Mirogabalin and emerging therapies for diabetic neuropathy

Novel drug treatments for pain in advanced cancer and serious illness: a focus on neuropathic pain and chemotherapy-induced peripheral neuropathy

Drugs that are commercially available but have novel mechanisms of action should be explored as analgesics. This review will discuss haloperidol, miragabalin, palmitoylethanolamide (PEA), and clonidine as adjuvant analgesics or analgesics. Haloperidol is a sigma-1 receptor antagonist. Under stress and neuropathic injury, sigma-1 receptors act as a chaperone protein, which downmodulates opioid receptor activities and opens several ion channels. Clinically, there is only low-grade evidence that haloperidol improves pain when combined with morphine, methadone, or tramadol in patients who have cancer, pain from fibrosis, radiation necrosis, or neuropathic pain. Miragabalin is a gabapentinoid approved for the treatment of neuropathic pain in Japan since 2019. In randomized trials, patients with diabetic neuropathy have responded to miragabalin. Its long binding half-life on the calcium channel subunit may provide an advantage over other gabapentinoids. PEA belongs to a group of endogenous bioactive lipids called ALIAmides (autocoid local injury antagonist amides), which have a sense role in modulating numerous biological processes in particular non-neuronal neuroinflammatory responses to neuropathic injury and systemic inflammation. Multiple randomized trials and meta-analyses have demonstrated PEA's effectiveness in reducing pain severity arising from diverse pain phenotypes. Clonidine is an alpha2 adrenoceptor agonist and an imidazoline2 receptor agonist, which is U.S. Federal Drug Administration approved for attention deficit hyperactivity disorder in children, Tourette's syndrome, adjunctive therapy for cancer-related pain, and hypertension. Clonidine activation at alpha2 adrenoceptors causes downstream activation of inhibitory G-proteins (Gi/Go), which inhibits cyclic Adenosine monophosphate (AMP) production and hyperpolarizes neuron membranes, thus reducing allodynia. Intravenous clonidine has been used in terminally ill patients with poorly controlled symptoms, in particular pain and agitation.

Home-based high tone therapy may alleviate chemotherapy-induced neuropathic symptoms in patients with colorectal cancer: A randomized double-blind placebo-controlled pilot evaluation

BACKGROUND

Most oncologic patients receiving chemotherapy suffer from neuropathy, which not only severely affects quality of life but also may lead to chemotherapy dose reductions or even discontinuation of cancer therapy. Still, it is difficult to sufficiently control these symptoms with the currently available pharmacological treatments. High tone therapy was reported to be an effective option for neuropathies due to different etiologies. However, to date, there are no studies on high tone therapy in patients with chemotherapy-induced peripheral neuropathy.

METHODS

This randomized, double-blind, and placebo-controlled two-center study was conducted at the Departments of Physical and Rehabilitation Medicine at the Clinics Donaustadt and Ottakring, Vienna, Austria. Patients with histologically verified colorectal carcinoma treated with a platin derivate and neuropathic symptoms were invited to participate. High tone therapy took place in a home-based setting using the HiToP 191 PNP ® or placebo device for three weeks. Neuropathic symptoms and quality of life were assessed via questionnaires. After the follow-up examination, an opt-in was offered to the patients in the placebo group in terms of an open-label treatment with a verum HiToP PNP ® device. In addition, patients with chemotherapy-induced peripheral neuropathy due to various malignant diseases were treated in an open-label setting reflecting a clinical application observation. These patients are reported as a separate group.

RESULTS

In the verum group, there was a significant reduction of paresthesias and mental stress due to paresthesias from baseline until end of therapy, compared to placebo. These findings were observed in the opt-in subgroup, as well. In the open-label clinical application observation group, intensity and mental stress due to paresthesia, pain, cramps, and intensity of tightness/pressure were significantly lower at the end of therapy, compared to baseline.

CONCLUSIONS

Home-based high tone therapy brought about a significant alleviation in paresthesias and mental stress due to paresthesias in the verum but not the placebo group. In the clinical application observation, a significant alleviation in several further neuropathic symptoms was seen.

