Gabapentin and pregabalin in bipolar disorder, anxiety states, and insomnia: Systematic review, meta-analysis, and rationale

Global trends and hotspots in pain associated with bipolar disorder in the last 20 years: a bibliometric analysis

Purpose

The prevalence of comorbid pain and Bipolar Disorder in clinical practice continues to be high, with an increasing number of related publications. However, no study has used bibliometric methods to analyze the research progress and knowledge structure in this field. Our research is dedicated to systematically exploring the global trends and focal points in scientific research on pain comorbidity with bipolar disorder from 2003 to 2023, with the goal of contributing to the field.

Methods

Relevant publications in this field were retrieved from the Web of Science core collection database (WOSSCC). And we used VOSviewer, CiteSpace, and the R package "Bibliometrix" for bibliometric analysis.

Results

A total of 485 publications (including 360 articles and 125 reviews) from 66 countries, 1019 institutions, were included in this study. Univ Toront and Kings Coll London are the leading research institutions in this field. J Affect Disorders contributed the largest number of articles, and is the most co-cited journal. Of the 2,537 scholars who participated in the study, Stubbs B, Vancampfort D, and Abdin E had the largest number of articles. Stubbs B is the most co-cited author. "chronic pain," "neuropathic pain," "psychological pain" are the keywords in the research.

Conclusion

This is the first bibliometric analysis of pain-related bipolar disorder. There is growing interest in the area of pain and comorbid bipolar disorder. Focusing on different types of pain in bipolar disorder and emphasizing pain management in bipolar disorder are research hotspots and future trends. The study of pain related bipolar disorder still has significant potential for development, and we look forward to more high-quality research in the future.

Effects of Gabapentin on the Treatment of Behavioral Disorders in Dogs: A Retrospective Evaluation

The use of gabapentin in treating dogs with behavioral disorders is not well described. To characterize behavioral effects of gabapentin, this study surveyed 50 owners whose dogs were prescribed gabapentin at a veterinary behavior-focused practice over a five-year period. Most owners (72%) reported that gabapentin was moderately or very effective at improving their dog's behavior. The majority of owners reported at least one side effect (70%), with sedation being the most common. Sedation was more likely to be seen at doses higher than 30 mg/kg. Specific dose ranges (mg/kg) did not correlate with any other reports of side effects nor effectiveness. Dogs with a diagnosis of conflict-related aggression were more likely to have owners report that gabapentin was effective at improving behavior compared to dogs with other behavioral diagnoses (p = 0.04), while dogs diagnosed with aggression secondary to high arousal were less likely to have owners report that gabapentin was effective (p = 0.01). Overall, reports of effect varied widely and, with the exception of sedation, did not correlate with specific mg/kg dose ranges. Results suggest that some dogs may be more sensitive or resistant to adverse and/or therapeutic effects than others and multiple dosage trials may be needed before finding the best fit.

Molecular Mechanisms and Therapeutic Potential of Gabapentin with a Focus on Topical Formulations to Treat Ocular Surface Diseases

Gabapentin (GBP) was originally developed as a potential agonist for Gamma-Amino-Butyric-Acid (GABA) receptors, aiming to inhibit the activation of pain-signaling neurons. Contrary to initial expectations, it does not bind to GABA receptors. Instead, it exhibits several distinct pharmacological activities, including: (1) binding to the alpha-2-delta protein subunit of voltage-gated calcium channels in the central nervous system, thereby blocking the excitatory influx of calcium; (2) reducing the expression and phosphorylation of CaMKII via modulation of ERK1/2 phosphorylation; (3) inhibiting glutamate release and interfering with the activation of NMDA receptors; (4) enhancing GABA synthesis; (5) increasing cell-surface expression of δGABA_A receptors, contributing to its antinociceptive, anticonvulsant, and anxiolytic-like effects. Additionally, GBP displays (6) inhibition of NF-kB activation and subsequent production of inflammatory cytokines, and (7) stimulation of the purinergic adenosine A1 receptor, which supports its anti-inflammatory and wound-healing properties. Initially approved for treating seizures and postherpetic neuralgia, GBP is now broadly used for various conditions, including psychiatric disorders, acute and chronic neuropathic pain, and sleep disturbances. Recently, as an eye drop formulation, it has also been explored as a therapeutic option for ocular surface discomfort in conditions such as dry eye, neurotrophic keratitis, corneal ulcers, and neuropathic ocular pain. This review aims to summarize the evidence supporting the molecular effects of GBP, with a special emphasis on its applications in ocular surface diseases.

Psychotropic prescribing after hospital discharge in survivors of critical illness, a retrospective cohort study (2012-2019)

Background

Many people survive critical illness with the burden of new or worsened mental health issues and sleep disturbances. We examined the frequency of psychotropic prescribing after critical illness, comparing critical care to non-critical care hospitalised survivors, and whether this varied in important subgroups.

Methods

This retrospective cohort study included 23,340 critical care and 367,185 non-critical care hospitalised adults from 2012 through 2019 in Lothian, Scotland, who survived to discharge.

