Duloxetine in the treatment of chronic pain due to fibromyalgia and diabetic neuropathy

Peripheral neuropathy associated with monomethyl auristatin E-based antibody-drug conjugates

Since the successful approval of gemtuzumab ozogamicin, antibody-drug conjugates (ADCs) have emerged as a pivotal category of targeted therapies for cancer. Among these ADCs, the use of monomethyl auristatin E (MMAE) as a payload is prevalent in the development of ADC drugs, which has significantly improved overall therapeutic efficacy against various malignancies. However, increasing clinical observations have raised concerns regarding the potential nervous system toxicity associated with MMAE-based ADCs. Specifically, a higher incidence of peripheral neuropathy has been reported in ADCs incorporating MMAE as payloads. Considering the increasing global use of MMAE-based ADCs, it is imperative to provide an inclusive overview of diagnostic and management strategies for this adverse event. In this review, we examine current information and what future research directions are required to better understand and manage this type of clinical challenge.

Chronic Pain: A Case Application of a Novel Framework to Guide Interprofessional Assessment and Intervention in Primary Care

Background

Chronic pain is a complex condition that poses challenges in assessment and treatment. Primary care teams, especially in rural areas, may have a role in managing this population, providing interprofessional care to optimize patient outcomes. Tools are needed to aid these clinicians in assessing chronic pain.

Aims

The aim of this article is to present the case application of a clinical reasoning framework proposed by Walton and Elliott, which is used to identify drivers of chronic pain in a 61-year-old male patient with a remote history of spinal injury. Furthermore, it aims to demonstrate that an interprofessional, individualized intervention strategy can improve patient outcomes.

Methods

This case took place in a multidisciplinary primary care team in rural northern Ontario, Canada. An assessment was completed by the author, including collection of the patient's history, a medication review, and the use of multiple validated patient-reported outcome measures (PROMs), all of which were used in applying the framework.

Results

Three relevant drivers of his pain experience were identified: central nociplastic, cognitive/belief, and emotional/affective. A pharmacist and social worker then used multimodal interventions to address these drivers, which yielded improvements in scores on multiple validated pain measures but also improved the patient's self-reported quality of life.

Conclusions

A clinical reasoning framework can provide a basis for identifying drivers of chronic pain during assessment and guide primary care clinicians to targeted interventions. Broader applications of this framework by primary care providers could serve to increase capacity for managing chronic pain in Canada.

Recent Developments in Pharmacotherapy of Depression: Bench to Bedside

For the last 70 years, we did not move beyond the monoamine hypothesis of depression until the approval of the S-enantiomer of ketamine, an N-methyl-D-aspartate (NMDA) receptor blocker and the first non-monoaminergic antidepressant characterized by rapid antidepressant and antisuicidal effects. A similar profile has been reported with another NMDA receptor antagonist, dextromethorphan, which has also been approved to manage depression in combination with bupropion. More recently, the approval of a positive allosteric modulator of GABA-A receptors, brexanolone, has added to the list of recent breakthroughs with the relatively rapid onset of antidepressant efficacy. However, multiple factors have compromised the clinical utility of these exciting discoveries in the general population, including high drug acquisition costs, mandatory monitoring requirements, parenteral drug administration, lack of insurance coverage, indirect COVID-19 effects on healthcare systems, and training gaps in psychopharmacology. This narrative review aims to analyze the clinical pharmacology of recently approved antidepressants and discuss potential barriers to the bench-to-bedside transfer of knowledge and clinical application of exciting recent discoveries. Overall, clinically meaningful advances in the treatment of depression have not reached a large proportion of depressed patients, including those with treatment-resistant depression, who might benefit the most from the novel antidepressants.

Outcomes and Predictors of Response of Duloxetine for the Treatment of Persistent Idiopathic Dentoalveolar Pain: A Retrospective Multicenter Observational Study

Background

Duloxetine has been reported to significantly relieve the pain of persistent idiopathic dentoalveolar pain (PIDP); however, the number of studies available is scarce and no study has identified the predictors of response of duloxetine for the treatment of PIDP.

