Pharmacologic management of diabetic peripheral neuropathic pain

Alleviative effect of microRNA-497 on diabetic neuropathic pain in rats in relation to decreased USP15

The current study tries to discuss the functional role of microRNA-497 (miR-497) in diabetic neuropathic pain (DNP) and the related downstream mechanism. Bioinformatics analysis was implemented for the identification of differentially expressed miRNAs and genes. DNP was simulated in rats through intraperitoneal injection of streptozotocin. The expression patterns of miR-497, USP15, NRF2, and G6PD were then determined. The binding of miR-497 and USP15 was confirmed. Using gain- and loss-of-function assays, we analyzed the critical role of miR-497-mediated USP15 in DNP through the NRF2/G6PD axis. Downregulated miR-497 and elevated USP15 were observed in the dorsal root ganglion neurons isolated from spinal cord tissues of STZ-induced DNP rats. miR-497 could alleviate DNP, which was associated with suppression of USP15, a confirmed target of miR-497. USP15 enhanced the degradation and ubiquitination of NRF2 and induced G6PD expression, leading to the progression of DNP. We highlighted the crucial role of miR-497-mediated USP15 in DNP through the NRF2/G6PD axis. 1. miR-497 is downregulated in DRG neurons from spinal cord tissues of STZ-induced DNP rats. 2. miR-497 inhibits the expression of USP15, thereby alleviating STZ-induced DNP in rats. 3. USP15 promotes ubiquitination and degradation of NRF2, reducing the expression of G6PD. 4. miR-497 alleviates STZ-induced DNP in rats by regulating the USP15/NRF2/G6PD axis.

New Advances on Pathophysiology of Diabetes Neuropathy and Pain Management: Potential Role of Melatonin and DPP-4 Inhibitors

Pre-diabetes and diabetes are growing threats to the modern world. Diabetes mellitus (DM) is associated with comorbidities such as hypertension (83.40%), obesity (90.49%), and dyslipidemia (93.43%), creating a substantial burden on patients and society. Reductive and oxidative (Redox) stress level imbalance and inflammation play an important role in DM progression. Various therapeutics have been investigated to treat these neuronal complications. Melatonin and dipeptidyl peptidase IV inhibitors (DPP-4i) are known to possess powerful antioxidant and anti-inflammatory properties and have garnered significant attention in the recent years. In this present review article, we have reviewed the recently published reports on the therapeutic efficiency of melatonin and DPP-4i in the treatment of DM. We summarized the efficacy of melatonin and DPP-4i in DM and associated complications of diabetic neuropathy (DNP) and neuropathic pain. Furthermore, we discussed the mechanisms of action and their efficacy in the alleviation of oxidative stress in DM.

Cost-Effectiveness of Mirogabalin for the Treatment of Diabetic Peripheral Neuropathic Pain in Taiwan

OBJECTIVES

To assess the cost-effectiveness of 30 mg of mirogabalin versus no treatment or 300 mg of pregabalin in patients with diabetic peripheral neuropathic pain (DPNP) from a third-party perspective in Taiwan.

METHODS

A Markov model, developed with cycles of 2-week and a 1-year timeframes, consisted of 3 health states: mild, moderate, and severe pain. Average daily pain score (ADPS) was assessed at the end of each 2-week cycle. All patients entered the model in moderate (4 ≤ ADPS < 7) or severe (7 ≤ ADPS ≤ 10) pain health states. At the end of each cycle, patients remained in their assigned health state or transitioned to a different health state according to their pain score change. Efficacy data were informed by the pivotal phase III clinical trial (J303, NCT02318706) or by a network meta-analysis. Utility values were obtained from published literature, and resource use and cost data from Taiwanese clinical experts and Taiwan National Health Insurance Administration. One-way sensitivity, scenario, and probabilistic analyses were conducted to test the robustness of the results.

