Alpha-2 adrenergic receptor agonists: a review of current clinical applications

Structure-activity relationship of pharmacophores and toxicophores: the need for clinical strategy

OBJECTIVES

Sometimes clinical efficacy and potential risk of therapeutic and toxic agents are difficult to predict over a long period of time. Hence there is need for literature search with a view to assessing cause of toxicity and less efficacy of drugs used in clinical practice.

METHOD

Hence literatures were searched for physicochemical properties, chemical formulas, molecular masses, pH values, ionization, receptor type, agonist and antagonist, therapeutic, toxic and structure-activity relationship of chemical compounds with pharmacophore and toxicophore, with a view to identifying high efficacious and relative low toxic agents. Inclusion criteria were manuscripts published on PubMed, Scopus, Web of Science, PubMed Central, Google Scholar among others, between 1960 and 2023. Keywords such as pharmacophore, toxicophore, structure-activity-relationship and disease where also searched. The exclusion criteria were the chemicals that lack pharmacophore, toxicophore and manuscripts published before 1960.

RESULTS

Findings have shown that pharmacophore and toxicophore functional groups determine clinical efficacy and safety of therapeutics, but if they overlap therapeutic and toxicity effects go concurrently. Hence the functional groups, dose, co-administration and concentration of drugs at receptor, drug-receptor binding and duration of receptor binding are the determining factors of pharmacophore and toxicophore activity. Molecular mass, chemical configuration, pH value, receptor affinity and binding capacity, multiple pharmacophores, hydrophilic/lipophilic nature of the chemical contribute greatly to functionality of pharmacophore and toxicophore.

CONCLUSION

Daily single therapy, avoidance of reversible pharmacology, drugs with covalent adduct, maintenance of therapeutic dose, and the use of multiple pharmacophores for terminal diseases will minimize toxicity and improve efficacy.

Classics in Chemical Neuroscience: Medetomidine

Medetomidine is an FDA-approved α2-adrenoreceptor (α2-AR) agonist used as a veterinary sedative due to its analgesic, sedative, and anxiolytic properties. While it is marketed for veterinary use as a racemic mixture under the brand name Domitor, the pharmacologically active enantiomer, dexmedetomidine, is approved for sedation and analgesia in the hospital setting. Medetomidine has recently been detected in the illicit drug supply alongside fentanyl, xylazine, cocaine, and heroin, producing pronounced sedative effects that are not reversed by naloxone. The pharmacological effects along with the low cost of supply and lack of regulation for medetomidine has made it a target for misuse. Since 2022, medetomidine has been found as an adulterant in samples of seized drugs, as well as in toxicological analyses of patients admitted to the emergency department after suspected overdoses across several U.S. states and Canada. This Review will discuss the history, chemistry, structure-activity relationships, drug metabolism and pharmacokinetics (DMPK), pharmacology, and emergence of medetomidine as an adulterant in drug mixtures in the context of the current opioid drug crisis.

Efficacy and Safety of Alpha-2 Agonists in Autism Spectrum Disorder: A Systematic Review

BACKGROUND

This analysis is a systematic literature review assessing efficacy and adverse effects of three alpha-2 agonists for the symptomatic management of autism spectrum disorder (ASD).

METHODS

The present investigation involved an extensive systematic search for eligible studies in PubMed, Embase, Cochrane Library, and Google Scholar. Nine studies, collectively incorporating 226 patients, were assessed.

RESULTS

The results demonstrated promising indications for use of alpha-2 agonists in the symptomatic management of autism spectrum disorders, including improvement of hyperactivity, impulsivity, attention deficit symptoms, irritability, and stereotypies in many of the participants studied.

CONCLUSION

The present investigation encourages physicians to consider treatment outcomes of clonidine, guanfacine, and lofexidine to determine the most effective management of ASD-related symptoms and to minimize adverse effects. However, our review cannot provide definitive treatment protocols related to various study limitations.

