Gabapentinoids: pharmacokinetics, pharmacodynamics and considerations for clinical practice

Presynaptic antiseizure medications - basic mechanisms and clues for their rational combinations

Among clinically highly efficient antiseizure medications (ASMs) there are modifiers of the presynaptic release machinery. Of them, levetiracetam and brivaracetam show a high affinity to the synaptic vesicle protein type 2 A (SV2A), whereas pregabalin and gabapentin are selective ligands for the α2δ1 subunits of the voltage-gated calcium channels. In this paper, we present recent progress in understanding the significance of presynaptic release machinery in the neurochemical mechanisms of epilepsy and ASMs. Furthermore, we discuss whether the knowledge of the basic mechanisms of the presynaptically acting ASMs might help establish a rational polytherapy for drug-resistant epilepsy.

Patterns of gabapentinoid use among long-term opioid users

OBJECTIVE

Understanding the clinical and demographic profile of patients on gabapentinoids can highlight areas of prescribing disparities, inform clinical practice, and guide future research to optimize effectiveness and safety of gabapentinoids for pain management. We used a national sample of Medicare beneficiaries to examine trends, patterns, and patient-level predictors of gabapentinoid use among long-term opioid users.

METHODS

Using a national Medicare sample between 2014 and 2020, we examined factors associated with gabapentinoid use among long-term opioid users. We included Medicare eligible long-term opioid users with no prior gabapentinoid use. The primary outcome was gabapentinoid use after the long-term opioid use episode. Logistic regression was used to test the association with gabapentinoid use for year, age, sex, race/ethnicity, region, Medicare entitlement, low-income status, frailty, pain locations, anxiety, depression, opioid use disorder, and opioid morphine milligrams equivalent.

RESULTS

Gabapentinoid use among long-term opioid users increased from 12.6% in 2014 to 16.8% in 2019 (p < .0001). Factors associated with increased gabapentinoid use were Hispanic ethnicity, back pain, nerve pain, and moderate or high opioid usage. Factors associated with decreased gabapentinoid use were older age and Medicare entitlement due to old age.

CONCLUSIONS

Variation of gabapentinoid use by socio-demographics and insurance status indicates opportunities to improve pain management and a need for shared therapeutic decision making informed by discussion between pain patients and providers regarding safety and effectiveness of pain therapies. Our findings underscore the need for future research into the comparative effectiveness and safety of gabapentinoids for non-cancer chronic pain in various subpopulations.

Association of adverse cardiovascular events with gabapentin and pregabalin among patients with fibromyalgia

OBJECTIVE

Fibromyalgia, a chronic pain disorder, impacts approximately 2% of adults in the US. Gabapentin and pregabalin are common treatments to manage fibromyalgia-related pain. Our recent study showed the risk of adverse cardiovascular events increased in diabetic neuropathy patients who were prescribed gabapentin or pregabalin. Here, we investigated whether the prescription of gabapentin or pregabalin has similar cardiovascular risk in patients with fibromyalgia.

METHODS

This retrospective cohort study leveraged electronic health records from 64 US healthcare organizations with 112 million patients. The study population included 105,602 patients first diagnosed with fibromyalgia and followed by a prescription of gabapentin, pregabalin, or other FDA-approved drugs for treating fibromyalgia from 2010 to 2019. Outcomes were deep venous thrombosis (DVT), myocardial infarcts (MI), peripheral vascular disease (PVD), strokes, heart failure, and pulmonary embolism (PE). In propensity-score-matched cohorts, 1-year and 5-year hazard ratios (HRs) were computed with their respective 95% confidence intervals (CIs). Additionally, we conducted sensitivity analyses on the subpopulations without other possible indications.

RESULTS

For 5-year follow-up, gabapentin increased the risk of PVD (HR = 1.46, 95% CI = 1.17-1.80), MI (HR = 1.31, 95% CI = 1.03-1.66), heart failure (HR = 1.27, 95% CI = 1.10-1.48), DVT (HR = 1.80, 95% CI = 1.33-2.44), and PE (HR = 2.23, 95% CI = 1.62-3.07). Pregabalin increased the risk of DVT (HR = 1.49, 95% CI = 1.01-2.20), and PE (HR = 2.24, 95% CI = 1.43-3.50). For 1-year follow-up, gabapentin increased the risk of PVD (HR = 1.32, 95% CI = 1.11-1.57), DVT (HR = 1.35, 95% CI = 1.09-1.68), and PE (HR = 1.36, 95% CI = 1.17-1.57). Pregabalin increased the risk of PVD (HR = 1.32, 95% CI = 1.06-1.63) and PE (HR = 1.25, 95% CI = 1.03-1.52). Sensitivity analyses showed similar trends.

CONCLUSION

In fibromyalgia patients, the prescription of gabapentin and pregabalin moderately increased the risk of several adverse cardiovascular events. This risk, together with benefits and other adverse reactions, should be considered when prescribing these medications for fibromyalgia patients.

Frontiers in Acute Pain Management: Emerging Concepts in Pain Pathways and the Role of VX-548 as a Novel NaV1.8 Inhibitor: A Narrative Review

PURPOSE OF REVIEW

Despite ongoing research into alternative postsurgical pain treatments, opioids remain widely used analgesics regardless of associated adverse effects, including dependence and overdose, as demonstrated throughout the current opioid crisis. This is likely related to a failure in proving the efficacy of alternative analgesics in clinical trials, despite strong evidence supporting the potential for effective analgesia through in vitro studies. While NaV1.7 and NaV1.8 channels have shown to be key components of pain perception, studies regarding pharmacological agents utilizing these channels as targets have largely failed to demonstrate the efficacy of these proposed analgesics when compared to current multimodal pain treatment regimens.

RECENT FINDINGS

However, the novel NaV1.8 channel inhibitor, VX-548 has surpassed previously studied NaV1.8 inhibitors in clinical trials and continues to hold promise of a novel efficacious analgesic to potentially be utilized in multimodal pain treatment on postsurgical patients. Additionally, NaV1.8 is encoded by the SCN10A, which has been shown to be minimally expressed in the brain, suggesting a lower likelihood of adverse effects in the CNS, including dependence and abuse. Novel pharmacologic analgesics that are efficacious without the significant side effects associated with opioids have lacked meaningful development. However, recent clinical trials have shown promising results in the safety and efficacy of the pharmacological agent VX-548. Still, more clinical trials directly comparing the efficacy of VX-548 to standard of care post-surgical drugs, including opioids like morphine and hydromorphone are needed to demonstrate the long-term viability of the agent replacing current opioids with an unfavorable side effect profile.

Pharmacokinetic profile and physiological effects of oral and compounded intravenous gabapentin in goats

OBJECTIVE

To determine the pharmacokinetics and physiological effects following oral and intravenous (IV) administration of gabapentin in goats.

STUDY DESIGN

Prospective, crossover study with a 3 week washout period between treatments.

ANIMALS

A total of eight healthy, client-owned, female goats.

METHODS

Gabapentin (10 mg kg-1) was administered to goats either orally or IV. Gabapentin concentrations were measured in serum samples collected 0-96 hours post-administration using liquid chromatography-quadrupole time-of-flight mass spectrometry. Heart rate, respiratory rate, blood pressure and temperature were recorded before and throughout the study. Correlations of the mean serum concentrations of gabapentin to those of each physiological parameter were determined using the Pearson method.

RESULTS

The mean and standard deviation of oral bioavailability for gabapentin was 60.9 ± 11.2%. Maximum serum concentration of gabapentin was lower following oral (1.19 ± 0.29 μg mL-1) than after IV administration (59.76 ± 14.38 μg mL-1, p < 0.0001). Half-lives were longer following PO (8.18 ± 0.57 hours) than after IV administration (1.79 ± 0.06 hours, p < 0.0001). Time to maximum concentration was 6.86 ± 2.27 hours following oral administration. Heart rate was inversely correlated with serum gabapentin concentrations. Slight ataxia was observed in three animals, and one became recumbent following IV gabapentin.

CONCLUSIONS AND CLINICAL RELEVANCE

Gabapentin is well-absorbed following oral administration to goats but yielded significantly lower serum concentrations than the IV route. The longer half-life of gabapentin following oral than after IV administration may result from prolonged absorption throughout the caprine gastrointestinal tract. IV gabapentin may cause slight ataxia in some goats.

The effect of pre-emptive oral pregabalin on opioid consumption in patients undergoing laparoscopic sleeve gastrectomy with an analysis of intraoperative hemodynamic stability and quality of recovery: study protocol for a randomized, prospective, double-blind study

BACKGROUND

Obese patients undergoing laparoscopic sleeve gastrectomy (LSG) are particularly at risk of opioid-related side effects. To reduce patient exposure to opioids, multimodal analgesia, which involves the use of drugs of different classes, may be utilized. One of the drugs under consideration is pregabalin. Despite an opioid-sparing potential, few studies assess the role of pregabalin as an element of multimodal analgesia in LSG. Considering the limited number and inconsistent results of available studies, we decided to conduct a randomized, prospective study on the effect of preemptive pregabalin administration in obese patients on opioid consumption, pain scores, the incidence of opioid side effects, and hemodynamical stability.