TRIAL REGISTRATION

This study was registered at clinicaltrials.gov (NCT06048471, 03/02/2020).

Naturally Inspired Molecules for Neuropathic Pain Inhibition-Effect of Mirogabalin and Cebranopadol on Mechanical and Thermal Nociceptive Threshold in Mice

BACKGROUND

Neuropathic pain is drug-resistant to available analgesics and therefore novel treatment options for this debilitating clinical condition are urgently needed. Recently, two drug candidates, namely mirogabalin and cebranopadol have become a subject of interest because of their potential utility as analgesics for chronic pain treatment. However, they have not been investigated thoroughly in some types of neuropathic pain, both in humans and experimental animals.

METHODS

This study used the von Frey test, the hot plate test and the two-plate thermal place preference test supported by image analysis and machine learning to assess the effect of intraperitoneal mirogabalin and subcutaneous cebranopadol on mechanical and thermal nociceptive threshold in mouse models of neuropathic pain induced by streptozotocin, paclitaxel and oxaliplatin.

RESULTS

Mirogabalin and cebranopadol effectively attenuated tactile allodynia in models of neuropathic pain induced by streptozotocin and paclitaxel. Cebranopadol was more effective than mirogabalin in this respect. Both drugs also elevated the heat nociceptive threshold in mice. In the oxaliplatin model, cebranopadol and mirogabalin reduced cold-exacerbated pain.

CONCLUSIONS

Since mirogabalin and cebranopadol are effective in animal models of neuropathic pain, they seem to be promising novel therapies for various types of neuropathic pain in patients, in particular those who are resistant to available analgesics.

Neuropathic pain: From actual pharmacological treatments to new therapeutic horizons

Neuropathic pain, caused by a lesion or disease affecting the somatosensory system, affects between 3 and 17% of the general population. The treatment of neuropathic pain is challenging due to its heterogeneous etiologies, lack of objective diagnostic tools and resistance to classical analgesic drugs. First-line treatments recommended by the Special Interest Group on Neuropathic Pain (NeuPSIG) and European Federation of Neurological Societies (EFNS) include gabapentinoids, tricyclic antidepressants (TCAs) and selective serotonin noradrenaline reuptake inhibitors (SNRIs). Nevertheless these treatments have modest efficacy or dose limiting side effects. There is therefore a growing number of preclinical and clinical studies aim at developing new treatment strategies to treat neuropathic pain with better efficacy, selectivity, and less side effects. In this review, after a brief description of the mechanisms of action, efficacy, and limitations of current therapeutic drugs, we reviewed new preclinical and clinical targets currently under investigation, as well as promising non-pharmacological alternatives and their potential co-use with pharmacological treatments.

DDD-028: A potent, neuroprotective, non-opioid compound for the treatment of diabetic neuropathy

Diabetic neuropathy (DN) is a painful, chronic ailment that affects a large segment of diabetic population worldwide. Current medications such as pregabalin or duloxetine treat only the pain symptom associated with DN, but not the underlying nerve damage. DDD-028 (1) is a small molecule that displays potent pain-relieving activity in streptozotocin (STZ)-induced rodent model of DN. Combined with other studies indicating that DDD-028 suppresses astrogliosis and nerve damage induced by the anti-cancer drug, paclitaxel, the present study suggests that DDD-028 would be useful as a disease modifying therapeutic in the treatment of DN. The 3-dimensional structure of DDD-028 was confirmed by single crystal X-ray crystallography.

The Clinical Application and Progress of Mirogabalin on Neuropathic Pain as a Novel Selective Gabapentinoids

Background

Neuropathic pain is a complex sort of pain that is detrimental to individuals' health, both physically and mentally, but merely a small portion of them could witness pain alleviation. Mirogabalin, by distinctive binding characteristics of voltage-gated calcium channels, has won approval from the Japanese authority as a third member of gabapentinoids in Japan. Our review was aimed at encompassing the bulk of clinical research on mirogabalin, which included clinical trials, special considerations, coadministration studies, case reports, and cost-effectiveness studies.

