The use of antineuropathic medications for the treatment of chronic pain

Diabetic Neuropathy: A Guide to Pain Management

PURPOSE OF REVIEW

Diabetic neuropathy is a common complication of diabetes mellitus (DM) and can affect up to 50% of DM patients during their lifetime. Patients typically present with numbness, tingling, pain, and loss of sensation in the extremities. Since there is no treatment targeting the underlying mechanism of neuropathy, strategies focus on preventative care and pain management.

RECENT FINDINGS

Up to 69% of patients with diabetic neuropathy receive pharmacological treatment for neuropathic pain. The United States Food and Drug Administration (FDA) confirmed four drugs for painful diabetic neuropathy (PDN): pregabalin, duloxetine, tapentadol, and the 8% capsaicin patch. Nonpharmacological treatments such as spinal cord stimulation (SCS) and transcutaneous electrical nerve stimulation (TENS) both show promise in reducing pain in DM patients. Despite the high burden associated with PDN, effective management remains challenging. This update covers the background and management of diabetic neuropathy, including its epidemiology, pathogenesis, preventative care, and current therapeutic strategies.

Pain mitigation and management strategies for anti-GD2 infusions: An expert consensus

Monoclonal antibodies (mAbs) targeting disialoganglioside 2 (GD2) are an important treatment advance for high-risk neuroblastoma, including in patients with refractory or relapsed disease. Dinutuximab and dinutuximab beta are administered for ≥8 hours (and up to 10 days for dinutuximab beta), whereas naxitamab is administered over 0.5 to 2 hours as tolerated. As acute pain is a class effect of anti-GD2 mAbs, effective pain management is crucial to successful treatment. Here, we provide an overview of current pain-management strategies for anti-GD2 mAb infusions, with a focus on strategies suitable for naxitamab infusions, which cause a more rapid onset of often severe pain. We discuss opioid analgesics, ketamine, gabapentin, and other similar agents and nonpharmacologic approaches. Potential future pain-management options are also discussed, in addition to the use of sedatives to reduce the anxiety that may be associated with infusion-related pain. In this expert consensus paper, specific guidance for pain management during naxitamab infusions is provided, as these infusions are administered over 0.5 to 2 hours and may not need overnight hospitalization based on the physician's assessment, and require rapid-onset analgesia options suitable for potential outpatient administration.

New Synthetic Opioids: Clinical Considerations and Dangers

Since the early 2010s, synthetic opioids have significantly contributed to overall opioid-related overdose mortalities. For point of reference, of the 68,630 opioid-related deaths recorded in 2020, 56,516 involved synthetic opioids. During much of this period, fentanyl has been the most commonly used synthetic opioid. This time when fentanyl was the most popular opioid has been called the "third wave" of the opioid crisis, partly because it led to a sharp rise in deaths from overdoses. Other synthetic opioids, such as carfentanil, protonitazene, and isotonitazene, have also become more widely diverted for nonmedical used. Carfentanil is an even more potent fentanyl derivative that was initially used in the mid-1980s as a general anesthetic for large animals such as elephants. Related to its strong affinity for mu opioid receptors, carfentanil is still utilized in medicine and science today as a radiotracer for positron emission tomography imaging. Protonitazene and isotonitazene belong to a novel class of synthetic opioids called benzimidazoles that were manufactured in the 1950s as novel analgesics. These agents have come under recent scrutiny as designer synthetic opioids becoming more prevalent. However, to date, there is incomplete data regarding the prevalence of synthetic opioids, as traditional toxicology screenings may not be sensitive to detect these compounds at such low doses post-mortem, particularly when blood is drawn from the periphery instead of central tissues such as the brain, lung, or heart. This narrative review aims to highlight the clinical challenges presented by these new synthetic opioids.

Alternative pain management via endocannabinoids in the time of the opioid epidemic: Peripheral neuromodulation and pharmacological interventions

The use of opioids in pain management is hampered by the emergence of analgesic tolerance, which leads to increased dosing and side effects, both of which have contributed to the opioid epidemic. One promising potential approach to limit opioid analgesic tolerance is activating the endocannabinoid system in the CNS, via activation of CB1 receptors in the descending pain inhibitory pathway. In this review, we first discuss preclinical and clinical evidence revealing the potential of pharmacological activation of CB1 receptors in modulating opioid tolerance, including activation by phytocannabinoids, synthetic CB1 receptor agonists, endocannabinoid degradation enzyme inhibitors, and recently discovered positive allosteric modulators of CB1 receptors. On the other hand, as non-pharmacological pain relief is advocated by the US-NIH to combat the opioid epidemic, we also discuss contributions of peripheral neuromodulation, involving the electrostimulation of peripheral nerves, in addressing chronic pain and opioid tolerance. The involvement of supraspinal endocannabinoid systems in peripheral neuromodulation-induced analgesia is also discussed. LINKED ARTICLES: This article is part of a themed issue on Advances in Opioid Pharmacology at the Time of the Opioid Epidemic. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.7/issuetoc.

