Desipramine for neuropathic pain in adults

Therapeutic Approach for Trigeminal Neuralgia: A Systematic Review

This umbrella review aimed to determine the various drugs used to treat trigeminal neuralgia (TN) and to evaluate their efficacies as well as side effects by surveying previously published reviews. An online search was conducted using PubMed, CRD, EBSCO, Web of Science, Scopus, and the Cochrane Library with no limits on publication date or patients' gender, age, and ethnicity. Reviews and meta-analyses of randomized controlled trials pertaining to drug therapy for TN, and other relevant review articles added from their reference lists, were evaluated. Rapid reviews, reviews published in languages other than English, and reviews of laboratory studies, case reports, and series were excluded. A total of 588 articles were initially collected; 127 full-text articles were evaluated after removing the duplicates and screening the titles and abstracts, and 11 articles were finally included in this study. Except for carbamazepine, most of the drugs had been inadequately studied. Carbamazepine and oxcarbazepine continue to be the first choice for medication for classical TN. Lamotrigine and baclofen can be regarded as second-line drugs to treat patients not responding to first-line medication or for patients having intolerable side effects from carbamazepine. Drug combinations using carbamazepine, baclofen, gabapentin, ropivacaine, tizanidine, and pimozide can yield satisfactory results and improve the tolerance to the treatment. Intravenous lidocaine can be used to treat acute exaggerations and botulinum toxin-A can be used in refractory cases. Proparacaine, dextromethorphan, and tocainide were reported to be inappropriate for treating TN. Anticonvulsants are successful in managing trigeminal neuralgia; nevertheless, there have been few studies with high levels of proof, making it challenging to compare or even combine their results in a statistically useful way. New research on other drugs, combination therapies, and newer formulations, such as vixotrigine, is awaited. There is conclusive evidence for the efficacy of pharmacological drugs in the treatment of TN.

Trends in Prescriptions for Non-opioid Pain Medications Among U.S. Adults With Moderate or Severe Pain, 2014-2018

As opioid prescribing has declined, it is unclear how the landscape of prescription pain treatment across the U.S. has changed. We used nationally-representative data from the Medical Expenditure Health Survey, 2014 to 2018 to examine trends in prescriptions for opioid and non-opioid pain medications, including acetaminophen, non-steroidal anti-inflammatory drugs, gabapentinoids, and antidepressants among U.S. adults with self-reported pain. Overall, from 2014 to 2018, the percentage of participants receiving a prescription for opioids declined, (38.8% vs 32.8%), remained stable for non-steroidal anti-inflammatory drugs (26.8% vs 27.7%), and increased for acetaminophen (1.6% vs 2.3%), antidepressants (9.6% vs 12.0%) and gabapentinoids (13.2% vs 19.0%). In this period, the adjusted odds of receiving an opioid prescription decreased (aOR = .93, 95% CI = .90-.96), while the adjusted odds of receiving antidepressant, gabapentinoid and acetaminophen prescriptions increased (antidepressants: aOR = 1.08, 95% CI = 1.03-1.13 gabapentinoids: aOR = 1.11, 95% CI = 1.06-1.17; acetaminophen: aOR = 1.10, 95% CI: 1.02-1.20). Secondary analyses stratifiying within the 2014 to 2016 and 2016 to 2018 periods revealed particular increases in prescriptions for gabapentinoids (aOR = 1.13, 95% CI = 1.05-1.21) and antidepressants (aOR = 1.23, 95% CI = 1.12-1.35) since 2016. PERSPECTIVE: These data demonstrate that physicians are increasingly turning to CDC-recommended non-opioid medications for pain management, particularly antidepressants and gabapentinoids. However, evidence for these medications' efficacy in treating numerous common pain conditions, including low back pain, remains limited.

Management of diabetic neuropathy

Diabetic neuropathy is a neurodegenerative disorder that may alter both the somatic and autonomic peripheral nervous systems in the context of diabetes mellitus (DM). It is a prevalent and burdensome chronic complication of DM, that requires timely management. Optimized glycemic control (mainly for type 1 DM), multifactorial intervention (mainly for type 2 DM), with lifestyle intervention/physical exercise, and weight loss represent the basis of management for diabetic distal symmetrical polyneuropathy, and should be implemented early in the disease course. Despite better understanding of the pathogenetic mechanisms of diabetic peripheral neuropathy, there is still a stringent need for more pathogenetic-based agents that would significantly modify the natural history of the disease. The paper reviews the available drugs and current recommendations for the management of distal symmetrical polyneuropathy, including pain management, and for diabetic autonomic neuropathy. Evaluation of drug combinations that would perhaps be more efficient in slowing the progression of the disease or even reversing it, and that would provide a better pain management is still needed.

