The effect of venlafaxine HCl on painful peripheral diabetic neuropathy in patients with type 2 diabetes mellitus

Chemical Constituents and Hypoglycemic Mechanisms of Dendrobium nobile in Treatment of Type 2 Diabetic Rats by UPLC-ESI-Q-Orbitrap, Network Pharmacology and In Vivo Experimental Verification

This study aimed to systematically explore the chemical constituents of D. nobile and its hypoglycemic effect by UPLC-ESI-Q-Orbitrap, network pharmacology and in vivo experiment. The chemical constituents of D. nobile were qualitatively analyzed, and the hypoglycemic compounds were quickly identified. Network pharmacological analysis and molecular docking technique were applied to assist in the elucidation of the hypoglycemic mechanisms of D. nobile. A type 2 diabetic mellitus (T2DM) rat model was established using the HFD and STZ method for in vivo experimental verification, and these T2DM rats were treated with D. nobile extract and D. nobile polysaccharide for two months by gavage. The results showed that a total of 39 chemical constituents of D. nobile, including alkaloids, bibenzyls, phenanthrenes and other types of compounds, were identified. D. nobile extract and D. nobile polysaccharide could significantly ameliorate the body weight, hyperglycemia, insulin resistance, dyslipidemia and morphological impairment of the liver and pancreas in the T2DM rats. α-Linolenic acid, dihydroconiferyl dihydro-p-coumarate, naringenin, trans-N-feruloyltyramine, gigantol, moscatilin, 4-O-methylpinosylvic acid, venlafaxine, nordendrobin and tristin were regarded as the key hypoglycemic compounds of D. nobile, along with the hypoglycemic effect on the PI3K-AKT signaling pathway, the insulin signaling pathway, the FOXO signaling pathway, the improvement of insulin resistance and the AGE-RAGE signaling pathway. The Western blotting experiment results confirmed that D. nobile activated the PI3K/AKT pathway and insulin signaling pathway, promoted glycogen synthesis via regulating the expression of glycogen synthase kinase 3 beta (GSK-3β) and glucose transporter 4 (GLUT4), and inhibited liver gluconeogenesis by regulating the expression of phosphoenolpyruvate carboxykinase (PEPCK) and glucose 6 phosphatase (G6pase) in the liver. The results suggested that the hypoglycemic mechanism of D. nobile might be associated with liver glycogen synthesis and gluconeogenesis, contributing to improving insulin resistance and abnormal glucose metabolism in the T2DM rats.

Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a debilitating side effect of many common anti-cancer agents that can lead to dose reduction or treatment discontinuation, which decrease chemotherapy efficacy. Long-term CIPN can interfere with activities of daily living and diminish the quality of life. The mechanism of CIPN is not yet fully understood, and biomarkers are needed to identify patients at high risk and potential treatment targets. Metabolomics can capture the complex behavioral and pathophysiological processes involved in CIPN. This chapter is to review the CIPN metabolomics studies to find metabolic pathways potentially involved in CIPN. These potential CIPN metabolites are then investigated to determine whether there is evidence from studies of other neuropathy etiologies such as diabetic neuropathy and Leber hereditary optic neuropathy to support the importance of these pathways in peripheral neuropathy. Six potential biomarkers and their putative mechanisms in peripheral neuropathy were reviewed. Among these biomarkers, histidine and phenylalanine have clear roles in neurotransmission or neuroinflammation in peripheral neuropathy. Further research is needed to discover and validate CIPN metabolomics biomarkers in large clinical studies.

A Look at Commonly Utilized Serotonin Noradrenaline Reuptake Inhibitors (SNRIs) in Chronic Pain

Purpose of Review

Chronic pain continues to be one of the leading healthcare cost burdens in the United States and is typically defined as ongoing pain, lasting longer than six months. Various treatment options exist for chronic pain, including physical therapy, medical management, pain psychology, and interventional therapies. Pain medications have been the mainstay of treatment for chronic pain conditions with an increasing use of membrane stabilizers and antidepressants to treat neuropathic pain conditions. Specifically, serotonin noradrenaline reuptake inhibitors (SNRIs) have been used to treat a range of pain conditions expanding from everyday use for depressive disorders.

Recent Findings

SNRIs, including duloxetine, venlafaxine, and milnacipran, have demonstrated efficacy in reducing pain in musculoskeletal pain (chronic low back pain and osteoarthritis), fibromyalgia, and neuropathic pain conditions (peripheral diabetic neuropathy).

Summary

The article describes the function, role, and use of SNRIs to treat chronic and neuropathic pain by altering the noradrenergic descending inhibitory pathways.

Early Optimized Pharmacological Treatment in Patients With Depression and Chronic Pain

Major depressive disorder (MDD) is the leading cause of disability worldwide. Patients with MDD have high rates of comorbidity with mental and physical conditions, one of which is chronic pain. Chronic pain conditions themselves are also associated with significant disability, and the large number of patients with MDD who have chronic pain drives high levels of disability and compounds healthcare burden. The management of depression in patients who also have chronic pain can be particularly challenging due to underlying mechanisms that are common to both conditions, and because many patients with these conditions are already taking multiple medications. For these reasons, healthcare providers may be reluctant to treat such patients. The Canadian Network for Mood and Anxiety Treatments (CANMAT) guidelines provide evidence-based recommendations for the management of MDD and comorbid psychiatric and medical conditions such as anxiety, substance use disorder, and cardiovascular disease; however, comorbid chronic pain is not addressed. In this article, we provide an overview of the pathophysiological and clinical overlap between depression and chronic pain and review evidence-based pharmacological recommendations in current treatment guidelines for MDD and for chronic pain. Based on clinical experience with MDD patients with comorbid pain, we recommend rapidly and aggressively treating depression according to CANMAT treatment guidelines, using antidepressant medications with analgesic properties, while addressing pain with first-line pharmacotherapy as treatment for depression is optimized. We review options for treating pain symptoms that remain after response to antidepressant treatment is achieved.