Methods

A review was carried out on a series of platforms, such as PubMed, MEDLINE, and Scopus, up to December 2021 using the keywords as follows: "mirogabalin OR mirogabalin besylate OR Tarlige OR DS-5565" AND "neuropathic pain OR Neuropathy."

Results

Mirogabalin demonstrated analgesic activity and manageable adverse reactions and provides a new alternative for individuals with PHN or DPNP in 3 phase II and 4 III trials. Mirogabalin alleviated pain markedly in comparison with placebo. Administration of mirogabalin on a long-term basis is a flexible dosage regimen for patients with PHN. It is noteworthy that mirogabalin should be administrated cautiously when combined with probenecid and cimetidine on account of a slight increase in pharmacodynamics effects of mirogabalin.

Conclusion

The development of mirogabalin allows further optimization of individual treatment strategies so as to provide more therapeutic choices in this medical domain.

Effects of Gabapentin and Pregabalin on Calcium Homeostasis: Implications for Physical Rehabilitation of Musculoskeletal Tissues

PURPOSE OF REVIEW

In this review, we discuss the mechanism of action of gabapentinoids and the potential consequences of long-term treatment with these drugs on the musculoskeletal system.

RECENT FINDINGS

Gabapentinoids, such as gabapentin (GBP) and pregabalin (PGB) were designed as antiepileptic reagents and are now commonly used as first-line treatment for neuropathic pain and increasingly prescribed off-label for other pain disorders such as migraines and back pain. GBP and PGB exert their analgesic actions by selectively binding the α₂δ₁ auxiliary subunit of voltage-sensitive calcium channels, thereby inhibiting channel function. Numerous tissues express the α₂δ₁ subunit where GBP and PGB can alter calcium-mediated signaling events. In tissues such as bone, muscle, and cartilage, α₂δ₁ has important roles in skeletal formation, mechanosensation, and normal tissue function/repair that may be affected by chronic use of gabapentinoids. Long-term use of gabapentinoids is associated with detrimental musculoskeletal outcomes, including increased fracture risk. Therefore, understanding potential complications is essential for clinicians to guide appropriate treatments.

The Evidence for Effective Inhibition of INa Produced by Mirogabalin ((1R,5S,6S)-6-(aminomethyl)-3-ethyl-bicyclo [3.2.0] hept-3-ene-6-acetic acid), a Known Blocker of CaV Channels

Mirogabalin (MGB, Tarlige^®), an inhibitor of the α₂δ-1 subunit of voltage-gated Ca²⁺ (Ca_V) channels, is used as a way to alleviate peripheral neuropathic pain and diabetic neuropathy. However, to what extent MGB modifies the magnitude, gating, and/or hysteresis of various types of plasmalemmal ionic currents remains largely unexplored. In pituitary tumor (GH₃) cells, we found that MGB was effective at suppressing the peak (transient, I_Na(T)) and sustained (late, I_Na(L)) components of the voltage-gated Na⁺ current (I_Na) in a concentration-dependent manner, with an effective IC₅₀ of 19.5 and 7.3 μM, respectively, while the K_D value calculated on the basis of minimum reaction scheme was 8.2 μM. The recovery of I_Na(T) inactivation slowed in the presence of MGB, although the overall current-voltage relation of I_Na(T) was unaltered; however, there was a leftward shift in the inactivation curve of the current. The magnitude of the window (I_Na(W)) or resurgent I_Na (I_Na(R)) evoked by the respective ascending or descending ramp pulse (V_ramp) was reduced during cell exposure to MGB. MGB-induced attenuation in I_Na(W) or I_Na(R) was reversed by the further addition of tefluthrin, a pyrethroid insecticide known to stimulate I_Na. MGB also effectively lessened the strength of voltage-dependent hysteresis of persistent I_Na in response to the isosceles triangular V_ramp. The cumulative inhibition of I_Na(T), evoked by pulse train stimulation, was enhanced in its presence. Taken together, in addition to the inhibition of Ca_V channels, the Na_V channel attenuation produced by MGB might have an impact in its analgesic effects occurring in vivo.