Objective

To report the efficacy, safety, and identification of positive predictors of duloxetine for PIDP patients through a retrospective multicenter observational study.

Methods

We retrospectively reviewed the clinical database of PIDP patients who were prescribed duloxetine at 3 hospitals between January 2018 and November 2021. Demographic and pain-related baseline data, efficacy of patients after 3 months of medication by visual analog scale (VAS) scores for pain and adverse events were extracted and analyzed. The predictors of pain-relieving effect of duloxetine were identified by logistic regression analysis.

Results

A total of 135 patients were included in this study. Side effects occurred immediately after taking duloxetine in 24 (17.8%) patients, and the treatment with duloxetine was discontinued on 13 of them because they could not tolerate the side effects. Other 11 (8.1%) patients gradually tolerated the side effects within 2 weeks. Ninety-four out of 122 (77.0%) patients obtained pain relief with VAS significantly decreased (p < 0.01) and the other 28 (23.0%) patients stopped taking the drug because of weak efficacy. Binary logistic regression analysis showed that short disease duration (OR = 1.017, 95% CI = 1.004–1.030, P = 0.012) was an independent predictor of the positive response of duloxetine.

Conclusion

This study confirmed that duloxetine can significantly improve chronic pain of PIDP patients, and the safety was tolerable. Patients with shorter disease duration had more benefit from duloxetine.

Limitations

This is a retrospective observational study. Long-term efficacy and safety of duloxetine in the treatment of PIDP patients were not evaluated.

Prevalence and Determinants of Long-Term Utilization of Antidepressant Drugs: A Retrospective Cohort Study

PURPOSE

Antidepressant consumption has risen in recent years, driven by longer treatment duration. The objective of this study was to measure the prevalence of antidepressant long-term and chronic use in the Bologna area, Italy, and to identify their main determinants.

MATERIALS AND METHODS

We conducted a retrospective claims-based cohort study by using the Bologna Local Health Authority data. A cohort of 18,307 incident users of antidepressant drugs in 2013 was selected, and subjects were followed for three years. A long-term utilization was defined as having at least one prescription claimed during each year of follow-up, while chronic utilization was defined as claiming at least 180 defined daily doses per year. Factors associated with chronic and long-term use were identified by univariate and multivariate logistic regressions.

RESULTS

In our cohort, 5448 (29.8%) and 1817 (9.9%) subjects were dispensed antidepressants for a long-term course and in a chronically way, respectively. Older age, antidepressant polytherapy, polypharmacy, and being prescribed the first antidepressant by a hospital physician were all factors independently associated with chronic and long-term prescriptions of antidepressant drugs. Results were reported separately for men and women.

CONCLUSION

Antidepressant long-term and chronic prescriptions are common in the Bologna area. Because longer treatment should be clinically motivated, these results strongly prompt the need to evaluate the actual relevance, as they may indicate potentially inappropriate prescription patterns.

Targeting tumor necrosis factor in the brain relieves neuropathic pain

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

Pharmacologic management of chronic neuropathic pain: Review of the Canadian Pain Society consensus statement

OBJECTIVE

To provide family physicians with a practical clinical summary of the Canadian Pain Society (CPS) revised consensus statement on the pharmacologic management of neuropathic pain.

QUALITY OF EVIDENCE

A multidisciplinary interest group within the CPS conducted a systematic review of the literature on the current treatments of neuropathic pain in drafting the revised consensus statement.

MAIN MESSAGE

Gabapentinoids, tricyclic antidepressants, and serotonin-norepinephrine reuptake inhibitors are the first-line agents for treating neuropathic pain. Tramadol and other opioids are recommended as second-line agents, while cannabinoids are newly recommended as third-line agents. Other anticonvulsants, methadone, tapentadol, topical lidocaine, and botulinum toxin are recommended as fourth-line agents.