Different Drugs for the Treatment of Painful Diabetic Peripheral Neuropathy: A Meta-Analysis

Objective: To systematically evaluate the effects of different drugs for the treatment of painful diabetic peripheral neuropathy.

Methods: All literature from PubMed, Embase, and Cochrane Central Register of Controlled Trials published over the past 12 years (from January 1, 2008 to June 1, 2020) was searched, and two reviewers independently assessed study eligibility, continuous data extraction, independent assessment of bias risk, and graded strength of evidence. The pain score was used as the main result, and 30 and 50% pain reduction and adverse events were used as secondary results.

Results: A total of 37 studies were included. Pregabalin, duloxetine, tapentadol, lacosamide, mirogabalin, and capsaicin were all more effective than placebo in alleviating the pain associated with diabetic peripheral neuropathy, while ABT-894 and gabapentin showed no significant effect. In addition, the efficacy of buprenorphine, tanezumab, fulranumab and others could not be concluded due to insufficient studies.

Conclusion: Pregabalin and duloxetine showed good therapeutic effects on painful DPN, but adverse events were also significant. The analgesic effects of ABT-894 and gabapentin need to be further studied with longer and larger RCTs. As an opioid drug, tapentadol has a good analgesic effect, but due to its addiction, it needs to be very cautious in clinical use. Although lacosamide, mirogabalin, and capsaicin are more effective than placebo, the therapeutic effect is weaker than pregabalin. For the results of our meta-analysis, long-term studies are still needed to verify their efficacy and safety in the future.

Systematic Review Registration: PROSPERO, identifier: CRD42020197397.

Chronic Pain: A Complex Condition With a Multi-Tangential Approach

Chronic pain is known as ongoing pain that lasts longer than three months with increasing healing time. It is approximated that 20% of adults of different sexes, races, and socioeconomic backgrounds fall victim to chronic pain. It is a result of several factors and can have lifelong effects. Pain is a complex matter to measure; therefore, the physician needs to understand the patient's health state to create a management plan tending to each issue adequately. There are many complications of such pain, and it can interfere terribly with an individual's quality of life. This article has reviewed the complex pathogenesis of chronic pain and the spectrum of non-pharmacologic modalities and pharmacological treatment options. It has also explored the efficacy of certain drugs and underlined the importance of nonpharmacological options such as physical exercise, cognitive therapy, and physical modalities to treat chronic pain and all the conditions that accompany this disorder.

Alleviating neuropathy of diabetic foot ulcer by co-delivery of venlafaxine and matrix metalloproteinase drug-loaded cellulose nanofiber sheets: production, in vitro characterization and clinical trial

BACKGROUND

The objective of the present study was co-delivery of venlafaxin (VEN) and doxycycline (DOX), a matrix metalloproteinase inhibitor drug, for alleviating inflammation and neuropathy in diabetic foot ulcer (DFU).

METHODS

Bacterial cellulose nanofiber sheets (BCNS) were loaded with DOX and VEN and categorized by their loading efficiency, release profiles and ex vivo permeation throughrat skin. The optimized nanofibers were used in patients with DFU to compare with the standard wound care regimen during a 12-week trial. Wound area was measured every 2 weeks. Biochemical parameters and microscopic studies of the skin were examined prior and at the end of the treatment. The Michigan Neuropathy Screening Instrument (MNSI) questionnaire was utilized to assess diabetic neuropathy.

RESULTS

The optimum formulation showed loading efficiency of 37.8 ± 1.6% for DOX and 48 ± 1.9% for VEN. Rat skin permeation was 40% for DOX after 7-29 h and 83% for VEN during 105 h. Patients treated with BCNS showed no significant difference in their biochemical parameters before and after intervention. The ulcer size showed faster reduction after 12 weeks in the treatment group compared to the control group. The abnormal responses in the MNSI questionnaire decreased and pain-free walking distance increased significantly in the treatment group compared with the control group (p < 0.001). Microscopic studies of the skin after using nanofibers showed a large number of polymorphonuclear chronic inflammatory cells and formation of new capillary beds.

CONCLUSIONS

The BCNS loaded with DOX and VEN may expedite healing and reduce neuropathy in the DFU of diabetic patients.

Considerations for single- versus multiple-drug pharmacotherapy in the management of painful diabetic neuropathy

INTRODUCTION

The efficacy of monotherapy to reduce pain from diabetic peripheral neuropathy (DPN) is frequently not satisfactory and guidelines do not provide unanimous treatment options. In this context, multiple drug pharmacotherapy may provide benefit.

AREAS COVERED

The aim of the present review is to describe the clinical trials addressing the pharmacotherapy of painful DPN. Studies discussing efficacy and tolerability of pharmacological agents that were assessed in monotherapy and in combination treatment are reported and discussed.

EXPERT OPINION

Several clinical trials have reported benefit of multiple-drug pharmacotherapy. Nevertheless, untoward effects of combination treatment are of concern. Importantly, some trials were restricted to comparison with placebo and other compared only with active comparator(s). Only limited clinical trials assessed selected cohorts of individuals experiencing different stages of painful DPN. Despite current limitations, some evidence of studies implicating a comparison to all active comparators points to safety and effectiveness of the combination of oxycodone with pregabalin and that of pregabalin with the 5% lidocaine plaster but future, clear-cut studies are required to drive evidence-based decisions in the clinical setting.