RESULTS

A head-to-head analysis demonstrated that 30 mg of mirogabalin is a cost-effective treatment option versus placebo for DPNP. The base-case deterministic analysis estimated quality-adjusted life years (QALY) gains of 0.02 at an incremental cost of 9697 New Taiwan dollars (NT$) (equal to $323) versus placebo (incremental cost-effectiveness ratio [ICER]: 489 310 NT$/QALY [$15 860/QALY]). Mirogabalin was also cost-effective compared with 300 mg of pregabalin (ICER: 18 476 NT$/QALY [$600/QALY]). Sensitivity and scenario analyses results confirmed the robustness.

CONCLUSION

Economic analysis suggests that mirogabalin 30 mg, a potent and selective α2δ ligand, is a cost-effective treatment option for DPNP in Taiwan, with an ICER below the willingness-to-pay threshold.

A Review on Mechanistic and Pharmacological Findings of Diabetic Peripheral Neuropathy including Pharmacotherapy

BACKGROUND

Chronic hyperglycemia and related complications involving peripheral nerves in diabetes are one of the most severe microvascular complications with an average prevalence of 50-60%. Diabetic neuropathy is among the vascular disorders of diabetes, the most debilitating and crippled, lethal condition impacting patients's quality of life.

METHODS

In the present review article, several hypotheses associated with the pathogenesis of Diabetic Peripheral Neuropathy (DPN) have been introduced, among them metabolic pathways associated with polyol pathway, oxidative stress, production of reactive oxygen species (ROS) amplified under chronic hyperglycemic conditions and activation of transcription factor Nuclear factor-κB (NF- κB). The review article also possesses pathogenetic and pharmacologic treatments along with others, including acupressure, lidocaine, and capsaicin for DPN.

CONCLUSION

It may be concluded that we can combat the pathogenesis of DPN with different suggested treatments.

Naringenin ameliorates diabetic neuropathic pain by modulation of oxidative-nitrosative stress, cytokines and MMP-9 levels

Diabetes mellitus is a serious debilitating epidemic affecting all social strata, imposing huge health, social and economic burdens.

Prevention, assessment, diagnosis and management of diabetic foot based on clinical practice guidelines: A systematic review

AIM

Diabetic foot complications are the main reason for hospitalization and amputation in people with diabetes and have a prevalence of up to 25%. Clinical practice guidelines are recommendations based on evidence with the aim of improving health care. The main aim of this study was to carry out a systematic review of the levels of the evaluation and treatment strategies that appear in the clinical practice guidelines focus on diabetic foot or diabetes with diabetic foot section. Another objective of this study was to perform an analysis of the levels of evidence in support of the recommendations made by the selected clinical practice guidelines.

METHODS

A systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and a quality assessment by the Appraisal of Guidelines for Research and Evaluation (AGREE II) were performed. The databases checked were "NICE", "Cinahl", "Health Guide", "RNAO", "Sign", "PubMed", "Scopus" and "NCG". The search terms included were "diabetic foot", "guideline(s)", "practice guideline(s)" and "diabetes."

RESULTS

Twelve articles were selected after checked inclusion criteria and quality assessment. A summary and classification of the recommendations was completed.

CONCLUSIONS

The heterogeneity of levels of evidence and grades of recommendation of the CPGs included regarding the management, approach and treatment of DF makes it difficult to interpret and assume them in clinical practice in order to select the most correct procedures. Despite this and according to the detailed study of the guidelines included in this work, it can be concluded that the highly recommendable interventions for DF management are debridement (very high level of evidence and strongly recommended), foot evaluation (moderate level of evidence and fairly recommended) and therapeutic footwear (moderate level of evidence and fairly recommended).