ViphyllinTM, a Standardized Black Pepper Extract Exerts Antihyperglycemic Effect and Improves Sciatic Nerve Conduction in High Fat Diet/Streptozotocin-Induced Diabetic Model Rats

PURPOSE

Research on plant-based formulations has drawn considerable attention in the management of diabetic neuropathy (DN) for having lesser side effects than the synthetic counterparts. Here, we have investigated for the first time the therapeutic effects of a standardized Piper nigrum L., (black pepper) seed extract, Viphyllin^TM in mitigating hyperglycemia and neuropathic pain of type 2 diabetes model rats.

METHODS

Type 2 diabetes was induced in male Wistar rats using high fat diet and a single dose of streptozotocin (60 mg/kg i.p.). The diabetic rats were orally administered with Viphyllin containing not less than 30% β-caryophyllene (BCP), at 25 mg, 50 mg and 100 mg/kg/day doses for 6 weeks. Changes in body weight, fasting blood glucose (FBG), glucose tolerance, and blood biochemical parameters were measured. The nociceptive response to thermal stimulus (tail flick test) and sciatic nerve conduction velocity (NCV) were recorded at the end of study.

RESULTS

Viphyllin treatment markedly improved the body weight and glucose tolerance in diabetic rats. Also, the extract could significantly reduce the diabetes-induced elevation in FBG, liver and kidney indices. Further, Viphyllin dose-dependently increased the nociception latency in tail flick test compared to untreated diabetic rats (p<0.05). Viphyllin at 100 mg/kg significantly increased the NCV (44.12±1.91*** m/s vs diabetic control 25.80±1.88 m/s). The antioxidant enzyme activities in sciatic nerve tissue were considerably increased in Viphyllin-treated groups compared to diabetic control. A 6-week treatment with Viphyllin markedly reversed the pathological manifestations of diabetes in vital organs such as liver, kidney and pancreas.

CONCLUSION

The study concludes that Viphyllin exerts antidiabetic effects and improves nerve conduction to mitigate neuropathic pain.

The Treatment of Painful Diabetic Neuropathy

Painful diabetic peripheral neuropathy (painful-DPN) is a highly prevalent and disabling condition, affecting up to one-third of patients with diabetes. This condition can have a profound impact resulting in a poor quality of life, disruption of employment, impaired sleep, and poor mental health with an excess of depression and anxiety. The management of painful-DPN poses a great challenge. Unfortunately, currently there are no Food and Drug Administration (USA) approved disease-modifying treatments for diabetic peripheral neuropathy (DPN) as trials of putative pathogenetic treatments have failed at phase 3 clinical trial stage. Therefore, the focus of managing painful- DPN other than improving glycaemic control and cardiovascular risk factor modification is treating symptoms. The recommended treatments based on expert international consensus for painful- DPN have remained essentially unchanged for the last decade. Both the serotonin re-uptake inhibitor (SNRI) duloxetine and α2δ ligand pregabalin have the most robust evidence for treating painful-DPN. The weak opioids (e.g. tapentadol and tramadol, both of which have an SNRI effect), tricyclic antidepressants such as amitriptyline and α2δ ligand gabapentin are also widely recommended and prescribed agents. Opioids (except tramadol and tapentadol), should be prescribed with caution in view of the lack of definitive data surrounding efficacy, concerns surrounding addiction and adverse events. Recently, emerging therapies have gained local licenses, including the α2δ ligand mirogabalin (Japan) and the high dose 8% capsaicin patch (FDA and Europe). The management of refractory painful-DPN is difficult; specialist pain services may offer off-label therapies (e.g. botulinum toxin, intravenous lidocaine and spinal cord stimulation), although there is limited clinical trial evidence supporting their use. Additionally, despite combination therapy being commonly used clinically, there is little evidence supporting this practise. There is a need for further clinical trials to assess novel therapeutic agents, optimal combination therapy and existing agents to determine which are the most effective for the treatment of painful-DPN. This article reviews the evidence for the treatment of painful-DPN, including emerging treatment strategies such as novel compounds and stratification of patients according to individual characteristics (e.g. pain phenotype, neuroimaging and genotype) to improve treatment responses.

