Alpha2delta ligands, gabapentin, pregabalin and mirogabalin: a review of their clinical pharmacology and therapeutic use

Risk of Fracture Associated with Pregabalin or Mirogabalin Use: A Case-Case-Time-Control Study Based on Japanese Health Insurance Claims Data

BACKGROUND

Pregabalin is widely used for neuropathic pain. Mirogabalin, a newer gabapentinoid, was recently introduced in several Asian countries. A previous case-crossover study showed an association between pregabalin and fall-related injuries, but the findings may have been affected by biases from individual- and population-level exposure time trends, and generalizability was limited due to a focus on a middle-aged population. Further, no findings have appeared on mirogabalin and its association with fall-related fractures.

OBJECTIVE

We conducted a case-case-time-control study to investigate the risk of fracture associated with pregabalin and mirogabalin in a population with broad demographic coverage.

METHODS

Incident fractures were identified from a Japanese claims database. For each case, hazard (days 1-30 before the fracture event) and control windows (days 61-90 before the event) were set. Each current case was matched by age and sex to a future case, defined as a patient who experienced a fracture 120-365 days later. Odds ratios (ORs) were estimated using conditional logistic regression models.

RESULTS

A total of 814,216 and 460,811 cases were included in the pregabalin and mirogabalin analyses, respectively. ORs were 1.35 (95% confidence interval 1.28-1.43) for pregabalin and 1.53 (1.35-1.72) for mirogabalin, indicating an increased risk of fracture with both drugs. These results remained consistent and robust across sensitivity and subgroup analyses, except in patients under 65 years of age.

CONCLUSION

Given this observed risk and the fact that these medications are commonly prescribed to older populations, caution is warranted in clinical use.

Co-treatment with Gabapentinoid and Japanese Herbal Medicine Goshajinkigan for CIPN is Associated with Longer Duration and Higher Dose of Chemotherapy

INTRODUCTION

In Japan, both gabapentinoids and the Japanese traditional herbal medicine goshajinkigan (GJG) are used to manage chemotherapy-induced peripheral neuropathy (CIPN); however, evidence for their effectiveness is inconclusive. Patients with CIPN experience reduced quality of life and often undergo reductions in dose or discontinuation of chemotherapy. Therefore, this retrospective cohort study used a real-world database to examine the efficacy of gabapentinoids and GJG therapy for patients with CIPN by evaluating chemotherapy duration and dose.

METHODS

Data from 145,384 patients diagnosed with CIPN while receiving platinum- or taxane-based chemotherapy between April 1, 2008 and March 31, 2022 were stratified by CIPN treatment: simultaneous gabapentinoid (mirogabalin or pregabalin) plus GJG (prescription dates overlap); non-simultaneous gabapentinoid plus GJG (prescription dates do not overlap); gabapentinoid alone; GJG alone; and neither gabapentinoids nor GJG. Duration and dose of chemotherapy were the primary outcomes.

RESULTS

Treatment with either a gabapentinoid or GJG alone was associated with longer duration and higher doses of chemotherapy versus neither gabapentinoids nor GJG in patients treated with carboplatin, cisplatin, or paclitaxel. Combined gabapentinoid plus GJG treatment elicited further longer duration and higher doses of chemotherapy versus gabapentinoid alone or GJG alone in patients treated with carboplatin, oxaliplatin, cisplatin, paclitaxel, or docetaxel. When stratified by cancer type, similar trends were observed regarding combination gabapentinoid plus GJG treatment among patients with colorectal cancer treated with oxaliplatin and patients with gastric, lung, or breast cancer treated with paclitaxel.

CONCLUSION

Combination treatment with gabapentinoid plus GJG might prevent reductions in dose or discontinuation of chemotherapy, and might be effective for the treatment of CIPN.

Preoperative History of Gabapentinoids Use is Associated with Longer Length of Hospital Stay in Patients Undergoing Lower Extremity Bypass Surgery for Severe Peripheral Artery Disease

BACKGROUND

This study aimed to assess the association of preoperative gabapentinoids (GBP) use with the postoperative length of stay for patients undergoing peripheral artery lower extremity bypass (LEB) surgery for lifestyle-limiting claudication and chronic limb-threatening ischemia at a tertiary care hospital.

METHODS

Patients undergoing LEB surgery during the period between 2000 and 2020 at Penn State Health Milton S. Hershey Medical Center were stratified into 2 groups based on the preoperative use of prescribed GBPs (GBPs versus no GBPs). Patients' preoperative characteristics, comorbidities and medications were assessed, and the outcomes of interest were analyzed in univariate analysis, stratified analysis, and by multivariable regression models. Primary outcomes were 30-day mortality and length of stay. The secondary outcomes included readmissions, unplanned return to the operating room, amputation, myocardial infarction, cerebrovascular accident, pneumonia, pulmonary embolism, urinary tract infections, wound complications, acute congestive heart failure exacerbation and nonhome discharge. A P value of <0.05 was considered significant for all the analyses.

RESULTS

The study cohort comprised 359 patients. The GBPs group comprised 125 patients with a mean (standard deviation) age of 61.6 (±10.2) years and the no-GBPs group consisted of 234 patients with a mean (standard deviation) age of 64.6 (±12.2) years. Patients in GBPs group were likely to be younger (P = 0.014), undergo LEB for chronic limb-threatening ischemia (P = 0.039), and have insulin-dependent diabetes mellitus (P < 0.001) than the no-GBPs group. In terms of outcomes, the patients in the GBPs group were more likely to have longer postoperative length of stay (9.3 ± 11.1 vs. 6.4 ± 5.0 days no GBPs, P = 0.008). In multivariable analysis, the patients in the GBPs group had 92% (adjusted odds ratio 1.92 [1.16, 3.18], P = 0.01) increase in the odds of having a length of stay above 6-day calculated median in comparison to the no-GBPs group.

CONCLUSION

This retrospective analysis of patients undergoing LEB at a tertiary care hospital shows a significant association between preoperative GBPs use and the longer postoperative length of stay. This study bridges a gap in the current body of knowledge regarding the association of GBP use with the postoperative outcomes in patients undergoing LEB for severe peripheral artery disease.

Discovery of (3-Phenylcarbamoyl-3,4-dihydro-2H-pyrrol-2-yl)phosphonates as Imidazoline I2 Receptor Ligands with Anti-Alzheimer and Analgesic Properties

Imidazoline I2 receptors (I2-IRs) are altered in Alzheimer's disease (AD) patients and are associated with analgesia. I2-IRs are not structurally described, and their pharmacological characterization relies on their modulation by highly affine ligands. Herein, we describe the synthesis of (3-phenylcarbamoyl-3,4-dihydro-2H-pyrrol-2-yl)phosphonates endowed with relevant affinities for I2-IRs in human brain tissues. The optimal ADME and pharmacokinetic profile of a selected compound, 12d, secured its in vivo exploration in a senescence accelerated prone 8 mice revealing improvement in the cognitive impairment and unveiling the mechanism of action by analyzing specific AD biomarkers. The treatment of a capsaicin-induced mechanical hypersensitivity murine model with 12d revealed analgesic properties devoid of motor coordination issues. The target engagement of 12d was demonstrated by suppression of the analgesic effect by pretreatment with idazoxan. Overall, 12d is a putative candidate for advancing preclinical phases and supports the modulation of I2-IRs as an innovative approach for therapeutics.

Geographic Atrophy in Age-Related Macular Degeneration

BACKGROUND

Age-related macular degeneration (AMD), a condition of multifactorial origin, is a major cause of irreversible vision loss in industrialized countries. The dry late stage of the disease, known as geographic atrophy (GA), is characterized by progressive loss of photoreceptor cells and retinal pigment epithelial cells in the central retina. An estimated 300 000 to 550 000 people in Germany suffer from GA.

METHODS

This review is based on pertinent literature retrieved by a selective search in the PubMed and Web of Science databases.