METHODS

The study is designed as a prospective randomized controlled trial with double-blinding. Randomization will be performed in a block with a parallel 1:1 allocation. The intervention will involve receiving a pregabalin 150 mg capsule 1-2 h before the surgery, whereas the control group will receive an identically looking placebo. The primary outcome measure will be total oxycodone consumption in the first 24 h following surgery. Secondary outcome measures will be pain severity assessed using the Numerical Rating Scale (NRS) 1, 6, 12, and 24 h after surgery, postoperative sedation on the Ramsay scale, PONV impact scale, the incidence of desaturation episodes < 94%, and episodes of blurred vision at 1, 6, 12, and 24 h after surgery, intraoperative hemodynamic parameters such as heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), total fluid volume, and total ephedrine dose. Patient comfort will be additionally assessed using the QoR-40 questionnaire at discharge.

DISCUSSION

The study will explore the efficacy and safety of preemptive pregabalin in a dose of 150 mg as a co-analgesic used in multimodal analgesia for LSG. As studies on opioid-sparing regimes concern the safety of obese patients, we aim to contribute objective data with a relatively large study sample size. The result of the present clinical trial may support the reassessment of recommendations to use pregabalin in the studied population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05804591. Registered on 07.04.2023.

Topical gabapentin and its relation to cutaneous innervation in symptomatic lymphocytic primary cicatricial alopecia

In this pilot study, participants with symptomatic lymphocytic primary cicatricial alopecia applied 6% topical gabapentin solution twice daily to affected areas for 12 weeks. There was a significant reduction in symptoms, but no pronounced effect on nerve fibre density or neuropeptide expression.

Association of Psoas: Lumbar Vertebral Index (PLVI) with Postherpetic Neuralgia in Patients Aged 60 and Older with Herpes Zoster

Background/Objectives: The psoas: lumbar vertebral index (PLVI) is a simple and convenient measure to assess central sarcopenia. Recent studies have utilized the psoas area to indirectly assess sarcopenia and frailty, exploring their associations with various health outcomes. This study aims to investigate the relationship between the PLVI and postherpetic neuralgia (PHN) in patients aged 60 years and above following a herpes zoster (HZ) infection. Methods: We conducted a retrospective analysis of data from 351 patients (≥60 years) who developed HZ between January 2019 and December 2023; the patients were divided into two groups based on the presence or absence of PHN after HZ onset. Results: The analyses using receiver operating characteristic curves revealed a value for the area under the curve of 0.813 for PLVI and 0.769 for the modified frailty index (mFI). In a multivariate logistic regression analysis, numerical rating scale scoring, a low PLVI, and a greater number of categorical mFI variables (adjusted odds ratio: 1.30, 3.27, and 2.46, respectively) were found to be significant independent predictors of PHN. Conclusions: Our findings highlight the association between a low PLVI and PHN in an older population. The PLVI may have potential as a predictive tool for PHN in older patients with HZ, but further research is needed to confirm these results.

Sleep disorders in chronic kidney disease

Sleep disorders are highly prevalent in chronic kidney disease (CKD) but are often under-recognized. Restless legs syndrome, which is common in CKD owing to issues with dopamine metabolism and is exacerbated by iron deficiency and uraemia, can lead to poor sleep quality and increased daytime fatigue. Insomnia is also prevalent in CKD, particularly in patients requiring dialysis, with increased sleep latency and sleep fragmentation being reported. The cause of insomnia in CKD is multifactorial - poor sleep habits and frequent napping during dialysis, uraemia, medications and mood disorders have all been suggested as potential contributing factors. Sleep apnoea and CKD are also now recognized as having a bi-directional relationship. Sleep apnoea is a risk factor for accelerated progression of CKD, and fluid overload, which is associated with kidney failure, can lead to both obstructive and central sleep apnoea. The presence of obstructive sleep apnoea in CKD can exacerbate the already heightened cardiovascular morbidity and mortality in these patients, as well as leading to daytime fatigue and reduced quality of life. Increased awareness, timely diagnosis and appropriate therapeutic interventions are essential to reduce the negative impact of sleep disorders in patients with kidney disease.

Effects of gabapentin on slow-wave sleep period in critically ill adult patients: A randomized controlled trial

Sleep deprivation is a prevalent problem in critically ill patients, which leads to delayed recovery and delirium. Slow-wave sleep (SWS) is essential to energy restoration, tissue repair, and immune system strengthening. This study aimed to investigate the effects of gabapentin on SWS in critically ill patients. We performed a prospective open-label randomized controlled study to compare SWS and the clinical outcomes of gabapentin versus a control intervention in critically ill adult patients admitted to the intensive care unit (ICU) within 24 h. The patients' characteristics and sleep-related outcomes were recorded. The sleep-related outcomes, namely, bispectral analysis (BIS), the Richards-Campbell Sleep Questionnaire (RCSQ), and insulin-like growth factor-1 (IGF-1) levels, were evaluated. Furthermore, clinical outcomes and safety were assessed. Sixty patients from 348 cases were eligible for randomization. On day 3 of the study, patients in the gabapentin group had significantly increased SWS (66.79 vs. 0.00 min; p < 0.001), total sleep time (TST) (331.39 vs. 46.16 min; p = 0.001), RCSQ score (55.05 ± 20.18 vs. 32.80 ± 15.31; p < 0.001), and IGF-1 concentrations (84.33 ± 12.40 vs. 44.00 ± 10.20 ng/mL, p < 0.001) compared with the control group. Improvements in clinical outcomes, such as delirium, ICU-free days, and mechanical ventilator-free days, were observed; however, these differences did not reach statistically significant. Gabapentin at bedtime increased SWS, TST, and IGF-1 concentrations in critically ill patients. This regimen might be beneficial to critically ill patients for improving their sleep quality.

Use of Baclofen as a Treatment for Nocturnal Calf Cramps in Individuals With Lumbar Spinal Stenosis: A Prospective Randomized Study

OBJECTIVE

This study aimed to compare the efficacy and safety of baclofen and gabapentin in reducing leg pain from nocturnal calf cramps in lumbar spinal stenosis patients.

DESIGN

In a randomized clinical trial, the patients with lumbar spinal stenosis who commonly experienced nocturnal calf cramps were included. Patients were randomly assigned to either the baclofen or gabapentin group. Overall leg pain intensity, nocturnal calf cramp frequency and severity, sleep disturbances and functional disability were assessed at baseline and after 4 and 12 wks.

RESULTS

Thirty-six patients completed the 3-mo study. Both gabapentin and baclofen groups showed a significant reduction in overall leg pain, calf cramp frequency and intensity, and insomnia severity index scores from baseline to the endpoint. However, there were no significant differences between the two groups in terms of symptom reduction at different time points. The baclofen group also demonstrated a significant decrease in Oswestry Disability Index scores ( P < 0.001), while the gabapentin group did not ( P = 0.344). No adverse effects were reported in either group.

CONCLUSIONS

Baclofen seems to be as effective and as safe as gabapentin in treating nocturnal calf cramps in lumbar spinal stenosis patients and even shows superiority in enhancing functional outcomes.

Non-Opioid Analgesics and Adjuvants after Surgery in Adults with Obesity: Systematic Review with Network Meta-Analysis of Randomized Controlled Trials

Background/Objectives: Managing postoperative pain in patients with obesity is challenging. Although using a combination of pain relief methods is recommended for these patients, the true effectiveness of various intravenous non-opioid analgesics and adjuvants in multimodal anesthesia needs to be better defined. Methods: A systematic review and network meta-analysis was performed to evaluate the efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, ketamine, α-2 agonists, lidocaine, magnesium, and oral gabapentinoids in adult surgical patients with obesity. The analysis aimed to compare these treatments to a placebo/no treatment or alternative analgesics, with a primary focus on postoperative pain and secondary endpoints including rescue analgesia, postoperative nausea and vomiting (PONV), and recovery quality. English-language randomized controlled trials across PubMed, Scopus, Web of Science, CINAHL, and EMBASE were considered. Quality and evidence certainty were assessed with the RoB 2 tool and GRADE, and data was analyzed with R software. Results: NSAIDs, along with acetaminophen, lidocaine, α-2 agonists, ketamine, and oral gabapentinoids, effectively reduce early postoperative pain. NSAIDs, particularly ibuprofen, as well as acetaminophen, ketamine, and lidocaine, also show benefits in later postoperative stages. Intravenous non-opioid analgesics and adjuvants show some degree of benefit in reducing PONV and the need for rescue analgesic therapy when using α-2 agonists alone or combined with oral gabapentinoids, notably decreasing the likelihood of PONV. Ketamine, lidocaine, and α-2 agonists are shown to enhance postoperative recovery and care quality. Conclusions: Intravenous non-opioid analgesics and adjuvants are valuable in multimodal anesthesia for pain management in adult surgical patients suffering from obesity.