Mirogabalin as a Novel Gabapentinoid for the Treatment of Chronic Pain Conditions: An Analysis of Current Evidence

: Neuropathic pain is a challenge for physicians to treat and often requires a multimodal approach with both pharmacologic and lifestyle interventions. Mirogabalin, a potent, selective ligand of the α2δ-1 and α2δ-2 subunits of voltage-gated calcium channels (VGCCs), provides analgesia by inhibiting neurotransmitter release at the presynaptic end of the neuron. Mirogabalin offers more sustained analgesia than its gabapentinoid counterparts in addition to a wider safety margin for adverse events. Recent clinical trials of mirogabalin have demonstrated both efficacy and tolerability of the drug for the treatment of diabetic peripheral neuropathic pain and postherpetic neuralgia, leading to its approval in Japan. While still not yet FDA approved, mirogabalin is still in its infancy and offers potential into the treatment of neuropathic pain and its associated comorbidities.

Pathogenesis, diagnosis and clinical management of diabetic sensorimotor peripheral neuropathy

Diabetic sensorimotor peripheral neuropathy (DSPN) is a serious complication of diabetes mellitus and is associated with increased mortality, lower-limb amputations and distressing painful neuropathic symptoms (painful DSPN). Our understanding of the pathophysiology of the disease has largely been derived from animal models, which have identified key potential mechanisms. However, effective therapies in preclinical models have not translated into clinical trials and we have no universally accepted disease-modifying treatments. Moreover, the condition is generally diagnosed late when irreversible nerve damage has already taken place. Innovative point-of-care devices have great potential to enable the early diagnosis of DSPN when the condition might be more amenable to treatment. The management of painful DSPN remains less than optimal; however, studies suggest that a mechanism-based approach might offer an enhanced benefit in certain pain phenotypes. The management of patients with DSPN involves the control of individualized cardiometabolic targets, a multidisciplinary approach aimed at the prevention and management of foot complications, and the timely diagnosis and management of neuropathic pain. Here, we discuss the latest advances in the mechanisms of DSPN and painful DSPN, originating both from the periphery and the central nervous system, as well as the emerging diagnostics and treatments.

The time to develop treatments for diabetic neuropathy

BACKGROUND

Diabetic neuropathy is a multifaceted condition affecting up to 50% of individuals with long standing diabetes. The most common presentation is peripheral diabetic sensory neuropathy (DPN).

METHODS

We carried out a systematic review of papers dealing with diabetic neuropathy on Pubmed in addition to a targeted Google search.Search terms included small fiber neuropathy,diffuse peripheral neuropathy, quantitative sensory testing, nerve conduction testing, intra-epidermal nerve fiber density, corneal confocal reflectance microscopy, aldose reductase inhbitors, nerve growth factor, alpha-lipoic acid, ruboxistaurin, nerve growth factor antibody, and cibinetide.

RESULTS

Over the past half century, there have been a number of agents undergoing unsuccessful trials for treatment of DPN.There are several approved agents for relief of pain caused by diabetic neuropathy, but these do not affect the pathologic process.

EXPERT OPINION

The failure to find treatments for diabetic neuropathy can be ascribed to (1) the complexity of design of studies and (2) the slow progression of the condition, necessitating long duration trials to prove efficacy.We propose a modification of the regulatory process to permit early introduction of agents with demonstrated safety and suggestion of benefit as well as prolongation of marketing exclusivity while long term trials are in progress to prove efficacy.

Mirogabalin: could it be the next generation gabapentin or pregabalin?

