Duloxetine in Painful Diabetic Neuropathy: A Systematic Review

Novel Drug Targets and Emerging Pharmacotherapies in Neuropathic Pain

Neuropathic pain is a debilitating condition characterized by abnormal signaling within the nervous system, resulting in persistent and often intense sensations of pain. It can arise from various causes, including traumatic nerve injury, neuropathy, and certain diseases. We present an overview of current and emerging pharmacotherapies for neuropathic pain, focusing on novel drug targets and potential therapeutic agents. Current pharmacotherapies, including tricyclic antidepressants, gabapentinoids, and serotonin norepinephrine re-uptake inhibitors, are discussed, as are emerging treatments, such as ambroxol, cannabidiol, and N-acetyl-L-cysteine. Additionally, the article highlights the need for further research in this field to identify new targets and develop more effective and targeted therapies for neuropathic pain management.

The P2X4 Receptor: Cellular and Molecular Characteristics of a Promising Neuroinflammatory Target

The adenosine 5′-triphosphate-gated P2X4 receptor channel is a promising target in neuroinflammatory disorders, but the ability to effectively target these receptors in models of neuroinflammation has presented a constant challenge. As such, the exact role of P2X4 receptors and their cell signalling mechanisms in human physiology and pathophysiology still requires further elucidation. To this end, research into the molecular mechanisms of P2X4 receptor activation, modulation, and inhibition has continued to gain momentum in an attempt to further describe the role of P2X4 receptors in neuroinflammation and other disease settings. Here we provide an overview of the current understanding of the P2X4 receptor, including its expression and function in cells involved in neuroinflammatory signalling. We discuss the pharmacology of P2X4 receptors and provide an overview of P2X4-targeting molecules, including agonists, positive allosteric modulators, and antagonists. Finally, we discuss the use of P2X4 receptor modulators and antagonists in models of neuroinflammatory cell signalling and disease.

An Insight into Potential Pharmacotherapeutic Agents for Painful Diabetic Neuropathy

Diabetes is the 4th most common disease affecting the world's population. It is accompanied by many complications that deteriorate the quality of life. Painful diabetic neuropathy (PDN) is one of the debilitating consequences of diabetes that effects one-third of diabetic patients. Unfortunately, there is no internationally recommended drug that directly hinders the pathological mechanisms that result in painful diabetic neuropathy. Clinical studies have shown that anticonvulsant and antidepressant therapies have proven fruitful in management of pain associated with PDN. Currently, the FDA approved medications for painful diabetic neuropathies include duloxetine, pregabalin, tapentadol extended release, and capsaicin (for foot PDN only). The FDA has also approved the use of spinal cord stimulation system for the treatment of diabetic neuropathy pain. The drugs recommended by other regulatory bodies include gabapentin, amitriptyline, dextromethorphan, tramadol, venlafaxine, sodium valproate, and 5 % lidocaine patch. These drugs are only partially effective and have adverse effects associated with their use. Treating painful symptoms in diabetic patient can be frustrating not only for the patients but also for health care workers, so additional clinical trials for novel and conventional treatments are required to devise more effective treatment for PDN with minimal side effects. This review gives an insight on the pathways involved in the pathogenesis of PDN and the potential pharmacotherapeutic agents. This will be followed by an overview on the FDA-approved drugs for PDN and commercially available topical analgesic and their effects on painful diabetic neuropathies.

A randomized comparative study of methylcobalamin, methylcobalamin plus pregabalin and methylcobalamin plus duloxetine in patients of painful diabetic neuropathy

CONTEXT:

Diabetic neuropathy affects 10.5%–32.2% of diabetic population posing clinical burden onto society.

AIMS:

We aimed to study the efficacy, safety, and tolerability of methylcobalamin, methylcobalamin plus pregabalin, and methylcobalamin plus duloxetine in patients of painful diabetic neuropathy.

SETTINGS AND DESIGN:

It is a prospective, randomized, open-label, interventional, and parallel-group study done in patients of painful diabetic neuropathy.

MATERIALS AND METHODS:

A total of 100 patients were recruited and randomized to three study groups A, B, and C on methylcobalamin, methylcobalamin and pregabalin, and methylcobalamin and duloxetine, respectively. Patients were assessed at day 0 and 4, 8, and 12 weeks. The tuning fork test, monofilament test, Thermal Sensitivity testing, and Visual Analog Scale (VAS) were used to analyze vibration, pressure, thermal sensitivity, and pain.