RESULTS

In 2023, the complement inhibitors pegcetacoplan and avacincaptad pegol were approved in the USA for repeated intravitreal injections and thereby became the first drugs ever approved for the treatment of GA. In Europe, the marketing authorization application for both drugs was withdrawn by the manufacturers after a negative judgment was expressed by the European Medicines Agency (EMA) Committee for Medicinal Products for Human Use. The EMA stated that the significant slowing of atrophy progression that had been achieved in the approval trials did not lead to any clinically relevant functional benefit for the patients. Further treatment approaches, including gene therapy, are now being studied in clinical trials. There is evidence that micronutrients may slow the progression of atrophy.

CONCLUSION

In Europe at present, there is no approved treatment for GA due to AMD. There is thus a continuing need for preventive and rehabilitative measures such as smoking cessation, a balanced diet, and magnifying visual aids for patients in the advanced stages of the disease.

Pregabalin vs. gabapentin in the treatment of neuropathic pain: a comprehensive systematic review and meta-analysis of effectiveness and safety

Introduction

Neuropathic pain is a prevalent and burdensome condition, and both pregabalin and gabapentin are widely used for its treatment. However, there is a lack of clarity regarding their comparative efficacy and safety. This meta-analysis aims to evaluate and compare the effectiveness and safety of pregabalin vs. gabapentin in managing neuropathic pain.

Methods

This study followed PRISMA guidelines and employed the PICOS search strategy. Comparative studies (clinical trials and cohort studies) were included, with patients with neuropathic pain treated either with pregabalin or gabapentin. Primary outcomes assessed were efficacy and safety. Data were extracted from PubMed, Embase, Scopus, and the Cochrane Collaboration Library databases. The risk of bias was evaluated using the Cochrane Review Manager tool. Statistical analysis was performed using Review Manager 5.4.1 software, calculating effect sizes and conducting sensitivity analysis based on medication dosage.

Results

A total of 14 studies with 3,346 patients were analyzed. Pregabalin showed superior results compared to gabapentin in the Visual Analog Scale (VAS) at various time intervals up to 12-14 weeks (SMD -0.47, 95% CI -0.74 to -0.19). The pregabalin group also had significant improvements in SF-12/SF-36/EQ-5D scores (SMD 0.39, 95% CI 0.11-0.68) and experienced more days with no/mild pain (MD 9.00, 95% CI 8.93-9.07) and fewer days with severe pain (MD -3.00, 95% CI -4.96 to -1.04). Pregabalin resulted in lower opioid consumption (OR 0.50, 95% CI 0.33-0.76). Gabapentin had a higher incidence of nausea and vomiting. Sensitivity analysis supported the efficacy of pregabalin.

Conclusion

In conclusion, pregabalin demonstrated superior and faster efficacy in alleviating neuropathic pain than gabapentin did. Additionally, it improved patient-reported outcomes, resulted in lower opioid consumption, and led to fewer adverse events.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=565208, PROSPERO (CRD42024565208).

A case series examining the efficacy of gabapentin as a substitution therapy for the treatment of pregabalin use disorder

Background: Gabapentinoids are ligands of a brain calcium channel, which are approved for different indications, including epilepsy, neuropathic pain, or generalized anxiety disorder. Among gabapentinoids, pregabalin has been increasingly associated with a risk of pregabalin use disorder (PUD). To date, there is no recommended medical treatment for PUD. However, gabapentin, which has a lower abuse potential, could be used as a substitution therapy to reduce pregabalin withdrawal and craving.Objectives: To report on the experimental use of high dose of gabapentin among those with PUD.Methods: Case series of four patients (3 males and 1 female) with severe PUD (average daily doses ranging from 1,200 to 8,400 mg of pregabalin), in whom high dose of gabapentin was prescribed as a substitution treatment.Results: Upon gabapentin being administered as substitution therapy for pregabalin, all four patients experienced intense craving and distress. Despite receiving high doses of gabapentin, due to the observed levels of craving and distress, all four patients had to be rapidly switched back to pregabalin.Conclusions: Preliminary clinical findings suggest that gabapentin is unlikely to be a suitable, lower-risk alternative treatment for people with PUD. Additional examination of candidate medications, including other gabapentinoids, could be useful to identify an effective treatment for PUD.

Community pharmacists' experience of gabapentin misuse and abuse: A quantitative study from Jordan

Gabapentin is an anticonvulsant that has an abuse potential. The aim of this study was to investigate the misuse and abuse of gabapentin in Jordan from the perspective of community pharmacists. A cross-sectional survey using a self-reported structured questionnaire was used with a convenience sample of pharmacists employed by various independent and chain community pharmacies. An online technique was used in this study using Google forms. A total of 215 questionnaires were completed, with 200 respondents (93%) reporting awareness of cases of gabapentin abuse in their pharmacies. Less than half of the respondents (n = 94; 43.7%) indicated that gabapentin requests were not accompanied by prescriptions. Almost two-thirds of respondents (63.6%) noticed an increased pattern of gabapentin abuse/misuse during the last 6 months. The study underscores the need for regulatory efforts and pharmacovigilance to manage potential gabapentin abuse, along with pharmacist and patient education at the community pharmacy, regarding potential abuse of gabapentin.

Malignant glioma remodeling of neuronal circuits: therapeutic opportunities and repurposing of antiepileptic drugs

Tumor-associated epilepsy is the most common presenting symptom in patients diagnosed with diffuse gliomas. Recent evidence illustrates the requirement of synaptic activity to drive glioma proliferation and invasion. Class 1, 2, and 3 evidence is limited regarding the use of antiepileptic drugs (AEDs) as antitumor therapy in combination with chemotherapy. Furthermore, no central mechanism has emerged as the most targetable. The optimal timing of AED regimen remains unknown. Targeting aberrant neuronal activity is a promising avenue for glioma treatment. Clinical biomarkers may aid in identifying patients most likely to benefit from AEDs. Quality evidence is needed to guide treatment decisions.

Efficacy and Safety of Crisugabalin (HSK16149) in Adults with Postherpetic Neuralgia: A Phase 3 Randomized Clinical Trial

Importance

China carries a heavy burden of postherpetic neuralgia, with an unmet need for novel drugs with greater efficacy and less prominent neurotoxic effects than existing calcium channel ligands.

Objective

To investigate the efficacy and safety of crisugabalin, an oral calcium channel α2δ-1 subunit ligand, for postherpetic neuralgia.

Design, Setting, and Participants

This randomized clinical trial, carried out between November 9, 2021, and January 5, 2023, at 48 tertiary care centers across China had 2 parts. Part 1 was a phase 3, multicenter, randomized, double-blind, placebo-controlled, parallel-group study consisting of a 2-week screening period, a 7-day run-in period, and a 12-week double-blind treatment period. Part 2 was a 14-week open-label extension study. Investigators, statisticians, trial clinicians, and patients were blinded to trial group assignments. Participants included adults with postherpetic neuralgia with an average daily pain score (ADPS) of at least 4 on the 11-point Numeric Pain Rating Scale over the preceding week, with the exclusion of patients with pain not controlled by prior therapy with pregabalin (≥300 mg/d) or gabapentin (≥1200 mg/d).

Interventions

Patients were randomized 1:1:1 to receive crisugabalin, 20 mg twice daily (ie, 40 mg/d), and crisugabalin, 40 mg twice daily (ie, 80 mg/d), or placebo for 12 weeks. Eligible patients received crisugabalin, 40 mg, twice daily during extension.

Main Outcome and Measure

The primary efficacy end point was the change from baseline in ADPS at week 12.

Results

The study enrolled 366 patients (121 patients receiving crisugabalin, 40 mg/d; 121 patients receiving crisugabalin, 80 mg/d; 124 patients receiving placebo; median [IQR] age, 63.0 [56.0-69.0] years; 193 men [52.7%]). At week 12, the least squares mean (SD) change from baseline in ADPS was -2.2 (0.2) for crisugabalin, 40 mg/d, and -2.6 (0.2) for crisugabalin, 80 mg/d, vs -1.1 (0.2) for placebo, with a least squares mean difference of -1.1 (95% CI, -1.6 to -0.7; P < .001) and -1.5 (-95% CI, -2.0 to -1.0; P < .001) vs placebo, respectively. No new safety concerns emerged.

Conclusions and Relevance

Crisugabalin, 40 mg/d, or crisugabalin, 80 mg/d, was well tolerated and demonstrated a statistically significant improvement in ADPS over placebo.