Update on Treating Painful Diabetic Peripheral Neuropathy: A Review of Current US Guidelines with a Focus on the Most Recently Approved Management Options

Painful diabetic peripheral neuropathy (DPN) is a highly prevalent and disabling complication of diabetes that is often misdiagnosed and undertreated. The management of painful DPN involves treating its underlying cause via lifestyle modifications and intensive glucose control, targeting its pathogenesis, and providing symptomatic pain relief, thereby improving patient function and health-related quality of life. Four pharmacologic options are currently approved by the US Food and Drug Administration (FDA) to treat painful DPN. These include three oral medications (duloxetine, pregabalin, and tapentadol extended release) and one topical agent (capsaicin 8% topical system). More recently, the FDA approved several spinal cord stimulation (SCS) devices to treat refractory painful DPN. Although not FDA-approved specifically to treat painful DPN, tricyclic antidepressants, serotonin/norepinephrine reuptake inhibitors, gabapentinoids, and sodium channel blockers are common first-line oral options in clinical practice. Other strategies may be used as part of individualized comprehensive pain management plans. This article provides an overview of the most recent US guidelines for managing painful DPN, with a focus on the two most recently approved treatment options (SCS and capsaicin 8% topical system), as well as evidence for using FDA-approved and guideline-supported drugs and devices. Also discussed are unmet needs for this patient population, and evidence for potential future treatments for painful DPN, including drugs with novel mechanisms of action, electrical stimulation devices, and nutraceuticals.

A comprehensive update on the ADMET considerations for α2δ calcium channel ligand medications for treating restless legs syndrome

INTRODUCTION

Restless legs syndrome/Willis-Ekbom disease (RLS/WED) is a sleep-related sensory-motor disorder associated with poor sleep quality and impaired daily functioning. In patients affected by chronic RLS/WED, a pharmacological therapy is recommended. International guidelines suggest to start the treatment with a α2δ calcium channel ligand in most cases, unless contraindicated.

AREAS COVERED

The present review is based on an extensive Internet and PubMed search from 1986 to 2024. Our purpose is to describe the absorption, distribution, metabolism, and toxicology (ADMET) of the α2δ ligands, with common consideration for the therapeutic class, specificities of different compounds, efficacy, and safety in relation to other treatment options.

EXPERT OPINION

α2δ ligands are quite similar in their ADMET profiles, sharing most of the pharmacokinetics and potential adverse effects. However, we highlight the linear kinetic of gabapentin enacarbil and pregabalin, differently from gabapentin. α2δ ligands are safe and effective for the treatment of RLS/WED. Additional benefits can be obtained in comorbid insomnia, chronic pain syndromes, history of impulse control disorder, and comorbid anxiety. The use of α2δ ligands is associated with poor risk of augmentation. We still need new long-term safe and effective treatments, which could be developed along with our knowledge of RLS/WED pathophysiology.

Effects of Gabapentin on Postoperative Pain and Opioid Consumption Following Laparoscopic Cholecystectomy: A Systematic Review and Meta-analysis

PURPOSE

Examine the efficacy of gabapentin on postoperative pain scores and opioid consumption in laparoscopic cholecystectomy.

DESIGN

Systematic review and meta-analysis.

METHODS

PubMed, EBSCO, CINAHL, the Cochrane Central Register of Controlled Trials, Google Scholar, and gray literature was used to search the literature. Only randomized controlled trials were included. Outcomes were reported using the risk ratio and mean difference (MD). Risk of bias and the grades of recommendation, assessment, development, and evaluation (GRADE) system was used to the assessed quality of evidence.

FINDINGS

Nineteen trials involving 2,068 patients were analyzed. Compared to placebo, gabapentin reduced the cumulative pain scores in the first 24 hours after surgery (MD, -1.19; 95% CI, -1.39-0.99; P < .00011), opioid consumption (MD, -3.51; 95% CI, -4.67 to -2.35; P < .00001), and the incidence of postoperative nausea and vomiting (risk ratio, 0.64; 95% CI, 0.52-0.78; P < .00001) with prolonged time to first analgesic rescue (MD, 210.9; 95% CI, 76.90-344.91; P = .002). However, gabapentin has little to no effect on the incidence of sedation, somnolence, and respiratory depression.

CONCLUSIONS

Gabapentin can be added as part of the multimodal pain management for patients undergoing laparoscopic cholecystectomy. Extrapolation of these findings to clinical settings must take into consideration the limitations identified in this review.

Novel drugs affecting diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) poses a significant threat, affecting half of the global diabetic population and leading to severe complications, including pain, impaired mobility, and potential amputation. The delayed manifestation of diabetic neuropathy (DN) makes early diagnosis challenging, contributing to its debilitating impact on individuals with diabetes mellitus (DM). This review examines the multifaceted nature of DPN, focusing on the intricate interplay between oxidative stress, metabolic pathways, and the resulting neuronal damage. It delves into the challenges of diagnosing DN, emphasizing the critical role played by hyperglycemia in triggering these cascading effects. Furthermore, the study explores the limitations of current neuropathic pain drugs, prompting an investigation into a myriad of pharmaceutical agents tested in both human and animal trials over the past decade. The methodology scrutinizes these agents for their potential to provide symptomatic relief for DPN. The investigation reveals promising results from various pharmaceutical agents tested for DPN relief, showcasing their efficacy in ameliorating symptoms. However, a notable gap persists in addressing the underlying problem of DPN. The results underscore the complexity of DPN and the challenges in developing therapies that go beyond symptomatic relief. Despite advancements in treating DPN symptoms, there remains a scarcity of options addressing the underlying problem. This review consolidates the state-of-the-art drugs designed to combat DPN, highlighting their efficacy in alleviating symptoms. Additionally, it emphasizes the need for a deeper understanding of the diverse processes and pathways involved in DPN pathogenesis.

Gabapentinoids: a therapeutic review

The Australian Therapeutic Goods Administration's approved indications for prescription of gabapentinoids are refractory focal epilepsy and neuropathic pain. Use of gabapentinoids outside of the approved indications is common, but evidence for this is limited, especially for chronic nonspecific back pain and nonradicular leg pain. Some effects of gabapentinoids encourage their nonmedical use (e.g. euphoria, sedation, disinhibition). Widespread nonmedical use has increased the incidence of accidental and deliberate poisonings. Dependence may develop with chronic use of gabapentinoids and abrupt cessation may induce withdrawal symptoms. If the indication for continued use is unclear, gradual dose tapering as a means of deprescribing is recommended. Clinicians should consider the indication, patient characteristics and harm-benefit profile when prescribing gabapentinoids. Some people, such as those with kidney disease, have an increased risk of harm when using these drugs.

Validation of vaginal microbiome proxies for in vitro experiments that biomimic Lactobacillus-dominant vaginal cultures

The vaginal microbiome includes diverse microbiota dominated by Lactobacillus [L.] spp. that protect against infections, modulate inflammation, and regulate vaginal homeostasis. Because it is challenging to incorporate vaginal microbiota into in vitro models, including organ-on-a-chip systems, we assessed microbial metabolites as reliable proxies in addition to traditional vaginal epithelial cultures (VECs). Human immortalized VECs cultured on transwells with an air-liquid interface generated stratified cell layers colonized by transplanted healthy microbiomes (L. jensenii- or L. crispatus-dominant) or a community representing bacterial vaginosis (BV). After 48-h, a qPCR array confirmed the expected donor community profiles. Pooled apical and basal supernatants were subjected to metabolomic analysis (untargeted mass spectrometry) followed by ingenuity pathways analysis (IPA). To determine the bacterial metabolites' ability to recreate the vaginal microenvironment in vitro, pooled bacteria-free metabolites were added to traditional VEC cultures. Cell morphology, viability, and cytokine production were assessed. IPA analysis of metabolites from colonized samples contained fatty acids, nucleic acids, and sugar acids that were associated with signaling networks that contribute to secondary metabolism, anti-fungal, and anti-inflammatory functions indicative of a healthy vaginal microbiome compared to sterile VEC transwell metabolites. Pooled metabolites did not affect cell morphology or induce cell death (∼5.5%) of VEC cultures (n = 3) after 72-h. However, metabolites created an anti-inflammatory milieu by increasing IL-10 production (p = .06, T-test) and significantly suppressing pro-inflammatory IL-6 (p = .0001), IL-8 (p = .009), and TNFα (p = .0007) compared to naïve VEC cultures. BV VEC conditioned-medium did not affect cell morphology nor viability; however, it induced a pro-inflammatory environment by elevating levels of IL-6 (p = .023), IL-8 (p = .031), and TNFα (p = .021) when compared to L.-dominate microbiome-conditioned medium. VEC transwells provide a suitable ex vivo system to support the production of bacterial metabolites consistent with the vaginal milieu allowing subsequent in vitro studies with enhanced accuracy and utility.