Synergistic interaction between clonidine and ACPA on the modulation of anxiety-like behaviors in non-acute restraint stress and acute restraint stress conditions

The present research examined the possible role of α-2 adrenergic receptor drugs (clonidine, selective α-2 adrenergic receptor agonist, and yohimbine, competitive α-2 adrenoreceptor antagonist,) on the effect of arachidonylcyclopropylamide (ACPA), a cannabinoid CB1 receptor agonist, in non-acute restraint stress (NARS) and acute restraint stress (ARS) mice. The animals were unilaterally implanted with a cannula in the left lateral ventricle. ARS was carried out by movement restraint at a period of 4 h. An elevated plus-maze (EPM) apparatus was used to evaluate anxiety-like behaviors. The results indicated that induction of ARS for 4 h induced anxiogenic-like behavior due to the reduction of %OAT (the percentage of time spent in the open arms) in male mice. Additionally, ARS caused neuronal degeneration in the prefrontal cortex. On the other hand, alone intracerebroventricularly (i.c.v.) infusions of ACPA (0.5 µg/mouse) and clonidine (0.5 µg/mouse) increased %OAT, indicating an anxiolytic-like response in the NARS and ARS mice. In contrast, alone i.c.v. infusions of yohimbine (0.5 µg/mouse) decreased %OAT and %OAE (the percentage of entries to the open arms), proposing an anxiogenic-like effect in the NARS and ARS mice. When the subthreshold dose of ACPA and different doses of clonidine were co-injected, ACPA potentiated the anxiolytic-like behavior produced by clonidine in the ARS mice. On the other hand, when the ineffective dosage of ACPA and different dosages of yohimbine were co-infused, ACPA reversed the anxiogenic-like effect induced by yohimbine in the NARS and ARS mice. Moreover, the results revealed a synergistic effect between ACPA and clonidine upon induction of anxiolytic-like behaviors. It can be concluded that the interaction between clonidine and ACPA modulates the anxiety-like behaviors induced by stress in male mice.

Xylazine abuse, the growing risk: A review of its effects, upsurge use and associated fatalities in the USA and Puerto Rico

In the last decade, the opioid overdose epidemic has been exacerbated by the emerging drug of abuse, xylazine. This veterinary anesthetic, an alpha-2 agonist, not only potentiates the fatal effects of opioids but also causes toxic endothelial effects. This review aims to assess the impact of xylazine use and overdoses within the context of the opioid crisis as a public health issue. The research used data from scientific publications, state health reports, and analyses from the Institute of Forensic Sciences of Puerto Rico. The databases PubMed, Google Scholar, and Scopus were searched for relevant publications. The search strategy employed two groups of terms: the drug of interest (xylazine) and types of exposure (drug use, overdose, substance abuse, etc.). The initial search in PubMed was then extrapolated, and the search terms were adjusted for appropriate database syntax. According to the most recent publications and CDC data in the USA, approximately 95 % of fentanyl overdose cases involve xylazine, while the other 5 % of overdose cases are attributed solely to xylazine, predominantly administered intravenously. In the last four years, more than 4000 overdose deaths have been related to xylazine use; the northeastern United States had reported the most significant number of deaths. This number changes daily as reanalysis results and new data are published. Less than 50 % of states perform tests for xylazine detection or maintain statistical monitoring of overdoses related to this drug. The absence of testing impedes emergency room physicians from making accurate diagnoses, increasing the likelihood of fatal overdoses. This review highlights five major concerns: (1) The recognition of intoxication as a primary concern and the unavailability of alpha-2 antagonists for treatment. (2) The challenges in the clinical setting linked to xylazine abuse and its co-administration with substances like fentanyl and its analogs. (3) The necessity for robust government statistical resources for the unification and dissemination of critical overdose and emerging drug abuse detection information. (4) The need for effective rehabilitation programs, including psychosocial support and treatment interventions, to respond to this public health crisis. (5) The urgency for further research to understand the prevalence, toxic effects of chronic or acute use, and the clinical implications in xylazine users, including the development of alpha-2 antagonists for treatment. We conclude that addressing these concerns is crucial to working with the xylazine abuse situation.

Development progress of drugs for bipolar disorder: 75 Years after lithium proved effective

Bipolar disorder, a psychiatric condition identified by significant mood changes and a considerable genetic connection with schizophrenia, needs continuous and extensive management due to its common onset in adolescence and significant impact on psychosocial activities. While traditional mood stabilizers continue to be widely used, the pursuit of more effective treatments remains ongoing, with the current research targeting various stages of the disorder. This study provides a thorough examination of new pharmacological treatments for bipolar disorder, which are currently in Phase II and Phase III clinical trials up to 22 April 2024. A systematic search was conducted using the NIH National Library of Medicine, focusing on both repurposed and innovative drugs now in advanced stages of testing. The study identifies several promising therapeutic agents, including those intended for severe mood disorders with suicidal tendencies, and others aimed at treating mood-related neuroinflammation. Drugs that enhance dopamine stabilization and those that act on serotonin receptor activities were found notable. We also explored the strategic repurposing of already existing medications for broader therapeutic uses and looked into the potential of new formulations designed for the immediate management of symptoms. Our analysis highlights two main strategies for tackling bipolar disorder: finding new uses for existing drugs and developing new medications with unique actions. This approach shows continuous improvement in drug treatments, helping patients manage their condition better and addressing the complicated nature of bipolar disorder.