Trial Registration

ClinicalTrials.gov Identifier: NCT05140863.

Efficacy of gabapentin and pregabalin for treatment of post refractive surgery pain: a systematic review and meta-analysis

INTRODUCTION

For ophthalmic patients, eye discomfort is a major problem that requires efficient pain treatment techniques. Pregabalin and gabapentin have surfaced as viable treatments for post-refractive surgery pain. To manage pain after refractive surgery, gabapentin and pregabalin were evaluated in this systematic review and meta-analysis.

METHODOLOGY

A thorough search of databases including PubMed, Embase, Cochrane Library, and CINAHL was performed until March 2024. Inclusion criteria were randomized controlled trials assessing pregabalin and/or gabapentin's effectiveness in treating pain post-PRK, LASIK, and LASEK surgeries.

RESULTS

Six studies met inclusion criteria, comprising a total of 391 patients undergoing various corneal surgeries. The meta-analysis revealed that pregabalin was significantly more effective than placebo in reducing pain on the first and second postoperative days (SMD day 1: -0.32, 95% CI -0.54, -0.09; SMD day 2: -0.55, 95% CI -0.85, -0.25), while gabapentin showed significant pain reduction on the second day only (SMD day 2: -0.42, 95% CI -0.71, -0.13). Combined analysis for both medications showed significant pain reduction on the first- and second-days post-surgery. No significant increase in adverse events was associated with either medication. Publication bias was minimal except for a slight asymmetry noted on day 1 effectiveness.

CONCLUSION

Pregabalin and gabapentin are effective in reducing postoperative pain following refractive surgeries, with pregabalin showing a greater effect. Both medications are safe, with no significant increase in adverse events. Further research with standardized methodologies and long-term follow-up is recommended to optimize postoperative pain management in ocular surgeries.

Systematic review: The relationship between gabapentinoids, etizolam, and drug related deaths in Scotland

In recent years Scotland has been experiencing a disproportionally high number of drug related deaths compared to other European countries, causing significant individual, societal and economic burden. A possible cause of this is the increase in average number of substances involved in Scottish drug related deaths, as well as the changing pattern of substances involved. Opioids, cocaine, and alcohol have been consistently involved in the culture of drug use in Scotland, however recently National Records Scotland have identified that designer benzodiazepines such as etizolam, and prescription drugs such as gabapentinoids are increasingly being detected in Scottish toxicology reports. A systematic literature review following PRISMA guidelines was conducted through searching PubMed and Google Scholar to identify peer-reviewed articles published in English between 2013 and 2023 that investigated Scottish population data on gabapentinoids and etizolam to establish their contribution to the rise in Scottish drug related deaths. 18 studies were included in the review. A high use prevalence of etizolam and gabapentinoids in Scotland has been identified, with both substance-related deaths showing recent increase, marked since 2015. This pattern is replicated in the Scottish prison system. There has also been a significant increase of gabapentinoids prescriptions in Scotland. Polydrug use was identified as the most common determinant of both etizolam and gabapentinoids related adverse effects and fatality in Scotland, especially concurrent opioid use. The results indicate the literature on individual characteristics of Scottish at-risk users of gabapentinoids and etizolam is limited, however the data shows both substances are being used by older cohort, with adverse effects seen more in older women.

Efficacy and safety of TOMAC for treatment of medication-naïve and medication-refractory restless legs syndrome: A randomized clinical trial and meta-analysis

OBJECTIVE/BACKGROUND

There is a significant unmet need for safe and effective nonpharmacological therapies for restless legs syndrome (RLS). The objective was to evaluate the efficacy and safety of tonic motor activation (TOMAC) in patients with RLS.

PATIENTS/METHODS

A multicenter, randomized, participant-blinded, sham-controlled trial enrolled 45 adults with primary moderate-to-severe RLS who were either medication-naïve (n = 20) or medication-refractory (n = 25). Participants were 1:1 randomized to TOMAC (n = 22) or sham (n = 23) for two weeks and instructed to self-administer 30-min TOMAC sessions when they experienced RLS symptoms. The primary outcome was mean change in International RLS Study Group Rating Scale (IRLS) total score. A subsequent meta-analysis included the present trial and a previous randomized clinical trial that enrolled medication-naïve RLS patients.

RESULTS

IRLS reduction was significantly greater for TOMAC than sham (TOMAC -6.59 vs. sham -2.17; mean difference (MD) = -4.42; 95 % confidence interval [CI] -1.57 to -7.26; p = 0.0040). Subgroup analysis showed similar IRLS mean difference for medication-refractory (MD = -4.50; p = 0.02) and medication-naïve (MD = -4.40; p = 0.08) cohorts, which was significantly different from sham only for the medication-refractory cohort. Meta-analysis of combined data from 33 medication-naïve RLS patients showed a significant reduction in mean IRLS score after two weeks for TOMAC compared to sham (MD = -4.30; 95 % CI -1.36 to -7.24; p = 0.004).

CONCLUSIONS

The present trial confirmed previous reports documenting efficacy and safety of TOMAC in refractory RLS and indicated similar effect sizes in refractory versus naïve subgroups. The meta-analysis demonstrated that TOMAC significantly improves RLS symptoms in naïve participants.

Current and emerging pharmaceutical strategies for the treatment and management of restless legs syndrome

INTRODUCTION

Restless legs syndrome (RLS) is a sensory-motor sleep disorder that affects up to 13% of adults in the Western world and 2-4% of children. It impairs night sleep with an impact on daily performances and life quality. Thus, moderate-to-severe RLS requires pharmacological treatment.

AREAS COVERED

In the present review, which is based on PubMed searches with no time limits, the authors discuss the recommended pharmacotherapy for RLS in addition to other emerging treatment options. The authors provide coverage to the current recommendations for both adults and pediatric patients with RLS.

EXPERT OPINION

Current evidence suggests removing all causes of secondary RLS, including iron deficiency, chronic renal failure, drugs, and treating other sleep disorders that may worsen symptoms. Also, intermittent RLS should be addressed with behavioral measures and on-demand therapy. For chronic persistent RLS, α2δ calcium channel ligands are a first-line pharmacological approach, whereas dopamine agonists are associated with increased risk and should be spared. When RLS is refractory to first-line treatment, polytherapy, or opioid monotherapy should be considered. Nonetheless, some patients may not reach sustained symptom relief. Further research is needed to better understand the pathophysiology of RLS and to develop newer more effective drugs.

Epinephrine, Pregabalin, and Crizotinib as Three Medicines with Polish Implications over Three Last Centuries and in View of Three Different Drug Discovery Approaches

The discovery of epinephrine (adrenaline) and its subsequent implications in medicine owes significant contributions to Cybulski across different centuries, who, in 1894, was pivotal in identifying the adrenal medulla's role in blood pressure regulation and naming the active substance "nadnerczyna", known today as adrenaline. His work demonstrated the adrenal glands' critical function in the body's regulatory mechanisms beyond the nervous system. Cybulski's groundbreaking research laid foundational knowledge for future endocrinological studies and pharmaceutical advancements. In the late 20th century, Andruszkiewicz collaborated with Silverman at Northwestern University to develop pregabalin, the active ingredient in Lyrica. Their innovative synthesis of gamma-aminobutyric acid derivatives led to a significant advancement in treating epilepsy, neuropathic pain, and fibromyalgia. Andruszkiewicz's expertise in organic chemistry and enzymology was crucial in this collaborative effort, resulting in the successful development and commercialization of Lyrica. Additionally, Mroczkowski's leadership at Pfizer contributed to the development of crizotinib, a notable anaplastic lymphoma kinase and proto-oncogene 1 tyrosine-protein kinase inhibitor used to treat specific types of non-small cell lung cancer. Her work exemplifies the continuing influence of Polish researchers in pioneering drug discovery and advancing therapeutic treatments over the past three centuries. These contributions highlight Poland's significant role in global pharmaceutical innovations and medical research.