B vitamins as a treatment for diabetic pain and neuropathy

WHAT IS KNOWN AND OBJECTIVE

B vitamin therapy is a common treatment for diabetic pain and neuropathy, yet its use remains controversial in patients lacking B vitamin deficiencies. The aim of this review was to summarize the current evidence for the efficacy of B vitamin therapy in diabetic patients with neuropathy.

COMMENT

We screened the English literature for clinical studies evaluating B vitamins as a therapy for pain and neuropathy in diabetic patients. We selected 43 relevant studies for qualitative analysis based on our selection criteria. Our survey of the literature revealed substantive heterogeneity with respect to efficacies of reported outcomes, as well as study design. Most beneficial outcomes were reported against baseline measures, with few positive comparisons against placebo. This highlights the need for larger, placebo-controlled studies.

WHAT IS NEW AND CONCLUSION

B vitamins should be considered a plausible therapy for diabetic neuropathy, but its overall efficacy remains uncertain and requires further study.

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.

Treatment of Neuropathic Pain with Venlafaxine: A Systematic Review

Objective

To investigate the efficacy of venlafaxine for neuropathic pain and review literature to determine if the medication provides adequate neuropathic pain relief.

Methods

Literature was reviewed on MEDLINE using various key words. These key words include: "venlafaxine and pain," "venlafaxine ER and pain," "venlafaxine XR and pain," "venlafaxine and neuropathic pain," "venlafaxine and neuropathy," "SSRI and neuropathic pain," "SSRI and neuropathy," "SNRI and neuropathic pain," "SNRI and neuropathy," "serotonin reuptake inhibitor and neuropathic pain," "serotonin reuptake inhibitor and neuropathy," "serotonin norepinephrine reuptake inhibitor and neuropathic pain" and "serotonin norepinephrine reuptake inhibitor and neuropathy." Using this guideline, 13 articles were reviewed.

Results

A total of 13 studies reviewed, which are organized by date and diagnosis. It is evident that in the majority of studies, when compared with a placebo, there was a clinical significant reduction in neuropathic pain relief when using venlafaxine. Additionally, one study showed even more significant pain relief when using higher doses of venlafaxine (at least 150 mg). However, when compared with alternative neuropathic medications, venlafaxine for the most part did not perform any better in terms of efficacy.

Conclusion

In conclusion, venlafaxine is a safe and well-tolerated analgesic drug for the symptomatic treatment of neuropathic pain, and there is limited evidence that high-dose venlafaxine (150 mg/day) can be even more beneficial. While the present evidence is quite encouraging regarding venlafaxine's use for neuropathic pain, further research is needed to continue to expand on these findings, particularly when in consideration with other possible pharmacological agents.

Alternatives to Opioids in the Pharmacologic Management of Chronic Pain Syndromes: A Narrative Review of Randomized, Controlled, and Blinded Clinical Trials

Chronic pain exerts a tremendous burden on individuals and societies. If one views chronic pain as a single disease entity, then it is the most common and costly medical condition. At present, medical professionals who treat patients in chronic pain are recommended to provide comprehensive and multidisciplinary treatments, which may include pharmacotherapy. Many providers use nonopioid medications to treat chronic pain; however, for some patients, opioid analgesics are the exclusive treatment of chronic pain. However, there is currently an epidemic of opioid use in the United States, and recent guidelines from the Centers for Disease Control (CDC) have recommended that the use of opioids for nonmalignant chronic pain be used only in certain circumstances. The goal of this review was to report the current body of evidence-based medicine gained from prospective, randomized-controlled, blinded studies on the use of nonopioid analgesics for the most common noncancer chronic pain conditions. A total of 9566 studies were obtained during literature searches, and 271 of these met inclusion for this review. Overall, while many nonopioid analgesics have been found to be effective in reducing pain for many chronic pain conditions, it is evident that the number of high-quality studies is lacking, and the effect sizes noted in many studies are not considered to be clinically significant despite statistical significance. More research is needed to determine effective and mechanism-based treatments for the chronic pain syndromes discussed in this review. Utilization of rigorous and homogeneous research methodology would likely allow for better consistency and reproducibility, which is of utmost importance in guiding evidence-based care.

Evidence and clinical considerations for the use of serotonin and norepinephrine reuptake inhibitors for the treatment of painful neuropathy

Introduction

Peripheral neuropathy is a painful condition that can lead to a reduction in quality of life. The pain, which stems from damaged, hyperexcitable neurons, does not respond to traditional analgesics. However, due to the underlying mechanism of pain, some antidepressants are effective in managing peripheral neuropathy. The purpose of this review is to evaluate the available literature on serotonin-norepinephrine reuptake inhibitors for the management of peripheral neuropathy and outline clinical considerations for choosing an agent.

Methods

PubMed, Ovid/MEDLINE, and Scopus queries were conducted for relevant literature. Search types were limited to keyword searches and articles were limited to those published prior to March 31, 2015.

Results

There were 19 randomized controlled trials included in this review. No articles were found investigating the use of desvenlafaxine, milnacipran, or levomilnacipran for treatment of neuropathy. Both duloxetine and venlafaxine improved pain severity scores for patients suffering from painful peripheral neuropathy compared to placebo.

Discussion

Duloxetine and venlafaxine are able to decrease the severity of peripheral neuropathic pain. None of the trials found that either one of the therapies was able to completely eliminate pain for the patients, which should be an important counseling point for patients to understand. Additionally, patient-specific factors should be considered when choosing an agent, including comorbid disease states and potentially interacting medications.

