Wherefore Gabapentinoids?: Was There Rush Too Soon to Judgment?

What's old is new again: opioid and benzodiazepine actions on ventilation, a reminder of the importance of knowing one's drugs

Co-administering opioids and benzodiazepines can have deleterious effects on ventilation. However, little is known about the underlying mechanisms leading to hypoventilation. A recent article in the British Journal of Anaesthesia is not just another reminder of the hazards of combining opioids with benzodiazepines or other sedatives, but also applies mechanistic understanding to guide informed practice and future pharmaceutical development.

Development of Tetrahydroquinoline-Based Inhibitors for Chronic Pain

Chronic pain affects a substantial portion of the population, posing a significant health challenge. Current treatments often come with limitations and side effects, necessitating novel therapeutic approaches. Our study focuses on disrupting the Cav3.2-USP5 interaction as a strategy for chronic pain management. Through structure-activity relationship studies of a tetrahydroquinoline (THQ) scaffold, we identified a family of lead molecules that demonstrated potent inhibition of the Cav3.2-USP5 interaction. In vitro pharmacokinetic assessments and in vivo studies support the efficacy and drug-like properties of the lead compounds in mouse models of acute and chronic pain. Dependence on the Cav3.2 channels was validated in Cav3.2 null mice, consistent with the proposed mode of action of these small molecules. These findings provide a novel chronic pain treatment strategy, highlighting the potential of these small molecules for further development.

Gabapentinoid prescriptions for neuropathic and musculoskeletal pain in Lebanon

Aim: The purpose of this study is to analyze the different characteristics of gabapentinoids prescription by Lebanese orthopedics surgeons. Methods: This is an observational, cross-sectional study using a survey which was carried out in collaboration with the Lebanese Orthopedic Society over a 3-month period. Results: Forty-two orthopedic surgeons responded, most of them prescribing gabapentinoids in their daily practice with only half of the patients feeling relief after taking them. Furthermore, most of the surgeons prescribed these drugs for patients above 18 years old and for both acute and chronic pain. Conclusion: Even though almost half of the patients do not experience relief after taking gabapentinoids, these drugs are becoming more and more prescribed.

A Synthetically Accessible Small-Molecule Inhibitor of USP5-Cav3.2 Calcium Channel Interactions with Analgesic Properties

Cav3.2 calcium channels are important mediators of nociceptive signaling in the primary afferent pain pathway, and their expression is increased in various rodent models of chronic pain. Previous work from our laboratory has shown that this is in part mediated by an aberrant expression of deubiquitinase USP5, which associates with these channels and increases their stability. Here, we report on a novel bioactive rhodanine compound (II-1), which was identified in compound library screens. II-1 inhibits biochemical interactions between USP5 and the Cav3.2 domain III-IV linker in a dose-dependent manner, without affecting the enzymatic activity of USP5. Molecular docking analysis reveals two potential binding pockets at the USP5-Cav3.2 interface that are distinct from the binding site of the deubiquitinase inhibitor WP1130 (a.k.a. degrasyn). With an understanding of the ability of some rhodanines to produce false positives in high-throughput screening, we have conducted several orthogonal assays to confirm the validity of this hit, including in vivo experiments. Intrathecal delivery of II-1 inhibited both phases of formalin-induced nocifensive behaviors in mice, as well as abolished thermal hyperalgesia induced by the delivery of complete Freund's adjuvant (CFA) to the hind paw. The latter effects were abolished in Cav3.2 null mice, thus confirming that Cav3.2 is required for the action of II-1. II-1 also mediated a robust inhibition of mechanical allodynia induced by injury to the sciatic nerve. Altogether, our data uncover a novel class of analgesics─well suited to rapid structure-activity relationship studies─that target the Cav3.2/USP5 interface.

Pain management after complex spine surgery: A systematic review and procedure-specific postoperative pain management recommendations

BACKGROUND

Complex spinal procedures are associated with intense pain in the postoperative period. Adequate peri-operative pain management has been shown to correlate with improved outcomes including early ambulation and early discharge.

OBJECTIVES

We aimed to evaluate the available literature and develop recommendations for optimal pain management after complex spine surgery.

