Gabapentin-Friend or foe?

Are environmental levels of gabapentin (GBP) a cause for concern? Chronic reproductive effects of GBP in zebrafish

GBP, a widely used antiepileptic drug, is frequently detected in aquatic environments due to inefficient removal in wastewater treatment. This study investigates the chronic reproductive toxicity of GBP in zebrafish (Danio rerio), a model species for endocrine disruption. Exposure began at 20 days post-fertilization (dpf), coinciding with sex differentiation, and continued for 130 days at environmentally relevant concentrations (1, 10, and 100 μg/L). Our results demonstrated that chronic GBP exposure, even at 1 μg/L, significantly impaired reproductive health in zebrafish, including gonadal development, reduced fecundity, and even the developmental success in the F1 generation. Gene expression analysis revealed alterations in key genes of the hypothalamic-pituitary-gonadal (HPG) axis, resulting in sex-dependent hormonal dysregulation. These findings highlight the potential ecological risks of GBP contamination, where even low concentrations can profoundly affect fish reproduction. The study emphasizes the need for further research on pharmaceutical pollutants and their long-term impacts, as well as improved wastewater treatment processes to mitigate pharmaceutical contamination in aquatic ecosystems.

Pharmacology and Mechanism of Action of Suzetrigine, a Potent and Selective NaV1.8 Pain Signal Inhibitor for the Treatment of Moderate to Severe Pain

INTRODUCTION

There is a high unmet need for safe and effective non-opioid medicines to treat moderate to severe pain without risk of addiction. Voltage-gated sodium channel 1.8 (NaV1.8) is a genetically and pharmacologically validated pain target that is selectively expressed in peripheral pain-sensing neurons and not in the central nervous system (CNS). Suzetrigine (VX-548) is a potent and selective inhibitor of NaV1.8, which has demonstrated clinical efficacy and safety in multiple acute pain studies. Our study was designed to characterize the mechanism of action of suzetrigine and assess both nonclinical and clinical data to test the hypothesis that selective NaV1.8 inhibition translates into clinical efficacy and safety, including lack of addictive potential.

METHODS

Preclinical pharmacology and mechanism of action studies were performed in vitro using electrophysiology and radiolabeled binding methods in cells recombinantly expressing human NaV channels, human proteins, and primary human dorsal root ganglion (DRG) sensory neurons. Safety and addictive potential assessments included in vitro secondary pharmacology studies, nonclinical repeat-dose toxicity and dependence studies in rats and/or monkeys, and a systematic analysis of adverse event data generated from 2447 participants from phase 3 acute pain studies of suzetrigine.

RESULTS

Suzetrigine is selective against all other NaV subtypes (≥ 31,000-fold) and 180 other molecular targets. Suzetrigine inhibits NaV1.8 by binding to the protein's second voltage sensing domain (VSD2) to stabilize the closed state of the channel. This novel allosteric mechanism results in tonic inhibition of NaV1.8 and reduces pain signals in primary human DRG sensory neurons. Nonclinical and clinical safety assessments with suzetrigine demonstrate no adverse CNS, cardiovascular or behavioral effects and no evidence of addictive potential or dependence.

CONCLUSIONS

The comprehensive pharmacology assessment presented here indicates that suzetrigine represents the first in a new class of non-opioid analgesics that are selective NaV1.8 pain signal inhibitors acting in the peripheral nervous system to safely treat pain without addictive potential.

Metabolomic analysis of rat arterial serum under hypobaric hypoxia: Adaptive regulation of physiological systems by metabolic reprogramming

Objective

To investigate the associations between metabolic changes and functions, including energy metabolism, immune response, and redox balance, under short-term hypobaric hypoxia exposure. Non-targeted metabolomics and bioinformatics analysis were applied to explore the adaptive mechanisms of organisms in hypobaric hypoxia.