Delirium following pregabalin discontinuation in an individual with no psychiatric or substance use history

We report about a man in his mid-50s who was prescribed pregabalin (150 mg/day) for neuropathic pain due to a herniated intervertebral disc. Four weeks later, he presented to the emergency room with symptoms consistent with delirium. After ruling out acute intoxication with a substance and neurological causes, collateral information from the family and review of his medical chart indicated potential discontinuation syndrome owing to pregabalin. Following the successful treatment and resolution of delirium, the patient revealed he had been consistently consuming pregabalin doses upwards of 2 g/day over the past 2 weeks, leading to the premature exhaustion of his prescription and an abrupt cessation. The case findings underscore the necessity for physicians to recognise the potential for pregabalin misuse and the associated withdrawal risks, including delirium.

Comparison of the Severity of Zoster-Associated Pain and Incidence of Postherpetic Neuralgia in Patients with and without Pre-Existing Spinal Disorders at the Same Spinal Nerve Level: A Retrospective Multicenter Study

The incidences of herpes zoster (HZ) and postherpetic neuralgia (PHN) are significantly influenced by age. As individuals age, the occurrence of spinal disorders increases, thereby raising the likelihood of HZ and PHN coexistence. Considering this, our study aimed to explore the potential impact of pre-existing spinal disorders at the nerve level where HZ developed, on the severity of zoster-associated pain (ZAP) and the incidence of PHN. For our investigation, we retrospectively analyzed a total of 237 patients who presented with HZ and ZAP at various sensory levels (cervical, thoracic, lumbar, and sacral) with or without pre-existing spinal disorders. The presence or absence of spinal disorders at the sensory level affected by HZ was determined using computed tomography or magnetic resonance imaging. Our study results revealed that the group with spinal disorders at the sensory level where HZ developed did not exhibit an increased incidence of PHN. However, 3-6 months after HZ onset, this same group showed significantly higher ZAP scores compared to the group without spinal disorders. It implies a need for heightened pain management, as the coexistence of these conditions can increase pain severity. This study furnishes an initial standpoint to delve into intricate interactions between two diseases.

Effectiveness and Adverse Events of Gabapentinoids as Analgesics for Patients with Burn Injuries: A Systematic Review with Meta-Analysis and Trial Sequential Analysis

(1) Background: Pain after a burn injury is difficult to endure, and emerging studies aim to ascertain the effects of gabapentin and pregabalin as non-opioid treatment options. (2) Methods: We searched for randomised controlled trials (RCTs) in six databases. The risk of bias was assessed using the RoB 2.0 tool. We performed meta-analysis and trial sequential analysis and used the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology for judging the certainty of evidence (CoE). (3) Results: Five RCTs were included. Compared with placebo, gabapentinoids significantly decreased the pain intensity within 24 h (mean difference (MD) = -1.06, 95% confidence interval (CI): -1.47--0.65) and from 72 h to 9 days (MD = -0.82, 95% CI: -1.16--0.48), but not after 3 weeks (MD = -0.44, 95% CI: -1.31-0.42). Opioid consumption (mg/day) was reduced within 24 h (MD = -13.34, 95% CI: -22.16--4.52) and from 72 h to 9 days (MD = -7.87, 95% CI: -14.82--0.91). Increased risks of drowsiness (risk ratio (RR) = 3.255, 95% CI: 1.135-9.335) and dizziness (RR = 3.034, 95% CI: 1.006-9.147) were observed, but sensitivity analysis using the Bayesian method showed no increased risk. All endpoints were judged as low to very low CoE. (4) Conclusions: Gabapentinoids offer modest analgesic benefits as a component of multimodal pain management for burn injuries of less than 3 weeks. The adverse effects should be carefully monitored. Large-scale RCTs are warranted for the reinforcement of CoE in clinical use.

Multimodal Analgesia and Intraoperative Neuromonitoring

Intraoperative neuromonitoring has been a valuable tool for ensuring the functional integrity of vital neural structures by providing real-time feedback to the operative team during procedures where neurological structures are at risk. Commonly used intravenous and inhaled anesthetic drugs are known to affect waveform parameters measured with various intraoperative neuromonitoring modalities. While the concept of opioid-sparing multimodal analgesia has gained popularity in recent years, the impact of such a strategy on intraoperative neuromonitoring remains poorly characterized, in contrast to the more well-established concepts and literature regarding the effects of other hypnotic agents on neuromonitoring quality. The purpose of this focused review is to provide an overview of the clinical evidence pertaining to the pharmacological interaction of certain multimodal analgesics with routine intraoperative neuromonitoring modalities.

Efficacy and Safety of Gabapentin on Postoperative Pain Management After Bariatric Surgery: A Systematic Review and Meta-Analysis

PURPOSE

Examine the efficacy and safety of perioperative gabapentin in bariatric surgical patients.

DESIGN

Systematic Review and Meta-analysis.

METHODS

An exhaustive search was conducted using PubMed, Cochrane Library, MEDLINE, CINAHL, Google Scholar, and other gray literature. Only randomized controlled trials evaluating the use of gabapentin in bariatric surgery were included. Risk ratio (RR) and mean difference (MD) were used to estimate outcomes with suitable effect models. Quality of evidence was assessed using the Risk of Bias and GRADE system.

FINDINGS

Four trials consisting of 283 patients were analyzed. The use of gabapentin significantly lowered the cumulative pain score in the first 24 hours after surgery by an average of 1.04 (MD, -1.04; 95% CI, -1.45 to -0.63; P < .00001). Gabapentin also reduced the overall morphine equivalent consumption by 7.89 mg (MD, -7.89; 95% CI, -13.56 to -2.2; P = .006). However, gabapentin did not affect the incidence of PONV (RR, 0.61; 95% CI, 0.38-1.00; P = .05), somnolence (RR, 1.25; 95% CI, 0.57-2.73; P = .57), dizziness (RR, 1.01; 95% CI, 0.40-2.54; P = .99), and headache (RR, 0.76; 95% CI, 0.25-2.30; P = .62). Substantial heterogeneity, imprecision of the effect size, and potential publication bias were limitations of this review.

CONCLUSIONS

The use of gabapentin is effective in the management of postoperative pain in bariatric surgery. However, there is limited data regarding the opioid-sparing effect and adverse effect profiles of gabapentin in the bariatric surgical population.

Restless Legs Syndrome in Chronic Kidney Disease- a Systematic Review

Objectives

The objective of this review is to provide updated information on the epidemiology, correlating factors and treatment of chronic kidney disease associated restless legs syndrome (CKD-A-RLS) in both adult and pediatric population.

Materials and Methods

We have reviewed the Medline search and Google Scholar search up to May 2022, using key words restless legs syndrome, chronic kidney disease and hemodialysis and kidney transplant. The reviewed articles were studied for epidemiology, correlating factors, as well as pharmacologic and non-pharmacologic treatment options.

Results

Our search revealed 175 articles, 111 were clinical trials or cross- sectional studies and 64 were review articles. All 111 articles were retrieved and studied in detail. Of these, 105 focused on adults and 6 on children. A majority of studies on dialysis patients reported a prevalence between 15-30%, which is notably higher than prevalence of RLS in general population (5-10%). The correlation between presence of CKD-A-RLS with age, gender, abnormalities of hemogram, iron, ferritin, serum lipids, electrolytes and parathyroid hormones were also reviewed. The results were inconsistent and controversial. Limited studies have reported on the treatment of CKD-A-RLS. Non-pharmacological treatment focused on the effect(s) of exercise, acupuncture, massage with different oils and infra-red light whereas, pharmacologic treatment options include the effects of dopaminergic drugs, Alpha2-Delta ligands (gabapentin and pregabalin), vitamins E and C, and intravenous iron infusion.

Conclusion

This updated review showed that RLS is two to three times more common in patients with CKD compared to the general population. More patients with CKD-A-RLS demonstrated increased mortality, increased incidence of cardiovascular accident, depression, insomnia and impaired quality of life than those with CKD without RLS. Dopaminergic drugs such as levodopa, ropinirole, pramipexole and rotigotine as well as calcium channel blockers (gabapentin and pregabalin) are helpful for treatment of RLS. High quality studies with these agents are currently underway and hopefully confirm the efficacy and practicality of using these drugs in CKD-A-RLS. Some studies have shown that aerobic exercise and massage with lavender oil can improve symptoms of CKD-A- RLS suggesting that these measures can be useful as adjunct therapy.