DESIGN AND DATA SOURCES

A systematic review using the PROcedure SPECific postoperative pain managemenT methodology was undertaken. Randomised controlled trials and systematic reviews published in the English language from January 2008 to April 2020 assessing postoperative pain after complex spine surgery using analgesic, anaesthetic or surgical interventions were identified from MEDLINE, EMBASE and Cochrane Databases.

RESULTS

Out of 111 eligible studies identified, 31 randomised controlled trials and four systematic reviews met the inclusion criteria. Pre-operative and intra-operative interventions that improved postoperative pain were paracetamol, cyclo-oxygenase (COX)-2 specific-inhibitors or non-steroidal anti-inflammatory drugs (NSAIDs), intravenous ketamine infusion and regional analgesia techniques including epidural analgesia using local anaesthetics with or without opioids. Limited evidence was found for local wound infiltration, intrathecal and epidural opioids, erector spinae plane block, thoracolumbar interfascial plane block, intravenous lidocaine, dexmedetomidine and gabapentin.

CONCLUSIONS

The analgesic regimen for complex spine surgery should include pre-operative or intra-operative paracetamol and COX-2 specific inhibitors or NSAIDs, continued postoperatively with opioids used as rescue analgesics. Other recommendations are intra-operative ketamine and epidural analgesia using local anaesthetics with or without opioids. Although there is procedure-specific evidence in favour of intra-operative methadone, it is not recommended as it was compared with shorter-acting opioids and due to its limited safety profile. Furthermore, the methadone studies did not use non-opioid analgesics, which should be the primary analgesics to ultimately reduce overall opioid requirements, including methadone. Further qualitative randomised controlled trials are required to confirm the efficacy and safety of these recommended analgesics on postoperative pain relief.

Perioperative Opioid Administration

Opioids form an important component of general anesthesia and perioperative analgesia. Discharge opioid prescriptions are identified as a contributor for persistent opioid use and diversion. In parallel, there is increased enthusiasm to advocate opioid-free strategies, which include a combination of known analgesics and adjuvants, many of which are in the form of continuous infusions. This article critically reviews perioperative opioid use, especially in view of opioid-sparing versus opioid-free strategies. The data indicate that opioid-free strategies, however noble in their cause, do not fully acknowledge the limitations and gaps within the existing evidence and clinical practice considerations. Moreover, they do not allow analgesic titration based on patient needs; are unclear about optimal components and their role in different surgical settings and perioperative phases; and do not serve to decrease the risk of persistent opioid use, thereby distracting us from optimizing pain and minimizing realistic long-term harms.

Perioperative Use of Gabapentinoids for the Management of Postoperative Acute Pain

Background

Widely used for acute pain management, the clinical benefit from perioperative use of gabapentinoids is uncertain. The aim of this systematic review was to assess the analgesic effect and adverse events with the perioperative use of gabapentinoids in adult patients.

Methods

Randomized controlled trials studying the use of gabapentinoids in adult patients undergoing surgery were included. The primary outcome was the intensity of postoperative acute pain. Secondary outcomes included the intensity of postoperative subacute pain, incidence of postoperative chronic pain, cumulative opioid use, persistent opioid use, lengths of stay, and adverse events. The clinical significance of the summary estimates was assessed based on established thresholds for minimally important differences.

Results

In total, 281 trials (N = 24,682 participants) were included in this meta-analysis. Compared with controls, gabapentinoids were associated with a lower postoperative pain intensity (100-point scale) at 6 h (mean difference, −10; 95% CI, −12 to −9), 12 h (mean difference, −9; 95% CI, −10 to −7), 24 h (mean difference, −7; 95% CI, −8 to −6), and 48 h (mean difference, −3; 95% CI, −5 to −1). This effect was not clinically significant ranging below the minimally important difference (10 points out of 100) for each time point. These results were consistent regardless of the type of drug (gabapentin or pregabalin). No effect was observed on pain intensity at 72 h, subacute and chronic pain. The use of gabapentinoids was associated with a lower risk of postoperative nausea and vomiting but with more dizziness and visual disturbance.