Methods

Healthy adult male Sprague-Dawley rats were placed in environments simulating altitudes of 6500 m (HC group) and 1588 m (Control group). After 14 days, arterial serum samples were analyzed using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). Significant metabolites (P < 0.05, VIP >1) were identified, and KEGG enrichment analysis was conducted. Differential metabolites were globally analyzed with MetaboAnalyst 5.0.

Results

A total of 117 significantly altered metabolites were identified. In the HC group, 84 metabolites significantly increased, while 33 metabolites significantly decreased compared to the Control group. KEGG enrichment analysis revealed significant metabolic pathways, including the PPAR signaling pathway, bile secretion, arginine biosynthesis, alcoholism, and cholesterol metabolism (P < 0.05). Global analysis indicated that these differential metabolites were involved in various pathways, such as energy metabolism, amino acid metabolism, nucleotide metabolism, lipid metabolism, vitamin and cofactor metabolism, steroid metabolism, neurotransmitter metabolism, and heme metabolism, all of which play crucial roles in multiple biological processes.

Conclusion

Short-term hypobaric hypoxia exposure significantly altered the metabolite profiles in the arterial serum samples of rats, revealing adaptive metabolic reprogramming in energy metabolism, redox balance, immune function, endocrine regulation, and neurological systems.

Effectiveness and Safety of Gabapentin versus Pregabalin in the Treatment of Postherpetic Neuralgia: A Retrospective Cohort Study

Aims/Background Postherpetic neuralgia (PHN) is a common chronic pain disease that persists after the rash (clusters of clear blisters on the surface of the skin) has healed, adversely affecting the quality of life of affected patients. Gabapentin (GPT) and pregabalin (PGB) are two commonly used drugs for the treatment of PHN, but there have been broad concerns regarding their efficacy and safety. Thus, this retrospective cohort study was conducted to investigate the effectiveness and safety of GPT versus PGB in the treatment of PHN. Methods A total of 150 patients with PHN receiving routine antiviral and neurotrophic therapies, admitted between January 2022 and November 2023, were selected. 71 patients who were treated with GPT were included in the control group, while the remaining 79 patients who were given PGB were categorized in the observation group. Information on clinical effectiveness, safety (xerostomia, drowsiness, blurred vision, ataxia, and dizziness), analgesic effect (Visual Analogue Scale [VAS] and time to pain relief), sleep quality (Sleep Quality Scale [SQS] and Pittsburgh Sleep Quality Index [PSQI]), and adverse emotions (Self-rating Anxiety/Depression Scale [SAS/SDS]) was collected for analysis. Results Compared to the control group, the observation group exhibited significantly higher clinical effectiveness of PGB in the treatment of PHN (p < 0.05). In other aspects, the overall incidence of adverse events such as xerostomia, drowsiness, blurred vision, ataxia, and dizziness (p > 0.05) was equivalent in these two groups. In addition, significantly lower VAS, SQS, PSQI, SAS, and SDS scores were observed in the observation group after treatment, compared with the control group (p < 0.05). The observation group showed evidently shorter time to pain relief than the other group (p < 0.05). Conclusion PGB is an effective and safe medication for the treatment of PHN, by improving the analgesic effect and sleep quality, and alleviating negative emotions.

Erector spinae plane block for intractable, nonsurgical abdominal pain: a scoping review

Abdominal pain is one of the most common presenting chief complaints in the emergency department. Erector spinae plane block (ESPB) is an ultrasound-guided nerve block with proven effectiveness in treating visceral and somatic abdominal pain. Despite the increasing popularity of ESPB, its role in the management of nonsurgical abdominal pain has not yet been characterized. Our scoping review aims to synthesize current knowledge on the safety and efficacy of ESPB in the management of patients experiencing intractable, nonsurgical abdominal pain. We searched PubMed and Scopus to evaluate the existing literature on ESPB for nonsurgical abdominal pain. A total of 14 journal articles were included: 12 case-based studies, one systematic review, and one narrative review. All cases described the successful use of ESPB in treating abdominal pain refractory to oral or intravenous analgesic medications, and no complications were reported in any cases. This scoping review provides support for the use of ESPB to manage intractable, nonsurgical abdominal pain. ESPB has demonstrated efficacy in alleviating various conditions such as functional abdominal pain, renal colic, pancreatitis, herpetic pain, and cancer-related pain. Theoretical risks such as pneumothorax, bleeding, and infection are possible, although the studies reviewed did not report such complications.