STATISTICAL ANALYSIS USED:

The results are expressed as mean ± standard deviation. Appropriate statistical methods were used to calculate P value (<0.05 – significant).

RESULTS:

The increase in number of patients with vibration perception is 11.6%, 37.9%, and 41.4%; pressure sensation is 7.6%, 37.9%, and 37.9%; and thermal sensitivity is 15.4%, 31.1%, and 37.9% in Groups A, B, and C, respectively. The decrease in VAS scores is 0.58 ± 0.14, 3.82 ± 0.05, and 4.17 ± 0.48 in Groups A, B, and C correspondingly. The adverse effects reported in Groups A, B, and C are 0%, 6.9%, and 10.3%, respectively.

CONCLUSIONS:

Group C is more efficacious when compared to Groups A and B while Group B is safer.

WITHDRAWN: Preoperative duloxetine to prevent postoperative shoulder pain after gynecologic laparoscopy: a randomized controlled trial

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Effect of High-frequency (10-kHz) Spinal Cord Stimulation in Patients With Painful Diabetic Neuropathy: A Randomized Clinical Trial

Question

Will 10-kHz spinal cord stimulation improve pain relief for patients with painful diabetic neuropathy refractory to medical management?

Findings

In this randomized clinical trial including 216 patients, there was a significant benefit of 10-kHz spinal cord stimulation, with 79% of treatment responders whose underlying neurological deficits did not worsen compared with 5% of controls treated with conventional medical management.

Meaning

Patients with painful diabetic neuropathy with inadequate pain relief despite best available medical treatments should be considered for 10-kHz spinal cord stimulation.

Importance

Many patients with diabetic peripheral neuropathy experience chronic pain and inadequate relief despite best available medical treatments.

Objective

To determine whether 10-kHz spinal cord stimulation (SCS) improves outcomes for patients with refractory painful diabetic neuropathy (PDN).

Design, Setting, and Participants

The prospective, multicenter, open-label SENZA-PDN randomized clinical trial compared conventional medical management (CMM) with 10-kHz SCS plus CMM. Participants with PDN for 1 year or more refractory to gabapentinoids and at least 1 other analgesic class, lower limb pain intensity of 5 cm or more on a 10-cm visual analogue scale (VAS), body mass index (calculated as weight in kilograms divided by height in meters squared) of 45 or less, hemoglobin A_1c (HbA_1c) of 10% or less, daily morphine equivalents of 120 mg or less, and medically appropriate for the procedure were recruited from clinic patient populations and digital advertising. Participants were enrolled from multiple sites across the US, including academic centers and community pain clinics, between August 2017 and August 2019 with 6-month follow-up and optional crossover at 6 months. Screening 430 patients resulted in 214 who were excluded or declined participation and 216 who were randomized. At 6-month follow-up, 187 patients were evaluated.

Interventions

Implanted medical device delivering 10-kHz SCS.

Main Outcomes and Measures

The prespecified primary end point was percentage of participants with 50% pain relief or more on VAS without worsening of baseline neurological deficits at 3 months. Secondary end points were tested hierarchically, as prespecified in the analysis plan. Measures included pain VAS, neurological examination, health-related quality of life (EuroQol Five-Dimension questionnaire), and HbA_1c over 6 months.

Results

Of 216 randomized patients, 136 (63.0%) were male, and the mean (SD) age was 60.8 (10.7) years. Additionally, the median (interquartile range) duration of diabetes and peripheral neuropathy were 10.9 (6.3-16.4) years and 5.6 (3.0-10.1) years, respectively. The primary end point assessed in the intention-to-treat population was met by 5 of 94 patients in the CMM group (5%) and 75 of 95 patients in the 10-kHz SCS plus CMM group (79%; difference, 73.6%; 95% CI, 64.2-83.0; P < .001). Infections requiring device explant occurred in 2 patients in the 10-kHz SCS plus CMM group (2%). For the CMM group, the mean pain VAS score was 7.0 cm (95% CI, 6.7-7.3) at baseline and 6.9 cm (95% CI, 6.5-7.3) at 6 months. For the 10-kHz SCS plus CMM group, the mean pain VAS score was 7.6 cm (95% CI, 7.3-7.9) at baseline and 1.7 cm (95% CI, 1.3-2.1) at 6 months. Investigators observed neurological examination improvements for 3 of 92 patients in the CMM group (3%) and 52 of 84 in the 10-kHz SCS plus CMM group (62%) at 6 months (difference, 58.6%; 95% CI, 47.6-69.6; P < .001).