Results

One-third of critical care survivors (32%; 7527/23,340) received a psychotropic prescription within 90 days after hospital discharge (25% antidepressants; 14% anxiolytics/hypnotics; 4% antipsychotics/mania medicines). In contrast, 15% (54,589/367,185) of non-critical care survivors received a psychotropic prescription (12% antidepressants; 5% anxiolytics/hypnotics; 2% antipsychotics/mania medicines). Among patients without psychotropic prescriptions within 180 days prior to hospitalisation, after hospital discharge, the critical care group had a higher incidence of psychotropic prescription (10.3%; 1610/15,609) compared with the non-critical care group (3.2%; 9743/307,429); unadjusted hazard ratio (HR) 3.39, 95% CI: 3.22-3.57. After adjustment for potential confounders, the risk remained elevated (adjusted HR 2.03, 95% CI: 1.91-2.16), persisted later in follow-up (90-365 days; adjusted HR 1.38, 95% CI: 1.30-1.46), and was more pronounced in those without recorded comorbidities (adjusted HR 3.49, 95% CI: 3.22-3.78).

Conclusions

Critical care survivors have a higher risk of receiving psychotropic prescriptions than hospitalised patients, with a significant proportion receiving benzodiazepines and other hypnotics. Future research should focus on the requirement for and safety of psychotropic medicines in survivors of critical illness, to help guide policy for clinical practice.

Reimagining old drugs with new tricks: Mechanisms, strategies and notable success stories in drug repurposing for neurological diseases

Recent evolution in drug repurposing has brought new anticipation, especially in the conflict against neurodegenerative diseases (NDDs). The traditional approach to developing novel drugs for these complex disorders is laborious, time-consuming, and often abortive. However, drug reprofiling which is the implementation of illuminating novel therapeutic applications of existing approved drugs, has shown potential as a promising strategy to accelerate the hunt for therapeutics. The advancement of computational approaches and artificial intelligence has expedited drug repurposing. These progressive technologies have enabled scientists to analyse extensive datasets and predict potential drug-disease interactions. By prospecting into the existing pharmacological knowledge, scientists can recognise potential therapeutic candidates for reprofiling, saving precious time and resources. Preclinical models have also played a pivotal role in this field, confirming the effectiveness and mechanisms of action of repurposed drugs. Several studies have occurred in recent years, including the discovery of available drugs that demonstrate significant protective effects in NDDs, relieve debilitating symptoms, or slow down the progression of the disease. These findings highlight the potential of repurposed drugs to change the landscape of NDD treatment. Here, we present an overview of recent developments and major advances in drug repurposing intending to provide an in-depth analysis of traditional drug discovery and the strategies, approaches and technologies that have contributed to drug repositioning. In addition, this chapter attempts to highlight successful case studies of drug repositioning in various therapeutic areas related to NDDs and explore the clinical trials, challenges and limitations faced by researchers in the field. Finally, the importance of drug repositioning in drug discovery and development and its potential to address discontented medical needs is also highlighted.

Orexinergic Receptor Antagonists as a New Therapeutic Target to Overcome Limitations of Current Pharmacological Treatment of Insomnia Disorder

Insomnia disorder is a common condition that is considered a risk factor for multiple physical and mental disorders, contributing to reduced quality of life and increased healthcare expenditures. Although cognitive behavioral therapy (CBT) is typically recommended as the primary intervention, its accessibility is hindered by limited resources, prompting the prevalent use of pharmacological interventions as the primary treatment in clinical settings. This study reviews the benefits and risks of current pharmacological treatments for insomnia, with special reference to the orexinergic system as a novel therapeutic target for treatment. The prescription of GABAergic mechanism enhancers (benzodiazepine (BZD) and "Z drugs") has shown efficacy in short-term insomnia treatment (less than 4 weeks), however, concerns arise regarding their long-term effectiveness, unfavorable tolerability and safety profiles, including the potential for dependency. Drugs with antihistamine properties, including certain antidepressants and antipsychotics, exhibit short-term efficacy but have documented tolerability limitations, especially in the elderly. The use of melatonin, available in various formulations, lacks comprehensive long-term data. Dual orexin receptor antagonists (DORAs) such as daridorexant, lemborexant, and suvorexant, represent a novel approach to insomnia treatment by inhibiting wakefulness rather than enhancing sedation. As the only DORA approved for insomnia treatment by the European Medicines Agency (EMA) and Food and Drug Administration (FDA), daridorexant has demonstrated sustained efficacy over a 12-month period, improving nocturnal sleep parameters and daytime functionality, with a favorable safety and tolerability profile.

Irrational Use of Medications among Adults with Insomnia: An Observational Study at a Sleep Clinic in Mexico

BACKGROUND

To determine the patterns of irrational use of medications among a sample of adult patients with insomnia.

METHODS

We included 89 adult patients diagnosed with chronic insomnia who had consumed medications for this disorder during the 12 months prior to admission to a specialized Sleep Disorders Clinic (SDC) in Mexico City. With a 13-item survey, information was gathered on patterns of medication use and irrational use, considering therapeutic indications, dose, route of administration, and duration of treatment.

RESULTS

The participants had taken hypnotics (65%), antidepressants (21%), anticonvulsants (8%), and antipsychotics (6%), and 92% had irrational use of their medication. Irrational use was greatest with benzodiazepines and antipsychotics. There were two main types of irrational use: (1) 47% of participants had consumed a drug unsuitable for their condition, although it was almost always prescribed by a doctor, and (2) 43% had consumed a drug for longer than the maximum time recommended.