Negative allosteric modulator of Group Ⅰ mGluRs: Recent advances and therapeutic perspective for neuropathic pain

Neuropathic pain (NP) is a widespread public health problem that existing therapeutic treatments cannot manage adequately; therefore, novel treatment strategies are urgently required. G-protein-coupled receptors are important for intracellular signal transduction, and widely participate in physiological and pathological processes, including pain perception. Group I metabotropic glutamate receptors (mGluRs), including mGluR1 and mGluR5, are predominantly implicated in central sensitization, which can lead to hyperalgesia and allodynia. Many orthosteric site antagonists targeting Group I mGluRs have been found to alleviate NP, but their poor efficacy, low selectivity, and numerous side effects limit their development in NP treatment. Here we reviewed the advantages of Group I mGluRs negative allosteric modulators (NAMs) over orthosteric site antagonists based on allosteric modulation mechanism, and the challenges and opportunities of Group I mGluRs NAMs in NP treatment. This article aims to elucidate the advantages and future development potential of Group I mGluRs NAMs in the treatment of NP.

Enhancing analgesia in acute renal colic pain: a randomized controlled trial of gabapentin adjunct to ketorolac-based regimen

Background

Renal colic is characterized by severe pain that is highly disabling. Gabapentin, an antiepileptic medication, is often recommended as a first-line therapy for neuropathic pain. However, its effectiveness in managing somatic pain, which is defined as the result of activity by pain receptors in the deep tissues, such as renal colic pain, is not as well-established.

Method

A phase 3 randomized clinical trial was conducted to evaluate the adjuvant analgesic effects of gabapentin on acute renal colic pain. Eligible patients participated in the study via random allocation to the control or gabapentin groups using the block randomization method. All patients received a shared regimen of ketorolac and rescue morphine as the conventional analgesic treatment for renal colic pain. Gabapentin was added as an adjuvant analgesic for the gabapentin group.

Result

A total of 63 individuals with an average age of 41.35 ± 13.08, were enrolled and completed the study. At the time of admission, there were no significant differences between the baseline characteristics of two groups, with exception of weight. The gabapentin group showed a significantly higher percentage of patients with pain severity of less than 5 after 60 and 90 min, as well as a significantly lower percentage of morphine rescue requirement and total morphine intake (mg) and mg/kg.

Conclusion

In cases of acute renal colic, gabapentin significantly decreases both the amount of morphine required and the degree of pain, indicating that it may be a useful adjutant to standard analgesic regimens. Treatment regimens that include gabapentin may help individuals manage their pain and become less reliant on opioids.

Clinical Trial Registration

https://irct.behdasht.gov.ir/trial/56066, identifier: IRCT20200322046833N2.

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.

Ways of modulating GABA transporters to treat neurological disease

INTRODUCTION

The main inhibitory neurotransmitter in the central nervous system (CNS), γ-aminobutyric acid (GABA), is involved in a multitude of neurological and psychiatric disorders characterized by an imbalance in excitatory and inhibitory signaling. Regulation of extracellular levels of GABA is maintained by the four GABA transporters (GATs; GAT1, GAT2, GAT3, and BGT1), Na+/Cl--coupled transporters of the solute carrier 6 (SLC6) family. Despite mounting evidence for the involvement of the non-GAT1 GABA transporters in diseases, only GAT1 has successfully been translated into clinical practice via the drug tiagabine.