Conclusions

No clinically significant analgesic effect for the perioperative use of gabapentinoids was observed. There was also no effect on the prevention of postoperative chronic pain and a greater risk of adverse events. These results do not support the routine use of pregabalin or gabapentin for the management of postoperative pain in adult patients.

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Effects of Acetaminophen, NSAIDs, Gabapentinoids, and Their Combinations on Postoperative Pulmonary Complications After Total Hip or Knee Arthroplasty

Objective

Multimodal analgesia has gained popularity in total hip arthroplasty (THA) and total knee arthroplasty (TKA), but large multicenter studies evaluating specific analgesic combinations are lacking.

Design

A retrospective study using the Premier Healthcare Database (2009–2014).

Subjects

Adults who underwent elective primary THA or TKA.

Methods

We categorized day-of-surgery analgesic exposure using eight mutually exclusive categories: acetaminophen (Ac), nonsteroidal anti-inflammatory drugs (Ns), gabapentinoids (Ga; gabapentin or pregabalin), Ac+Ns, Ac+Ga, Ns+Ga, Ac+Ns+Ga, and none of the three drugs. Multilevel models measured associations of the analgesic categories with a composite of postoperative pulmonary complications (PPCs).

Results

Among 863,139 patients, 75.2% received at least one of the three drugs. In multilevel models, compared with none of the three drugs, Ga use was associated with increased odds of PPCs when used alone (adjusted odds ratio [aOR] = 1.35, 95% confidence interval [CI] = 1.27 to 1.44), combined with Ac (aOR = 1.16, 95% CI = 1.08 to 1.26), or combined with Ns (aOR = 1.28, 95% CI = 1.21 to 1.34). In contrast, the Ac+Ns pair was associated with decreased odds of PPCs (OR = 0.86, 95% CI = 0.83 to 0.90) and lower opioid consumption. Ac+Ns+Ga was not associated with PPCs, whereas it was associated with the lowest opioid consumption on the day of surgery.

Conclusions

Gabapentinoids, alone and in single combination with either acetaminophen or nonsteroidal anti-inflammatory drugs, were associated with higher PPCs, whereas the Ac+Ns pair was associated with fewer PPCs and an opioid-sparing effect. Ac+Ns+Ga was not associated with PPCs, whereas it was associated with the lowest opioid consumption on the day of surgery.

Pain And The Use Of Gabapentinoids In German Nursing Home Residents - Results From An Analysis Based On Statutory Health Insurance Data

BACKGROUND

Gabapentinoids (gabapentin and pregabalin) are psychoactive medications that are increasingly used for different conditions. Since there is evidence that psychotropic drugs, in general, are often inappropriately prescribed in elderly patients, we aimed to determine frequency and indications of gabapentinoid prescribing for nursing home residents.

METHODS

We analyzed data from a large German statutory health insurance database. Included were records from people ≥65 years-of-age, who were admitted to a nursing home between January 2010 and December 2014. We determined the number and proportion of common indications for on- and off-label prescriptions, the most frequent co-medications, and the characteristics of patients and prescribers.

RESULTS

Of 127,277 residents, 9539 (7.5%) received gabapentinoids and 4852 initiated treatment (4.0%; with 66.3% pregabalin). Median age of gabapentinoid initiators was 84 years (78.5% females). In these users, on-label prescribing was found in 57.4%, predominantly for neuropathic pain. Other painful conditions were also chief causes (84.7%) for off-label prescribing. Gabapentinoids were mainly started by general practitioners (64.5%) while pain specialists contributed <2%. Forty-six percent of users received additional opioids and in 27.5% gabapentinoids were prescribed only once.

CONCLUSION

Gabapentinoids were frequently used in nursing home residents. Regular co-prescribing with opioids and psychotropic drugs might indicate employment to improve pain or assist treatment of conditions that are frequently associated with disruptive behavior such as dementia. However, more research is needed to better understand decision-making regarding gabapentinoid prescribing, especially in view of aggressive marketing, uncertain analgesic effects, problematic side effects, and uncritical use in the elderly.