Combined antiallodynic effects of Neurotropin®-tramadol and Neurotropin®-mirogabalin in rats with L5-spinal nerve ligation

We aimed to examine the efficacy of combination therapies of Neurotropin® with tramadol and Neurotropin with mirogabalin for neuropathic pain management. A neuropathic pain model (L5 spinal nerve ligation model: L5-SNL) using male Wistar rats was generated through tight ligation of the left fifth lumbar nerve using silk sutures. Mechanical allodynia was assessed using the 50% paw withdrawal threshold. The combined antiallodynic effects were evaluated using isobolographic analyses. Small intestinal transit was evaluated using the charcoal meal test, and motor coordination using the rota-rod test. Neurotropin (50-200 NU/kg, p.o.), tramadol (7.5-60 mg/kg, p.o.), and mirogabalin (3-30 mg/kg, p.o.) showed a dose-dependent antiallodynic effect in L5-SNL rats. The combined antiallodynic effects of Neurotropin and tramadol were additive or synergistic, whereas those of Neurotropin and mirogabalin were additive. Neurotropin (100-400 NU/kg, p.o.) did not affect the small intestinal transit, whereas tramadol (30-100 mg/kg, p.o.) significantly inhibited it. Neurotropin (100-400 NU/kg, p.o.) did not affect the walking time, whereas mirogabalin (10-100 mg/kg, p.o.) significantly decreased it. Neurotropin dose-dependently ameliorated mechanical allodynia in rats, and combination therapy with Neurotropin-tramadol or Neurotropin-mirogabalin may alleviate neuropathic pain without aggravating the adverse effects of tramadol and mirogabalin.

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.

Novel drug treatments for pain in advanced cancer and serious illness: a focus on neuropathic pain and chemotherapy-induced peripheral neuropathy

Drugs that are commercially available but have novel mechanisms of action should be explored as analgesics. This review will discuss haloperidol, miragabalin, palmitoylethanolamide (PEA), and clonidine as adjuvant analgesics or analgesics. Haloperidol is a sigma-1 receptor antagonist. Under stress and neuropathic injury, sigma-1 receptors act as a chaperone protein, which downmodulates opioid receptor activities and opens several ion channels. Clinically, there is only low-grade evidence that haloperidol improves pain when combined with morphine, methadone, or tramadol in patients who have cancer, pain from fibrosis, radiation necrosis, or neuropathic pain. Miragabalin is a gabapentinoid approved for the treatment of neuropathic pain in Japan since 2019. In randomized trials, patients with diabetic neuropathy have responded to miragabalin. Its long binding half-life on the calcium channel subunit may provide an advantage over other gabapentinoids. PEA belongs to a group of endogenous bioactive lipids called ALIAmides (autocoid local injury antagonist amides), which have a sense role in modulating numerous biological processes in particular non-neuronal neuroinflammatory responses to neuropathic injury and systemic inflammation. Multiple randomized trials and meta-analyses have demonstrated PEA's effectiveness in reducing pain severity arising from diverse pain phenotypes. Clonidine is an alpha2 adrenoceptor agonist and an imidazoline2 receptor agonist, which is U.S. Federal Drug Administration approved for attention deficit hyperactivity disorder in children, Tourette's syndrome, adjunctive therapy for cancer-related pain, and hypertension. Clonidine activation at alpha2 adrenoceptors causes downstream activation of inhibitory G-proteins (Gi/Go), which inhibits cyclic Adenosine monophosphate (AMP) production and hyperpolarizes neuron membranes, thus reducing allodynia. Intravenous clonidine has been used in terminally ill patients with poorly controlled symptoms, in particular pain and agitation.

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.

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.

Edema related to treatment with psychotropic drugs

Edema as an adverse drug reaction is a commonly underestimated yet potentially debilitating condition. This study analyzes the incidence of severe psychotropic drug-induced edema (e.g., edema affecting the face, legs, or multiple body parts and lasting for more than 1 week, or in any case necessitating subsequent diuretic use) among psychiatric inpatients. The cases under examination are derived from an observational pharmacovigilance program conducted in German-speaking countries ("Arzneimittelsicherheit in der Psychiatrie", AMSP) from 1993 to 2016. Among the 462,661 inpatients monitored, severe edema was reported in 231 cases, resulting in an incidence of 0.05%. Edema occurred more frequently in women (80% of all cases) and older patients (mean age 51.8 years). Pregabalin had the highest incidence of severe edema, affecting 1.46‰ of patients treated with pregabalin, followed by mirtazapine (0.8‰). The majority of edema cases showed a positive response to appropriate countermeasures, such as dose reduction and drug discontinuation, and resolved by the end of the observation period. While most instances of drug-induced edema are reversible, they can have a significant impact on patient well-being and potentially result in decreased treatment adherence. It is, therefore, crucial to remain vigilant regarding risk-increasing circumstances during treatment with psychotropic drugs.

Pregabalin versus Gabapentin Efficacy in the Management of Neuropathic Pain Associated with Failed Back Surgery Syndrome

OBJECTIVE

Failed back surgery syndrome (FBSS) is a common long-term complication following spine surgeries characterized by chronic persistent pain; different strategies of management were employed to deal with it. This clinical trial aims to compare the efficacy of Pregabalin and Gabapentin in the management of this condition.

METHODS

A double-blind, randomized, comparative study (clinical trial registry NCT05324761 on 11th April 2022) with two parallel arms with Pregabalin and Gabapentin were used in arms one and two, respectively. Visual analog scale was used for basal and endpoint assessment of pain. T-test and analysis of covariance were used to deal with different variables. A pairwise test was used to compare pairs of means.

RESULTS

Of 66 patients referred to the trial, 64 were eligible, with 60 patients completing the 30 days trial. Both pregabalin and gabapentin effectively reduce pain, with significant p-values of 0.001 for each group. However, the pregabalin group was superior to gabapentin in pain reduction (p=0.001). Gender was an insignificant factor (p=0.574 and p=0.445 for the pregabalin and gabapentin groups, respectively, with a non-significant reduction (p=0.393) for both groups in total. Location of stenosis before surgery and type of surgery performed show non-significant effect on pain reduction for both groups.

CONCLUSION

Both pregabalin and gabapentin effectively and safely relieve neuropathic pain associated with FBSS; pregabalin was significantly more effective irrespective of the patients' gender.

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.

Oral self-administration of pregabalin in a mouse model and the resulting drug addiction features

Prescription drug abuse is an issue that is rapidly growing globally. Pregabalin, an anticonvulsant, analgesic, and anxiolytic medication, is effective in the management of multiple neurological disorders; however, there is increasing concern regarding its widespread illicit use. It has been previously reported in mice that pregabalin can induce conditioned place preference. In this current investigation, the potential of pregabalin to elicit free-choice drinking in a mouse model of drug addiction, and its effect on recognition and withdrawal behaviors after forced abstinence, were studied. Twenty-two male BALB/c mice were randomly divided into three groups (n = 7-8/group); control, pregabalin-30, and pregabalin-60. The study had three phases: habituation (days 1-5) with free water access, free-choice drinking (days 6-13) with pregabalin groups receiving one water and one pregabalin bottle, and forced abstinence (days 14-21) with free water access. On day 13, the first open field test was conducted, followed by the Novel Object Recognition Test. On day 21, the second open field test was performed, followed by the Tail Suspension Test and Forced Swimming Test. Pregabalin elicited voluntary drinking in the higher-dose group, concurrently causing a decline in recognition memory performance in the novel object recognition test. Moreover, pregabalin induced withdrawal behavior after a period of forced abstinence in the forced swimming and tail suspension tests. This is the first report to establish an animal model of free-choice pregabalin drinking that may be used for further molecular studies and targeted therapy for pregabalin addiction.

Pregabalin use in forensic hospitals and prisons in German speaking countries-a survey study of physicians

Background

Pregabalin is a gamma-aminobutyric acid (GABA) analog that was approved in the EU in 2004 for the treatment of neuropathic pain, generalized anxiety disorder and epilepsy. Since its introduction, pregabalin abuse and misuse has increased significantly. In Switzerland, clinical reports suggest that pregabalin misuse is common among patients in forensic hospitals and prisons. However, data on pregabalin use is scarce, especially in these settings. Therefore, we conducted a study to explore patterns of pregabalin use among prison and forensic patients.

Methods

We used a questionnaire to survey physicians working in prison and forensic medicine in German-speaking countries. A total of 131 responses were received.