Conclusions and Relevance

Substantial pain relief and improved health-related quality of life sustained over 6 months demonstrates 10-kHz SCS can safely and effectively treat patients with refractory PDN.

Trial Registration

ClincalTrials.gov Identifier: NCT03228420

Diabetic neuropathy: A narrative review of risk factors, classification, screening and current pathogenic treatment options (Review)

Diabetic neuropathy (DN) is a frequent complication of diabetes mellitus (DM) with severe consequences as it progresses and influences all human body systems. This review discusses the risk factors for DN, the main characteristics of the clinical forms of DN, the screening methods and the current therapeutic options. Distal symmetric DN is the primary clinical form, and DM patients should be screened for this complication. The most important treatment of DN remains good glucose control, generally defined as HbA1c ≤7%. Symptomatic treatment improves life quality in diabetic patients. Pharmacological agents such as alpha (α)-lipoic acid and benfotiamine have been validated in several studies since they act on specific pathways such as increased oxidative stress (α-lipoic acid exerts antioxidant effects) and the excessive production of advanced glycosylation products (benfotiamine may inhibit their production via the normalization of glucose). Timely diagnosis of DN is significant to avoid several complications, including lower limb amputations and cardiac arrhythmias.

Beneficial effects of galanin system on diabetic peripheral neuropathic pain and its complications

Diabetic peripheral neuropathic pain (DPNP) is a distal spontaneous pain, caused by lesion of sensory neurons and accompanied by depression and anxiety frequently, which reduce life quality of patients and increase society expenditure. To date, antidepressants, serotonin-noradrenaline reuptake inhibitors and anticonvulsants are addressed as first-line therapy to DPNP, alone or jointly. It is urgently necessary to develop novel agents to treat DPNP and its complications. Evidences indicate that neuropeptide galanin can regulate multiple physiologic and pathophysiological processes. Pain, depression and anxiety may upregulate galanin expression. In return, galanin can modulate depression, anxiety, pain threshold and pain behaviors. This article provides a new insight into regulative effects of galanin and its subtype receptors on antidepressant, antianxiety and against DPNP. Through activating GALR1, galanin reinforces depression-like and anxiogenic-like behaviors, but exerts antinociceptive roles. While via activating GALR2, galanin is referred to as anti-depressive and anti-anxiotropic compounds, and at low and high concentration facilitates and inhibits nociceptor activity, respectively. The mechanism of the galanin roles is relative to increase in K⁺ currents and decrease in Ca²⁺ currents, as well as neurotrophic and neuroprotective roles. These data are helpful to develop novel drugs to treat DPNP and its complications.

Oral pharmacotherapeutics for the management of peripheral neuropathic pain conditions - a review of clinical trials

INTRODUCTION

Epidemiological studies have shown that 6.9-10% of people suffer from neuropathic pain, a complex painful condition which is often undertreated. Data regarding the effectiveness of treatment options for patients with neuropathic pain is inconsistent, and there is no single treatment option that shows cost-effectiveness across studies.

AREAS COVERED

In this narrative review, the authors present the results of different prospective, randomized controlled trials, systematic reviews and meta-analyses assessing the effects of different oral medications in the management of various peripheral neuropathic pain conditions. The authors discuss the effectiveness of commonly used oral medications such as voltage-gated calcium channels antagonists, voltage-gated sodium channel antagonists, serotonin-norepinephrine reuptake inhibitors, NMDA antagonists, and medications with other mechanisms of action.

EXPERT OPINION

Most of the presented medications were more effective than placebo; however, when compared to each other, none of them were significantly superior. The heterogeneity of the studies looking into different oral neuropathic conditions has been the major issue that prevents us from making stronger recommendations. There are multiple reasons including high placebo responsiveness, improperly treated underlying comorbidities (particularly anxiety and depression), and inter-patient variability. Different sensory phenotypes should also be taken into consideration when designing future clinical trials for neuropathic pain.