CONCLUSION

It is worrisome to find that the irrational use of medications to treat insomnia, especially benzodiazepines and antipsychotics is widespread. Although most participants had acquired their medication by prescription, for many the drug was inappropriate to treat their condition. It should be mandatory that patients with insomnia receive specialized medical attention in primary clinical care.

Molecular mechanisms of cholinergic neurotransmission in visceral smooth muscles with a focus on receptor-operated TRPC4 channel and impairment of gastrointestinal motility by general anaesthetics and anxiolytics

Acetylcholine is the primary excitatory neurotransmitter in visceral smooth muscles, wherein it binds to and activates two muscarinic receptors subtypes, M2 and M3, thus causing smooth muscle excitation and contraction. The first part of this review focuses on the types of cells involved in cholinergic neurotransmission and on the molecular mechanisms underlying acetylcholine-induced membrane depolarisation, which is the central event of excitation-contraction coupling causing Ca2+ entry via L-type Ca2+ channels and smooth muscle contraction. Studies of the muscarinic cation current in intestinal myocytes (mICAT) revealed its main molecular counterpart, receptor-operated TRPC4 channel, which is activated in synergy by both M2 and M3 receptors. M3 receptors activation is of permissive nature, while activation of M2 receptors via Gi/o proteins that are coupled to them plays a direct role in TRPC4 opening. Our understanding of signalling pathways underlying mICAT generation has vastly expanded in recent years through studies of TRPC4 gating in native cells and its regulation in heterologous cells. Recent studies using muscarinic receptor knockout have established that at low agonist concentration activation of both M2 receptor and the M2/M3 receptor complex elicits smooth muscle contraction, while at high agonist concentration M3 receptor function becomes dominant. Based on this knowledge, in the second part of this review we discuss the cellular and molecular mechanisms underlying the numerous anticholinergic effects on neuroactive drugs, in particular general anaesthetics and anxiolytics, which can significantly impair gastrointestinal motility. This article is part of the Special Issue on "Ukrainian Neuroscience".

Insomnia: A Current Review

Insomnia is a prevalent sleep disorder with pervasive effects on quality of life. The deleterious effects of insomnia are largely preventable with appropriate therapeutic interventions. Pharmacotherapy should be initiated in patients with inadequate response to CBT-I and tailored to comorbidities. Referral to a sleep medicine specialist should be considered in patients with a suboptimal response.

Gabapentin Use Among Individuals Initiating Buprenorphine Treatment for Opioid Use Disorder

Importance

Gabapentin prescriptions have drastically increased in the US due to off-label prescribing in settings such as opioid use disorder (OUD) treatment to manage a range of comorbid conditions and withdrawal symptoms, despite a lack of evidence.

Objective

To assess the purpose and associated risks of off-label gabapentin use in OUD treatment.

Design, Setting, and Participants

This retrospective recurrent-event case-control study with a crossover design used administrative claims data from MarketScan Commercial and Multi-State Medicaid databases from January 1, 2006, to December 31, 2016. Individuals aged 12 to 64 years with an OUD diagnosis and filling buprenorphine prescriptions were included in the primary analysis conducted from July 1, 2022, through June 1, 2023. Unit of observation was the person-day.

Exposures

Days covered by filled gabapentin prescriptions.

Main Outcomes and Measures

Primary outcomes were receipt of gabapentin in the 90 days after initiation of buprenorphine treatment and drug-related poisoning. Drug-related poisonings were defined using codes from International Classification of Diseases, Ninth Revision, and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision.

Results

A total of 109 407 patients were included in the analysis (mean [SD] age, 34.0 [11.2] years; 60 112 [54.9%] male). Among the 29 967 patients with Medicaid coverage, 299 (1.0%) were Hispanic, 1330 (4.4%) were non-Hispanic Black, 23 112 (77.1%) were non-Hispanic White, and 3399 (11.3%) were other. Gabapentin was significantly less likely to be prescribed to Black or Hispanic patients, and more likely to be prescribed to female patients, those with co-occurring substance use or mood disorders, and those with comorbid physical conditions such as neuropathic pain. Nearly one-third of persons who received gabapentin (4336 [31.1%]) had at least 1 drug-related poisoning after initiating buprenorphine treatment, compared with 13 856 (14.5%) among persons who did not receive gabapentin. Adjusted analyses showed that days of gabapentin use were not associated with hospitalization for drug-related poisoning (odds ratio, 0.98 [95% CI, 0.85-1.13]). Drug-related poisoning risks did not vary based on dosage.

Conclusions and Relevance

Gabapentin is prescribed in the context of a myriad of comorbid conditions. Even though persons receiving gabapentin are more likely to have admissions for drug-related poisoning, these data suggest that gabapentin is not associated with an increased risk of drug-related poisoning alongside buprenorphine in adjusted analyses. More data on the safety profile of gabapentin in OUD settings are needed.