Results

According to the physicians' subjective assessment, 82.5% of them had observed a recent increase in pregabalin use by their patients and 89.1% of them reported that their patients requested pregabalin without a clear medical indication. Patients misusing pregabalin in combination with other illicit substances were observed by 93.3% of the physicians surveyed. According to 73.5% of the physicians surveyed, they had already encountered patients on pregabalin doses of more than 600 mg/day (the maximum recommended daily dose); the highest dose reported was 4,200 mg/day. According to 85.0% of physicians surveyed, they have observed patients experiencing withdrawal symptoms from pregabalin, with the most commonly reported symptoms being displeasure and high aggression. Regarding the nationality of pregabalin-misusing patients, 58.3% of the interviewed physicians reported to be rather in contact with foreign patients, mainly from Northwest Africa (Maghreb). Only 45.0% of the surveyed physicians prescribe pregabalin. Among patients who developed behavioral problems while taking pregabalin, none of the physicians (0.0%) showed a tendency to continue pregabalin at the same dose; all respondents chose to reduce/substitute/discontinue.

Conclusion

Our study has provided confirmatory evidence that the use of pregabalin presents a significant issue in forensic and prison medicine across German-speaking countries. Prescribing pregabalin in this field can compound use disorder problems and exacerbate challenges in daily life for those in forensic institutions or prisons. It is necessary that all physicians who prescribe pregabalin are clearly informed about the management (including the risks) of this drug.

Mechanism of Analgesia by Gabapentinoid Drugs: Involvement of Modulation of Synaptogenesis and Trafficking of Glutamate-Gated Ion Channels

Gabapentinoids have clinically been used for treating epilepsy, neuropathic pain, and several other neurologic disorders for >30 years; however, the definitive molecular mechanism responsible for their therapeutic actions remained uncertain. The conventional pharmacological observation regarding their efficacy in chronic pain modulation is the weakening of glutamate release at presynaptic terminals in the spinal cord. While the α2/δ-1 subunit of voltage-gated calcium channels (VGCCs) has been identified as the primary drug receptor for gabapentinoids, the lack of consistent effect of this drug class on VGCC function is indicative of a minor role in regulating this ion channel's activity. The current review targets the efficacy and mechanism of gabapentinoids in treating chronic pain. The discovery of interaction of α2/δ-1 with thrombospondins established this protein as a major synaptogenic neuronal receptor for thrombospondins. Other findings identified α2/δ-1 as a powerful regulator of N-methyl-D-aspartate receptor (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) by potentiating the synaptic expression, a putative pathophysiological mechanism of neuropathic pain. Further, the interdependent interactions between thrombospondin and α2/δ-1 contribute to chronic pain states, while gabapentinoid ligands efficaciously reverse such pain conditions. Gabapentin normalizes and even blocks NMDAR and AMPAR synaptic targeting and activity elicited by nerve injury. SIGNIFICANCE STATEMENT: Gabapentinoid drugs are used to treat various neurological conditions including chronic pain. In chronic pain states, gene expression of cacnα2/δ-1 and thrombospondins are upregulated and promote aberrant excitatory synaptogenesis. The complex trait of protein associations that involve interdependent interactions between α2/δ-1 and thrombospondins, further, association of N-methyl-D-aspartate receptor and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor with the C-tail of α2/δ-1, constitutes a macromolecular signaling complex that forms the crucial elements for the pharmacological mode of action of gabapentinoids.

Pharmacokinetic properties of a new sustained-release pregabalin tablet in subjects with reduced renal function

A new sustained-release (SR) pregabalin tablet, YHD1119, was formulated for once-daily dosing. In the current study, we aimed to evaluate the pharmacokinetics of YHD1119 tablets in patients with reduced renal function. Subjects were grouped by creatinine clearance: > 60 mL/min/1.73m2 (Cohort A) and 30-60 mL/min/1.73m2 (Cohort B). Eight subjects in Cohort A received a YHD1119 75 mg tablet (Y75T) and a YHD1119 150 mg tablet (Y150T) in each period, and eight subjects in Cohort B received a Y75T. Non-compartment analysis and population pharmacokinetic analysis using a one-compartment model with first-order elimination and first-order absorption with lag time were performed. Sixteen subjects completed the study. The geometric mean ratio (GMR) (90% confidence intervals [CI]) for maximum concentration (Cmax), and area under the concentration-time profile from 0 to the last measurable time (AUClast) after Y75T of Cohort B to those of Y75T of Cohort A were 1.2273 (1.0245-1.4701), and 2.4146 (1.8142-3.2138), respectively. The GMR (90% CI) for Cmax, and AUClast after Y75T of Cohort B to those of Y150T of Cohort A were 0.6476 (0.5229-0.8021), and 1.1471 (0.8418-1.5632), respectively. Simulated steady-steady pregabalin concentrations after once-daily Y75T dosing in subjects with eGFR 45 mL/min/1.73 m2 were within the range of steady-state concentrations simulated after once-daily Y150T dosing in subjects with eGFR 90 mL/min/1.73 m2. The total pregabalin exposure of Y75T in patients with moderate renal impairment was comparable with that of Y150T in subjects with near-normal renal function.

Trial Registration

ClinicalTrials.gov Identifier: NCT05012436.

Naturally Inspired Molecules for Neuropathic Pain Inhibition-Effect of Mirogabalin and Cebranopadol on Mechanical and Thermal Nociceptive Threshold in Mice

BACKGROUND

Neuropathic pain is drug-resistant to available analgesics and therefore novel treatment options for this debilitating clinical condition are urgently needed. Recently, two drug candidates, namely mirogabalin and cebranopadol have become a subject of interest because of their potential utility as analgesics for chronic pain treatment. However, they have not been investigated thoroughly in some types of neuropathic pain, both in humans and experimental animals.

METHODS

This study used the von Frey test, the hot plate test and the two-plate thermal place preference test supported by image analysis and machine learning to assess the effect of intraperitoneal mirogabalin and subcutaneous cebranopadol on mechanical and thermal nociceptive threshold in mouse models of neuropathic pain induced by streptozotocin, paclitaxel and oxaliplatin.

RESULTS

Mirogabalin and cebranopadol effectively attenuated tactile allodynia in models of neuropathic pain induced by streptozotocin and paclitaxel. Cebranopadol was more effective than mirogabalin in this respect. Both drugs also elevated the heat nociceptive threshold in mice. In the oxaliplatin model, cebranopadol and mirogabalin reduced cold-exacerbated pain.

CONCLUSIONS

Since mirogabalin and cebranopadol are effective in animal models of neuropathic pain, they seem to be promising novel therapies for various types of neuropathic pain in patients, in particular those who are resistant to available analgesics.

Spinal cord stimulation in severe pharmacoresistant restless legs syndrome-two case reports

Restless legs syndrome is a prevalent, sleep-related sensorimotor disorder with relevant impact on the patients' quality of life. For patients suffering from severe, pharmacoresistant restless legs syndrome, few therapeutic options remain to alleviate symptoms. In this case series, two patients with severe, pharmacoresistant restless legs syndrome were treated with epidural spinal cord stimulation and repeatedly assessed with polysomnography, including sleep structure and periodic limb movements as objective biomarkers not subject to placebo effects, during a 6-month follow-up period. One of the patients experienced excellent short- and long-term efficacy on subjective symptom severity (International RLS Study group rating scale 1 vs. 34 points at 3 months) and objective sleep parameters such as sleep architecture and periodic limb movements during sleep, while the second patient only reported short-term benefits from spinal cord stimulation. Ultimately, both patients opted for removal of the device for inefficacy. Based on the complex pathophysiology of restless legs syndrome and presumed mechanism of action of spinal cord stimulation in chronic pain disorders, we provide a detailed hypothesis on the possible modulating effect of spinal cord stimulation on the key symptoms of restless legs syndrome. Apart from describing a new therapeutic option for pharmacoresistant restless legs syndrome, our findings might also provide further insights into the pathophysiology of the syndrome.