Except for carbamazepine for trigeminal neuralgia, gabapentinoid anticonvulsants have been the standard for the treatment of neuropathic pain. Pregabalin, which followed gabapentin, was developed with the benefit of rapid peak blood concentration and better bioavailability. Mirogabalin besylate (DS-5565, Tarlige^®) shows greater sustained analgesia due to a high affinity to, and slow dissociation from, the α₂δ-1 subunits in the dorsal root ganglion (DRG). Additionally, it produces a lower level of central nervous system-specific adverse drug reactions (ADRs), due to a low affinity to, and rapid dissociation from, the α₂δ-2 subunits in the cerebellum. Maximum plasma concentration is achieved in less than 1 hour, compared to 1 hour for pregabalin and 3 hours for gabapentin. The plasma protein binding is relatively low, at less than 25%. As with all gabapentinoids, it is also largely excreted via the kidneys in an unchanged form, and so the administration dose should also be adjusted according to renal function. The equianalgesic daily dose for 30 mg of mirogabalin is 600 mg of pregabalin and over 1,200 mg of gabapentin. The initial adult dose starts at 5 mg, given orally twice a day, and is gradually increased by 5 mg at an interval of at least a week, to 15 mg. In conclusion, mirogabalin is anticipated to be a novel, safe gabapentinoid anticonvulsant with a greater therapeutic effect for neuropathic pain in the DRG and lower ADRs in the cerebellum.

State-of-the-art pharmacotherapy for diabetic neuropathy

INTRODUCTION

The global epidemic of diabetes has led to an epidemic of diabetes complications. Diabetic neuropathy is the most common microvascular complication, of which diabetic peripheral neuropathy (DPN) and autonomic neuropathy (AN) are the most prevalent, affecting ~50% of patients. DPN results in pain with a poor quality of life and a loss of sensation with an increased risk of foot ulceration. Autonomic neuropathy can cause significant morbidity in a minority and is associated with increased mortality. The cornerstone of treatment to prevent or limit the progression of DPN/AN is multifactorial risk factor modification including treatment of glycemia, lipids and blood pressure. Whilst, there are no FDA-approved disease-modifying therapies, there are a number of therapies to relieve symptoms in DPN and AN.

AREAS COVERED

The authors discuss current approved therapies for painful diabetic neuropathy and autonomic neuropathy. They also address the potential role of improving risk factors to limit the development and progression of diabetic neuropathy and new pathogenetic and pain-relieving treatments.

EXPERT OPINION

The FDA-approved Pregabalin and Duloxetine over 25 years ago and Tapentadol, 6 years ago for painful diabetic neuropathy. There are currently no FDA-approved disease-modifying treatments for diabetic neuropathy which has been attributed to inappropriate models of the disease with limited translational capacity and major limitations of trial designs and endpoints in clinical trials.

Roles of circular RNAs in diabetic complications: From molecular mechanisms to therapeutic potential

Diabetes is characterized by changed homeostasis of blood glucose levels, which is associated with various complications, including cardiomyopathy, atherosclerosis, endothelial dysfunction, nephropathy, retinopathy and neuropathy. In recent years, accumulative evidence has demonstrated that circular RNAs are identified as a novel type of noncoding RNAs (ncRNAs) involving in the regulation of various physiological processes and pathologic conditions. Specifically, the emergence of complications response to diabetes is finely controlled by a complex gene regulatory network in which circular RNAs play a critical role. Recently, circular RNAs are emerging as messengers that could influence cellular functions under diabetic conditions. Dysregulation of circular RNAs has been closely linked to the pathophysiology of diabetes-related complications. In this review, we aimed to summarize the current progression and underlying mechanisms of circular RNA in the development of diabetes-related complications. We will also provide an overview of circular RNA-regulated cell communications in different types of cells that have been linked to diabetic complications. We anticipated that the completion of this review will provide potential clues for developing novel circular RNAs-based biomarkers or therapeutic targets for diabetes and its associated complications.