[Recommendations for treatment and prevention of herpes zoster and associated pain in aged adults]

Initiated within the first 72 hours of the rash, prescribing antiviral drugs reduces both acute neuralgia (AN) and later complications and especially postherpetic neuralgia (PHN). But their analgesic as well as preventative effect on AN and PHN is modest. Combination with analgesic drugs is more often needed for pain management. However, the pharmacological management of pain, in the context of old patients' frailty, co-morbidities and often polypharmacy, must be carefully considered. Based on analyses of the evidences from the literature, this review presents the therapeutic options we have at one's disposal and proposes a stepwise management for both AN and PHN specifically designed for aged population.

Venlafaxine for neuropathic pain in adults

BACKGROUND

Neuropathic pain, which is caused by nerve damage, is increasing in prevalence worldwide. This may reflect improved diagnosis, or it may be due to increased incidence of diabetes-associated neuropathy, linked to increasing levels of obesity. Other types of neuropathic pain include post-herpetic neuralgia, trigeminal neuralgia, and neuralgia caused by chemotherapy. Antidepressant drugs are sometimes used to treat neuropathic pain; however, their analgesic efficacy is unclear. A previous Cochrane review that included all antidepressants for neuropathic pain is being replaced by new reviews of individual drugs examining chronic neuropathic pain in the first instance. Venlafaxine is a reasonably well-tolerated antidepressant and is a serotonin reuptake inhibitor and weak noradrenaline reuptake inhibitor. Although not licensed for the treatment of chronic or neuropathic pain in most countries, it is sometimes used for this indication.

OBJECTIVES

To assess the analgesic efficacy of, and the adverse effects associated with the clinical use of, venlafaxine for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) via The Cochrane Library, and MEDLINE and EMBASE via Ovid up to 14 August 2014. We reviewed the bibliographies of any randomised trials identified and review articles, contacted authors of one excluded study and searched www.clinicaltrials.gov to identify additional published or unpublished data. We also searched the meta-Register of controlled trials (mRCT) (www.controlled-trials.com/mrct) and the WHO International Clinical Trials Registry Platform (ICTRP) (apps.who.int/trialsearch/) for ongoing trials but did not find any relevant trials.

SELECTION CRITERIA

We included randomised, double-blind studies of at least two weeks' duration comparing venlafaxine with either placebo or another active treatment in chronic neuropathic pain in adults. All participants were aged 18 years or over and all included studies had at least 10 participants per treatment arm. We only included studies with full journal publication.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data using a standard form and assessed study quality. We intend to analyse data in three tiers of evidence as described by Hearn 2014, but did not find any first-tier evidence (ie evidence meeting current best standards, with minimal risk of bias) or second-tier evidence, that was considered at some risk of bias but with adequate participant numbers (at least 200 in the comparison). Third-tier evidence is that arising from studies with small numbers of participants; studies of short duration, studies that are likely to be of limited clinical utility due to other limitations, including selection bias and attrition bias; or a combination of these.

MAIN RESULTS

We found six randomised, double-blind trials of at least two weeks' duration eligible for inclusion. These trials included 460 participants with neuropathic pain, with most participants having painful diabetic neuropathy. Four studies were of cross-over design and two were parallel trials. Only one trial was both parallel design and placebo-controlled. Mean age of participants ranged from 48 to 59 years. In three studies (Forssell 2004, Jia 2006 and Tasmuth 2002), only mean data were reported. Comparators included placebo, imipramine, and carbamazepine and duration of treatment ranged from two to eight weeks. The risk of bias was considerable overall in the review, especially due to the small size of most studies and due to attrition bias. Four of the six studies reported some positive benefit for venlafaxine. In the largest study by Rowbotham, 2004, 56% of participants receiving venlafaxine 150 to 225 mg achieved at least a 50% reduction in pain intensity versus 34% of participants in the placebo group and the number needed to treat for an additional beneficial outcome was 4.5. However, this study was subject to significant selection bias. Known adverse effects of venlafaxine, including somnolence, dizziness, and mild gastrointestinal problems, were reported in all studies but were not particularly problematic and, overall, adverse effects were equally prominent in placebo or other active comparator groups.

AUTHORS' CONCLUSIONS

We found little compelling evidence to support the use of venlafaxine in neuropathic pain. While there was some third-tier evidence of benefit, this arose from studies that had methodological limitations and considerable risk of bias. Placebo effects were notably strong in several studies. Given that effective drug treatments for neuropathic pain are in current use, there is no evidence to revise prescribing guidelines to promote the use of venlafaxine in neuropathic pain. Although venlafaxine was generally reasonably well tolerated, there was some evidence that it can precipitate fatigue, somnolence, nausea, and dizziness in a minority of people.

Review of antidepressants in the treatment of neuropathic pain

Introduction

Neuropathy is a pathological pain disorder characterized by burning, stabbing, and cramping sensations. There are multiple etiologies for this pain such as diabetes, vascular disorders, and chemotherapy treatment. Neurotransmitters, such as norepinephrine and serotonin, are thought to play a part in the modulation of this pain. The objective of this review is to summarize the current literature to support the efficacy and impact of adverse events of the various classes of antidepressants utilized in the treatment of neuropathic pain.

Methods

A Medline/Pubmed search was conducted to identify randomized clinical trials within the last 12 years examining the efficacy and safety of antidepressants for the treatment of neuropathy. Systematic reviews and meta-analyses were also included.