Effects of Acute and Chronic Gabapentin Treatment on Cardiovascular Function of Rats

Gabapentin (GBP), a GABA analogue, is primarily used as an anticonvulsant for the treatment of partial seizures and neuropathic pain. Whereas a majority of the side effects are associated with the nervous system, emerging evidence suggests there is a high risk of heart diseases in patients taking GBP. In the present study, we first used a preclinical model of rats to investigate, firstly, the acute cardiovascular responses to GBP (bolus i.v. injection, 50 mg/kg) and secondly the effects of chronic GBP treatment (i.p. 100 mg/kg/day × 7 days) on cardiovascular function and the myocardial proteome. Under isoflurane anesthesia, rat blood pressure (BP), heart rate (HR), and left ventricular (LV) hemodynamics were measured using Millar pressure transducers. The LV myocardium and brain cortex were analyzed by proteomics, bioinformatics, and western blot to explore the molecular mechanisms underlying GBP-induced cardiac dysfunction. In the first experiment, we found that i.v. GBP significantly decreased BP, HR, maximal LV pressure, and maximal and minimal dP/dt, whereas it increased IRP-AdP/dt, Tau, systolic, diastolic, and cycle durations (* p < 0.05 and ** p < 0.01 vs. baseline; n = 4). In the second experiment, we found that chronic GBP treatment resulted in hypotension, bradycardia, and LV systolic dysfunction, with no change in plasma norepinephrine. In the myocardium, we identified 109 differentially expressed proteins involved in calcium pathways, cholesterol metabolism, and galactose metabolism. Notably, we found that calmodulin, a key protein of intracellular calcium signaling, was significantly upregulated by GBP in the heart but not in the brain. In summary, we found that acute and chronic GBP treatments suppressed cardiovascular function in rats, which is attributed to abnormal calcium signaling in cardiomyocytes. These data reveal a novel side effect of GBP independent of the nervous system, providing important translational evidence to suggest that GBP can evoke adverse cardiovascular events by depression of myocardial function.

Experiences of misuse and symptoms of dependence among people who use gabapentinoids: a qualitative systematic review protocol

INTRODUCTION

Gabapentinoids are among the most widely prescribed pain medications. However, there is growing evidence to suggest that gabapentinoids may be associated with dependence and misuse. The aim of this systematic review is to synthesise the qualitative literature on gabapentinoid misuse and symptoms of dependence. The findings of this study will inform efforts to mitigate emerging harms.

METHODS AND ANALYSIS

A systematic review of qualitative research will explore lived experiences of misuse and symptoms of dependence among people who use gabapentinoids. Six databases (MEDLINE, Scopus, Web of Science, CINAHL, EMBASE and PsycINFO) and grey literature sources will be searched from inception to May 2023. Qualitative studies that include people with lived experiences of gabapentinoid misuse and symptoms of gabapentinoid dependence will be included. Reference lists of included studies will also be screened for additional studies. The methodological quality of included studies will be appraised using the Critical Appraisal Skills Programme qualitative checklist, and higher quality studies will be prioritised in the thematic synthesis. The GRADE-CERQual approach will be used to assess confidence in the overall findings of the review.

ETHICS AND DISSEMINATION

Ethical approval is not required for this systematic review. The findings of this review will be disseminated in peer-reviewed journals, at conferences and on social media.

PROSPERO REGISTRATION NUMBER

CRD42023401832.

Single-Soma Deep RNA sequencing of Human DRG Neurons Reveals Novel Molecular and Cellular Mechanisms Underlying Somatosensation

The versatility of somatosensation arises from heterogeneous dorsal root ganglion (DRG) neurons. However, soma transcriptomes of individual human DRG (hDRG) neurons-critical in-formation to decipher their functions-are lacking due to technical difficulties. Here, we developed a novel approach to isolate individual hDRG neuron somas for deep RNA sequencing (RNA-seq). On average, >9,000 unique genes per neuron were detected, and 16 neuronal types were identified. Cross-species analyses revealed remarkable divergence among pain-sensing neurons and the existence of human-specific nociceptor types. Our deep RNA-seq dataset was especially powerful for providing insight into the molecular mechanisms underlying human somatosensation and identifying high potential novel drug targets. Our dataset also guided the selection of molecular markers to visualize different types of human afferents and the discovery of novel functional properties using single-cell in vivo electrophysiological recordings. In summary, by employing a novel soma sequencing method, we generated an unprecedented hDRG neuron atlas, providing new insights into human somatosensation, establishing a critical foundation for translational work, and clarifying human species-species properties.

Misuse of gabapentinoids (pregabalin and gabapentin) in patients with neuropathic pain related to spinal cord injury

OBJECTIVE

To investigate the misuse of gabapentinoids (pregabalin and gabapentin) in patients with neuropathic pain related to spinal cord injury.

STUDY DESIGN

Cross-sectional study.

SETTING

Outpatient clinic in a physical therapy and rehabilitation hospital.

PARTICIPANTS

127 patients, aged 18-70 years, who had neuropathic pain related to spinal cord injury (SCI) and disease duration of at least 12 months.

OUTCOME MEASURES

Gabapentinoid use disorder of the patients was determined based on the DSM-5 diagnostic criteria for substance-related disorders. Patients were divided into 2 groups as those with drug misuse and those without drug misuse. Demographic and clinical information of the patients were compared between the groups. Factors associated with drug misuse were analyzed.

RESULTS

The misuse rate was 81.9% in patients using pregabalin and 69.69% in patients using gabapentin. Duration of disease and the Leeds assessment of neuropathic symptoms and signs (LANSS) score were statistically significantly higher in the drug misuse group. A statistically significant difference was found between the groups in terms of marital status, education and income level, and smoking and alcohol use. A statistically significant relationship was observed between drug misuse and duration of disease and LANSS score.

CONCLUSION

Misuse of gabapentinoids is prevalent in patients with neuropathic pain related to spinal cord injury. The duration of disease and the severity of NP are associated with misuse. Clinicians should exercise caution when prescribing gabapentinoids to patients with SCI.

Trends in overdose deaths involving gabapentinoids and Z-drugs in the United States

INTRODUCTION

As policies have been implemented to limit access to prescription opioids, other drugs have been prescribed off-label, sometimes concurrently with opioids, to manage pain. There are concerns about the use of gabapentinoids and "Z-drugs" with opioids. As the opioid crisis transitions to illicit opioids and polysubstance use, little work quantifies the concurrent involvement of non-opioid prescription drugs and illicit opioids in overdose deaths.

METHODS

Data from the census of deaths in the United States for 1999-2020 were used to understand trends in deaths involving gabapentinoids/Z-drugs and opioid co-involvement. These trends were studied overall and by sex, race, age, and education.

RESULTS

Per capita overdose deaths involving gabapentinoids/Z-drugs increased almost continuously since 1999, averaging 15.8% annual growth. This rate increased to 32% in 2020, primarily due to overdoses involving synthetic opioids. Women typically had higher rates of overdose deaths involving both opioids and gabapentinoids/Z-drugs, though this disparity disappeared in 2020. White Americans and American Indians/Alaskan Natives historically had higher rates than other racial groups; however, Black Americans experienced over 60% annual growth in recent years. Low education groups have been disproportionately impacted. The age incidence tends to be older than overdoses involving opioids more generally.

CONCLUSION

Overdose deaths involving opioids and gabapentinoids/Z-drugs have tended to disproportionately affect women and older age groups compared to all opioid-involved overdoses. As deaths involving synthetic opioids likely reflect use of illicitly-obtained opioids, there may be less of a role for policies targeting the concurrent prescribing of gabapentinoids/Z-drugs with opioids to reduce these deaths.

Understanding the rise in overdose deaths involving opioids and non-opioid prescription drugs in the United States

BACKGROUND

Previous studies demonstrate that the reformulation of OxyContin in the U.S. in 2010 induced substitution to illicit opioids, causing illicit opioid markets to grow disproportionately fast in states more exposed to the reformulation. In this paper, we examine if this shift to the illicit market also led to a rise in polysubstance overdose deaths involving non-opioid prescription drugs, including gabapentinoids and "Z-drugs" and, separately, benzodiazepines.

METHODS

Using a difference-in-differences framework, the relationship between exposure to reformulation and overdose death rates including specific substances was studied in each year from 1999 to 2020 while accounting for fixed differences across states, common nationwide shocks, and state-level differences in pain reliever misuse prior to reformulation. Exposure to reformulation was measured as the pre-reformulation rate of OxyContin misuse.