Mirogabalin in Japanese Patients with Renal Impairment and Pain Associated with Diabetic Peripheral Neuropathy or Post-Herpetic Neuralgia: A Phase III, Open-Label, 14-Week Study

Purpose

Mirogabalin was recently approved in Japan for the treatment of peripheral neuropathic pain, based on data from clinical trials in diabetic peripheral neuropathic pain (DPNP) and post-herpetic neuralgia (PHN), common clinical conditions which cause intense distress for patients. We characterized the safety and tolerability of mirogabalin in Japanese patients with renal impairment.

Patients and Methods

This multicenter, open-label study (ClinicalTrials.gov identifier NCT02607280) enrolled renally impaired individuals aged ≥20 years diagnosed with DPNP or PHN, and with an average daily pain score (ADPS) of ≥4 over the 7 days prior to treatment initiation. Mirogabalin dosage was titrated for 2 weeks, followed by a fixed dose for 12 weeks according to degree of renal impairment: 7.5 mg twice daily for moderate impairment and 7.5 mg once daily for severe impairment. The primary endpoint was safety and tolerability of mirogabalin, evaluated via treatment-emergent adverse events (TEAEs). Secondary efficacy endpoints included change in ADPS from baseline to Week 14.

Results

Overall, 35 patients were enrolled (30 with moderate and 5 with severe renal impairment). Most TEAEs were mild or moderate in severity; the most commonly reported were nasopharyngitis (22.9%) and somnolence (11.4%). Only 4 patients (11.4%) discontinued treatment due to TEAEs. Mirogabalin significantly decreased ADPS from baseline in patients with renal impairment; least squares mean change from baseline at Week 14 was −1.9 (95% confidence interval: −2.8, −1.0).

Conclusion

Mirogabalin was well tolerated and significantly reduced pain levels when used to treat DPNP/PHN at a fixed dose of 7.5 mg once or twice daily in patients with renal impairment.

Short-term outcomes of mirogabalin in patients with peripheral neuropathic pain: a retrospective study

Background

Mirogabalin, which is approved for the treatment of peripheral neuropathic pain in Japan, is a ligand for the α2δ subunit of voltage-gated calcium channels. Both pregabalin and mirogabalin act as nonselective ligands at the α2δ-1 and α2δ-2 subunits. Mirogabalin has a unique binding profile and long duration of action. Pregabalin has been reported to produce intolerable adverse effects in some patients. This study investigated outcomes associated with mirogabalin administration in patients with peripheral neuropathic pain who ceased treatment with pregabalin.

Methods

We retrospectively assessed peripheral neuropathic pain using the neuropathic pain screening questionnaire (NeP score) in 187 patients (58 men, 129 women) who were treated with mirogabalin. All patients had switched from pregabalin to mirogabalin due to lack of efficacy or adverse events. Differences in the treatment course (i.e., numeric rating scale (NRS) scores) were compared using one-way analysis of variance with Bonferroni post hoc tests.

Results

The mean age of the patients was 72.3 years (range, 30–94 years), and the mean duration of disease was 37 months (range, 3–252 months). After treatment with mirogabalin for 1 week, NRS scores significantly decreased compared with baseline and continued to decrease over time. After 8 weeks, NRS scores improved by ≥ 30% from baseline in 113 patients (69.3%). Twenty-four patients (12.8%) stopped mirogabalin treatment due to adverse events. Somnolence (26.7%), dizziness (12.3%), edema (5.9%), and weight gain (0.5%) were noted as adverse events of mirogabalin.

Conclusions

The results of this investigation indicate that mirogabalin is safe and effective for reducing peripheral neuropathic pain.

An engineered non-erythropoietic erythropoietin-derived peptide, ARA290, attenuates doxorubicin induced genotoxicity and oxidative stress