Management of gabapentin misuse in a patient with previous history of opioid use disorder: Case report

We present a 37-year-old male who misuses 12 g of gabapentin per day associated with dependence and withdrawal. He had a previous history of opioid use disorder (OUD) which has been in remission. An outpatient gradual dose reduction regimen was tried and failed and the patient decided to discontinue gabapentin abruptly. Symptomatic medication to relieve gabapentin withdrawal was also unsuccessful and resulted in the reinstatement of OUD. Finally, the patient was stabilized using buprenorphine maintenance treatment and discontinued opioids and gabapentin misuse. The clinical implications and significance of taking regulatory actions to control gabapentin misuse have been discussed.

A Meta-Analysis Showing the Quantitative Evidence Base of Preemptive Pregabalin for Postoperative Pain from Cancer-Related Surgery

Background and Objectives: As an adjunct to postoperative multimodal analgesic regimens, pregabalin has been reported in reducing postoperative acute pain and opioid consumption. However, there is only a small amount of evidence for preemptive pregabalin in patients undergoing cancer-related surgery. This systematic review was conducted to integrate high-quality evidence to evaluate the preemptive analgesic effects of pregabalin in cancer-related surgery. Materials and Methods: Seven electronic databases were searched in a combination of subject terms and free words. Efficacy and safety of preemptive pregabalin on postoperative pain for cancer-related surgery were evaluated by assessing resting and dynamic pain scores postoperatively, cumulative morphine equivalent consumption, time to first analgesic request, hemodynamic parameters, and the safety indicators. Results: Thirteen trials were incorporated for quantitative synthesis. The pooled results showed administration of pregabalin preoperatively is clinically significant for improving resting (weighted mean difference (WMD), -1.53 cm; 95% CI, -2.30 to -0.77) and dynamic (WMD, -1.16 cm; 95% CI, -2.22 to -0.11) pain severity scores at 2 h postoperatively and prolonging time to first analgesic request (WMD, 2.28 h; 95% CI, 0.79 to 3.77) in cancer-related surgery. Preemptive pregabalin was also statistically effective in some other pain indicators but would increase the risk of pregabalin-related side effects after surgery. Conclusions: Our findings do not support the administration of pregabalin in doses larger than 300 mg when put in cancer-related surgery. Taken together, more high-quality research particularly focused on the optimal dosages and timing of pregabalin in cancer-related surgery is needed in the future to establish stronger evidence for therapeutic effects.

Rise of Pregabalin Poisoning and Abuse Cases in Serbia: A Ten-Year Retrospective Study

Purpose

The aim of this study was to analyze data on gabapentinoid-related attendances to the National Poison Control Center of Serbia (NPCC), particularly abuse cases; to estimate its changes and to compare it with trends in national consumption rates of these drugs. We also aimed to analyze the main characteristics of the study population and to investigate the major clinical effects in poisoned patients.

Patients and Methods

This is a retrospective study of patients admitted to the NPCC for acute poisoning involving gabapentinoids from 1 May 2012 to 1 October 2022.

Results

There were 357 (95.5%) pregabalin-related and 17 (4.5%) gabapentin-related poisoning cases in 302 patients. Abuse of pregabalin was detected in 27.8% (84/302), while gabapentin abuse occurred in 0.7% (2/302) of all patients. A steady increase in rates of pregabalin poisoning and abuse cases strongly correlated with the increase in overall consumption of this drug, while there were no significant changes in rates of gabapentin consumption, poisoning and abuse rate during the study period. Most patients who abused pregabalin pregabalin were males (84.5%) and the median age was 26 years (range: 15-45 years). Almost 60% of patients who abused pregabalin (48/84) belonged to the migrant population. Co-ingestions occurred in 89.4% of pregabalin-related cases (319/357), resulting in more severe poisoning. The most often co-ingested drugs were benzodiazepines and among them clonazepam was detected in the largest number of cases.

Conclusion

The poisoning and abuse cases involving pregabalin are on the rise in Serbia, which coincided with an increase in its overall consumption during the study period. Isolated pregabalin ingestions resulted in mild poisoning, although severe symptoms such as coma and bradycardia were recorded. When prescribing pregabalin to patients at risk of abuse caution is needed. Strengthening the measures for dispensing of pregabalin may reduce the risks associated with its abuse.

Association between road traffic accidents and drugs belonging to the antiseizure medications class: A pharmacovigilance analysis in VigiBase

AIMS

Due to their central mechanism of action, antiseizure medications (ASMs) could lead to adverse effects likely to impair driving skills. Their extended use to neuropsychiatric disorders makes it a class of drugs to monitor for their road traffic accidental (RTA) potential. We aimed to assess the reporting association between ASMs and RTAs using the World Health Organization pharmacovigilance database (VigiBase).

METHODS

We performed a disproportionality analysis to compute adjusted reporting odds ratios to evaluate the strength of reporting association between ASMs and RTAs. A univariate analysis using the reporting odds-ratio was used to assess drug-drug interactions between ASMs and RTAs.

RESULTS

There were 1 341 509 reports associated with at least 1 ASM in VigiBase of whom 2.91‰ were RTAs reports. Eight ASMs were associated with higher reporting of RTAs compared to others (ranging from 1.35 [95% confidence interval 1.11-1.64] for lamotrigine to 4.36 [95% confidence interval 3.56-5.32] for cannabis). Eight significant drug-drug interactions were found between ASMs and the onset of RTA, mainly involving CYP450 induction.

CONCLUSION

A significant safety signal between RTAs and some ASMs was identified. Association of several ASMs might further increase the occurrence of RTA. ASMs prescription in patients with identified risk factors of RTA should be considered with caution. Study number: ClinicalTrials.gov, NCT04480996.

Antiseizure Medications for the Prophylaxis of Migraine during the Anti- CGRP Drugs Era

Migraine and epilepsy are fundamentally distinct disorders that can frequently coexist in the same patient. These two conditions significantly differ in diagnosis and therapy but share some widely- used preventive treatments. Antiseizure medications (ASMs) are the mainstay of therapy for epilepsy, and about thirty different ASMs are available to date. ASMs are widely prescribed for other neurological and non-neurological conditions, including migraine. However, only topiramate and valproic acid/valproate currently have an indication for migraine prophylaxis supported by high-quality evidence. Although without specifically approved indications and with a low level of evidence or recommendation, several other ASMs are used for migraine prophylaxis. Understanding ASM antimigraine mechanisms, including their ability to affect the pro-migraine calcitonin gene-related peptide (CGRP) signaling pathway and other pathways, may be instrumental in identifying the specific targets of their antimigraine efficacy and may increase awareness of the neurobiological differences between epilepsy and migraine. Several new ASMs are under clinical testing or have been approved for epilepsy in recent years, providing novel potential drugs for migraine prevention to enrich the treatment armamentarium and drugs that inhibit the CGRP pathway.

The risk of fragility fractures following initiation of gabapentin and pregabalin-A Danish, nationwide, high-dimensional propensity score-matched cohort study

Gabapentin and pregabalin have been associated with an increased risk of fragility fractures. Due to differences in pharmacokinetics, we aimed to assess the fracture-risk difference between the two medicines. We performed a Danish nationwide new user, high-dimensional propensity score-matched cohort study to assess the 90-day risk of fragility fractures among adults, from January 1996 to December 2018. We applied a high-dimensional propensity score to match new users of gabapentin with new users of pregabalin in a 1:1 intention-to-treat approach. Hazard ratios (HRs), incidence rates (IRs) and incidence rate difference (IRD) were obtained. We identified 388 236 eligible patients of which 294 223 and 98 869 initiated gabapentin and pregabalin, respectively. We included 48 272 matched pairs for further analysis. The mean age was 56 (IQR 44-69) years, and the average follow-up was approximately 11 500 person-years (PY). The IRs of fragility fractures were 23.7 (95%CI 21.0-26.7) and 23.2 (95%CI 20.5-26.2) per 1000 PY for gabapentin and pregabalin-exposed patients, respectively. This yielded an HR of 1.02 (95%CI 0.86-1.21) when using gabapentin as the intervention drug and pregabalin as the reference drug. The IRD was estimated to 0.5 PY (95%CI -3.5-4.5). In conclusion, short-term risk of fragility fractures among gabapentin initiators was not different compared to those initiating pregabalin.

Evaluation of children with severe neurological impairment admitted to hospital with pain and irritability

BACKGROUND

Pain is the most common symptom reported by caregivers of children with severe neurological impairment (SNI), a descriptive term for children with disorders affecting the neurological system across multiple domains. In SNI, cognition, communication, and motor skills are impaired and other organ systems are impacted. Pain is difficult to identify and treat in children with SNI because of communication impairment. When a clear cause of pain is not determined, the term "Pain and Irritability of Unknown Origin (PIUO)" is used to describe pain-like behaviours. This study explores the clinical care received by children with SNI admitted to hospital after presenting to the emergency department of a tertiary pediatric hospital with pain or irritability. Findings are compared to the approach suggested in the PIUO pathway, an integrated clinical pathway for identifying and treating underlying causes of pain and irritability in children with complex conditions and limited communication.