Diabetic Neuropathy Collection: Treatment of Diabetic Neuropathy

Video: Treatment of Diabetic Neuropathy podcast recording (MP4 61908 kb).

The potential of transdermal nitric oxide treatment for diabetic peripheral neuropathy and diabetic foot ulcers

The Center for Disease Control (CDC) estimates that 29 million Americans have diabetes, and 70% of diabetic patients develop diabetic peripheral neuropathy [1,2]. Up to 27% of the direct medical cost of diabetes may be attributed to DPN [3]. A 2013 article from the American Diabetes Association reported a $176 billion direct medical cost of diabetes in 2012 [4]. DPN patients often suffer from shooting and burning pain in their distal limbs and a severe loss of sensation. Diabetic foot ulcers, infections, and amputations may follow. Currently available treatments: tricyclic antidepressants, anticonvulsants such as gabapentin and pregabalin, serotonin and norepinephrine reuptake inhibitor, duloxetine, topical 5% lidocaine (applied to the most painful area) can manage painful symptoms but do not address the underlying pathologies of DPN and diabetic wound ulcers. A combination of pain-reducing medications can provide relief when individual medications fail, and opioids such as tramadol and oxycodone may be administered with these medications to reduce pain [5]. Due to the prevalence of diabetes, DPN, and diabetic foot ulcers, and because of the lack of available effective treatments to directly address the pathology contributing to these conditions, novel treatments are being sought. Our hypothesis is that a deficiency of nitric oxide synthase in diabetic patients leads to a lack of vascularization of the peripheral nerves, which causes DPN; and this could be treated with vasodilators such as nitric oxide. In this paper, the mechanisms of DPN are reviewed and analyzed to elucidate the potential of a transdermal nitric oxide application for the treatment of DPN and diabetic wound ulcers by increasing vasodilation.

Contribution of Nrf2 Modulation to the Mechanism of Action of Analgesic and Anti-inflammatory Drugs in Pre-clinical and Clinical Stages

Despite the progress that has occurred in recent years in the development of therapies to treat painful and inflammatory diseases, there is still a need for effective and potent analgesics and anti-inflammatory drugs. It has long been known that several types of antioxidants also possess analgesic and anti-inflammatory properties, indicating a strong relationship between inflammation and oxidative stress. Understanding the underlying mechanisms of action of anti-inflammatory and analgesic drugs, as well as essential targets in disease physiopathology, is essential to the development of novel therapeutic strategies. The Nuclear factor-2 erythroid related factor-2 (Nrf2) is a transcription factor that regulates cellular redox status through endogenous antioxidant systems with simultaneous anti-inflammatory activity. This review summarizes the molecular mechanisms and pharmacological actions screened that link analgesic, anti-inflammatory, natural products, and other therapies to Nrf2 as a regulatory system based on emerging evidences from experimental disease models and new clinical trial data.

Overlaps in pharmacology for the treatment of chronic pain and mental health disorders

There is significant overlap in the pharmacological management of pain and psychological disorders. Appropriate treatment of patients' comorbid psychological disorders, including sleep disturbances often leads to an improvement in reported pain intensity. The three first line agents for neuropathic pain include tricyclic antidepressants and serotonin norepinephrine reuptake inhibitors which are medications originally developed as antidepressants. The other first line medication for chronic neuropathic pain are anticonvulsant medications initially brought to the market-place for the treatment of epilepsy and are also now being used for the treatment of anxiety disorders and substance withdrawal symptoms. The efficacy of opioids for chronic pain is contentious, but it is agreed that the patients at highest risk for opioid misuse and addiction are patients with underlying psychological disorders who use opioids for their euphoric effects. Similarly, benzodiazepines may present a problem in patients with chronic pain, as up to one third of patients with pain are concomitantly prescribed benzodiazepines, and when combined with other sedating analgesic medications they put patients at increased risk for adverse events and polysubstance misuse. Finally, there is growing evidence for the efficacy of cannabis for treating neuropathic pain, but the consumption of cannabis has been associated with increased risk of psychosis in adolescents, and may be associated with an increased risk for developing bipolar disorder and anxiety disorders. The use of cannabis is associated with an increased risk of substance misuse in both adolescents and adults. In this narrative review, we examine the evidence for the use of several medications used for the treatment of both pain and psychological disorders, and their proposed mechanisms of action, in addition to special concerns for patients with comorbid pain and psychological disorders.