The 95% effective dose of dexmedetomidine to induce adequate sedation in patients with chronic insomnia disorder: a biased coin design up-and-down sequential allocation trial

BACKGROUND

Chronic insomnia disorder is a common sleep disorder. Previous studies have reported increased demand for anesthetics in patients with chronic insomnia disorder. However, few studies have investigated the effective dose of dexmedetomidine for sedation in patients with chronic insomnia disorder. We aimed to determine the 95% effective dose of dexmedetomidine to induce adequate sedation in patients with chronic insomnia disorder.

METHODS

This is a biased coin design up-and-down sequential allocation trial in patients aged 18-65 years with chronic insomnia disorder (n = 60). The dose of dexmedetomidine for the subsequent patient was determined based on the response of the previous patient, with an interval of 0.1 µg/kg. Sedation was assessed using the bispectral index. The 95% effective dose was calculated using isotonic regression.

RESULTS

The 95% effective dose of dexmedetomidine to induce adequate sedation in patients with chronic insomnia disorder was 1.75 (95% confidence interval, 1.70-1.94) µg/kg. Four patients (6.7%) experienced bradycardia and no other adverse events were observed during the study.

CONCLUSIONS

The 95% effective dose of dexmedetomidine to induce adequate sedation in patients with chronic insomnia disorder was 1.75 µg/kg.

TRIALS REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2200063212); first registered 01/09 /2022.

Exploring Novel Pharmacotherapy Candidates for Cannabis Use Disorder: Uncovering Promising Agents on the Horizon by Mechanism of Action

With rapid expansion of cannabis legalization worldwide, rates of cannabis use and cannabis use disorder (CUD) are increasing; the need for safe and effective medications to treat CUD is urgent. This narrative review evaluates evidence for promising pharmacotherapies to treat CUD from randomized, placebo-controlled trials. Pharmacotherapies for CUD are categorized based on compound targets (e.g., cannabinoid receptor 1 [CB1] agonists such as nabilone, serotonergic compounds such as bupropion, GABAergic compounds such as zolpidem) and outcomes are organized by predetermined withdrawal symptoms, cannabis craving, and cannabis relapse/use. Most promising pharmacotherapies for CUD are drugs that act on the endocannabinoid system and specifically at the CB1 receptor. Priority populations such as females, certain racial/ethnic groups, and age groups experience a different course of CUD progression, symptoms, and drug effects that are important to consider when evaluating outcomes related to CUD. Possible explanations for these disparities are explored, along with the clinical trials that explore these demographics in treating CUD with pharmacotherapies.

Cardiovascular health in kratom users; a narrative review

BACKGROUND

Kratom, also known as Mitragyna speciosa, is a plant that originates in Southeast Asia and possesses unique pharmacological characteristics. It is commonly consumed in the form of tea made by boiling the leaves or using the leaves to create the powder. According to its pain-relieving effects, the prevalence of kratom use around the world has increased, which has various implications for healthcare providers. Mitragynine is a well-known active compound in kratom.

OBJECTIVE

This review aims to provide a comprehensive perspective on the cardiovascular effects of mitragynine and its potential cardiotoxicity through the literature.

METHOD

Authors searched PubMed, Scopus, and Google Scholar databases using appropriate search strategies for each database. After the screening, all relevant studies were included.

RESULTS

Although kratom may have the potential for therapeutic benefits, it has been associated with multi-organ damage and cardiac toxicity in some cases. According to the available data, tachycardia and hypertension are the most common adverse effects. Other possible cardiovascular effects include atherosclerosis, ventricular arrhythmia, cardiomyopathy, dose-dependent prolonged QTc interval, myocarditis, cardiomegaly, and cardiopulmonary arrest.

CONCLUSION

While prior research has indicated the possible negative effects of mitragynine overdose on the cardiovascular system, there are no definitive conclusions, and additional investigations are needed.