Results

Antidepressants are commonly used in the treatment of neuropathy, with meta-analyses supporting the use of tricyclic antidepressants and selective norepinephrine serotonin reuptake inhibitors. Trials indicate that venlafaxine, duloxetine, and tricyclic antidepressants (TCAs) have comparable efficacy, but TCAs have a higher incidence of adverse effects. Other antidepressants, such as citalopram, paroxetine, and bupropion have limited evidence supporting their use in neuropathy.

Discussion

Based on the evidence reviewed, venlafaxine and duloxetine should be used as first-line agents. TCAs should be used as second-line agents, due to higher incidence of adverse effects. Other treatment options include citalopram, paroxetine, and bupropion, but data supporting their efficacy is limited.

Clinical experience with desvenlafaxine in treatment of pain associated with diabetic peripheral neuropathy

Purpose

To assess the safety and efficacy of the serotonin–norepinephrine reuptake inhibitor desvenlafaxine in adults with painful diabetic peripheral neuropathy (DPN).

ClinicalTrials.gov identifiers

NCT00283842, NCT01050218.

Patients and methods

This was a 13-week, randomized, double-blind, placebo-controlled, fixed-dose study of desvenlafaxine in adults with painful DPN. The primary efficacy endpoint was change from baseline in numeric rating scale (NRS) score. Patients who completed the 13-week trial could continue in a 9-month open-label, flexible-dose extension study.

Results

A total of 412 patients were randomized to treatment with placebo or desvenlafaxine 50, 100, 200, or 400 mg/day. Of those, 240 patients continued in the extension study. After a planned interim analysis, conducted when the first 225 patients had completed 6 weeks of treatment in the short-term study, randomization to the 50 mg or 400 mg doses was stopped. At week 13, the mean change from baseline in NRS score was significantly greater compared with placebo in the desvenlafaxine 200 mg (difference [95% confidence interval {CI}]: 1.10 [0.50 to 1.70]; P<0.001) and 400 mg groups (0.91 [95% CI: 0.23 to 1.59]; P=0.027); differences from placebo were not statistically significant for the 50 mg (0.58 [95% CI: −0.08 to 1.25]) and 100 mg (0.59 [95% CI: –0.03 to 1.21]) groups. Nausea and dizziness were the most common treatment-emergent adverse events reported in the short-term study, and the most common adverse events leading to discontinuation in the short-term study and the extension. Adverse events rates were dose-dependent in the short-term studies.

Conclusion

Desvenlafaxine was effective in relieving pain associated with DPN at doses of 200 and 400 mg/day, and improved activity impairment at all doses assessed. Desvenlafaxine was generally well-tolerated in the short-term and long-term studies.

Management options for established chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and debilitating condition associated with a variety of chemotherapeutic agents. Clinicians are cognizant of the negative impact of CIPN on cancer treatment outcomes and patients' psychosocial functioning and quality of life. In an attempt to alleviate this problem, clinicians and patients try various therapeutic interventions, despite limited evidence to support efficacy of these treatments. The rationale for such use is mostly based on the evidence for the treatment options in non-CIPN peripheral neuropathy syndromes, as this area is more robustly studied than is CIPN treatment. In this manuscript, we examine the existing evidence for both CIPN and non-CIPN treatments and develop a summary of the best available evidence with the aim of developing a practical approach to the treatment of CIPN, based on available literature and clinical practice experience.

Drug repositioning: playing dirty to kill pain

The number of approved new molecular entity drugs has been decreasing as the pharmaceutical company investment in research and development is increasing. As we face this painful crisis, called an innovation gap, there is increasing awareness that development of new uses of existing drugs may be a powerful tool to help overcome this obstacle because it takes too long, costs too much and can be risky to release drugs developed de novo. Consequently, drug repositioning is emerging in different therapeutic areas, including the pain research area. Worldwide, pain is the main reason for seeking healthcare, and pain relief represents an unmet global clinical need. Therefore, development of analgesics with better efficacy, safety and cost effectiveness is of paramount importance. Despite the remarkable advancement in research on cellular and molecular mechanisms underlying pain pathophysiology over the past three decades, target-based therapeutic opportunities have not been pursued to the same extent. Phenotypic screening remains a more powerful tool for drug development than target-based screening so far. It sounds somewhat heretical, but some multi-action drugs, rather than very selective ones, have been developed intentionally. In the present review, we first critically discuss the utility of drug repositioning for analgesic drug development and then show examples of 'old' drugs that have been successfully repositioned or that are under investigation for their analgesic actions. We conclude that drug repositioning should be more strongly encouraged to help build a bridge between basic research and pain relief worldwide.

Diabetic neuropathy and oxidative stress: therapeutic perspectives

Diabetic neuropathy (DN) is a widespread disabling disorder comprising peripheral nerves' damage. DN develops on a background of hyperglycemia and an entangled metabolic imbalance, mainly oxidative stress. The majority of related pathways like polyol, advanced glycation end products, poly-ADP-ribose polymerase, hexosamine, and protein kinase c all originated from initial oxidative stress. To date, no absolute cure for DN has been defined; although some drugs are conventionally used, much more can be found if all pathophysiological links with oxidative stress would be taken into account. In this paper, although current therapies for DN have been reviewed, we have mainly focused on the links between DN and oxidative stress and therapies on the horizon, such as inhibitors of protein kinase C, aldose reductase, and advanced glycation. With reference to oxidative stress and the related pathways, the following new drugs are under study such as taurine, acetyl-L-carnitine, alpha lipoic acid, protein kinase C inhibitor (ruboxistaurin), aldose reductase inhibitors (fidarestat, epalrestat, ranirestat), advanced glycation end product inhibitors (benfotiamine, aspirin, aminoguanidine), the hexosamine pathway inhibitor (benfotiamine), inhibitor of poly ADP-ribose polymerase (nicotinamide), and angiotensin-converting enzyme inhibitor (trandolapril). The development of modern drugs to treat DN is a real challenge and needs intensive long-term comparative trials.