METHODS

Retrospective chart review of children (age 0 to 18 years inclusive) with diagnoses compatible with SNI presenting with pain, irritability, and/or unexplained crying that required hospitalization between January 1st, 2019 and December 31st, 2019. Descriptive statistics were used to analyze the clinical care received by children in whom a source of pain was identified or not. In children for whom no cause of pain was identified, investigations completed were compared to the PIUO pathway.

RESULTS

Eight hospital admissions of six unique children were included for data analysis. A cause for pain and irritability was identified and resolved in three patients. In children with PIUO, there were gaps in history taking, physical examination, and investigations that might have allowed a cause of pain and irritability to be found. Pain was assessed using the r-FLACC pain scale and varying medications for pain/irritability were given during each hospital admission.

CONCLUSION

Children with SNI admitted to a tertiary pediatric hospital did not undergo a standardized approach to identifying a cause of pain and irritability. Future efforts should explore the effectiveness of the PIUO pathway, a standardized approach to reducing and resolving pain in children with SNI.

Subunit-dependent interaction of propoxazepam and its metabolite with the -aminobuturic acid type A receptor

Benzodiazepines (BDZ) are widely used in clinics in the treatment of psychiatric disorders, and their main action is considered to be determined by more selective binding with α1, α2, α3 or α5 subunits of GABA receptor. The aim of this work was studying of the molecular mechanism of action of new analgesic – propoxazepam and its metabolite (3-hydroxypropoxazepam) on α1, α2, α3, α4 or α5 subunits containing GABAA channels. Materials and methods GABA ha1b3g2, ha2b3g2, ha3b3g2, ha4b3g2 and ha5b3g2 ionotropic GABAARs expressed in HEK293 were used on the automated SP384PE Patch Clamp system. In addition, Propoxazepam, 3-hydroxypropoxazepam, diazepam (positive allosteric modulator) and GABA (positive control) were administered at concentrations 0.001–300 nM to determine the EC50 and Emax for corresponding substances. Results The α subunit plays a significantl role in determining the receptor’s affinity for propoxazepam and 3-hydroxypropoxazepam. The rank order of decreasing EC50 are α1 = α5> α2 > α3 > α4 (propoxazepam) and α1> α2> α5 > α3 > α4 (3-hydroxypropoxazepam), and for Emax α3 > α2 >α5 > α1 > α4 (propoxazepam), α3 > α1 > α2> α5 > α4 (3-hydroxypropoxazepam). The data, transformed to Emax/EC50, show that propoxazepam exhibits tenfold (compared to diazepam) activity (taking into account the magnitude of the maximum effect) to the α3 subunit, which distinguishes it from 3-hydroxypropoxazepam. Conclusion Due to the determined selectivity of propoxazepam for binding with different α subunit-containing GABAA-receptors (mostly α3 and α2 types), it has the potential to provide analgesia with less sedation than non-selective BDZ.

The Effects of Gabapentin on Post-Operative Pain and Anxiety, Morphine Consumption and Patient Satisfaction in Paediatric Patients Following the Ravitch Procedure-A Randomised, Double-Blind, Placebo-Controlled, Phase 4 Trial

The aim of the study was to investigate whether the use of pre- and postoperative gabapentin can decrease postoperative pain, morphine consumption, anxiety and side effects, as well as improve patient satisfaction. A total of 56 patients, 9−17 years of age, undergoing a modified Ravitch procedure, were randomised (allocation ratio 1:1) to receive multiple perioperative doses of gabapentin (preoperatively 15 mg/kg, postoperatively 7.5 mg/kg, two times per day for three days) or a placebo. All the patients received intravenous infusion of morphine, paracetamol and non-steroidal anti-inflammatory drugs. Metamizole was given as a “rescue drug”. The observation period included the day of surgery and three postoperative days. The primary outcomes were postoperative pain intensity (at rest, during deep breathing and coughing). Additional outcomes included the consumption of morphine, the total number of doses of metamizole, anxiety, postoperative side effects and patient satisfaction. Median average and maximal pain scores (on the day of surgery and on the second postoperative day) were significantly lower only in the gabapentin group at rest (p < 0.05). Compared to the placebo group, gabapentin treatment reduced the demand for morphine on the first postoperative day (median 0.016 vs. 0.019 mg/kg/h; p = 0.03) and the total number of metamizole doses (median 1 vs. 2 p = 0.04). Patient satisfaction was significantly greater in the gabapentin group (median 10 vs. 9; p = 0.018). Anxiety and postoperative side effects were similar in both groups (p > 0.05). Pre- and postoperative gabapentin administration as part of a multimodal analgesic regimen may decrease postoperative pain, opioid consumption and demand for a “rescue drug”, as well as improve patient satisfaction.

Current Review of Traumatic Optic Neuropathy and Traumatic Brain Injury among Military Service Members

Traumatic optic neuropathy (TON) is a form of optic nerve damage that while rare in the general population, is commonly associated with traumatic brain injury (TBI). With increasingly high rates of TBI in the military community, our service members and veterans represent a population where traumatic optic neuropathy is prevalent. Parachute jumpers have been identified as a high-risk group for under-reported head injury and therefore many cases of TBI are easily overlooked. With recent insights into the limitations of the veteran's disability exam, we review the current understanding of TON and propose an updated protocol for TON evaluation. We also urge for development of safer helmet design to reduce and prevent further cases of TBI, mTBI, and TON in our military personnel.

Pharmacotherapy for Spine-Related Pain in Older Adults

As the population ages, spine-related pain is increasingly common in older adults. While medications play an important role in pain management, their use has limitations in geriatric patients due to reduced liver and renal function, comorbid medical problems, and polypharmacy. This review will assess the evidence basis for medications used for spine-related pain in older adults, with a focus on drug metabolism and adverse drug reactions. A PubMed/OVID search crossing common spine, neck, and back pain terms with key words for older adults and geriatrics was combined with common drug classes and common drug names and limited to clinical trials and age over 65 years. The results were then reviewed with identification of commonly used drugs and drug categories: nonsteroidal anti-inflammatories (NSAIDs), acetaminophen, corticosteroids, gabapentin and pregabalin, antispastic and antispasmodic muscle relaxants, tricyclic antidepressants (TCAs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tramadol, and opioids. Collectively, 138 double-blind, placebo-controlled trials were the focus of the review. The review found a variable contribution of high-quality studies examining the efficacy of medications for spine pain primarily in the geriatric population. There was strong evidence for NSAID use with adjustments for gastrointestinal and renal risk factors. Gabapentin and pregabalin had mixed evidence for neuropathic pain. SNRIs had good evidence for neuropathic pain and a more favorable safety profile than TCAs. Tramadol had some evidence in older patients, but more so in persons aged < 65 years. Rational therapeutic choices based on geriatric spine pain diagnosis are helpful, such as NSAIDs and acetaminophen for arthritic and myofascial-based pain, gabapentinoids or duloxetine for neuropathic and radicular pain, antispastic agents for myofascial-based pain, and combination therapy for mixed etiologies. Tramadol can be well tolerated in older patients, but has risks of cognitive and classic opioid side effects. Otherwise, opioids are typically avoided in the treatment of spine-related pain in older adults due to their morbidity and mortality risk and are reserved for refractory severe pain. Whenever possible, beneficial geriatric spine pain pharmacotherapy should employ the lowest therapeutic doses with consideration of polypharmacy, potentially decreased renal and hepatic metabolism, and co-morbid medical disorders.

Curcumin and metformin synergistically modulate peripheral and central immune mechanisms of pain

Metformin is a well-tolerated antidiabetic drug and has recently been repurposed for numerous diseases, including pain. However, a higher dose of metformin is required for effective analgesia, which can potentiate its dose-dependent gastrointestinal side effects. Curcumin is a natural polyphenol and has beneficial therapeutic effects on pain. Curcumin has been used as an analgesic adjuvant with several analgesic drugs, allowing synergistic antinociceptive effects. Nevertheless, whether curcumin can exert synergistic analgesia with metformin is still unknown. In the present study, the nature of curcumin-metformin anti-inflammatory interaction was evaluated in in vitro using lipopolysaccharide-induced RAW 264.7 macrophage and BV-2 microglia cells. In both macrophage and microglia, curcumin effectively potentiates the anti-inflammatory effects of metformin, indicating potential synergistic effects in both peripheral and central pathways of pain. The nature of the interaction between curcumin and metformin was further recapitulated using a mouse model of formalin-induced pain. Coadministration of curcumin and metformin at a 1:1 fixed ratio of their ED₅₀ doses significantly reduced the dose required to produce a 50% effect compared to the theoretically required dose in phase II of the formalin test with a combination index value of 0.24. Besides, the synergistic interaction does not appear to involve severe CNS side effects indicated by no motor alterations, no alterations in short-term and long-term locomotive behaviors, and the general well-being of mice. Our findings suggest that curcumin exerts synergistic anti-inflammation with metformin with no potential CNS adverse effects.