A peptidomimetic modulator of the CaV2.2 N-type calcium channel for chronic pain

Transmembrane Cav2.2 (N-type) voltage-gated calcium channels are genetically and pharmacologically validated, clinically relevant pain targets. Clinical block of Cav2.2 (e.g., with Prialt/Ziconotide) or indirect modulation [e.g., with gabapentinoids such as Gabapentin (GBP)] mitigates chronic pain but is encumbered by side effects and abuse liability. The cytosolic auxiliary subunit collapsin response mediator protein 2 (CRMP2) targets Cav2.2 to the sensory neuron membrane and regulates their function via an intrinsically disordered motif. A CRMP2-derived peptide (CBD3) uncouples the Cav2.2-CRMP2 interaction to inhibit calcium influx, transmitter release, and pain. We developed and applied a molecular dynamics approach to identify the A1R2 dipeptide in CBD3 as the anchoring Cav2.2 motif and designed pharmacophore models to screen 27 million compounds on the open-access server ZincPharmer. Of 200 curated hits, 77 compounds were assessed using depolarization-evoked calcium influx in rat dorsal root ganglion neurons. Nine small molecules were tested electrophysiologically, while one (CBD3063) was also evaluated biochemically and behaviorally. CBD3063 uncoupled Cav2.2 from CRMP2, reduced membrane Cav2.2 expression and Ca2+ currents, decreased neurotransmission, reduced fiber photometry-based calcium responses in response to mechanical stimulation, and reversed neuropathic and inflammatory pain across sexes in two different species without changes in sensory, sedative, depressive, and cognitive behaviors. CBD3063 is a selective, first-in-class, CRMP2-based peptidomimetic small molecule, which allosterically regulates Cav2.2 to achieve analgesia and pain relief without negative side effect profiles. In summary, CBD3063 could potentially be a more effective alternative to GBP for pain relief.

Growing Utilization of Radical Chemistry in the Synthesis of Pharmaceuticals

Our current unhealthy lifestyle and the exponential surge in the population getting affected by a variety of diseases have made pharmaceuticals or drugs an imperative part of life, making the development of innovative strategies for drug discovery or the introduction of refined, cost-effective and modern technologies for the synthesis of clinically used drugs, a need of the hour. Ever since their discovery, free radicals and radical cations or anions as reactive intermediates have captivated the chemists, resulting in an exceptional utilization of these moieties throughout the field of chemical synthesis, owing to their unprecedented and widespread reactivity. Sticking with the idea of not judging the book by its cover, despite the conventional thought process of radicals being unstable and difficult to control entities, scientists and academicians around the globe have done an appreciable amount of work utilizing both persistent as well as transient radicals for a variety of organic transformations, exemplifying them with the synthesis of significant biologically active pharmaceutical ingredients. This review truly accounts for the organic radical transformations including radical addition, radical cascade cyclization, radical/radical cross-coupling, coupling with metal-complexes and radical cations coupling with nucleophiles, that offers fascinating and unconventional approaches towards the construction of intricate structural frameworks of marketed APIs with high atom- and step-economy; complementing the otherwise employed traditional methods. This tutorial review presents a comprehensive package of diverse methods utilized for radical generation, featuring their reactivity to form critical bonds in pharmaceutical total synthesis or in building key starting materials or intermediates of their synthetic journey, acknowledging their excellence, downsides and underlying mechanisms, which are otherwise poorly highlighted in the literature. Despite great achievements over the past few decades in this area, many challenges and obstacles are yet to be unraveled to shorten the distance between the academics and the industry, which are all discussed in summary and outlook.

2023 Guidelines on the Diagnosis and Treatment of Insomnia in Adults - Brazilian Sleep Association

Chronic insomnia disorder (simplified in this document as insomnia) is an increasingly common clinical condition in society and a frequent complaint at the offices of different areas of health practice (particularly Medicine and Psychology). This scenario has been accompanied by a significant evolution in treatment, as well as challenges in approaching patients in an appropriately way. This clinical guideline, coordinated by the Brazilian Sleep Association and the Brazilian Association of Sleep Medicine and counting on the active participation of various specialists in the area, encompasses an update on the diagnosis and treatment of insomnia in adults. To this end, it followed a structured methodology. Topics of interest related to diagnosis were written based on theoretical framework, evidence in the literature, and professional experience. As for the topics related to the treatment of insomnia, a series of questions were developed based on the PICO acronym (P - Patient, problem, or population; I - Intervention; C - Comparison, control, or comparator; O - Outcome). The work groups defined the eligible options within each of these parameters. Regarding pharmacological interventions, only the ones currently available in Brazil or possibly becoming available in the upcoming years were considered eligible. Systematic reviews were conducted to help prepare the texts and define the level of evidence for each intervention. The final result is an objective and practical document providing recommendations with the best scientific support available to professionals involved in the management of insomnia.

Gabapentinoid consumption in 65 countries and regions from 2008 to 2018: a longitudinal trend study

Recent studies raised concerns about the increasing use of gabapentinoids in different countries. With their potential for misuse and addiction, understanding the global consumption of gabapentinoids will offer us a platform to examine the need for any interventional policies. This longitudinal trend study utilised pharmaceutical sales data from 65 countries and regions across the world to evaluate the global trends in gabapentinoid consumption between 2008-2018. The multinational average annual percentage change of gabapentinoid consumption was +17.20%, increased from 4.17 defined daily dose per ten thousand inhabitants per day (DDD/TID) in 2008 to 18.26 DDD/TID in 2018. High-income countries had the highest pooled gabapentinoid consumption rate (39.92 DDD/TID) in 2018, which was more than six times higher than the lower-middle income countries (6.11 DDD/TID). The study shows that despite differences in healthcare system and culture, a consistent increase in gabapentinoid consumption is observed worldwide, with high-income countries remaining the largest consumers.