CONCLUSION

Many pharmacologic analgesics exist for the treatment of neuropathic pain. Through evidence-based recommendations, the CPS revised consensus statement helps guide family physicians in the management of patients with neuropathic pain.

Factors associated with tender point count in Puerto Ricans with fibromyalgia syndrome

OBJECTIVE

To examine the factors associated with fibromyalgia syndrome (FMS) tender point count (TPC) in a group of Hispanic patients from Puerto Rico.

METHODS

A cross-sectional study was performed in 144 FMS patients as determined using American College of Rheumatology [ACR] classification). Sociodemographic features, clinical manifestations, comorbidities, and pharmacologic agents were determined during the study visit. Tender points were assessed as described in the ACR classification for FMS. A t-test and one-way ANOVA test were used to examine the relationships between continuous, dichotomous, and nominal variables.

RESULTS

The mean (standard deviation, [SD]) age of the FMS patients in this study was 50.2 (9.9) years; 95.1% were females. The mean (SD) TPC was 15.0 (4.7). Dysmenorrhea, the sicca syndrome, subjective swelling, increased urinary frequency, shortness of breath, headache, constipation, paresthesia, cognitive dysfunction, arthralgia, tiredness, morning stiffness, depression, and anxiety were associated with higher TPC. No associations were seen between socio-demographic features and FMS pharmacologic therapies.

CONCLUSION

In this group of Puerto Ricans with FMS, TPC was associated with several FMS symptoms and comorbidities. This study suggests that TPC may be a simple and effective tool for assessing disease severity in FMS patients.

Opioid and noradrenergic contributions of tapentadol in experimental neuropathic pain

Tapentadol is a dual action molecule with mu opioid agonist and norepinephrine (NE) reuptake blocking activity that has recently been introduced for the treatment of moderate to severe pain. The effects of intraperitoneal (i.p.) morphine (10mg/kg), tapentadol (10 or 30 mg/kg) or duloxetine (30 mg/kg), a norepinephrine/serotonin (NE/5HT) reuptake inhibitor, were evaluated in male, Sprague-Dawley rats with spinal nerve ligation (SNL) or sham surgery. Additionally, the effects of these drugs on spinal cerebrospinal fluid (CSF) NE levels were quantified. Response thresholds to von Frey filament stimulation decreased significantly from baseline in SNL, but not sham, operated rats. Duloxetine, tapentadol and morphine produced significant and time-related reversal of tactile hypersensitivity. Duloxetine significantly increased spinal CSF NE levels in both sham and SNL rats and no significant differences were observed in these groups. Tapentadol (10 mg/kg) produced a significant increase in spinal NE levels in SNL, but not in sham, rats. At the higher dose (30 mg/kg), tapentadol produced a significant increase in spinal CSF NE levels in both SNL and sham groups; however, spinal NE levels were elevated for an extended period in the SNL rats. This could be detected 30 min following tapentadol (30 mg/kg) in both sham and SNL groups. Surprisingly, while the dose of morphine studied reversed tactile hypersensitivity in nerve-injured rats, CSF NE levels were significantly reduced in both sham- and SNL rats. The data suggest that tapentadol elicits enhanced elevation in spinal NE levels in a model of experimental neuropathic pain offering a mechanistic correlate to observed clinical efficacy in this pain state.