Analgesic Efficacy of Gabapentin and Pregabalin in Patients Undergoing Laparoscopic Bariatric Surgeries: a Systematic Review and Meta-analysis

This meta-analysis investigated the effect of oral gabapentinoids (i.e., pregabalin and gabapentin) on analgesic consumption (i.e., primary outcome) and pain relief (i.e., secondary outcome) in patients following bariatric surgery. Analysis of five eligible trials published between 2010 and 2019 including 363 participants receiving gabapentinoids revealed a significantly lower morphine consumption [mean difference (MD) =  - 15.1 mg, p = 0.004; evidence certainty: low] and risk of nausea/vomiting [risk ratio (RR) = 0.49, p = 0.002; evidence certainty: high] at postoperative 6-24 h. There was also a lower pain score at postoperative 0-4 h (MD =  - 1.41, p < 0.00001; evidence certainty: low) and 6-12 h (MD =  - 0.9, p = 0.007; evidence certainty: low) compared with controls, while pain severity at postoperative 24 h was comparable between two groups. In summary, preoperative oral gabapentinoids optimized postoperative pain outcomes and reduced risk of nausea/vomiting following bariatric surgery.

Gabapentinoid-induced peripheral edema and acute heart failure: A translational study combining pharmacovigilance data and in vitro animal experiments

INTRODUCTION

Gabapentinoids are ligands of the α2-δ subunit of voltage-gated calcium channels (Cav) that have been associated with a risk of peripheral edema and acute heart failure in connection with a potentially dual mechanism, vascular and cardiac.

OBJECTIVES & METHODS

All cases of peripheral edema or heart failure involving gabapentin or pregabalin reported to the French Pharmacovigilance Centers between January 1, 1994 and April 30, 2020 were included to describe their onset patterns (e.g., time to onset). Based on these data, we investigated the impact of gabapentinoids on the myogenic tone of rat third-order mesenteric arteries and on the electrophysiological properties of rat ventricular cardiomyocytes.

RESULTS

A total of 58 reports were included (gabapentin n = 5, pregabalin n = 53). The female-to-male ratio was 4:1 and the median age was 77 years (IQR 57-85, range 32-95). The median time to onset were 23 days (IQR 10-54) and 17 days (IQR 3-30) for non-cardiogenic edema and acute heart failure, respectively. Cardiogenic and non-cardiogenic peripheral edema occurred frequently after a dose escalation (27/45, 60%), and the course was rapidly favorable after discontinuation of gabapentinoid (median 7 days, IQR 5-13). On rat mesenteric arteries, gabapentinoids significantly decreased the myogenic tone to the same extent as verapamil and nifedipine. Acute application of gabapentinoids had no significant effect on Ca_v1.2 currents of ventricular cardiomyocytes.

CONCLUSION

Gabapentinoids can cause concentration-dependent peripheral edema of early onset. The primary mechanism of non-cardiogenic peripheral edema is vasodilatory edema secondary to altered myogenic tone, independent of Ca_v1.2 blockade under the experimental conditions tested.

Systematic Review of Voltage-Gated Calcium Channel α2δ Subunit Ligands for the Treatment of Chronic Neuropathic Pain and Insight into Structure-Activity Relationship (SAR) by Pharmacophore Modeling

BACKGROUND

Neuropathic pain (NP) is a complex symptom related to the nerve damage. The discovery of new drugs for treating chronic NP has been continuing for several decades, while more progress is still needed to be made because of the unsatisfactory efficacy and the side effects of the currently available drugs. Among all the approved drugs for chronic NP, voltage-gated calcium channel (VGCC) α2δ subunit ligands, also known as gabapentinoids, are among the first-line treatment and represent a class of efficacious and relatively safe therapeutic agents. However, new strategies are still needed to be explored due to the unsatisfied response rate.

OBJECTIVES

To review the latest status of the discovery and development of gabapentinoids for the treatment of chronic NP by covering both the marketed and the preclinical/clinical ones. To analyze the structure-activity relationship (SAR) of gabapentinoids to facilitate the future design of structurally novel therapeutic agents targeting VGCC α2δ subunit.

METHODS

We searched PubMed Central, Embase, Cochrane Library, Web of Science, Scopus and Espacenet for the literature and patents of diabetic peripheral neuropathic pain, postherpetic neuralgia, fibromyalgia, voltage-gated calcium channel α2δ subunit and related therapeutic agents from incipient to June 10, 2021. The SAR of gabapentinoids were analyzed by pharmacophore modeling using Phase module in Schrödinger suite.

RESULTS

A variety of gabapentinoids were identified as VGCC α2δ ligands that have ever been under development for the treatment of chronic NP. Among them, four gabapentinoids are marketed, one is at the active late clinical trials, and eight have been discontinued. Pharmacophore models were generated by using Phase module in Schrödinger suite, and common pharmacophores were predicted based on pharmacophoric features and analyzed.

CONCLUSION

The latest progress of the discovery and development of gabapentinoids for the treatment of chronic NP was reviewed. Moreover, the structure-activity relationship (SAR) of gabapentinoids is analyzed by pharmacophore modeling, which will be valuable for the future design of structurally novel therapeutic agents targeting VGCC α2δ subunit.

A single injection of pregabalin induces short- and long-term beneficial effects on fear memory and anxiety-like behavior in rats with experimental type-1 diabetes mellitus

Anxiety Disorders and Posttraumatic Stress Disorders (PTSD) associated with type-1 diabetes mellitus (T1DM) are increasingly common comorbidities and the treatment is quite challenging. In that sense, evidence indicates that the anticonvulsant pregabalin is highly effective in treating severe cases of anxiety, as well as PTSD and diabetic neuropathic pain which is also very prevalent in T1DM. Herein, the short- and long-term effects of a single injection of pregabalin on the acquisition of a fear extinction memory and parameters of anxiety in induced-T1DM animals were investigated. For that, we used the contextual fear conditioning (CFC) and elevated plus maze paradigms, respectively. A putative antioxidant activity was also evaluated. Our findings demonstrated that induced-T1DM animals presented greater expression of fear memory, difficulty in extinguishing this fear memory, associated with a more pronounced anxiety-like response. Pregabalin was able to induce a short and long-lasting effect by facilitating the acquisition of the fear extinction memory and inducing a later anxiolytic-like effect. Also, the increased lipid peroxidation levels in the hippocampus and prefrontal cortex of induced-T1DM rats were reduced after pregabalin injection, while the decreased levels of reduced glutathione were increased in the hippocampus. Despite the need for more studies to understand the mechanism of action of pregabalin under these conditions, our data demonstrate for the first time that a single injection of pregabalin in a specific time window was able to improve behavioral parameters in addition to inducing neuroprotective effect. Thus, pregabalin has potential worth exploring for the treatment of PTSD and/or Anxiety associated with T1DM.

Moving Toward a Multimodal Analgesic Regimen for Acute Sickle Cell Pain with Non-Opioid Analgesic Adjuncts: A Narrative Review

Purpose of Review

Sickle cell disease (SCD) is an inherited hemoglobinopathy with potential life-threatening complications that affect millions of people worldwide. Severe and disabling acute pain, referred to as a vaso-occlusive crisis (VOC), is a fundamental symptom of the disease and the primary driver for acute care visits and hospitalizations. Despite the publication of guidelines for VOC management over the past decade, management of VOCs remains unsatisfactory for patients and providers.

Recent Findings

Acute SCD pain includes pain secondary to VOCs and other forms of acute pain. Distinguishing VOC from non-VOC pain may be challenging for both patients and clinicians. Further, although opioids have been the gold-standard for VOC pain management for decades, the current highest standard of care for all acute pain is a multimodal approach that is less dependent on opioids, and, instead incorporates analgesics and adjuvants from different mechanistic pathways. In this narrative review, we focus on a multimodal pharmacologic approach for acute SCD pain management and explore the evidence for existing non-opioid pharmacological adjuncts. Moreover, we present an explanatory model of pain, which is not only novel in its application to SCD pain but also captures the multidimensional nature of the SCD pain experience and supports the need for such a multimodal approach. This model also highlights opportunities for new investigative and therapeutic targets - both pharmacological and non-pharmacological.

Summary

Multimodal pain regimens that are less dependent on opioids are urgently needed to improve acute pain outcomes for individuals with SCD. The proposed explanatory model for SCD pain offers novel opportunities to improve acute pain management for SCD patients.

Effects of Gabapentin Enacarbil on Postoperative Pain After Hip and Knee Arthroplasty: A Placebo-controlled Randomized Trial

OBJECTIVES

Total joint arthroplasties are among the most common elective procedures performed in the United States, and they are associated with postoperative pain. Gabapentin enacarbil is a prodrug with an extended-release formulation that has been proposed for multimodal postoperative analgesia, but the drug's efficacy for major arthroplasties remains unclear.