Systematic review and meta-analysis of pharmacological therapies for painful diabetic peripheral neuropathy

BACKGROUND

Painful diabetic peripheral neuropathy (pDPN) is prevalent among persons with diabetes and increases over time. Published guidelines recommend a number of medications to treat this condition providing clinicians with a variety of treatment options. This study provides a comprehensive systematic review and meta-analysis of published pharmacologic therapies for pDPN.

METHODS

The published literature was systematically searched to identify randomized, controlled trials of all available pharmacologic treatments for pDPN (recommended or nonrecommended) reporting predefined efficacy and safety outcomes. Bayesian fixed-effect mixed treatment comparison methods were used to assess relative therapeutic efficacy and harms.

RESULTS

Data from 58 studies including 29 interventions and 11,883 patients were analyzed. Pain reduction over that of placebo on the 11-point numeric rating scale ranged from -3.29 for sodium valproate (95% credible interval [CrI] = [-4.21, -2.36]) to 1.67 for Sativex (-0.47, 0.60). Estimates for most treatments were clustered between 0 and -1.5 and were associated with more study data and smaller CrIs. Pregabalin (≥ 300 mg/day) was the most effective on the 100-point visual analog scale (-21.88; [-27.06, -16.68]); topiramate was the least (-3.09; [-3.99, -2.18]). Relative risks (RRs) of 30% pain reduction ranged from 0.78 (Sativex) to 1.84 (lidocaine 5% plaster). Analysis of the RR ratio of these 2 treatments reveals marginal significance for Sativex (3.27; [1.07, 9.81]), indicating the best treatment is only slightly better than the worst. Relative risks of 50% pain reduction ranged from 0.98 (0.56, 1.52) (amitriptyline) to 2.25 (1.51, 3.00) (alpha-lipoic acid). RR ratio for these treatments was not statistically different (3.39; [0.88, 3.34]). Fluoxetine had the lowest risk of adverse events (0.94; [0.62, 1.23]); oxycodone had the highest (1.55; [1.45, 1.64]). Discontinuation RRs were clustered around 0.8 to 1.5, with those on the extreme having greater uncertainty.

CONCLUSIONS

Selecting an appropriate pDPN therapy is key given the large number of available treatments. Comparative results revealed relative equivalence among many of the studied interventions having the largest overall sample sizes and highlight the importance of standardization of methods to effectively assess pain.

Effects of antidepressants on glucose metabolism and diabetes mellitus type 2 in adults

PURPOSE OF REVIEW

Depression and diabetes mellitus type 2 (DM2) are frequently comorbid conditions. It is of considerable clinical significance to avoid metabolic risks in nondiabetic depressed patients and to consider effects on glucose regulation in depressed DM2 patients. This review is an overview on antidepressant treatment and its potential metabolic risks.

RECENT FINDINGS

It is increasingly recognized that effective treatment with antidepressants improves glucose homeostasis in nondiabetic depressed patients in the short run, whereas long-term effects are a matter of debate. Cognitive behavioral and selective serotonin reuptake inhibitor (SSRI) treatment may improve glycemic control in depressed DM2 patients, whereas noradrenergic antidepressants and tricyclic antidepressants (TCAs) may cause the metabolic situation to deteriorate.

SUMMARY

SSRIs are preferable in nondiabetic depressed patients since they improve glucose regulation in the short run and may have little untoward effects in the long run. In depressed DM2 patients, SSRIs are the only class of antidepressants with confirmed favorable effects on glycemic control.

Management of painful diabetic neuropathy: guideline guidance or jungle?

The treatment of painful diabetic polyneuropathy (PDPN) remains a major challenge. A number of reasons have made the guidelines on PDPN management of particular interest, including its high prevalence, health and socioeconomic impact, interdisciplinary nature and the need for updated evidence-based information to refine patient-tailored treatment by weighing up the risks of each treatment against its proven benefits, as well as optimizing the use of all available resources. The various guidelines on the management of neuropathic pain developed so far contain some differences in their work methodology and results. Some variations in the recommendations are to be expected but could be disorienting and confusing for stakeholders. In this review, a critical evaluation of the more recent guidelines on the management of PDPN is provided together with highlights on points of agreement and disagreement as well as insights into their clinical aspects.

Role of oxidative stress and Ca²⁺ signaling on molecular pathways of neuropathic pain in diabetes: focus on TRP channels

Diabetes mellitus, a debilitating chronic disease, affects ~100 million people. Peripheral neuropathy is one of the most common early complications of diabetes in ~66 % of these patients. Altered Ca(2+) handling and Ca(2+) signaling were detected in a huge variety of preparations isolated from animals with experimentally induced type 1 and 2 diabetes as well as patients suffering from the disease. We reviewed the role of Ca(2+) signaling through cation channels and oxidative stress on diabetic neuropathic pain in sensory neurons. The pathogenesis of diabetic neuropathy involves the polyol pathway, advanced glycation end products, oxidative stress, protein kinase C activation, neurotrophism, and hypoxia. Experimental studies with respect to oxidative stress and Ca(2+) signaling, inhibitor roles of antioxidants in diabetic neuropathic pain are also summarized in the review. We hypothesize that deficits in insulin, triggers alterations of sensory neurone phenotype that are critical for the development of abnormal Ca(2+) homeostasis and oxidative stress and associated mitochondrial dysfunction. The transient receptor potential channels are a large family of proteins with six main subfamilies. The sheer number of different TRPs with distinct functions supports the statement that these channels are involved in a wide range of processes ranging in diabetic neuropathic pain and it seems that the TRPC, TRPM and TRPV groups are mostly responsible from diabetic neuropathic pain. In conclusion, the accumulating evidence implicating Ca(2+) dysregulation and over production of oxidative stress products in diabetic neuropathic pains, along with recent advances in understanding of genetic variations in cation channels such as TRP channels, makes modulation of neuronal Ca(2+) handling an increasingly viable approach for therapeutic interventions against the painful and degenerative aspects of many diabetic neuropathies.