Erythropoietin (EPO) applies anti-inflammatory, anti-apoptotic, anti-oxidant and cytoprotective effects besides its hematopoietic action. A nonhematopoietic peptide engineered from EPO, ARA 290, interacts selectively with the innate repair receptor and has similar possessions. ARA290 mediates tissue protection without hematopoietic side-effects of EPO which limit its clinical application. Doxorubicin (DOX) is the broad-spectrum chemotherapeutic agent, but its use is limited by the development of nonspecific toxicity on noncancerous tissues especially in cardiac cells. Mechanisms behind the DOX-induced toxicities are enhanced level of oxidative damage, inflammation and apoptosis. In the present study, we have investigated whether ARA290 acts as a chemoprotective agent modulating the cytotoxicity, genotoxicity and oxidative stress induced in vitro by DOX. The genoprotective effect of ARA290 on DOX-induced toxicity in three cell line (HepG2, HGF & Stem cell) were assessed. Cells were treated with ARA290 (50-400 nM) and DOX (1 μM) in pretreatment condition. Cytotoxicity was evaluated using the MTT assay, genoprotective effect of ARA290 were evaluated using the micronucleus test and comet assay. AR290 significantly reduced the percentage of DNA in tail and the frequency of micronuclei induced by DOX. Besides, DOX impaired anti-oxidant defense enzyme activities and induced inflammation and apoptotic cell death. ARA290 markedly attenuated DOX induced oxidative stress and protected against DOX induced inflammation and apoptotic cell death. This result proposes that ARA290 can act as a protective agent, reducing DOX-induced DNA damage and oxidative stress, and it is possible that this protection could also extend to cardiac cells.

All about pain pharmacology: what pain physicians should know

From the perspective of the definition of pain, pain can be divided into emotional and sensory components, which originate from potential and actual tissue damage, respectively. The pharmacologic treatment of the emotional pain component includes antianxiety drugs, antidepressants, and antipsychotics. The anti-anxiety drugs have anti-anxious, sedative, and somnolent effects. The antipsychotics are effective in patients with positive symptoms of psychosis. On the other hand, the sensory pain component can be divided into nociceptive and neuropathic pain. Non-steroidal anti-inflammatory drugs (NSAIDs) and opioids are usually applied for somatic and visceral nociceptive pain, respectively; anticonvulsants and antidepressants are administered for the treatment of neuropathic pain with positive and negative symptoms, respectively. The NSAIDs, which inhibit the cyclo-oxygenase pathway, exhibit anti-inflammatory, antipyretic, and analgesic effects; however, they have a therapeutic ceiling. The adverse reactions (ADRs) of the NSAIDs include gastrointestinal problems, generalized edema, and increased bleeding tendency. The opioids, which bind to the opioid receptors, present an analgesic effect only, without anti-inflammatory, antipyretic, or ceiling effects. The ADRs of the opioids start from itching and nausea/vomiting to cardiovascular and respiratory depression, as well as constipation. The anticonvulsants include carbamazepine, related to sodium channel blockade, and gabapentin and pregabalin, related to calcium blockade. The antidepressants show their analgesic actions mainly through inhibiting the reuptake of serotonin or norepinephrine. Most drugs, except NSAIDs, need an up-dose titration period. The principle of polypharmacy for analgesia in case of mixed components of pain is increasing therapeutic effects while reducing ADRs, based on the origin of the pain.

New Perspective in Diabetic Neuropathy: From the Periphery to the Brain, a Call for Early Detection, and Precision Medicine

Diabetic peripheral neuropathy (DPN) is a common chronic complication of diabetes mellitus. It leads to distressing and expensive clinical sequelae such as foot ulceration, leg amputation, and neuropathic pain (painful-DPN). Unfortunately, DPN is often diagnosed late when irreversible nerve injury has occurred and its first presentation may be with a diabetic foot ulcer. Several novel diagnostic techniques are available which may supplement clinical assessment and aid the early detection of DPN. Moreover, treatments for DPN and painful-DPN are limited. Only tight glucose control in type 1 diabetes has robust evidence in reducing the risk of developing DPN. However, neither glucose control nor pathogenetic treatments are effective in painful-DPN and symptomatic treatments are often inadequate. It has recently been hypothesized that using various patient characteristics it may be possible to stratify individuals and assign them targeted therapies to produce better pain relief. We review the diagnostic techniques which may aid the early detection of DPN in the clinical and research environment, and recent advances in precision medicine techniques for the treatment of painful-DPN.

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.