AREAS COVERED

In this review, all four GATs will be described in terms of their involvement in disease, and the most recent data on structure, function, expression, and localization discussed in relation to their potential role as drug targets. This includes an overview of various ways to modulate the GATs in relation to treatment of diseases caused by imbalances in the GABAergic system.

EXPERT OPINION

The recent publication of various GAT1 structures is an important milestone for future development of compounds targeting the GATs. Such information can provide much needed insight into mechanistic aspects of all GAT subtypes and be utilized to design improved ligands for this highly interesting drug target class.

Recent advances in the understanding and management of chronic pancreatitis pain

Abdominal pain is the most common symptom of chronic pancreatitis (CP) and is often debilitating for patients and very difficult to treat. To date, there exists no cure for the disease. Treatment strategies focus on symptom management and on mitigation of disease progression by reducing toxin exposure and avoiding recurrent inflammatory events. Traditional treatment protocols start with medical management followed by consideration of procedural or surgical intervention on selected patients with severe and persistent pain. The incorporation of adjuvant therapies to treat comorbidities including psychiatric disorders, exocrine pancreatic insufficiency, mineral bone disease, frailty, and malnutrition, are in its early stages. Recent clinical studies and animal models have been designed to improve investigation into the pathophysiology of CP pain, as well as to improve pain management. Despite the array of tools available, many therapeutic options for the management of CP pain provide incomplete relief. There still remains much to discover about the neural regulation of pancreas-related pain. In this review, we will discuss research from the last 5 years that has provided new insights into novel methods of pain phenotyping and the pathophysiology of CP pain. These discoveries have led to improvements in patient selection for optimization of outcomes for both medical and procedural management, and identification of potential future therapies.

Postoperative analgesic options after spine surgery: finding the optimal treatment strategies

INTRODUCTION

Spine surgery is one of the most common types of surgeries performed in the United States; however, managing postoperative pain following spine surgery has proven to be challenging. Patients with spine pathologies have higher incidences of chronic pain and resultant opioid use and potential for tolerance. Implementing a multimodal plan for postoperative analgesia after spine surgery can lead to enhanced recovery and outcomes.

AREAS COVERED

This review presents several options for analgesia following spine surgery with an emphasis on multimodal techniques to best aid this specific patient population. In addition to traditional therapeutics, such as acetaminophen, non-steroidal anti-inflammatory medications, and opioids, we discuss intrathecal morphine administration and emerging regional anesthesia techniques.

EXPERT OPINION

Several adjuncts to improve analgesia following spine surgery are efficacious in the postoperative period. Intrathecal morphine provides sustained analgesia and can be instilled intraoperatively by the surgical team under direct visualization. Local anesthetics deposited under ultrasound guidance by an anesthesiologist trained in regional techniques also provide the opportunity for single injections or continuous analgesia via an indwelling catheter.

Home-based high tone therapy may alleviate chemotherapy-induced neuropathic symptoms in patients with colorectal cancer: A randomized double-blind placebo-controlled pilot evaluation

BACKGROUND

Most oncologic patients receiving chemotherapy suffer from neuropathy, which not only severely affects quality of life but also may lead to chemotherapy dose reductions or even discontinuation of cancer therapy. Still, it is difficult to sufficiently control these symptoms with the currently available pharmacological treatments. High tone therapy was reported to be an effective option for neuropathies due to different etiologies. However, to date, there are no studies on high tone therapy in patients with chemotherapy-induced peripheral neuropathy.

METHODS

This randomized, double-blind, and placebo-controlled two-center study was conducted at the Departments of Physical and Rehabilitation Medicine at the Clinics Donaustadt and Ottakring, Vienna, Austria. Patients with histologically verified colorectal carcinoma treated with a platin derivate and neuropathic symptoms were invited to participate. High tone therapy took place in a home-based setting using the HiToP 191 PNP ® or placebo device for three weeks. Neuropathic symptoms and quality of life were assessed via questionnaires. After the follow-up examination, an opt-in was offered to the patients in the placebo group in terms of an open-label treatment with a verum HiToP PNP ® device. In addition, patients with chemotherapy-induced peripheral neuropathy due to various malignant diseases were treated in an open-label setting reflecting a clinical application observation. These patients are reported as a separate group.