Inhibition of the NMDA and AMPA receptor channels by antidepressants and antipsychotics

It is known that some antidepressants and antipsychotics directly inhibit NMDA-type ionotropic glutamate receptors. In this study we systematically studied action of seven drugs (Fluoxetine, Citalopram, Desipramine, Amitriptyline, Atomoxetine, Chlorpromazine, and Clozapine) on NMDA receptors and Ca²⁺-permeable and -impermeable AMPA receptors in rat brain neurons by whole-cell patch-clamp technique. Except for weak effect of fluoxetine, all drugs were virtually inactive against Ca²⁺-impermeable AMPA receptors. Fluoxetine and desipramine significantly inhibited Ca²⁺-permeable AMPA receptors (IC₅₀=43±7 and 105±12µM, respectively). Desipramine, atomoxetine and chlorpromazine inhibited NMDA receptors in clinically relevant low micromolar concentrations, while citalopram had only weak effect. All tested medicines have been clustered into two groups by their action on NMDA receptors: desipramine, amitriptyline, chlorpromazine, and atomoxetine display voltage- and magnesium-dependent open channel blocking mechanism. Action of fluoxetine and clozapine was found to be voltage- and magnesium-independent. All voltage-dependent compounds could be trapped in closed NMDA receptor channels. Possible contribution of NMDA receptor inhibition by certain antidepressants and antipsychotics to their analgesic effects in neuropathic pain is discussed.

Definition, diagnosis and treatment strategies for opioid-induced bowel dysfunction–Recommendations of the Nordic Working Group

Background and aims

Opioid-induced bowel dysfunction (OIBD) is an increasing problem due to the common use of opioids for pain worldwide. It manifests with different symptoms, such as dry mouth, gastro-oesophageal reflux, vomiting, bloating, abdominal pain, anorexia, hard stools, constipation and incomplete evacuation. Opioid-induced constipation (OIC) is one of its many symptoms and probably the most prevalent. The current review describes the pathophysiology, clinical implications and treatment of OIBD.

Methods

The Nordic Working Group was formed to provide input for Scandinavian specialists in multiple, relevant areas. Seven main topics with associated statements were defined. The working plan provided a structured format for systematic reviews and included instructions on how to evaluate the level of evidence according to the GRADE guidelines. The quality of evidence supporting the different statements was rated as high, moderate or low. At a second meeting, the group discussed and voted on each section with recommendations (weak and strong) for the statements.

Results

The literature review supported the fact that opioid receptors are expressed throughout the gastrointestinal tract. When blocked by exogenous opioids, there are changes in motility, secretion and absorption of fluids, and sphincter function that are reflected in clinical symptoms. The group supported a recent consensus statement for OIC, which takes into account the change in bowel habits for at least one week rather than focusing on the frequency of bowel movements. Many patients with pain receive opioid therapy and concomitant constipation is associated with increased morbidity and utilization of healthcare resources. Opioid treatment for acute postoperative pain will prolong the postoperative ileus and should also be considered in this context. There are no available tools to assess OIBD, but many rating scales have been developed to assess constipation, and a few specifically address OIC. A clinical treatment strategy for OIBD/OIC was proposed and presented in a flowchart. First-line treatment of OIC is conventional laxatives, lifestyle changes, tapering the opioid dosage and alternative analgesics. Whilst opioid rotation may also improve symptoms, these remain unalleviated in a substantial proportion of patients. Should conventional treatment fail, mechanism-based treatment with opioid antagonists should be considered, and they show advantages over laxatives. It should not be overlooked that many reasons for constipation other than OIBD exist, which should be taken into consideration in the individual patient.

Conclusion and implications

It is the belief of this Nordic Working Group that increased awareness of adverse effects and OIBD, particularly OIC, will lead to better pain treatment in patients on opioid therapy. Subsequently, optimised therapy will improve quality of life and, from a socio-economic perspective, may also reduce costs associated with hospitalisation, sick leave and early retirement in these patients.

From guideline to patient: a review of recent recommendations for pharmacotherapy of painful diabetic neuropathy

Painful diabetic peripheral neuropathy (DPN) is a common complication of diabetes mellitus, affecting, by some estimates, up to one quarter of diabetic patients. Since 2010, no fewer than 5 major international treatment guidelines for painful DPN have been issued, and there are meaningful differences among them. Duloxetine, pregabalin, gabapentin, and tricyclic antidepressants are the mainstays of treatment, but the choice of which class or agent to use in any given patient should be informed by patient characteristics. This review seeks to describe the differences among the recently issued guidelines, to assess the evidence on which they are based, and to offer insight into the most appropriate treatment choices based on patient characteristics.