Duloxetine in panic disorder with somatic gastric pain

PANIC DISORDER IS THE MOST COMMON TYPE OF ANXIETY DISORDER, AND ITS MOST COMMON EXPRESSION IS PANIC ATTACKS CHARACTERIZED WITH SUDDEN ATTACKS OF ANXIETY WITH NUMEROUS SYMPTOMS, INCLUDING PALPITATIONS, TACHYCARDIA, TACHYPNEA, NAUSEA, AND VERTIGO: ie, cardiovascular, gastroenterologic, respiratory, and neuro-otologic symptoms. In clinical practice, panic disorder manifests with isolated gastroenteric or cardiovascular symptoms, requiring additional clinical visits after psychiatric intervention. The first-line treatment for anxiety disorders, and in particular for panic disorder, is the selective serotonin reuptake inhibitors. However, these drugs can have adverse effects, including sexual dysfunction, increased bodyweight, and abnormal bleeding, that may be problematic for some patients. Here we report the case of a 29-year-old Caucasian woman affected by panic disorder with agoraphobia who was referred to our clinic for recurrent gastroenteric panic symptoms. The patient reported improvement in her anxiety symptoms and panic attacks while on a selective serotonin reuptake inhibitor, but not in her gastric somatic problems, so the decision was taken to start her on duloxetine, a serotonin-norepinephrine reuptake inhibitor. After 6 months of treatment, the patient achieved complete remission of her gastric and panic-related symptoms, and was able to stop triple gastric therapy. Other authors have hypothesized and confirmed that duloxetine has greater initial noradrenergic effects than venlafaxine and is effective in patients with panic disorder. This case report underscores the possibility of tailoring therapeutic strategies for the gastroenteric expression of panic disorder.

Unmasking the mysteries of the habenula in pain and analgesia

The habenula is a small bilateral structure in the posterior-medial aspect of the dorsal thalamus that has been implicated in a remarkably wide range of behaviors including olfaction, ingestion, mating, endocrine and reward function, pain and analgesia. Afferent connections from forebrain structures send inputs to the lateral and medial habenula where efferents are mainly projected to brainstem regions that include well-known pain modulatory regions such as the periaqueductal gray and raphe nuclei. A convergence of preclinical data implicates the region in multiple behaviors that may be considered part of the pain experience including a putative role in pain modulation, affective, and motivational processes. The habenula seems to play a role as an evaluator, acting as a major point of convergence where external stimuli is received, evaluated, and redirected for motivation of appropriate behavioral response. Here, we review the role of the habenula in pain and analgesia, consider its potential role in chronic pain, and review more recent clinical and functional imaging data of the habenula from animals and humans. Even through the habenula is a small brain structure, advances in structural and functional imaging in humans should allow for further advancement of our understanding of its role in pain and analgesia.

Novel peptide ligands with dual acting pharmacophores designed for the pathophysiology of neuropathic pain

The conventional design of high affinity drugs targeted to a single molecule has not resulted in clinically useful therapies for pain relief. Recent reviews have suggested that newly designed analgesic drugs should incorporate multiple targets. The distributions of cholecystokinin (CCK) and CCK receptors in the central nervous system (CNS) overlap significantly with endogenous opioid systems and can be dually targeted. CCK has been shown to act as an endogenous "anti-analgesic" peptide and neuropathic pain conditions promote endogenous CCK release in CNS regions of pain modulation. Administration of CCK into nuclei of the rostral ventromedial medulla induces pronociceptive behaviors in rats. RSA 504 and RSA 601 are novel bifunctional compounds developed to target neuropathic pain by simultaneously acting as agonists at two distinct opioid receptors and antagonizing CCK receptors in the CNS. RSA 504 and RSA 601 demonstrate agonist activity in vitro and antihypersensitivity to mechanical and thermal stimuli in vivo using the spinal nerve ligation model of neuropathic pain. Intrathecal administration of RSA 504 and RSA 601 did not demonstrate antinociceptive tolerance over 7 days of administration and did not display motor impairment or sedation using a rotarod. These are the first behavioral studies that demonstrate how multi-targeted molecule design can address the pathology of neuropathic pain. These compounds with δ and μ opioid agonist activity and CCK antagonist activity within one molecule offer a novel approach with efficacy for neuropathic pain while lacking the side effects typically caused by conventional opioid therapies.