The effects of dry needling and neurodynamic exercise on idiopathic peripheral neuropathy: A case report

A single patient (male, 67) with a medical diagnosis of idiopathic peripheral neuropathy (G60.9) was referred to physical therapy. The patient presented with signs and symptoms consistent with peripheral neuropathy, including bilateral single leg balance deficits, sensation impairments, and antalgic gait. Treatment consisted of dry needling (DN) with electrical stimulation and a home exercise program involving a neurodynamic exercise to be performed daily. Dry needling included the use of thin filiform needles to stimulate the underlying structures directed at eliciting a change within the tissues. The needles were left in situ and connected to an electrical stimulation unit. The neurodynamic exercise used in this case study was designed to target the distal branches of the sciatic nerve. The patient was directed to complete 3 sets of 10 repetitions in the slumped position and moving between ankle plantar flexion and dorsiflexion. The patient was treated for a total of 4 visits over a 5-week period. The Foot and Ankle Ability Measure (FAAM), Numeric Pain Rating Scale (NPRS), Romberg Test, and sensation testing were collected at baseline and then again after the 4th treatment. A Global Rating of Change (GROC) score was obtained at the end of treatment. After the 4th visit, functional self-report scores were not improved (93.75%-86.9% at completion), while NPRS decreased to 2 from a baseline rating of 4. The eyes closed portion of the Rhomberg balance test improved from 5 s on the right limb to 15 s and from 8 s to 20 s on the left limb. Sharp/dull sensation testing of the L4 dermatome also improved from 2 out of 5 correctly selected on the left lower limb to 5 out of 5. At the S1 level, sensation improved on the left lower limb from 2 out of 5 to 4 out of 5 and from 2 out of 5 on the right lower limb to 5 out of 5. The patient's GROC score was rated as quite a bit better (+5). The outcomes of this case study suggest that clinicians may consider the addition of DN with electrical stimulation and neurodynamic exercises to the treatment of this patient population given the sizeable and rapid improvements in pain, balance, and sensation testing following only 4 treatments.

Painful Diabetic Peripheral Neuropathy Study of Chinese OutPatiEnts (PDN-SCOPE): protocol for a multicentre cross-sectional registry study of clinical characteristics and treatment in China

INTRODUCTION

Painful diabetic peripheral neuropathy (PDN) is a growing public health problem in China. Despite recent progress in treatment, there has been no nationwide study evaluating current medical practices and compliance with treatment guidelines. The primary aims of this study are to investigate the clinical characteristics and treatment practices for PDN and associated anxiety and depression in China.

METHODS AND ANALYSIS

Painful Diabetic Peripheral Neuropathy Study of Chinese OutPatiEnts is a cross-sectional, multicentre registry study with a target sample size of approximately 1500 people experiencing PDN. People with PDN will be treated according to current guidelines and local practices. The demographics, medical histories, Visual Analogue Scale pain scores, Patient Health Questionnaire-9 results, Generalised Anxiety Disorder-7 scores and therapies will be recorded to evaluate clinical characteristics of PDN and current treatment practices for pain, anxiety and depression.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Peking University Third Hospital Medical Science Research Ethics Committee (2018-182).The results of this study will be disseminated through peer-reviewed publications and scientific presentations.

TRIAL REGISTRATION NUMBER

NCT03520608.

Targeting tumor necrosis factor in the brain relieves neuropathic pain

Neuropathic pain is a chronic syndrome caused by direct damage to or disease of the somatosensory nervous system. The lack of safe, adequate and sustained pain relief offered by present analgesic treatments is most alarming. While many treatment options are available to manage chronic pain, such as antidepressants, non-steroidal anti-inflammatory agents, opioids, and anticonvulsants, chronic neuropathic pain remains largely unmanaged. Compounding the dilemma of ineffective chronic pain treatments is the need to provide relief from suffering and yet not contribute to the scourge of drug abuse. A recent epidemic of addiction and accidental drug prescription overdoses parallel the increased use of opioid treatment, even though opioids are rarely an effective treatment of relieving chronic pain. To make matters worse, opioids may contribute to exacerbating pain, and side-effects such as cognitive impairment, nausea, constipation, development of tolerance, as well as their potential for addiction and overdose deaths exist. Clearly, there is an urgent need for alternative, non-opiate treatment of chronic pain. Innovative discoveries of pertinent brain mechanisms and functions are key to developing effective, safe treatments. Pioneering work has revealed the essential effects of the pleiotropic mediator tumor necrosis factor (TNF) on brain functioning. These studies establish that TNF inhibits norepinephrine release from hippocampal neurons, and show that excess TNF production within the hippocampus occurs during neuropathic pain, which mobilizes additional mechanisms that further inhibit norepinephrine release. Significantly, it has been verified that elevated levels of TNF in the brain are actually required for neuropathic pain development. Since TNF decreases norepinephrine release in the brain, enhanced TNF levels would prevent engagement of the norepinephrine descending inhibitory neuronal pain pathways. Increased levels of TNF in the brain are therefore critical to the development of neuropathic pain. Therefore, strategies that decrease this enhanced TNF expression in the brain will have superior analgesic efficacy. We propose this novel approach of targeting the pathologically high levels of brain TNF as an effective strategy in the treatment of the devastating syndrome of chronic pain.