Diabetic neuropathy: clinical manifestations and current treatments

Diabetic peripheral neuropathy is a prevalent, disabling disorder. The most common manifestation is distal symmetrical polyneuropathy (DSP), but many patterns of nerve injury can occur. Currently, the only effective treatments are glucose control and pain management. While glucose control substantially decreases the development of neuropathy in those with type 1 diabetes, the effect is probably much smaller in those with type 2 diabetes. Evidence supports the use of specific anticonvulsants and antidepressants for pain management in patients with diabetic peripheral neuropathy. However, the lack of disease-modifying therapies for diabetic DSP makes the identification of new modifiable risk factors essential. Growing evidence supports an association between components of the metabolic syndrome, including prediabetes, and neuropathy. Studies are needed to further explore this association, which has implications for the development of new treatments for this common disorder.

Addressing both depression and pain in late life: the methodology of the ADAPT study

OBJECTIVE

To describe the methodology of the first NIH-funded clinical trial for seniors with comorbid depression and chronic low back pain.

METHODS

Randomized controlled effectiveness trial using stepped care methodology. Participants are ≥60 years old. Phase 1 (6 weeks) is open treatment with venlafaxine xr 150 mg/day and supportive management (SM). Response is 2 weeks of PHQ-9 ≤5 and at least 30% improvement in the average numeric rating scale for pain. Nonresponders progress to phase 2 (14 weeks) in which they are randomized to high-dose venlafaxine xr (up to 300 mg/day) with problem solving therapy for depression and pain (PST-DP) or high-dose venlafaxine xr and continued SM. Primary outcomes are the univariate pain and depression response and both observed and self-reported disability. Survival analytic techniques will be used, and the clinical effect size will be estimated with the number needed to treat. We hypothesize that self-efficacy for pain management will mediate response for subjects randomized to venlafaxine xr and PST-DP.

RESULTS

Not applicable.

CONCLUSIONS

The results of this trial will inform the care of these complex patients and further understanding of comorbid pain and depression in late life.

Evidence-based guideline: Treatment of painful diabetic neuropathy: report of the American Academy of Neurology, the American Association of Neuromuscular and Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation

OBJECTIVE

To develop a scientifically sound and clinically relevant evidence-based guideline for the treatment of painful diabetic neuropathy (PDN).

METHODS

We performed a systematic review of the literature from 1960 to August 2008 and classified the studies according to the American Academy of Neurology classification of evidence scheme for a therapeutic article, and recommendations were linked to the strength of the evidence. The basic question asked was: "What is the efficacy of a given treatment (pharmacological: anticonvulsants, antidepressants, opioids, others; and non-pharmacological: electrical stimulation, magnetic field treatment, low-intensity laser treatment, Reiki massage, others) to reduce pain and improve physical function and quality of life (QOL) in patients with PDN?"

RESULTS AND RECOMMENDATIONS

Pregabalin is established as effective and should be offered for relief of PDN (Level A). Venlafaxine, duloxetine, amitriptyline, gabapentin, valproate, opioids (morphine sulphate, tramadol, and oxycodone controlled-release), and capsaicin are probably effective and should be considered for treatment of PDN (Level B). Other treatments have less robust evidence or the evidence is negative. Effective treatments for PDN are available, but many have side effects that limit their usefulness, and few studies have sufficient information on treatment effects on function and QOL.

Pharmacological treatment of diabetic neuropathic pain

Neuropathic pain continues to be a difficult and challenging clinical issue to deal with effectively. Painful diabetic polyneuropathy is a complex pain condition that occurs with reasonable frequency in the population and it may be extremely difficult for clinicians to provide patients with effective analgesia. Chronic neuropathic pain may occur in approximately one of every four diabetic patients. The pain may be described as burning or a deep-seated ache with sporadic paroxysms of lancinating painful exacerbations. The pain is often constant, moderate to severe in intensity, usually primarily involves the feet and generally tends to worsen at night. Treatment may be multimodal but largely involves pharmacological approaches. Pharmacological therapeutic options include antidepressants (tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors), α2δ ligands and topical (5%) lidocaine patch. Other agents may be different antiepileptic drugs (carbamazepine, lamotrigine, topiramate), topical capsaicin, tramadol and other opioids. Progress continues with respect to understanding various mechanisms that may contribute to painful diabetic neuropathy. Agents that may hold some promise include neurotrophic factors, growth factors, immunomodulators, gene therapy and poly (adenosine diphosphate-ribose) polymerase inhibitors. It is hoped that in the future clinicians will be able to assess patient pathophysiology, which may help them to match optimal therapeutic agents to target individual patient aberrant mechanisms.