Noradrenergic Mechanisms and Circuitry of Hyperkatifeia in Alcohol Use Disorder

Hyperkatifeia, the manifestation of emotional distress or pain, is a conceptual framework gaining traction throughout the alcohol and other substance use fields as an important driver of addiction. It is well known that previous or current negative life experiences can serve as powerful motivators for excessive alcohol consumption and precipitate the development of an alcohol use disorder (AUD). A major hallmark of later stages of AUD is the emergence of hyperkatifeia during withdrawal, which can persist well into protracted abstinence to drive relapse. Given these complex interactions, understanding the specific neuroadaptations that lie at the intersection of hyperkatifeia and AUD can inform ongoing therapeutic development. The monoamine norepinephrine is of particular interest. Noradrenergic dysfunction is implicated in AUD, anxiety, chronic stress, depression, and emotional and physical pain. Importantly, there are key sexual dimorphisms within the noradrenergic system that are thought to differentially impact the development and trajectory of AUD in women and men. In the current review, we discuss past and recent work on noradrenergic influences at each stage of the AUD cycle (binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation) through the lens of hyperkatifeia. Evidence from these studies support the prioritization of norepinephrine-specific drug development to treat AUD and the identification of AUD subpopulations that may benefit the most from these therapies (e.g., women or people with comorbid chronic pain or anxiety/stress disorders).

Evaluating the Physiologic Effects of Alfaxalone, Dexmedetomidine, and Midazolam Combinations in Common Blue-Tongued Skinks (Tiliqua scincoides)

Common blue-tongued skinks (Tiliqua scincoides) are popular pet reptiles; however, there has been limited research to investigate sedatives for this species. The purpose of this study was to measure the physiologic effects of four combinations of alfaxalone, dexmedetomidine, and midazolam for minor procedures such as intubation and blood collection. Eleven common blue-tongued skinks (Tiliqua scincoides) were used for this prospective, randomized cross-over study. The subcutaneous combinations were used as follows: 20 mg/kg alfaxalone (A); 10 mg/kg alfaxalone and 1 mg/kg midazolam (AM); 0.1 mg/kg dexmedetomidine and 1 mg/kg midazolam (DM); and 5 mg/kg alfaxalone, 0.05 mg/kg dexmedetomidine, and 0.5 mg/kg midazolam (ADM). Heart rate, respiratory rate, palpebral reflex, righting reflex, escape reflex, toe pinch withdrawal reflex, tongue flicking, and the possibility of intubation were recorded at baseline and every 5 min for 60 min. Venous blood gases were measured at baseline, full sedation, and recovery. Heart and respiratory rates decreased significantly in all groups, but the reductions were most prominent in DM and ADM. Analgesic effects, as measured by the toe pinch withdrawal reflex, were only observed in DM and ADM. Intubation was possible in all four protocols; however, it was not possible in two DM skinks. Based on these trials, ADM and AM are recommended for minor procedures in blue-tongue skinks.

Distinct binding conformations of epinephrine with α- and β-adrenergic receptors

Agonists targeting α2-adrenergic receptors (ARs) are used to treat diverse conditions, including hypertension, attention-deficit/hyperactivity disorder, pain, panic disorders, opioid and alcohol withdrawal symptoms, and cigarette cravings. These receptors transduce signals through heterotrimeric Gi proteins. Here, we elucidated cryo-EM structures that depict α2A-AR in complex with Gi proteins, along with the endogenous agonist epinephrine or the synthetic agonist dexmedetomidine. Molecular dynamics simulations and functional studies reinforce the results of the structural revelations. Our investigation revealed that epinephrine exhibits different conformations when engaging with α-ARs and β-ARs. Furthermore, α2A-AR and β1-AR (primarily coupled to Gs, with secondary associations to Gi) were compared and found to exhibit different interactions with Gi proteins. Notably, the stability of the epinephrine-α2A-AR-Gi complex is greater than that of the dexmedetomidine-α2A-AR-Gi complex. These findings substantiate and improve our knowledge on the intricate signaling mechanisms orchestrated by ARs and concurrently shed light on the regulation of α-ARs and β-ARs by epinephrine.

Adjuvant Analgesics in Acute Pain - Evaluation of Efficacy

PURPOSE OF THE REVIEW

Acute postoperative pain impacts a significant number of patients and is associated with various complications, such as a higher occurrence of chronic postsurgical pain as well as increased morbidity and mortality.