Antinociceptive effects of nortriptyline and desipramine hydrochloride in Speke's hinge-back tortoise (Kinixys Spekii)

Some of the most commonly used analgesic drugs in animals are of questionable efficacy or present adverse side effects among the various species of reptiles. Tricyclic antidepressants have been demonstrated to have antinociceptive effects in several animal models of pain and could be a good alternative for use in reptiles. The aim of the study was to investigate the antinociceptive effects of nortriptyline and desipramine hydrochloride in Speke's hinge-back tortoise. A total of 24 animals weighing 600-1000 g were used for nociceptive tests, i.e., formalin, capsaicin, and hot plate tests. Drugs were administered intracoelomically 30 min before starting the tests. The time spent in nocifensive behavior and the associated observable effects during the tests were recorded. Only the highest dose of 40 mg/kg of nortriptyline hydrochloride caused statistically significant decrease in nocifensive behavior in both the formalin and the capsaicin test. Desipramine hydrochloride at doses of 20 and 40 mg/kg caused statistically significant decrease in nocifensive behavior in the formalin test. Also, desipramine hydrochloride at doses of 15, 20, and 60 mg/kg caused statistically significant decrease in nocifensive behavior in the capsaicin test. None of the doses used for both drugs had any statistically significant effect on nocifensive behavior in the hot plate test. The results show that nortriptyline and desipramine hydrochloride have significant antinociceptive effects in the chemical but not thermal inflammatory pain-related behavior in the Speke's hinge-back tortoise. The most common associated side effect following administration of the higher doses of either of the drugs is excessive salivation.

Efficacy and Safety of Ketamine in the Treatment of Neuropathic Pain: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Purpose

Ketamine is a N-methyl-D-aspartate (NMDA) antagonist with strong analgesic properties. Its addition to the treatment of neuropathic pain may reduce pain intensity and improve overall quality of life. A systematic review and meta-analysis of randomized controlled trials was performed to investigate the addition of ketamine to the treatment of patients with neuropathic pain.

Patients and Methods

GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach was used to rate the overall certainty of the evidence for each outcome. Eighteen (18) randomized controlled trials including 706 participants were included for further analysis.

Results

Ketamine addition to standard treatment of neuropathic pain (NP) resulted in a statistically significant reduction of pain intensity at one week after the end of treatment with ketamine (MD −2.14, 95% CI −2.65 to −1.63; p<0.00001) and after 30 days after the end of treatment with ketamine (MD −1.68, 95% CI −2.25 to −1.12; p<0.00001) and a statistically significant increase in discomfort (RR 4.06; 95% CI 1.18 to 13.95; p=0.03), and psychedelic effects (RR 4.94; 95% CI 2.76 to 8.84; p<0.00001).

Conclusion

There is a statistically significant pain reduction by adding ketamine to the treatment of chronic NP when compared to the standard treatment. However, such pain reduction comes at the expense of adverse outcomes, especially psychedelic effects related to the administration of ketamine. However, the overall quality of certainty of evidence is low due to the clinical heterogeneity among the intervention characteristics of the trials analyzed (different administration routes, dosing regimen, therapy durations, different clinical characteristics of the population investigated). Future large multi-centered trials are necessary to confirm or not the results of the present review.

New Serotonin-Norepinephrine Reuptake Inhibitors and Their Anesthetic and Analgesic Considerations

Serotonin-norepinephrine reuptake inhibitors (SNRIs) inhibit the presynaptic neuronal uptake of serotonin and norepinephrine and prolong the effects of the monoamines in the synaptic cleft within the central nervous system, leading to increased postsynaptic receptor activation and neuronal activities. Serotonin-norepinephrine reuptake inhibitors can have multiple clinical indications, including as the first-line agents for the management of depression and anxiety, and as analgesics in the treatment of chronic pain. The effects of reuptake inhibition of norepinephrine and serotonin are often dose-dependent and agent-dependent. There are five FDA-approved serotonin-norepinephrine reuptake inhibitors (desvenlafaxine, duloxetine, levomilnacipran, milnacipran and sibutramine) currently being marketed in the United States. As the COVID-19 pandemic significantly increased the incidence and prevalence of anxiety and depression across the country, there are significantly increased prescriptions of these medications perioperatively. Thus, anesthesiologists are more likely than ever to have patients administered with these agents and scheduled for elective or emergency surgical procedures. A thorough understanding of these commonly prescribed serotonin-norepinephrine reuptake inhibitors and their interactions with commonly utilized anesthetic agents is paramount. There are two potentially increased risks related to the continuation of SNRIs through the perioperative period: intraoperative bleeding and serotonin syndrome. SNRIs have some off-label uses, more new indications, and ever-increasing new applications in perioperative practice. This article aims to review the commonly prescribed serotonin-norepinephrine reuptake inhibitors and the current clinical evidence regarding their considerations in perioperative anesthesia and analgesia.

Use of Tramadol or Other Analgesics in Patients Treated in the Emergency Department as a Risk Factor for Opioid Use

The objective of this cohort study was to determine the association between the use of tramadol in emergency departments and the later consumption of opioids at the outpatient level in a group of patients from Colombia. Based on a medication dispensation database, patients over 18 years of age treated in different clinics in Colombia who for the first time received tramadol, dipyrone, or a nonsteroidal anti-inflammatory drug (NSAID) in the emergency room between January and December 2018 were identified. Three mutually exclusive cohorts were created, and each patient was followed up for 12 months after the administration of the analgesic to identify new formulations of any opioid. A Cox proportional-hazards regression model was constructed to identify variables associated with receiving a new opioid. A total of 12,783 patients were identified: 6020 treated with dipyrone, 5309 treated with NSAIDs, and 1454 treated with tramadol. The mean age was 47.1 ± 20.4 years, and 61.6% were women. A total of 17.3% (n = 2207) of all patients received an opioid during follow-up. Those treated with tramadol received a new opioid with a higher frequency (n = 346, 23.8%) than the other cohorts (14.7% NSAIDs and 17.9% dipyrone, both p < 0.001). In the tramadol group, using more than 10 mg of morphine equivalents was associated with a greater use of new opioids (HR:1.47, 95%CI:1.12-1.93). Patients treated with tramadol in emergency departments have a higher risk of opioid use at the one-year follow-up than those treated with NSAIDs or dipyrone.