Non-canonical pathways in the pathophysiology and therapeutics of bipolar disorder

Bipolar disorder (BD) is characterized by extreme mood swings ranging from manic/hypomanic to depressive episodes. The severity, duration, and frequency of these episodes can vary widely between individuals, significantly impacting quality of life. Individuals with BD spend almost half their lives experiencing mood symptoms, especially depression, as well as associated clinical dimensions such as anhedonia, fatigue, suicidality, anxiety, and neurovegetative symptoms. Persistent mood symptoms have been associated with premature mortality, accelerated aging, and elevated prevalence of treatment-resistant depression. Recent efforts have expanded our understanding of the neurobiology of BD and the downstream targets that may help track clinical outcomes and drug development. However, as a polygenic disorder, the neurobiology of BD is complex and involves biological changes in several organelles and downstream targets (pre-, post-, and extra-synaptic), including mitochondrial dysfunction, oxidative stress, altered monoaminergic and glutamatergic systems, lower neurotrophic factor levels, and changes in immune-inflammatory systems. The field has thus moved toward identifying more precise neurobiological targets that, in turn, may help develop personalized approaches and more reliable biomarkers for treatment prediction. Diverse pharmacological and non-pharmacological approaches targeting neurobiological pathways other than neurotransmission have also been tested in mood disorders. This article reviews different neurobiological targets and pathophysiological findings in non-canonical pathways in BD that may offer opportunities to support drug development and identify new, clinically relevant biological mechanisms. These include: neuroinflammation; mitochondrial function; calcium channels; oxidative stress; the glycogen synthase kinase-3 (GSK3) pathway; protein kinase C (PKC); brain-derived neurotrophic factor (BDNF); histone deacetylase (HDAC); and the purinergic signaling pathway.

Pro-Con Debate: Judicious Benzodiazepine Administration for Preoperative Anxiolysis in Older Patients

In this Pro-Con commentary article, we discuss the risks and benefits of administering preoperative benzodiazepines to older patients to decrease preoperative anxiety. The Pro side first focuses on the critical importance of treating preoperative anxiety and that benzodiazepines are the best tool to achieve that goal. The competing argument presented by the Con side is that myriad options exist to treat preoperative anxiety without simultaneously increasing the risk for devastating complications such as postoperative delirium. Both sides call for more high-quality investigations to determine the most effective strategies for decreasing preoperative anxiety in older adults while improving outcomes and reducing morbidity.

New "drugs and targets" in the GWAS era of bipolar disorder

OBJECTIVE

Due to the phenotypic heterogeneity and etiological complexity of bipolar disorder (BD), many patients do not respond well to the current medications, and developing novel effective treatment is necessary. Whether any BD genome-wide association study (GWAS) risk genes were targets of existing drugs or novel drugs that can be repurposed in the clinical treatment of BD is a hot topic in the GWAS era of BD.

METHODS

A list of 425 protein-coding BD risk genes was distilled through the BD GWAS, and 4479 protein-coding druggable targets were retrieved from the druggable genome. The overlapped genes/targets were subjected to further analyses in DrugBank, Pharos, and DGIdb datasets in terms of their FDA status, mechanism of action and primary indication, to identify their potential for repurposing.

RESULTS

We identified 58 BD GWAS risk genes grouped as the druggable targets, and several genes were given higher priority. These BD risk genes were targets of antipsychotics, antidepressants, antiepileptics, calcium channel antagonists, as well as anxiolytics and analgesics, either existing clinically-approved drugs for BD or the drugs than can be repurposed for treatment of BD in the future. Those genes were also likely relevant to BD pathophysiology, as many of them encode ion channel, ion transporter or neurotransmitter receptor, or the mice manipulating those genes are likely to mimic the phenotypes manifest in BD patients.

CONCLUSIONS

This study identifies several targets that may facilitate the discovery of novel treatments in BD, and implies the value of conducting GWAS into clinical translation.

Pharmacologic Management of Cancer-Related Pain in Pregnant Patients

Despite being an essential part of whole-person care, patients with cancer often experience complex and under-treated pain. Managing cancer-related pain in patients who are also pregnant compounds the challenge for adequate pain management, as studies have largely excluded this population. Therapy for pain management should be guided by the cause and mechanism of pain. The objective of this review is to provide clinicians with an understanding of pain experienced by pregnant patients with cancer and medications that may be used to help manage cancer-related pain. Nociceptive pain results from damage to somatic or visceral tissues that may be directly caused by cancer. This type of pain can be managed in pregnant patients using acetaminophen and/or nonsteroidal antiinflammatory drugs as first-line agents. In nociceptive pain not managed by non-opioid analgesics, buprenorphine is recommended for those requiring chronic opioids to help manage their pain. Neuropathic pain that results from damage to the peripheral or central nervous system may also be directly caused by cancer, particularly chemotherapy. In pregnant patients, duloxetine and gabapentin should be considered first. Venlafaxine, pregabalin, tricyclic antidepressants, and sodium channel blockers should be avoided, if possible. Nociplastic pain is not directly caused by cancer but may be caused by ongoing peripheral nociceptive input or a condition that predates the cancer diagnosis. Duloxetine and gabapentin are reasonable agents to consider for treatment of nociceptive pain in pregnant patients. Cyclobenzaprine may also be helpful for nociplastic pain.