RESULTS

Exposure to reformulation predicted growth in overdose deaths involving gabapentinoids and Z-drugs. There is less evidence that it predicted growth in overdose deaths involving benzodiazepines. However, for all substances, there is strong evidence that pre-reformulation OxyContin misuse rates predicted post-reformulation growth in overdose deaths concurrently involving synthetic opioids.

DISCUSSION

The opioid crisis has changed in radical ways. This study links a major supply-side intervention to the increase in polysubstance overdose deaths involving non-opioid prescription drugs, specifically gabapentinoids and Z-drugs.

Pregabalin can interact synergistically with Kv7 channel openers to exert antinociception in mice

Chronic pain is a common public health problem and remains an unmet medical need. Currently available analgesics usually have limited efficacy for the treatment of chronic pain, including neuropathic pain and persistent inflammatory pain, or they are accompanied by many adverse side effects. The voltage-gated calcium channel blocker (pregabalin) and potassium channel openers (flupirtine and retigabine) have been widely used for the management of chronic pain, but their effectiveness in combination is unclear. In this research, we evaluated the antinociceptive effects of pregabalin in combination with flupirtine or retigabine in carrageenan-induced inflammatory pain and paclitaxel-induced peripheral neuropathy in mice using the von Frey test. Isobolographic analysis indicated that pregabalin exerted synergistic antinociceptive effects when combined with flupirtine or retigabine in neuropathic and inflammatory pain models. Furthermore, the antinociceptive effects of pregabalin, flupirtine/retigabine, and their combinations were significantly attenuated by the Kv7 channel blocker XE991. The favored dose ratio between pregabalin and flupirtine/retigabine in combinations was also investigated. Finally, we evaluated the motor coordination of their combinations using the rotarod test, and the outcomes underpinned their safety. Collectively, our results support the potential use of pregabalin in combination with flupirtine or retigabine to alleviate chronic pain.

The association between Gabapentin or Pregabalin use and the risk of dementia: an analysis of the National Health Insurance Research Database in Taiwan

Objective: Previous studies have shown that gabapentin or pregabalin use is associated with cognitive decline. Herein, we aimed to evaluate the association between gabapentin or pregabalin use and the risk of dementia. Methods: In this retrospective, population-based matched cohort study, all research data were collected from the 2005 Longitudinal Health Insurance Database, which contains data of 2 million people randomly selected from the National Health Insurance Research Database of Taiwan in 2005. The study extracted data from 1 January 2000, to 31 December 2017. Adult patients taking gabapentin or pregabalin were included in the exposure group, and patients not using gabapentin or pregabalin matched to exposure subjects in a 1:5 ratio by propensity scores composed of age, sex and index date were included in the non-exposure group. Results: A total of 206,802 patients were enrolled in the study. Of them, 34,467 gabapentin- or pregabalin-exposure and 172,335 non-exposure patients were used for analysis. The mean follow-up day (±standard deviation) after the index date was 1724.76 (±1282.32) and 1881.45 (±1303.69) in the exposure and non-exposure groups, respectively; the incidence rates of dementia were 980.60 and 605.48 per 100,000 person-years, respectively. The multivariate-adjusted hazard ratio of risk of dementia for gabapentin or pregabalin exposure versus the matched non-exposed group was 1.45 (95% confidence interval [CI], 1.36-1.55). The risk of dementia increased with higher cumulative defined daily doses during the follow-up period. Moreover, the stratification analysis revealed that the risk of dementia associated with gabapentin or pregabalin exposure was significant in all age subgroups; however, it was higher in younger patients (age <50) than in the older patients (hazard ratio, 3.16; 95% CI, 2.23-4.47). Conclusion: Patients treated with gabapentin or pregabalin had an increased risk of dementia. Therefore, these drugs should be used with caution, particularly in susceptible individuals.

A Review of Recent Pharmacological Advances in the Management of Diabetes-Associated Peripheral Neuropathy

Diabetic peripheral neuropathy is a common complication of longstanding diabetes mellitus. These neuropathies can present in various forms, and with the increasing prevalence of diabetes mellitus, a subsequent increase in peripheral neuropathy cases has been noted. Peripheral neuropathy has a significant societal and economic burden, with patients requiring concomitant medication and often experiencing a decline in their quality of life. There is currently a wide variety of pharmacological interventions, including serotonin norepinephrine reuptake inhibitors, gapentanoids, sodium channel blockers, and tricyclic antidepressants. These medications will be discussed, as well as their respective efficacies. Recent advances in the treatment of diabetes mellitus with incretin system-modulating drugs, specifically glucagon-like peptide-1 agonists, have been promising, and their potential implication in the treatment of peripheral diabetic neuropathy is discussed in this review.

Recognition mechanism of a novel gabapentinoid drug, mirogabalin, for recombinant human α2δ1, a voltage-gated calcium channel subunit

Mirogabalin is a novel gabapentinoid drug with a hydrophobic bicyclo substituent on the γ-aminobutyric acid moiety that targets the voltage-gated calcium channel subunit α₂δ1. Here, to reveal the mirogabalin recognition mechanisms of α₂δ1, we present structures of recombinant human α₂δ1 with and without mirogabalin analyzed by cryo-electron microscopy. These structures show the binding of mirogabalin to the previously reported gabapentinoid binding site, which is the extracellular dCache_1 domain containing a conserved amino acid binding motif. A slight conformational change occurs around the residues positioned close to the hydrophobic group of mirogabalin. Mutagenesis binding assays identified that residues in the hydrophobic interaction region, in addition to several amino acid binding motif residues around the amino and carboxyl groups of mirogabalin, are critical for mirogabalin binding. The A215L mutation introduced to decrease the hydrophobic pocket volume predictably suppressed mirogabalin binding and promoted the binding of another ligand, L-Leu, with a smaller hydrophobic substituent than mirogabalin. Alterations of residues in the hydrophobic interaction region of α₂δ1 to those of the α₂δ2, α₂δ3, and α₂δ4 isoforms, of which α₂δ3 and α₂δ4 are gabapentin-insensitive, suppressed the binding of mirogabalin. These results support the importance of hydrophobic interactions in α₂δ1 ligand recognition.

Oral pregabalin is effective as preemptive analgesia in abdominal hysterectomy-A randomized controlled trial

Postoperative pain is one of the main negative symptoms resulting from surgery and the use of new methods to control this symptom is of ever-increasing relevance. Opioid-sparing strategies, such as multimodal analgesia, are trends in this scenario. Pregabalin is a well-established treatment for neuropathic pain; however, it is still controversial in the surgical context for postoperative analgesia. This study investigated the effect of pregabalin on postoperative analgesia in patients undergoing abdominal hysterectomy. It is a prospective, randomised, double-blind, placebo-controlled clinical trial. Female patients undergoing abdominal hysterectomy were randomised to use pregabalin (group P1), 300 mg orally 2 h before surgery, or identical placebo pills (group P0). The main outcome includes the postoperative pain index by visual analogue scale (VAS) and McGill's pain questionnaire. Secondary outcomes include opioid consumption and the presence of adverse effects. A value of p < 0.05 was used to reject type I error. Fifty-five patients were randomised amongst the groups. Patients in group P1 had lower pain rates by VAS scale, both at rest and in active motion, than group P0. In McGill's questionnaire, patients from group P1 also had lower pain rates (12 × 28.5). There was approximately twice as much opioid consumption amongst patients in group P0. Regarding side effects, there was a difference between the two groups only for dizziness, being more incident in group P1. This study suggests that pregabalin is an important adjuvant drug in treating postoperative pain in patients with abdominal hysterectomy.

A Meta-analysis of Randomized Controlled Trials Comparing the Efficacy and Safety of Pregabalin and Gabapentin in the Treatment of Postherpetic Neuralgia

OBJECTIVE

To systematically evaluate the clinical efficacy of pregabalin and gabapentin in the treatment of postherpetic neuralgia (PHN), including the difference in pain control and occurrence of adverse reactions.