RECENT FINDINGS

Opioids are often used to manage severe pain, but they come with serious adverse effects, such as sedation, respiratory depression, postoperative nausea and vomiting, and impaired bowel function. Therefore, most enhanced recovery after surgery protocols promote multimodal analgesia, which includes adjuvant analgesics, to provide optimal pain control. In this article, we aim to offer a comprehensive review of the contemporary literature on adjuvant analgesics in the management of acute pain, especially in the perioperative setting. Adjuvant analgesics have proven efficacy in treating postoperative pain and reducing need for opioids. While ketamine is an established option for opioid-dependent patients, magnesium and α2-agonists have, in addition to their analgetic effect, the potential to attenuate hemodynamic responses, which make them especially useful in painful laparoscopic procedures. Furthermore, α2-agonists and dexamethasone can extend the analgesic effect of regional anesthesia techniques. However, findings for lidocaine remain inconclusive.

Assessing suicide risk in chronic pain management: a narrative review across drug classes

INTRODUCTION

Chronic pain presents a multifaceted challenge in clinical practice, necessitating a nuanced understanding of pharmacological interventions to optimize treatment outcomes. This review provides an outline of various pharmacological agents commonly used in chronic pain management and highlights their safety considerations, particularly regarding suicide risk.

AREAS COVERED

This review discusses the role of antidepressants, anticonvulsants, GABA receptor agonists, NMDA receptor antagonists, corticosteroids, cannabis and cannabinoids, bisphosphonates, calcitonin, and alpha-2 adrenergic receptor agonists in chronic pain management. It assesses their therapeutic benefits, potential for misuse, and psychiatric adverse effects, including the risk of suicide. Each pharmacological class is evaluated in terms of its efficacy, safety profile, and considerations for clinical practice. We searched peer-reviewed English literature on the topic using the MEDLINE database without time restrictions.

EXPERT OPINION

While pharmacological interventions offer promise in alleviating chronic pain, healthcare providers must carefully weigh their benefits against potential risks, including the risk of exacerbating psychiatric symptoms and increasing suicide risk. Individualized treatment approaches, close monitoring, and multidisciplinary collaboration are essential for optimizing pain management strategies while mitigating adverse effects. Ongoing research efforts are crucial for advancing our understanding of these pharmacological interventions and refining pain management practices.

Emerging therapies for treatment of agitation, psychosis, or apathy in Alzheimer's disease

INTRODUCTION

Agitation, psychosis, and apathy are prevalent and highly distressing neuropsychiatric symptoms (NPS) of Alzheimer's disease (AD) that have been linked to numerous negative outcomes, including increased mortality, worsened cognitive decline, and caregiver burden. Current treatments for AD-associated agitation, namely atypical antipsychotics, provide some benefits but may increase the risk of serious adverse events and death. Meanwhile, no pharmacotherapies have been approved by regulatory agencies for the treatment of psychosis or apathy in AD. Over the past decade, many new and repurposed drugs have emerged as potential therapeutic options for managing these challenging NPS.

AREAS COVERED

This review aims to provide a comprehensive summary of pharmacotherapies that have recently been investigated in phase 2 and 3 clinical trials for the treatment of agitation, psychosis, or apathy in AD.

EXPERT OPINION

Novel atypical antipsychotics, serotonergic antidepressants, cannabinoids, and dextromethorphan combination drugs have shown promising results for alleviating agitation. Pimavanserin appears to be the most effective emerging therapy for psychosis, while methylphenidate has demonstrated good efficacy for apathy. Further research on biomarkers of NPS severity and treatment response, as well as continued improvements in methodological approaches are needed to advance the field.

Targeting α1- and α2-adrenergic receptors as a countermeasure for fentanyl-induced locomotor and ventilatory depression

This study assessed the ability of α1 and α2-adrenergic drugs to decrease fentanyl-induced locomotor and ventilatory depression. Rats were given saline or fentanyl, followed by: (1) naltrexone, (2) naloxone, (3) nalmefene, (4) α1 agonist phenylephrine, (5) α1 antagonist prazosin, (6) α1D antagonist BMY-7378, (7) α2 agonist clonidine, (8) α2 antagonist yohimbine or (9) vehicle. All µ-opioid antagonists dose-dependently reversed fentanyl-induced locomotor and ventilatory depression. While the α1 drugs did not alter the effects of fentanyl, clonidine dose-dependently decreased locomotion and respiration with and without fentanyl. Conversely, yohimbine given at a low dose (0.3-1 mg/kg) stimulated ventilation when given alone and higher doses (>1 mg/kg) partially reversed (∼50 %) fentanyl-induced ventilatory depression, but not locomotor depression. High doses of yohimbine in combination with a suboptimal dose of naltrexone reversed fentanyl-induced ventilatory depression, suggestive of additivity. Yohimbine may serve as an effective adjunctive countermeasure agent combined with naltrexone to rescue fentanyl-induced ventilatory depression.