Efficacy of Mirogabalin (DS-5565) on Patient-Reported Pain and Sleep Interference in Patients with Diabetic Neuropathic Pain: Secondary Outcomes of a Phase II Proof-of-Concept Study

Objective

To evaluate the effects of mirogabalin on patient-reported pain and sleep interference in diabetic peripheral neuropathic pain (DPNP).

Subjects

Adults (≥18 years) with type 1 or 2 diabetes, glycosylated hemoglobin of 10% or less at screening, and DPNP for six months or more were eligible for participation.

Methods

Subjects (N = 452) were randomly assigned (2:1:1:1:1:1:1) to receive placebo, dose-ranging mirogabalin (5, 10, 15, 20, 30 mg/day), or pregabalin (300 mg/day) for five weeks. Secondary efficacy end points studied here included patient global impression of change (PGIC), modified brief pain inventory (BPI), and average daily sleep interference score (ADSIS). Correlation plots were generated to examine the relationship between ADSIS and average daily pain score (ADPS).

Results

At week 5, significant reductions in ADSIS were observed in the mirogabalin 15, 20, and 30 mg/day groups, compared with placebo (P < 0.05). Baseline ADSIS and ADPS were strongly correlated (R2 = 0.4407), as were mean changes from baseline in ADSIS and ADPS at week 5 (R2 = 0.6694). The mirogabalin 30 mg/day group showed significant improvement compared with placebo in four of six BPI subscales at end point; the mirogabalin 15 mg/day group showed significant improvement in three of six BPI subscales (P < 0.05). At end of treatment, the percentage of subject with PGIC status of "much improved or better" was greater in all mirogabalin dose groups than in the placebo group (P < 0.05). A low incidence of treatment-related adverse events was reported for mirogabalin.

Conclusions

Results support the effectiveness of mirogabalin in improving patient-reported pain and sleep interference in DPNP.

Ammoxetine attenuates diabetic neuropathic pain through inhibiting microglial activation and neuroinflammation in the spinal cord

Background

Diabetic neuropathic pain (DNP) is a common and distressing complication in patients with diabetes, and the underlying mechanism remains unclear. Tricyclic antidepressants (TCAs) and serotonin and norepinephrine reuptake inhibitors (SNRIs) are recommended as first-line drugs for DNP. Ammoxetine is a novel and potent SNRI that exhibited a strong analgesic effect on models of neuropathic pain, fibromyalgia-related pain, and inflammatory pain in our primary study. The present study was undertaken to investigate the chronic treatment properties of ammoxetine on DNP and the underlying mechanisms for its effects.

Methods

The rat model of DNP was established by a single streptozocin (STZ) injection (60 mg/kg). Two weeks after STZ injection, the DNP rats were treated with ammoxetine (2.5, 5, and 10 mg/kg/day) for 4 weeks. The mechanical allodynia and locomotor activity were assayed to evaluate the therapeutic effect of ammoxetine. In mechanism study, the activation of microglia, astrocytes, the protein levels of pro-inflammatory cytokines, the mitogen-activated protein kinases (MAPK), and NF-κB were evaluated. Also, microglia culture was used to assess the direct effects of ammoxetine on microglial activation and the signal transduction mechanism.