Guidelines on multidisciplinary approaches for the prevention and management of diabetic foot disease (2020 edition)

In recent years, as living standards have continued to improve, the number of diabetes patients in China, along with the incidence of complications associated with the disease, has been increasing. Among these complications, diabetic foot disease is one of the main causes of disability and death in diabetic patients. Due to the differences in economy, culture, religion and level of medical care available across different regions, preventive and treatment methods and curative results for diabetic foot vary greatly. In multidisciplinary models built around diabetic foot, the timely assessment and diagnosis of wounds and appropriate methods of prevention and treatment with internal and external surgery are key to clinical practice for this pathology. In 2019, under the leadership of the Jiangsu Medical Association and Chinese Diabetes Society, the writing group for the Guidelines on multidisciplinary approaches for the prevention and management of diabetic foot disease (2020 edition) was established with the participation of scholars from the specialist areas of endocrinology, burn injury, vascular surgery, orthopedics, foot and ankle surgery and cardiology. Drawing lessons from diabetic foot guidelines from other countries, this guide analyses clinical practices for diabetic foot, queries the theoretical basis and grades and gives recommendations based on the characteristics of the pathology in China. This paper begins with assessments and diagnoses of diabetic foot, then describes treatments for diabetic foot in detail, and ends with protections for high-risk feet and the prevention of ulcers. This manuscript covers the disciplines of internal medicine, surgical, nursing and rehabilitation and describes a total of 50 recommendations that we hope will provide procedures and protocols for clinicians dealing with diabetic foot.

Registry number: IPGRP-2020cn124

Multi-region assessment of pharmaceutical exposures and predicted effects in USA wadeable urban-gradient streams

Human-use pharmaceuticals in urban streams link aquatic-ecosystem health to human health. Pharmaceutical mixtures have been widely reported in larger streams due to historical emphasis on wastewater-treatment plant (WWTP) sources, with limited investigation of pharmaceutical exposures and potential effects in smaller headwater streams. In 2014-2017, the United States Geological Survey measured 111 pharmaceutical compounds in 308 headwater streams (261 urban-gradient sites sampled 3-5 times, 47 putative low-impact sites sampled once) in 4 regions across the US. Simultaneous exposures to multiple pharmaceutical compounds (pharmaceutical mixtures) were observed in 91% of streams (248 urban-gradient, 32 low-impact), with 88 analytes detected across all sites and cumulative maximum concentrations up to 36,142 ng/L per site. Cumulative detections and concentrations correlated to urban land use and presence/absence of permitted WWTP discharges, but pharmaceutical mixtures also were common in the 75% of sampled streams without WWTP. Cumulative exposure-activity ratios (EAR) indicated widespread transient exposures with high probability of molecular effects to vertebrates. Considering the potential individual and interactive effects of the detected pharmaceuticals and the recognized analytical underestimation of the pharmaceutical-contaminant (unassessed parent compounds, metabolites, degradates) space, these results demonstrate a nation-wide environmental concern and the need for watershed-scale mitigation of in-stream pharmaceutical contamination.

An update on the diagnosis and treatment of diabetic somatic and autonomic neuropathy

Diabetic peripheral neuropathy (DPN) is the most common chronic complication of diabetes. It poses a significant challenge for clinicians as it is often diagnosed late when patients present with advanced consequences such as foot ulceration. Autonomic neuropathy (AN) is also a frequent and under-diagnosed complication unless it is overtly symptomatic. Both somatic and autonomic neuropathy are associated with increased mortality. Multiple clinical trials have failed because of limited efficacy in advanced disease, inadequate trial duration, lack of effective surrogate end-points and a lack of deterioration in the placebo arm in clinical trials of DPN. Multifactorial risk factor reduction, targeting glycaemia, blood pressure and lipids can reduce the progression of DPN and AN. Treatment of painful DPN reduces painful symptoms by about 50% at best, but there is limited efficacy with any single agent. This reflects the complex aetiology of painful DPN and argues for improved clinical phenotyping with the use of targeted therapy, taking into account co-morbid conditions such as anxiety, depression and sleep disturbance.

Diagnosing and managing diabetic somatic and autonomic neuropathy

The diagnosis and management of diabetic neuropathy can be a major challenge. Late diagnosis contributes to significant morbidity in the form of painful diabetic neuropathy, foot ulceration, amputation, and increased mortality. Both hyperglycaemia and cardiovascular risk factors are implicated in the development of somatic and autonomic neuropathy and an improvement in these risk factors can reduce their rate of development and progression. There are currently no US Food and Drug Administration (FDA)-approved disease-modifying treatments for either somatic or autonomic neuropathy, as a consequence of multiple failed phase III clinical trials. While this may be partly attributed to premature translation, there are major shortcomings in trial design and outcome measures. There are a limited number of partially effective FDA-approved treatments for the symptomatic relief of painful diabetic neuropathy and autonomic neuropathy.