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.

Bifunctional Iminophosphorane-Catalyzed Enantioselective Nitroalkane Addition to Unactivated α,β-Unsaturated Esters

Herein we describe the enantioselective intermolecular conjugate addition of nitroalkanes to unactivated α,β-unsaturated esters, catalyzed by a bifunctional iminophosphorane (BIMP) superbase. The transformation provides the most direct access to pharmaceutically relevant enantioenriched γ-nitroesters, utilizing feedstock chemicals, with unprecedented selectivity. The methodology exhibits a broad substrate scope, including β-(fluoro)alkyl, aryl and heteroaryl substituted electrophiles, and was successfully applied on a gram scale with reduced catalyst loading, and, additionally, catalyst recovery was carried out. The formal synthesis of a range of drug molecules, and an enantioselective synthesis of (S)-rolipram were achieved. Additionally, computational studies revealed key reaction intermediates and transition state structures, and provided rationale for high enantioselectivities, in good agreement with experimental results.

A Novel Flow Cytometry-Based Assay for the Identification of HCN4 CNBD Ligands

Hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels are promising therapeutic targets because of their association with the genesis of several diseases. The identification of selective compounds that alter cAMP-induced ion channel modulation by binding to the cyclic nucleotide-binding domain (CNBD) will facilitate HCN channel-specific drug development. In this study, a fast and protein purification-free ligand-binding approach with a surface-displayed HCN4 C-Linker-CNBD on E. coli is presented. 8-Fluo-cAMP ligand binding was monitored by single-cell analysis via flow cytometry, and a K_d-value of 173 ± 46 nM was determined. The K_d value was confirmed by ligand depletion analysis and equilibrium state measurements. Applying increasing concentrations of cAMP led to a concentration-dependent decrease in fluorescence intensity, indicating a displacement of 8-Fluo-cAMP. A K_i-value of 8.5 ± 2 µM was determined. The linear relationship of IC₅₀ values obtained for cAMP as a function of ligand concentration confirmed the competitive binding mode: IC₅₀: 13 ± 2 µM/16 ± 3 µM/23 ± 1 µM/27 ± 1 µM for 50 nM/150 nM/250 nM/500 nM 8-Fluo-cAMP. A similar competitive mode of binding was confirmed for 7-CH-cAMP, and an IC₅₀ value of 230 ± 41 nM and a K_i of 159 ± 29 nM were determined. Two established drugs were tested in the assay. Ivabradine, an approved HCN channel pore blocker and gabapentin, is known to bind to HCN4 channels in preference to other isoforms with an unknown mode of action. As expected, ivabradine had no impact on ligand binding. In addition, gabapentin had no influence on 8-Fluo-cAMP's binding to HCN4-CNBD. This is the first indication that gabapentin is not interacting with this part of the HCN4 channel. The ligand-binding assay as described can be used to determine binding constants for ligands such as cAMP and derivatives. It could also be applied for the identification of new ligands binding to the HCN4-CNBD.

Mood Stabilizers of First and Second Generation

The topic of this narrative review is mood stabilizers. First, the author's definition of mood-stabilizing drugs is provided. Second, mood-stabilizing drugs meeting this definition that have been employed until now are described. They can be classified into two generations based on the chronology of their introduction into the psychiatric armamentarium. First-generation mood stabilizers (FGMSs), such as lithium, valproates, and carbamazepine, were introduced in the 1960s and 1970s. Second-generation mood stabilizers (SGMSs) started in 1995, with a discovery of the mood-stabilizing properties of clozapine. The SGMSs include atypical antipsychotics, such as clozapine, olanzapine, quetiapine, aripiprazole, and risperidone, as well as a new anticonvulsant drug, lamotrigine. Recently, as a candidate for SGMSs, a novel antipsychotic, lurasidone, has been suggested. Several other atypical antipsychotics, anticonvulsants, and memantine showed some usefulness in the treatment and prophylaxis of bipolar disorder; however, they do not fully meet the author's criteria for mood stabilizers. The article presents clinical experiences with mood stabilizers of the first and second generations and with "insufficient" ones. Further, current suggestions for their use in preventing recurrences of bipolar mood disorder are provided.

Long-term benzodiazepine prescription in treatment-resistant depression: A national FACE-TRD prospective study

BACKGROUND

Benzodiazepine long-term use (BLTU) is a public health challenge. We lack data on the consequences of LBTU on the trajectory of treatment-resistant depression (TRD).

OBJECTIVE

To determine the prevalence of BLTU in a nationwide non-selected population of patients with TRD, to determine the rate of patients succeeding at withdrawing benzodiazepines at one year and to determine if persistent BLTU is associated with poorer mental health outcomes.

METHOD

The FACE-TRD cohort is a national cohort of TRD patients recruited in 13 resistant depression expert centers between 2014 and 2021 and followed-up at one year. A standardized one-day long comprehensive battery was carried out, including trained-clinician and patient-reported outcomes, and patients were reevaluated at one year.