Results

Treatment with ammoxetine for 4 weeks significantly relieved the mechanical allodynia and ameliorated depressive-like behavior in DNP rats. In addition, DNP rats displayed increased activation of microglia in the spinal cord, but not astrocytes. Ammoxetine reduced the microglial activation, accumulation of pro-inflammatory cytokines, and activation of p38 and c-Jun N-terminal kinase (JNK) in the spinal cord of DNP rats. Furthermore, ammoxetine displayed anti-inflammatory effects upon challenge with LPS in BV-2 microglia cells.

Conclusion

Our results suggest that ammoxetine may be an effective treatment for relieving DNP symptoms. Moreover, a reduction in microglial activation and pro-inflammatory release by inhibiting the p-p38 and p-JNK pathways is involved in the mechanism.

Knowledge, Perceptions and Attitudes toward Chronic Pain and Its Management: A Cross-Sectional Survey of Frontline Pharmacists in Ontario, Canada

The treatment of chronic pain consumes a significant share of primary care. Community and family health team pharmacists frequently see patients with chronic pain, thus have the opportunity to improve their care. To assess the knowledge, perceptions, and attitudes of Ontario pharmacists, we invited 5,324 Ontario pharmacists, to participate in an online survey we developed using Qualtrics. The 31-question survey gathered demographic information, assessed pharmacists' knowledge of three chronic pain conditions; chronic lower back pain (CLBP, eight true/false statements); chronic headache disorder (CHD, eight true/false statements) and painful diabetic neuropathy (PDN, seven true/false statements), and their attitudes toward and perceptions of patients with these conditions, and knowledge, attitudes, and perceptions of opioids in pain management. We received 688 responses (12.9%) and 392 pharmacists completed the survey. The mean age of respondents was 48.5 years and 48.5% were male. More than 50% of respondents were in practice for more than 20 years and 58.7% worked 25-40 hours per week. The mean knowledge scores were 4.5/8, 5.5/8, and 5.3/8 for CBLP, CHD, and PDN respectively. While 95% of respondents were aware of the increasing death rates due to opioid use, only half were familiar with the Canadian guideline for safe opioid prescribing for non-cancer use. Responses were compared based on gender, time in practice and location of practice. Pharmacists with more than ten years of experience scored significantly higher than those with less experience. Fewer differences were found in comparisons of gender and location of practice. Safe and effective care of chronic pain patients, particularly with opioids, will require additional pharmacist education.

Updates in diabetic peripheral neuropathy

Diabetes has become one of the largest global health-care problems of the 21 ^st century. According to the Centers for Disease Control and Prevention, the population prevalence of diabetes in the US is approaching 10% and is increasing by 5% each year. Diabetic neuropathy is the most common complication associated with diabetes mellitus. Diabetes causes a broad spectrum of neuropathic complications, including acute and chronic forms affecting each level of the peripheral nerve, from the root to the distal axon. This review will focus on the most common form, distal symmetric diabetic polyneuropathy. There has been an evolution in our understanding of the pathophysiology and the management of diabetic polyneuropathy over the past decade. We highlight these new perspectives and provide updates from the past decade of research.

The Relationships Between Parasympathetic Function and Pain Perception: The Role of Anxiety

BACKGROUND

Previous studies have identified relationships between autonomic function and pain perception. Anxiety was found to influence both autonomic and pain responses. We examined the effect of anxiety level on parasympathetic function and pain perception as well as on the relationships between these 2 systems.

METHODS

Thirty healthy females were divided into high- and low-anxiety groups according to their trait anxiety levels. Parasympathetic function was obtained using heart rate variability, deep breathing, and Valsalva ratios. Pain perception parameters of heat pain thresholds, pain rating of supra-thresholds stimulus, mechanical temporal summation, and conditioned pain modulation response were examined.

RESULTS

The low-anxiety and high-anxiety groups exhibited no significant differences in the parasympathetic function and pain perception parameters. Assessment of the associations revealed that in the high-anxiety group, higher mean ratings of the tonic heat pain stimulus were significantly correlated with higher rMSSD (r² = 0.358, P = 0.019), but this was not found for the low-anxiety group (P = 0.282). In addition, in the high-anxiety group, efficient conditioned pain modulation response was correlated with higher deep breathing ratio (r² = 0.363, P = 0.023); however, in the low-anxiety group, the correlation did not reach significance (P = 0.109).