MATERIALS AND METHODS

We enrolled 60 adult patients scheduled for primary knee or hip arthroplasty expected to remain hospitalized for at least 3 days. Eligible patients were randomly assigned to placebo or gabapentin enacarbil 600 mg twice daily starting the day before surgery continuing for 3 days thereafter.The primary outcome was analyzed using a joint hypothesis framework of pain (0 to 10 verbal response scores) and cumulative opioid consumption (mg of morphine equivalent) within the first 72 hours. Secondary outcomes were nausea and vomiting, pain persisting 90 days after surgery, duration of hospitalization, and early postoperative health status using quality of recovery score (QoR-15).

RESULTS

Twenty-eight patient in gabapentin enacarbil group and 32 in placebo group were analyzed. Since pain scores did not differ significantly (difference of means: -0.2 in pain scores; 95% confidence interval: -1.1, 0.7), nor did opioid consumption, conditions for joint hypothesis testing were not met. Moreover, there were no significant differences between groups for secondary outcomes.

DISCUSSION

We did not identify statistically significant or clinically meaningful differences in our primary and secondary outcomes related to perioperative use of gabapentin enacarbil in patients having primary hip or knee arthroplasties.

Preoperative preparation and premedication of bariatric surgical patient

The prevalence of obesity has tripled worldwide over the past four decades. The United States has the highest rates of obesity, with 88% of the population being overweight and 36% obese. The UK has the sixth highest prevalence of obesity. The problem of obesity is not isolated to the developed world and has increasingly become an issue in the developing world as well. Obesity carries an increased risk of many serious diseases and health conditions, including type 2 diabetes, heart disease, stroke, sleep apnea, and certain cancers. Our ability to take care of this population safely throughout the perioperative period begins with a thorough and in-depth preoperative assessment and meticulous preparation. The preoperative assessment begins with being able to identify patients who suffer from obesity by using diagnostic criteria and, furthermore, being able to identify patients whose obesity is causing pathologic and physiologic changes. A detailed and thorough anesthesia assessment should be performed, and the anesthesia plan individualized and tailored to the specific patient's risk factors and comorbidities. The important components of the preoperative anesthesia assessment and patient preparation in the patient suffering from obesity include history and physical examination, airway assessment, medical comorbidities evaluation, functional status determination, risk assessment, preoperative testing, current weight loss medication, and review of any prior weight loss surgeries and their implications on the upcoming anesthetic. The preoperative evaluation of this population should occur with sufficient time before the planned operation to allow for modifications of the preoperative management without needing to delay surgery as the perioperative management of patients suffering from obesity presents significant practical and organizational challenges.

Gabapentinoid Pharmacology in the Context of Emerging Misuse Liability

This article will review the epidemiology and pharmacology of gabapentinoids (gabapentin and pregabalin) relevant to their emerging misuse potential and provide guidance for clinical and regulatory management. Gabapentinoids are γ-aminobutyric acid analogues that produce their therapeutic effects by inhibiting voltage-gated calcium channels and decreasing neurotransmitter release. Recently gabapentinoid prescribing and use have increased tremendously. Although traditionally thought to possess a favorable safety profile, gabapentinoid misuse has also risen significantly. Gabapentinoid misuse generally occurs in combination with other substances, most notably opioids, and may be for purposes of eliciting euphoric effects, enhancing the effects of other substances, or self-treating conditions such as withdrawal, pain, anxiety, or insomnia. Given its faster onset, increased bioavailability and potency, and nonsaturable absorption, pregabalin's pharmacokinetics theoretically enhance its misuse liability versus gabapentin. However, gabapentin can produce similar euphoric effects, and epidemiologic studies have identified higher rates of gabapentin misuse in the United States, likely because of greater availability and less regulated prescribing. Although adverse events of gabapentinoid-only ingestion are relatively benign, a growing body of evidence indicates that gabapentinoids significantly increase opioid-related morbidity and mortality when used concomitantly. In addition, significant withdrawal effects may occur on abrupt discontinuation. As a result of these trends, several US states have begun to further regulate gabapentinoid prescribing, reclassifying it as a controlled substance or mandating reporting to local prescription drug-monitoring programs. Although increased regulation of gabapentin prescribing may be warranted, harm reduction efforts and increased patient and provider education are necessary to mitigate this concerning gabapentinoid misuse trend.

Trends in Gabapentin and Pregabalin Prescribing in a Tertiary Pediatric Medical Center

OBJECTIVES

Analgesic medications are commonly prescribed in pediatrics, with prescribing practices frequently extrapolated from adult trials. Gabapentinoids (gabapentin and pregabalin) are widely used as analgesics but are labeled in pediatrics only for epilepsy. We aim to (1) define trends in pediatric gabapentinoid prescribing (label and off-label) over 7 years, and (2) evaluate use in chronic pain clinic (CPC) patients during 2018.

METHODS

Retrospective data from a tertiary-care pediatric hospital were collected between 2013 and 2019. Annual numbers of gabapentinoid prescriptions were stratified by prescriber specialty. Additional information about gabapentinoid prescribing in the CPC was manually collected from initial clinic notes in 2018.

RESULTS

There were 15 808 outpatient prescriptions for gabapentinoids among 5172 patients over 7 years. Of these, 93% were gabapentin and 7% were pregabalin. Numbers of patients receiving gabapentin and pregabalin prescriptions increased by 1.4- and 1.3-fold, respectively, between 2013 and 2019. Few prescriptions were done for patients with a previous epilepsy diagnosis (in 2019, 16% for gabapentin and 13% for pregabalin). Approximately 28% of 650 CPC new patients were prescribed gabapentin or pregabalin before referral. Among those, 44% had discontinued the medication because of adverse events (35%), inefficacy (46%), or both (5%). Most side effects reported were mild to moderate. Diagnoses at first visit were diverse, not limited to neuropathic pain conditions, and did not differ between patients receiving or not receiving gabapentinoid prescriptions.

CONCLUSIONS

In our hospital, gabapentinoids are commonly prescribed off-label for diverse indications, including chronic pain. Future research is needed to evaluate gabapentinoid efficacy in these indications.

Monitoring and Managing Lorlatinib Adverse Events in the Portuguese Clinical Setting: A Position Paper

Rearrangements in the anaplastic lymphoma kinase (ALK) and proto-oncogene tyrosine-protein kinase ROS (ROS1) genes characterise two distinct molecular subsets of non-small cell lung cancer (NSCLC) tumours. Lorlatinib is a third-generation ALK/ROS1 tyrosine kinase inhibitor (TKI) shown to have systemic and intracranial activity in treatment-naive patients and in those who progressed on first- and second-generation TKIs. Despite being generally well tolerated, lorlatinib has a unique and challenging safety profile that includes hyperlipidaemia and central and peripheral nervous system adverse events (AEs). This article summarises a set of strategies designed to monitor and manage lorlatinib-related AEs that were agreed upon by a multidisciplinary panel of specialists in a meeting held in July 2020. Among the recommendations hereby described, special emphasis was placed on communication: prescribing physicians should inform patients and their families/caregivers about the likelihood and nature of lorlatinib AEs, encouraging them to report any symptoms, while at the same time reassuring them that most events are manageable and resolve spontaneously and have little to no interference with cancer treatment. Importantly, all patients should undergo a set of baseline assessments, including biochemical analysis, evaluation of cardiovascular risk, electrocardiogram (ECG), neurological evaluation and contrast-enhanced magnetic resonance imaging of the brain, which should be repeated regularly during lorlatinib treatment. Supportive medications to treat or relieve lorlatinib AEs were also discussed, as were the conditions requiring specialist consultations and/or adjustments in lorlatinib therapy. The overall goal of this article is to serve as a practical guide for oncologists to systematically and effectively approach lorlatinib AEs.

Perioperative Pain Management and Opioid Stewardship: A Practical Guide

Surgical procedures are key drivers of pain development and opioid utilization globally. Various organizations have generated guidance on postoperative pain management, enhanced recovery strategies, multimodal analgesic and anesthetic techniques, and postoperative opioid prescribing. Still, comprehensive integration of these recommendations into standard practice at the institutional level remains elusive, and persistent postoperative pain and opioid use pose significant societal burdens. The multitude of guidance publications, many different healthcare providers involved in executing them, evolution of surgical technique, and complexities of perioperative care transitions all represent challenges to process improvement. This review seeks to summarize and integrate key recommendations into a "roadmap" for institutional adoption of perioperative analgesic and opioid optimization strategies. We present a brief review of applicable statistics and definitions as impetus for prioritizing both analgesia and opioid exposure in surgical quality improvement. We then review recommended modalities at each phase of perioperative care. We showcase the value of interprofessional collaboration in implementing and sustaining perioperative performance measures related to pain management and analgesic exposure, including those from the patient perspective. Surgery centers across the globe should adopt an integrated, collaborative approach to the twin goals of optimal pain management and opioid stewardship across the care continuum.