RESULTS

At baseline, 45.2% of the patients were classified in the BLTU group. In multivariate analysis, compared to patients without BLTU, patients with BLTU were more frequently classified in the "low physical activity" group (adjusted odds ratio (aOR) = 1.885, p = 0.036), and had higher primary healthcare consumption (B = 0.158, p = 0.031) independently of age, sex and antipsychotic consumption. We found no significant difference for personality traits, suicidal ideation, impulsivity, childhood trauma exposure, earlier age at first major depressive episode, anxiety and sleep disorders (all p > 0.05). Despite recommendations for withdrawal, <5% of BLTU patients withdraw benzodiazepines during the one-year follow-up. Persistent BLTU at one-year was associated with higher depression severity (B = 0.189, p = 0.029), higher clinical global severity (B = 0.210, p = 0.016), higher state-anxiety (B = 0.266, p = 0.003), impaired sleep quality (B = 0.249, p = 0.008), increased peripheral inflammation (B = 0.241, p = 0.027), lower functioning level (B = -0.240, p = 0.006), decreased processing speed (B = -0.195, p = 0.020) and verbal episodic memory (B = -0.178, p = 0.048), higher absenteeism and productivity loss (B = 0.595, p = 0.016) and lower subjective global health status (B = -0.198, p = 0.028).

CONCLUSION

Benzodiazepines are over-prescribed in TRD (in almost a half of the patients). Despite recommendations for withdrawal and psychiatric follow-up, <5% of patients successfully stopped taking benzodiazepines at one-year. Maintaining BLTU may contribute to the worsening of clinical and cognitive symptoms and of daily functioning in TRD patients. Progressive and planed withdrawal of benzodiazepines seems therefore strongly recommended in TRD patients with BLTU. Pharmacological and non-pharmacological alternatives should be promoted when possible.

Co-prescribing of Central Nervous System-Active Medications for COPD Patients: Impact on Emergency Room Visits and Hospitalization

BACKGROUND

Anxiety and chronic pain are common comorbidities in patients with chronic obstructive pulmonary disease (COPD), which are frequently managed with benzodiazepines (BZDs) and opioids, respectively.

OBJECTIVE

The purpose of this study was to determine whether different combinations of opioids, BZD, and their substitutes-gabapentinoids (GABA) and selective serotonin reuptake inhibitors/serotonin-norepinephrine reuptake inhibitors (SSRIs/SNRIs)-are associated with lower risk of acute respiratory events in COPD patients with co-occurring chronic pain and anxiety.

METHODS

This retrospective cohort study used a nationally representative sample of Medicare beneficiaries with COPD, chronic pain, and anxiety. Patients were grouped based on drug combination (opioid + BZD/Z-hypnotics, opioid + GABA, opioid + SSRI/SNRI, BZD/Z-hypnotics + GABA, BZD/Z-hypnotics + SSRI/SNRI, GABA + SSRI/SNRI, or ≥3 drugs). The primary outcome was emergency room (ER) visit or hospitalization due to acute respiratory events assessed up to 180 days following initiation of drug combination. Overdose secondary to central nervous system (CNS)-related drugs was also assessed up to 180 days following initiation of drug combination.

RESULTS

The drug combination opioid + GABA was associated with decreased risk for ER visit (hazard ratio [HR] = 0.73; 95% CI = 0.61-0.87) and hospitalization (HR = 0.69; 95% CI = 0.55-0.85). Opioid + SSRI/SNRI also showed decreased risk for ER visit (HR = 0.84; 95% CI = 0.71-0.99). There was no significant difference in risk for CNS-related drug overdose among different drug combinations compared with opioid + BZD/Z-hypnotics.

CONCLUSION AND RELEVANCE

Opioids in combination with GABA and SSRI/SNRI demonstrate relatively lower risk for acute respiratory events among patients with COPD and comorbid chronic pain and anxiety. The findings emphasize the need for multimodal management in this vulnerable population.

Pharmacological treatment for older adults with epilepsy and comorbid neurodegenerative disorders

PURPOSE OF REVIEW

An increased interest in epilepsy in older adults has emerged as the global population ages. The purpose of this article is to review the literature regarding the pharmacological treatment of epilepsy in older adults, highlighting issues specifically pertinent to those living with comorbid neurodegenerative disorders.

RECENT FINDINGS

Although new original research remains sparse, in the last 5 years, there has been a growing number of studies addressing the relationship between epilepsy and neurodegenerative disorders. Accurate diagnosis is incredibly challenging with electroencephalogram findings often requiring circumspect interpretation. Older individuals are often excluded from or under-represented in clinical trials, and there are sparse guidelines offered on the management of these patients, with even less available in reference to those with neurodegenerative comorbidities.

SUMMARY

We propose that seizures occurring earlier in the neurodegenerative process should be treated aggressively, with the goal to inhibit neuro-excitotoxicity and the associated neuronal loss. By strategically choosing newer antiseizure medications with less adverse effects and a holistic approach to treatment, a patient's time living independently can be conserved. In addition, we advocate for original, multinational collaborative research efforts.

An update on potential pharmacotherapies for cognitive impairment in bipolar disorder

INTRODUCTION

Cognitive impairment is a core feature of bipolar disorder (BD) that impedes recovery by preventing the return to optimal socio-occupational functioning and reducing quality of life. Presently, there are no efficacious treatments for cognitive impairment in BD, but many pharmacological interventions are being considered as they have the potential to target the underlying pathophysiology of the disorder.

