations on the article "Recommendations based on evidence for the management of neuropathic pain (review of the literature)"

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