Cardiopulmonary adaptations of a diving marine mammal, the bottlenose dolphin: Physiology during anesthesia

Diving marine mammals are a diverse group of semi- to completely aquatic species. Some species are targets of conservation and rehabilitation efforts; other populations are permanently housed under human care and may contribute to clinical and biomedical investigations. Veterinary medical care for species under human care, at times, may necessitate the use of general anesthesia for diagnostic and surgical indications. However, the unique physiologic and anatomic adaptations of one representative diving marine mammal, the bottlenose dolphin, present several challenges in providing ventilatory and cardiovascular support to maintain adequate organ perfusion under general anesthesia. The goal of this review is to highlight the unique cardiopulmonary adaptations of the completely aquatic bottlenose dolphin (Tursiops truncatus), and to identify knowledge gaps in our understanding of how those adaptations influence their physiology and pose potential challenges for sedation and anesthesia of these mammals.

Effectiveness of dexmedetomidine on patient-centred outcomes in surgical patients: a systematic review and Bayesian meta-analysis

BACKGROUND

Dexmedetomidine is increasingly used for surgical patients requiring general anaesthesia. However, its effectiveness on patient-centred outcomes remains uncertain. Our main objective was to evaluate the patient-centred effectiveness of intraoperative dexmedetomidine for adult patients requiring surgery under general anaesthesia.

METHODS

We conducted a systematic search of MEDLINE, Embase, CENTRAL, Web of Science, and CINAHL from inception to October 2023. Randomised controlled trials (RCTs) comparing intraoperative use of dexmedetomidine with placebo, opioid, or usual care in adult patients requiring surgery under general anaesthesia were included. Study selection, data extraction, and risk of bias assessment were performed by two reviewers independently. We synthesised data using a random-effects Bayesian regression framework to derive effect estimates and the probability of a clinically important effect. For continuous outcomes, we pooled instruments with similar constructs using standardised mean differences (SMDs) and converted SMDs and credible intervals (CrIs) to their original scale when appropriate. We assessed the certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. Our primary outcome was quality of recovery after surgery. To guide interpretation on the original scale, the Quality of Recovery-15 (QoR-15) instrument was used (range 0-150 points, minimally important difference [MID] of 6 points).

RESULTS

We identified 49,069 citations, from which 44 RCTs involving 5904 participants were eligible. Intraoperative dexmedetomidine administration was associated with improvement in postoperative QoR-15 (mean difference 9, 95% CrI 4-14, n=21 RCTs, moderate certainty of evidence). We found 99% probability of any benefit and 88% probability of achieving the MID. There was a reduction in chronic pain incidence (odds ratio [OR] 0.42, 95% CrI 0.19-0.79, n=7 RCTs, low certainty of evidence). There was also increased risk of clinically significant hypotension (OR 1.98, 95% CrI 0.84-3.92, posterior probability of harm 94%, n=8 RCTs) and clinically significant bradycardia (OR 1.74, 95% CrI 0.93-3.34, posterior probability of harm 95%, n=10 RCTs), with very low certainty of evidence for both. There was limited evidence to inform other secondary patient-centred outcomes.

CONCLUSIONS

Compared with placebo or standard of care, intraoperative dexmedetomidine likely results in meaningful improvement in the quality of recovery and chronic pain after surgery. However, it might increase clinically important bradycardia and hypotension.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO (CRD42023439896).