Effects of a Preoperative Transdermal Fentanyl Patch on Proinflammatory Cytokine and Pain Levels During the Postoperative Period: A Randomized Controlled Trial

OBJECTIVE

The main objectives of this article were to assess the effect of preoperative transdermal fentanyl patch (TFP) on interleukin (IL)-6 and IL-8 levels and pain after laparoscopic cholecystectomy.

MATERIALS AND METHODS

Patients received a TFP (25 μg/h) (patch group, n=30) or a placebo patch (control group, n=30) applied 14 hours before operation. After surgery, control group received intravenous continuous fentanyl (25 μg/h) with loading dose (25 μg). IL-6 and IL-8 levels were measured at admission and 1, 6, 12, 24, and 48 hours postoperatively. Pain score and consumption of rescue analgesic were evaluated too.

RESULTS

At 24 hours postoperatively, IL-6 and IL-8 reached a peak and then decreased. The peak IL-6 levels were 21.92(±6.22) and 24.91(±6.81) pg/mL in the patch and control group. The significant differences of IL-6 between groups were shown at 6 and 12 hours postoperatively (P=0.032, 0.0001). There were no significant differences in IL-8 levels and pain score.

CONCLUSIONS

Preoperative TFP attenuated the increase in IL-6 levels after surgery and provided similar analgesia to continuous fentanyl infusion. Preemptive TFP may have influence on proinflammatory reactions and pain control after surgery.

Prevention and Treatment of Chronic Postsurgical Pain: A Narrative Review

Chronic postsurgical pain affects between 5 and 75% of patients, often with an adverse impact on quality of life. While the transition of acute to chronic pain is a complex process-involving multiple mechanisms at different levels-the current strategies for prevention have primarily been restricted to perioperative pharmacological interventions. In the present paper, we first present an up-to-date narrative literature review of these interventions. In the second section, we develop several ways by which we could overcome the limitations of the current approaches and enhance the outcome of our surgical patients, including the better identification of individual risk factors, tailoring treatment to individual patients, and improved acute and subacute pain evaluation and management. The third and final section covers the treatment of established CPSP. Given that evidence for the current therapeutic options is limited, we need high-quality trials studying multimodal interventions matched to pain characteristics.

Cognitive Effects of Perioperative Pregabalin

EDITOR’S PERSPECTIVE

What We Already Know about This Topic

Perioperative administration of pregabalin has been associated with decreased postoperative pain and opioid requirements

What This Article Tells Us That Is New

This secondary analysis of data demonstrating that perioperative administration of pregabalin was associated with a reduction in opioid requirements and incisional hyperalgesia suggests that these benefits may be compromised by an increased risk of developing impaired postoperative cognitive performance

Background

Pregabalin has shown opioid sparing and analgesic effects in the early postoperative period; however, perioperative effects on cognition have not been studied. A randomized, parallel group, placebo-controlled investigation in 80 donor nephrectomy patients was previously performed that evaluated the analgesic, opioid-sparing, and antihyperalgesic effects of pregabalin. This article describes a secondary exploratory analysis that tested the hypothesis that pregabalin would impair cognitive function compared to placebo.

Methods

Eighty patients scheduled for donor nephrectomy participated in this randomized, placebo-controlled study. Pregabalin (150 mg twice daily, n = 40) or placebo (n = 40) was administered on the day of surgery and the first postoperative day, in addition to a pain regimen consisting of opioids, steroids, local anesthetics, and acetaminophen. Specific cognitive tests measuring inhibition, sustained attention, psychomotor speed, visual memory, and strategy were performed at baseline, 24 h, and 3 to 5 days after surgery, using tests from the Cambridge Neuropsychological Test Automated Battery.

Results

In the spatial working memory within errors test, the number of errors increased with pregabalin compared to placebo 24 h after surgery; median (25th, 75th percentile) values were 1 (0, 6) versus 0 (0, 1; rate ratio [95% CI], 3.20 [1.55 to 6.62]; P = 0.002). Furthermore, pregabalin significantly increased the number of errors in the stop-signal task stop-go test compared with placebo; median (25th, 75th percentile) values were 3 (1, 6) versus 1 (0, 2; rate ratio, 2.14 [1.13 to 4.07]; P = 0.020). There were no significant differences between groups in the paired associated learning, reaction time, rapid visual processing, or spatial working memory strategy tests.