CONCLUSIONS

This study demonstrates the role of anxiety level on the relationships between parasympathetic function and pain perception. We suggest that a situation of high anxiety leads to higher norepinephrine levels that can influence both parasympathetic function and pain perception, thus explaining the significant relationships found between these 2 systems only in subjects with high anxiety.

Pathways in the diagnosis and management of diabetic polyneuropathy

Distal symmetric polyneuropathy (DSPN), the most common form of diabetic neuropathy, has a complex pathophysiology and can be a major source of physical and psychologic disability. The management of DSPN can be frustrating for both patient and physician. This article provides a general overview of typical patient pathways in DSPN, and highlights variations in diagnosis, management, and referral patterns among different providers. DSPN is managed in several settings by primary care physicians (PCPs), specialists, and nurse practitioners. The initial clinical management of the patient is often dependent on the presenting complaint, the referral pattern of the provider, level of comfort of the PCP in managing diabetic complications, and geographic access to specialists. The primary treatment of DSPN focuses mainly on glycemic control and adjustment of modifiable risk factors, but other causes of neuropathy should also be investigated. Several pharmacologic agents are recommended by treatment guidelines, and as DSPN typically exists with comorbid conditions, a multimodal therapeutic approach should be considered. Barriers to effective management include failure to recognize DSPN, and misdiagnosis. Patient education also remains important. Referral patterns vary widely according to geographic location, access to services, provider preferences, and comfort in managing complex aspects of the disease. The variability in patient pathways affects patient education, satisfaction, and outcomes. Standardized screening tools, a multidisciplinary team approach, and treatment algorithms for diabetic neuropathy should improve future care. To improve patient outcomes, DSPN needs to be diagnosed sooner and interventions made before significant nerve damage occurs.

Tapentadol extended release in the management of peripheral diabetic neuropathic pain

Tapentadol, a μ-opioid agonist and norepinephrine reuptake inhibitor, has been found to be an effective medication for a wide variety of chronic pain conditions, including back pain, cancer-related pain, and arthritic pain. It has also been found to have fewer gastrointestinal side effects than more traditional opioid-based therapies. More recently, tapentadol extended release has been demonstrated to be effective in the management of painful diabetic neuropathy, an often debilitating condition affecting approximately one-third of all patients with diabetes. This review highlights the most up-to-date basic and clinical studies by focusing on the mechanisms of action of tapentadol and its clinical efficacy, especially with regard to painful diabetic neuropathy.

Dopaminergic modulation of neuropathic pain: analgesia in rats by a D2-type receptor agonist

Experimental studies have shown that dopaminergic mechanisms can modulate both nociception and chronic pain perception, but such property is not exploited pharmacologically at the clinical level. We have previously shown that levodopa produces D2-receptor-mediated antiallodynic effects in rats with peripheral mononeuropathy. Here, we test the effects of a D2-type receptor (D2R) agonist, quinpirole, on neuropathic pain in rats. Allodynic responses to cooling and light touch were measured in the hind limbs of rats with chronic constriction injury of one sciatic nerve. Single intraperitoneal injection of quinpirole (1 mg/kg) totally inhibited cold and tactile allodynic responses for over 3 and 48 h, respectively. At that dose, quinpirole had no effect on nocifensive responses to heat. Lumbar intrathecal injection of quinpirole produced short-term inhibition of the responses to cold and tactile stimuli, suggesting that spinal mechanisms may contribute to the antiallodynic activity of quinpirole. Chronic subcutaneous infusion of quinpirole by implanted Alzet pumps (0.025 mg/kg·day) provided a slowly progressing inhibition of cold and tactile allodynic responses, which re-emerged after the pumps were removed. These experiments show the involvement of dopaminergic systems in the modulation of chronic allodynias and provide experimental support for proposing the use of D2R agonists for neuropathic pain relief.