METHODS

PubMed, MEDLINE, EMBASE, Cochrane Library, and Web of Science databases were searched for randomized controlled trials (RCTs) comparing the efficacy of pregabalin and gabapentin in patients with PHN. Data from studies meeting the inclusion criteria were extracted and the Cochrane Risk of Bias risk assessment tool was used to evaluate the quality of the included studies. Revman 5.3 and Stata17 were used to perform the meta-analysis and to detect publication bias.

RESULTS

A total of 14 RCTs with 3545 patients were included in this study, including 926 in the pregabalin treatment group, 1256 in the gabapentin treatment group, and 1363 in the placebo control group. Pregabalin was better than gabapentin in alleviating pain and improving the global perception of change in pain and sleep (P < 0.05). Gabapentin was associated with a lower incidence of adverse events than pregabalin (P < 0.05). Funnel plot and Begg's and Egger's tests showed no significant publication bias.

CONCLUSION

Pregabalin appears to have a better overall therapeutic effect than gabapentin for patients with PHN, but gabapentin has a lower incidence of adverse reactions and a better safety profile. Clinicians should comprehensively consider patient factors and fully evaluate the advantages and disadvantages of each treatment option to select the most suitable drugs for patient use. Considering the limited quantity and quality of the existing literature, high-quality RCTs are needed to confirm the advantages of pregabalin over gabapentin in the treatment of PHN and guide clinical decision-making.

The Role of Gabapentinoids in the Substance Use Pattern of Adult Germans Seeking Inpatient Detoxification Treatment - A Pilot Study

To shed more light on the addictive power of the gabapentinoids (GPTs) gabapentin and pregabalin, we performed a structured face-to-face interview with GPT-users about DSM-IV-dependence-criteria (sedatives), consume-motives and cessation-needs. Among 100 patients consecutively admitted to a detoxification-ward, fifteen (15%) reported lifetime GPT-use (18-50 years old, 2 females): seven (7%) used gabapentin, twelve (12%) pregabalin and four had lifetime experiences with both GPTs. Of the seven gabapentin-users, three patients were dependent including one person with a spontaneous remission. Of the 12 pregabalin-users, five were dependent, including two persons with a spontaneous remission. Fourteen of fifteen cases reported GPT-use side-by-side with an opioid-use, mostly for sparing opioids. Twelve GPT-users additionally co-used benzodiazepines. In no case, a GPT was the reason for detoxification treatment or reported to be involved in an emergency event. Altogether, every 7^th patient (n = 15) of our inpatient detoxification-seeking sample reported GPT-use including 50% (n = 8) who were dependent. Among them, 35% (3/8) had been already spontaneously remitted. As GPT-users reported no cession-need and the vast majority were primarily affected by co-occurring opioid- and benzodiazepine-addiction, we assume that GPTs more likely played a bystander-role than mediating the addictive behavior of this population with multiple recreational drug use experience.

Gabapentinoids for Pain: A Review of Published Comparative Effectiveness Trials and Data Submitted to the FDA for Approval

Use of the gabapentinoids for pain continues to increase. In 2018, the US Food and Drug Administration (FDA) strengthened the warnings for both gabapentin and pregabalin to emphasize the central nervous system side effects and the risk of respiratory depression, especially when combined with other centrally acting drugs. We reviewed the published comparative effectiveness literature for gabapentinoids for pain as well as all trials (published and unpublished) used by the FDA for the approval of the five pain indications for these agents (one for gabapentin, four for pregabalin). Among the findings of interest are the fact that the FDA rejected the application for gabapentin for diabetic peripheral neuropathy based on the risk versus benefit profile of that drug in the clinical trials that were submitted by the manufacturer. Additionally, both the comparative effectiveness trials as well as the studies used by the FDA tend to be short in duration and show only modest pain benefits for the gabapentinoids. The placebo response in these trials was frequently one-third to one-half as great as the pain benefit demonstrated by the gabapentinoid. Based on the available clinical trial evidence, we feel prescribers should be cautious when using gabapentinoids for pain, particularly when using these agents for a prolonged period or when combined with other, centrally acting agents.

The α2δ-1-NMDA receptor complex and its potential as a therapeutic target for ischemic stroke

N-methyl-_D-aspartate receptors (NMDARs) play a critical role in excitotoxicity caused by ischemic stroke, but NMDAR antagonists have failed to be translated into clinical practice for treating stroke patients. Recent studies suggest that targeting the specific protein-protein interactions that regulate NMDARs may be an effective strategy to reduce excitotoxicity associated with brain ischemia. α2δ-1 (encoded by the Cacna2d1 gene), previously known as a subunit of voltage-gated calcium channels, is a binding protein of gabapentinoids used clinically for treating chronic neuropathic pain and epilepsy. Recent studies indicate that α2δ-1 is an interacting protein of NMDARs and can promote synaptic trafficking and hyperactivity of NMDARs in neuropathic pain conditions. In this review, we highlight the newly identified roles of α2δ-1-mediated NMDAR activity in the gabapentinoid effects and NMDAR excitotoxicity during brain ischemia as well as targeting α2δ-1-bound NMDARs as a potential treatment for ischemic stroke.

Gabapentin Increases Intra-Epidermal and Peptidergic Nerve Fibers Density and Alleviates Allodynia and Thermal Hyperalgesia in a Mouse Model of Acute Taxol-Induced Peripheral Neuropathy

The clinical pathology of Taxol-induced peripheral neuropathy (TIPN), characterized by loss of sensory sensitivity and pain, is mirrored in a preclinical pharmacological mice model in which Gabapentin, produced anti-thermal hyperalgesia and anti-allodynia effects. The study aimed to investigate the hypothesis that gabapentin may protect against Taxol-induced neuropathic pain in association with an effect on intra-epidermal nerve fibers density in the TIPN mice model. A TIPN study schedule was induced in mice by daily injection of Taxol during the first week of the experiment. Gabapentin therapy was performed during the 2nd and 3rd weeks. The neuropathic pain was evaluated during the whole experiment by the Von Frey, tail flick, and hot plate tests. Intra-epidermal nerve fibers (IENF) density in skin biopsies was measured at the end of the experiment by immunohistochemistry of ubiquitin carboxyl-terminal hydrolase PGP9.5 pan-neuronal and calcitonin gene-related (CGRP) peptides-I/II- peptidergic markers. Taxol-induced neuropathy was expressed by 80% and 73% reduction in the paw density of IENFs and CGPR, and gabapentin treatment corrected by 83% and 46% this reduction, respectively. Gabapentin-induced increase in the IENF and CGRP nerve fibers density, thus proposing these evaluations as an additional objective end-point tool in TIPN model studies using gabapentin as a reference compound.

Behavioral and cardiovascular effects of a single dose of gabapentin or melatonin in cats: a randomized, double-blind, placebo-controlled trial

OBJECTIVES

The aim of this study was to verify whether a single oral dose of gabapentin (100 mg) or melatonin (3 mg) given 60 mins before a cardiac evaluation would reduce anxiety without interfering with heart rate (HR), systemic blood pressure (SBP), electrocardiogram (ECG) and echocardiographic indexes.

METHODS

Seventy-five client-owned healthy cats underwent two sets of cardiac assessments 60 mins apart, randomly divided into gabapentin, melatonin and placebo groups. The interval between treatment and the second ECG and SBP measurement was 60 mins, and 70 mins for echocardiography. A compliance score (CS) classified the behavior, focusing on the ease of handling.

RESULTS

Most variables did not change between the examinations. The placebo group showed more significant changes (SBP, tricuspid annular plane systolic excursion, HR during echocardiography, aortic flow velocity, S' wave from lateral mitral annulus), but they were not considered to be hemodynamically relevant. Gabapentin and melatonin significantly increased the cats' compliance without interfering with cardiac assessment. Eight cats presented with mild sedation, seven after gabapentin and one after melatonin. No major side effects were observed.

CONCLUSIONS AND RELEVANCE

Gabapentin tranquilized the cats when it was given 60 mins prior to ECG and SBP measurement, and 70 mins prior to echocardiography, without interfering with systolic echocardiographic indexes. Melatonin also decreased the CS, but without sedation in most cases. The waiting period may have relaxed the cats in the placebo group, resulting in lower SBP measurements. However, this tranquility did not last as some echocardiographic changes signaled a sympathetic predominance.