Clinical Approach to the Treatment of Painful Diabetic Neuropathy

Painful neuropathy is a common and often progressive complication of diabetes. Patients frequently report symptoms of tingling, burning, lancinating pain, hyperesthesia and allodynia. The natural history of the disease may vary from intermittent mild symptoms to severe chronic daily pain; the latter is often associated with diminished quality of life. There are a variety of pharmaceutical agents from different medicinal categories available for the symptomatic treatment of painful diabetic neuropathy, however selecting an agent is often challenging given the breadth of choices and lack of consistent guidelines. As a result, many patients remain untreated or undertreated.This article presents a practical clinical approach to the treatment of pain in diabetic neuropathy. Recommendations for first, second and third line medications are based on specific evidence for the treatment of painful diabetic neuropathy as well as safety, tolerability, drug interactions and cost. Additional topics of discussion include breakthrough pain, opioid use and topical therapies. This review does not comprehensively discuss all possible treatments for painful neuropathy, but provides a systematic approach designed to guide clinicians in tailoring therapies to the individual patient.

Duloxetine treatment and glycemic controls in patients with diagnoses other than diabetic peripheral neuropathic pain: a meta-analysis

OBJECTIVE

Mood disorders are often associated with poor glycemic control, and antidepressant treatments for mood and pain disorders can alter plasma glucose levels in patients with diabetes. A previous meta-analysis from three studies showed that duloxetine modestly increased fasting plasma glucose (FPG) and HbA(1c) levels in patients with diabetic peripheral neuropathic pain (DPNP). This meta-analysis examined whether there were any short- and long-term effects of duloxetine (20-120 mg/day) on glycemic control in patients with diagnoses other than DPNP.

RESEARCH DESIGN AND METHODS

Short-term data (9-27 weeks): seven studies of duloxetine in general anxiety disorder, fibromyalgia, and chronic lower back pain (CLBP). Long-term data: 41-week, uncontrolled extension of the short-term CLBP study and 52-week study in patients with recurrence of major depressive disorder.

MAIN OUTCOME MEASURES

Baseline-to-endpoint changes in FPG and HbA(1c) levels.

RESULTS

In short-term studies, patients were randomly assigned to placebo (n = 1098) or duloxetine (n = 1563). Mean baseline-to-endpoint changes in FPG and HbA(1c) did not significantly differ in duloxetine-treated patients compared with placebo-treated patients. In the 41-week study (n = 181), duloxetine-treated patients experienced a small but significant within-group baseline-to-endpoint increase in HbA(1c) (mean change = 0.1%; p < 0.001). This result was in contrast to absence of effect on mean baseline-to-endpoint within-group changes in FPG (p = 0.326) in that study, and to absence of between-treatment changes in FPG (p = 0.744) and HbA(1c) (p = 0.180) in the 52-week placebo-controlled study.

CONCLUSION

Duloxetine treatment did not significantly alter FPG and HbA(1c) levels compared with placebo treatment in the short-term studies. A small but statistically significant within-group increase in HbA(1c) was found in the 41-week study, but not in between-treatment group differences in the 52-week study. Neither of the long-term studies showed significant changes in the FPG levels. The small, non-reproducible HbA(1c) increase in one study of patients without DPNP may have resulted from patients with unrecognized diabetes in these trials.

EFNS guidelines on the pharmacological treatment of neuropathic pain: 2010 revision

BACKGROUND AND OBJECTIVES

This second European Federation of Neurological Societies Task Force aimed at updating the existing evidence about the pharmacological treatment of neuropathic pain since 2005.

METHODS

Studies were identified using the Cochrane Database and Medline. Trials were classified according to the aetiological condition. All class I and II randomized controlled trials (RCTs) were assessed; lower class studies were considered only in conditions that had no top-level studies. Treatments administered using repeated or single administrations were considered, provided they are feasible in an outpatient setting.

RESULTS

Most large RCTs included patients with diabetic polyneuropathies and post-herpetic neuralgia, while an increasing number of smaller studies explored other conditions. Drugs generally have similar efficacy in various conditions, except in trigeminal neuralgia, chronic radiculopathy and HIV neuropathy, with level A evidence in support of tricyclic antidepressants (TCA), pregabalin, gabapentin, tramadol and opioids (in various conditions), duloxetine, venlafaxine, topical lidocaine and capsaicin patches (in restricted conditions). Combination therapy appears useful for TCA-gabapentin and gabapentin-opioids (level A).

CONCLUSIONS

There are still too few large-scale comparative studies. For future trials, we recommend to assess comorbidities, quality of life, symptoms and signs with standardized tools and attempt to better define responder profiles to specific drug treatments.

Use of Antidepressants in the Treatment of Chronic Pain

Fibromyalgia syndrome (FMS) is a chronic and debilitating musculoskeletal pain disorder of unknown aetiology with usual accompanying features of fatigue, sleep disturbances and stiff- ness. Its place in medical textbooks was controversial with rheumatologists holding the helm of its management for many years. Over the last decade, abnormalities have been identified at multiple levels in the peripheral, central, and sympathetic nervous systems as well as the hypothalomo-pitutary-adrenal axis stress response system. With the elucidation of these pathways of pain, FMS is known more as a central sensitivity syndrome. This led to tremendous increment in interest in both pharmacological and non-pharmacological treatment of FMS. The United States Food and Drug Administration (FDA) has also successively approved 3 drugs for the management of fibromyalgia – pregabalin, duloxetine and milnacipran. Non-pharmacological modalities showed aerobic exercise, patient education and cognitive behavioural therapy to be most effective. Overall, management of FMS requires a multi-disciplinary approach. Key words: Aetiology, Fibromyalgia-Fibromyositis Syndromes, History, Pain syndrome