RESULTS

In the verum group, there was a significant reduction of paresthesias and mental stress due to paresthesias from baseline until end of therapy, compared to placebo. These findings were observed in the opt-in subgroup, as well. In the open-label clinical application observation group, intensity and mental stress due to paresthesia, pain, cramps, and intensity of tightness/pressure were significantly lower at the end of therapy, compared to baseline.

CONCLUSIONS

Home-based high tone therapy brought about a significant alleviation in paresthesias and mental stress due to paresthesias in the verum but not the placebo group. In the clinical application observation, a significant alleviation in several further neuropathic symptoms was seen.

TRIAL REGISTRATION

This study was registered at clinicaltrials.gov (NCT06048471, 03/02/2020).

Research trends and hotspots of neuropathic pain in neurodegenerative diseases: a bibliometric analysis

Background

Neuropathic pain is caused by a neurological injury or disease and can have a significant impact on people's daily lives. Studies have shown that neuropathic pain is commonly associated with neurodegenerative diseases. In recent years, there has been a lot of literature on the relationship between neuropathic pain and neurodegenerative diseases. However, bibliometrics is rarely used in analyzing the general aspects of studies on neuropathic pain in neurodegenerative diseases.

Methods

The bibliometric analysis software CiteSpace and VOSviewer were used to analyze the knowledge graph of 387 studies in the Science Citation Index Expanded of the Web of Science Core Collection Database.

Results

We obtained 2,036 documents through the search, leaving 387 documents after culling. 387 documents were used for the data analysis. The data analysis showed that 330 papers related to neuropathic pain in neurodegenerative diseases were published from 2007-2022, accounting for 85.27% of all published literature. In terms of contributions to the scientific study of neuropathic pain, the United States is in the top tier, with the highest number of publications, citations, and H-indexes.

Conclusion

The findings in our study may provide researchers with useful information about research trends, frontiers, and cooperative institutions. Multiple sclerosis, Parkinson's disease, and Alzheimer's disease are the three most studied neurodegenerative diseases. Among the pathological basis of neurodegenerative diseases, microglia-regulated neuroinflammation is a hot research topic. Deep brain stimulation and gamma knife radiosurgery are two popular treatments.

Gabapentin: Clinical Use and Pharmacokinetics in Dogs, Cats, and Horses

Gabapentin is an anticonvulsant drug, which presents an established clinical efficacy in human patients for the management of refractory partial seizures, secondarily generalized tonic-clonic seizures, and for the control of chronic neuropathic pain. Gabapentin was synthesized as a structural analogue of the inhibitory neurotransmitter GABA, with GABA-mimetic effects, able to cross the blood-brain barrier. In veterinary medicine, is extra-label used in combination with other treatments to control seizures when other drugs are no longer effective or become toxic or for neuropathic pain treatment and anxiety. This review aimed to clarify gabapentin use and pharmacokinetic aspects to promote conscious use in dogs, cats, and horses. In dogs, gabapentin was beneficial in the treatment of epilepsy, as well as chronic, neuropathic, and post-operative pain, as well as anxiety. In cats, it showed efficacy in post-ovariohysterectomy-related pain and in anxiety management. In horses, gabapentin has been administered as an analgesic for chronic pain management. In conclusion, when used in combination with other drugs, gabapentin can be considered an interesting therapeutic option for the treatment of neuropathic diseases and analgesia in postoperative and chronic pain. However, despite its beneficial use in different clinical settings, further trials and pharmacokinetic studies are needed for the definition of an effective dosage regimen through proper pharmacokinetic/pharmacodynamic correlation in dogs, cats, and horses.