Diabetic Peripheral Neuropathy: Epidemiology, Diagnosis, and Pharmacotherapy

PURPOSE

Diabetic peripheral neuropathy (DPN) is the commonest cause of neuropathy worldwide, and its prevalence increases with the duration of diabetes. It affects approximately half of patients with diabetes. DPN is symmetric and predominantly sensory, starting distally and gradually spreading proximally in a glove-and-stocking distribution. It causes substantial morbidity and is associated with increased mortality. The unrelenting nature of pain in this condition can negatively affect a patient's sleep, mood, and functionality and result in a poor quality of life. The purpose of this review was to critically review the current literature on the diagnosis and treatment of DPN, with a focus on the treatment of neuropathic pain in DPN.

METHODS

A comprehensive literature review was undertaken, incorporating article searches in electronic databases (EMBASE, PubMed, OVID) and reference lists of relevant articles with the authors' expertise in DPN. This review considers seminal and novel research in epidemiology; diagnosis, especially in relation to novel surrogate end points; and the treatment of neuropathic pain in DPN. We also consider potential new pharmacotherapies for painful DPN.

FINDINGS

DPN is often misdiagnosed and inadequately treated. Other than improving glycemic control, there is no licensed pathogenetic treatment for diabetic neuropathy. Management of painful DPN remains challenging due to difficulties in personalizing therapy and ascertaining the best dosing strategy, choice of initial pharmacotherapy, consideration of combination therapy, and deciding on defining treatment for poor analgesic responders. Duloxetine and pregabalin remain first-line therapy for neuropathic pain in DPN in all 5 of the major published guidelines by the American Association of Clinical Endocrinologists, American Academy of Neurology, European Federation of Neurological Societies, National Institute of Clinical Excellence (United Kingdom), and the American Diabetes Association, and their use has been approved by the US Food and Drug Administration.

IMPLICATIONS

Clinical recognition of DPN is imperative for allowing timely symptom management to reduce the morbidity associated with this condition.

Depression and chronic pain in the elderly: links and management challenges

Aging is an inevitable process and represents the accumulation of bodily alterations over time. Depression and chronic pain are highly prevalent in elderly populations. It is estimated that 13% of the elderly population will suffer simultaneously from the two conditions. Accumulating evidence suggests than neuroinflammation plays a critical role in the pathogenesis of both depression and chronic pain. Apart from the common pathophysiological mechanisms, however, the two entities have several clinical links. Their management is challenging for the pain physician; however, both pharmacologic and nonpharmacologic approaches are available and can be used when the two conditions are comorbid in the elderly patients.

Efficacy and safety of duloxetine in Chinese breast cancer patients with paclitaxel-induced peripheral neuropathy

Objective

Chemotherapy with paclitaxel is associated with significant neurotoxicity that may offset patients' quality of life and therapeutic benefits. This prospective, non-randomized control study evaluated the efficacy and safety of an antidepressant drug, duloxetine, at 30 or 60 mg/d, in the treatment of paclitaxel-induced peripheral neuropathy (PIPN) in Chinese breast cancer patients.

Methods

A total of 102 patients with a median age of 50 (range, 25-60) years, treated in the Department of Medical Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, between November 2014 and January 2017 were finally enrolled. Stratified by baseline characteristics, the patients were classified into two groups, receiving either duloxetine or alternative anti-neurotoxicity drugs. During the course of the paclitaxel regimen, the eligibility criteria included sensory neuropathy, as evaluated by the National Cancer Institute-Common Toxicity Criteria for Adverse Events. The treatment consisted of receiving 30 mg duloxetine (for the first 4 weeks) and 60 mg duloxetine for an additional 8 weeks, or any other anti-neurotoxicity drug daily during the same crossover period. The improvement associated with PIPN from the patient's perspective were assessed by the Functional Assessment of Cancer Therapy-Taxane (FACT-Tax) Scales, which contained questions scored from 0 to 4 (0, not at all; 4, very much; total score range, 0-44).

Results

Duloxetine was more effective in decreasing PIPN (odds ratio=5.426; 95% confidence interval, 1.898-15.514; P=0.002). Between duloxetine group and control group, the median (25th-75th percentiles) decreasing difference in the FACT-Tax pain score was 4 (2-6) vs. 1 (0-4) (P=0.005).

Conclusions

Duloxetine is a promising and safe option with tolerable toxicity at a dose of 60 mg/d for Chinese breast cancer patients with PIPN. Non-neuropathy adverse events were mild and similar in both groups. The major toxicities of duloxetine included nausea, constipation, somnolence, dizziness and distention of the eyes. Further examination of the benefits of duloxetine in the prevention of PIPN is required.