Conclusions

Perioperative pregabalin significantly negatively affected subdomains of executive functioning, including inhibition, and working memory compared to placebo, whereas psychomotor speed was not changed.

Intentional Drug Overdose Involving Pregabalin and Gabapentin: Findings from the National Self-Harm Registry Ireland, 2007-2015

INTRODUCTION

Intentional drug overdose (IDO) is a significant public health problem. Concerns about the misuse of gabapentinoids, i.e. pregabalin and gabapentin, including their consumption in IDO have grown in recent years. This paper examines the trends in the prevalence of gabapentinoids taken in IDO, the profile of individuals taking them, and associated overdose characteristics.

METHODS

Presentations to emergency departments involving IDO, recorded by the National Self-Harm Registry Ireland between 1 January 2007 and 31 December 2015 were examined. Data items included patient demographics, drug names, total tablet quantity consumed and alcohol involvement.

RESULTS

Gabapentinoids were involved in 2115 (2.9%) of the 72,391 IDOs recorded. Presentations involving a gabapentinoid increased proportionally from 0.5% in 2007 to 5.5% in 2015. The majority of IDOs involving a gabapentinoid were made by females (59.9%), with over one-third (37.2%) involving alcohol. Compared with IDOs involving other drugs, presentations with a gabapentinoid were made by persons who were older (median 37 vs. 32 years) and involved a significantly greater median quantity of tablets (30 vs. 21, p ≤ 0.001), with over one-quarter (27.4%) of these involving the ingestion of 50 tablets or more. Admission to hospital was significantly more common following IDOs with a gabapentinoid compared with those without (49.4% vs. 41.4%, p ≤ 0.001).

CONCLUSIONS

This study identified the increasing use of gabapentinoids in IDO, describing the profile and overdose characteristics of presentations. It is important for clinicians to exercise vigilance while prescribing gabapentinoids, including being aware of other medications that their patients may have access to. Our findings support the need for routine monitoring for signs of misuse among those prescribed gabapentinoids.

Injury-induced maladaptation and dysregulation of calcium channel α2 δ subunit proteins and its contribution to neuropathic pain development

Voltage-gated calcium channels (VGCCs) play important roles in physiological functions including the modulation of neurotransmitter release, neuronal network activities, intracellular signalling pathways and gene expression. Some pathological conditions, including nerve injuries, can cause the dysregulation of VGCCs and their subunits. This in turn can lead to a functional maladaptation of VGCCs and their subunits, which can contribute to the development of disorders such as pain sensations. This review has summarized recent findings related to maladaptive changes in the dysregulated VGCC α2 δ1 subunit (Cav α2 δ1 ) with a focus on exploring the mechanisms underlying the contribution of Cav α2 δ1 to pain signal transduction. At least under neuropathic pain conditions, the dysregulated Cav α2 δ1 can modulate VGCC functions as well as other plasticity changes. The latter includes abnormal excitatory synaptogenesis resulting from its interactions with injury-induced extracellular matrix glycoprotein molecule thrombospondins, which is independent of the VGCC functions. Blocking Cav α2 δ1 with gabapentinoids can reverse neuropathic pain significantly with relatively mild side effects, but only in a small population of neuropathic pain patients due to reasons yet to be explored. There are emerging data suggesting that early preventive treatment with gabapentinoids can prevent aberrant excitatory synapse formation and the development of chronic pain. If these findings are confirmed clinically, this could be an attractive approach for neuropathic pain management.

LINKED ARTICLES

This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.

Perioperative management in children with chronic pain

Children with chronic pain often undergo surgery and effective perioperative management of their pain can be challenging. Identification of the pediatric chronic pain patient preoperatively and development of a perioperative pain plan may help ensure a safer and more comfortable perioperative course. Successful management usually requires multiple different classes of analgesics, regional anesthesia, and adjunctive nonpharmacological therapies. Neuropathic and oncological pain can be especially difficult to treat and usually requires an individualized approach.