AREAS COVERED

This review summarizes the available evidence for pharmacological interventions for cognitive impairment in bipolar disorder. We searched PubMed, MedLine, and PsycInfo from inception to December 1^st, 2022. Traditional treatments, such as lithium, anticonvulsants (lamotrigine), antipsychotics (aripiprazole, asenapine, cariprazine, lurasidone, and olanzapine), antidepressants (vortioxetine, fluoxetine, and tianeptine) and psychostimulants (modafinil), and emerging interventions, such as acetylcholinesterase inhibitors (galantamine and donepezil), dopamine agonists (pramipexole), erythropoietin, glucocorticoid receptor antagonists (mifepristone), immune modulators (infliximab, minocycline and doxycycline), ketamine, metabolic agents (insulin, metformin, and liraglutide), probiotic supplements, and Withania somnifera are discussed.

EXPERT OPINION

The investigation of interventions for cognitive impairment in BD is a relatively under-researched area. In the past, methodological pitfalls in BD cognition trials have also been a critical limiting factor. Expanding on the existing literature and identifying novel pharmacological and non-pharmacological treatments for cognitive impairment in BD should be a priority.

Integrating mechanistic-based and classification-based concepts into perioperative pain management: an educational guide for acute pain physicians

Chronic pain begins with acute pain. Physicians tend to classify pain by duration (acute vs chronic) and mechanism (nociceptive, neuropathic and nociplastic). Although this taxonomy may facilitate diagnosis and documentation, such categories are to some degree arbitrary constructs, with significant overlap in terms of mechanisms and treatments. In clinical practice, there are myriad different definitions for chronic pain and a substantial portion of chronic pain involves mixed phenotypes. Classification of pain based on acuity and mechanisms informs management at all levels and constitutes a critical part of guidelines and treatment for chronic pain care. Yet specialty care is often siloed, with advances in understanding lagging years behind in some areas in which these developments should be at the forefront of clinical practice. For example, in perioperative pain management, enhanced recovery protocols are not standardized and tend to drive treatment without consideration of mechanisms, which in many cases may be incongruent with personalized medicine and mechanism-based treatment. In this educational document, we discuss mechanisms and classification of pain as it pertains to commonly performed surgical procedures. Our goal is to provide a clinical reference for the acute pain physician to facilitate pain management decision-making (both diagnosis and therapy) in the perioperative period.

Understanding motivations and use typologies of gabapentin with opioid agonist medications

BACKGROUND

Prior research suggests a potential relationship between the nonmedical use of gabapentin and use of opioid agonist medications (OAMs), buprenorphine and methadone. However, this research has been limited in scope and understanding despite increases in gabapentin prescribing in opioid use disorder (OUD) treatment settings and increased detection in opioid overdose fatalities.

METHODS

Data were analyzed for 346 participants of a follow-up program to an ongoing national opioid surveillance program of new entrants to treatment for opioid use disorder. Data were sourced from a cross-sectional online survey distributed in July/August 2021.

RESULTS

Lifetime exposure to gabapentin was reported by 60.0 % of the sample, while lifetime history of nonmedical use was reported by 43.2 %. Of those nonmedically using gabapentin, 50.0 % did so while also on a dosage of either buprenorphine or methadone, with 28.4 % engaged in concurrent nonmedical use of both gabapentin and OATs. Motivations for concurrent nonmedical use included high-seeking (38.6 %), self-management of pain/physical symptoms (33.3 %), and self-management of OUD (22.2 %).

CONCLUSIONS

Gabapentin exposure in treatment-seeking persons with OUD appears to be quite common, and use, both medically and nonmedically, frequently occurs alongside OAMs. Motivations for concurrent nonmedical use of gabapentin and OATs mirrors motivations for off-label prescribing by healthcare providers, but may also serve as a form of self-management of OUD when OAM regimens are interrupted, insufficiently prescribed or prescribed at insufficient dosages. Further research should seek to understand the risks versus benefits of gabapentin in OAM treatment settings.

CACNA1C (CaV1.2) and other L-type calcium channels in the pathophysiology and treatment of psychiatric disorders: Advances from functional genomics and pharmacoepidemiology

A role for voltage-gated calcium channels (VGCCs) in psychiatric disorders has long been postulated as part of a broader involvement of intracellular calcium signalling. However, the data were inconclusive and hard to interpret. We review three areas of research that have markedly advanced the field. First, there is now robust genomic evidence that common variants in VGCC subunit genes, notably CACNA1C which encodes the L-type calcium channel (LTCC) Ca_V1.2 subunit, are trans-diagnostically associated with psychiatric disorders including schizophrenia and bipolar disorder. Rare variants in these genes also contribute to the risk. Second, pharmacoepidemiological evidence supports the possibility that calcium channel blockers, which target LTCCs, might have beneficial effects on the onset or course of these disorders. This is especially true for calcium channel blockers that are brain penetrant. Third, long-range sequencing is revealing the repertoire of full-length LTCC transcript isoforms. Many novel and abundant CACNA1C isoforms have been identified in human and mouse brain, including some which are enriched compared to heart or aorta, and predicted to encode channels with differing functional and pharmacological properties. These isoforms may contribute to the molecular mechanisms of genetic association to psychiatric disorders. They may also enable development of therapeutic agents that can preferentially target brain LTCC isoforms and be of potential value for psychiatric indications.