Role of Adjuvants in Enhancing the Efficacy and Duration of Anesthesia Blocks: A Comprehensive Review

Anesthesia blocks are integral to modern pain management, offering targeted and effective relief for various surgical and procedural interventions. These techniques, including regional and peripheral nerve blocks (PNBs), involve the administration of local anesthetics to specific body areas, either through epidural, spinal, or direct nerve injections. While effective, incorporating adjuvants, substances added to local anesthetics, can significantly enhance their efficacy and prolong their duration. Adjuvants such as opioids, corticosteroids, alpha-2 agonists, and nonsteroidal anti-inflammatory drugs (NSAIDs) are used to amplify analgesic effects, reduce the need for general anesthesia, and improve postoperative outcomes. This review explores the role of adjuvants in optimizing anesthesia blocks, examining their mechanisms of action, clinical benefits, and safety considerations. Adding adjuvants can lead to enhanced pain control, reduced dosage of local anesthetics, and fewer systemic side effects. By integrating adjuvants into anesthesia practice, clinicians can achieve more precise and sustained pain management, tailoring approaches to individual patient needs and specific procedural demands. This comprehensive review highlights current evidence on using adjuvants, their impact on anesthesia block effectiveness, and future research directions. Understanding the role of adjuvants is crucial for improving patient outcomes and advancing pain management techniques in various surgical settings.

Are Alpha-2 Adrenergic Agonists Being Used in Infants?

Purpose: To identify and quantify adverse events (AEs) associated with alpha-2 adrenergic agonists prescribed for the treatment of glaucoma in infants. Methods: We queried the Federal Adverse Event Reporting System (FAERS) from 2004-2023Q1 for AE reports related to brimonidine use in patients aged 12 months or younger. We then conducted a disproportionality analysis using data mining algorithms, including the reporting odds ratio, proportional reporting ratio, empirical bayes geometric mean, and information component to identify significant symptoms. Results: We identified 35 unique AE reports associated with brimonidine. Of these, 27 cases involved hospitalization, 13 cases involved life-threatening complications, 18 cases reported other complications, and 1 case involved a congenital anomaly. The most commonly reported AE was hypotonia, occurring in 20 cases. This was followed by other systemic symptoms, including hypothermia, depressed level of consciousness, lethargy, general toxicity, and pallor, among others. All symptoms were found to be significant in the disproportionality analysis. Notably, most cases were not known to involve an ophthalmic route of exposure. Conclusions: The use of alpha-2 adrenergic agonists in infants aged 1 year or younger has been associated with various systemic AEs, including hypotension, respiratory depression, and central nervous system depression. Ophthalmologists should be aware of these potential risks. Further, more rigorous warnings should be in place to prevent unintentional exposure of infants to brimonidine.

Remimazolam in General Anesthesia: A Comprehensive Review of Its Applications and Clinical Efficacy

Remimazolam is a novel ultra-short-acting benzodiazepine with a unique pharmacokinetic profile that makes it an attractive option for use in general anesthesia. This review paper provides an in-depth analysis of remimazolam's applications in the field of general anesthesia, focusing on its pharmacological properties, clinical efficacy, safety profile, and potential advantages compared to other anesthetic agents. Remimazolam acts on GABAa receptors, offering rapid onset and recovery times due to its unique metabolic pathway involving tissue esterases. Clinical trials have demonstrated its efficacy in procedural sedation and general anesthesia, showing a favorable safety profile with minimal cardiovascular and respiratory depression. Compared to traditional anesthetics such as propofol, remimazolam presents distinct advantages, including predictable pharmacokinetics, reduced risk of prolonged sedation, and a reliable safety margin. These attributes position remimazolam as a promising agent in various clinical settings. The purpose of this review is to synthesize current evidence on remimazolam and discuss its potential to improve clinical outcomes in anesthesia practice.

Central α2-adrenergic mechanisms regulate human sympathetic neuronal discharge strategies

The present study investigated the impact of central α2-adrenergic mechanisms on sympathetic action potential (AP) discharge, recruitment and latency strategies. We used the microneurographic technique to record muscle sympathetic nerve activity and a continuous wavelet transform to investigate postganglionic sympathetic AP firing during a baseline condition and an infusion of a α2-adrenergic receptor agonist, dexmedetomidine (10 min loading infusion of 0.225 µg kg-1; maintenance infusion of 0.1-0.5 µg kg h-1) in eight healthy individuals (28 ± 7 years, five females). Dexmedetomidine reduced mean pressure (92 ± 7 to 80 ± 8 mmHg, P < 0.001) but did not alter heart rate (61 ± 13 to 60 ± 14 bpm; P = 0.748). Dexmedetomidine reduced sympathetic AP discharge (126 ± 73 to 27 ± 24 AP 100 beats-1, P = 0.003) most strongly for medium-sized APs (normalized cluster 2: 21 ± 10 to 5 ± 5 AP 100 beats-1; P < 0.001). Dexmedetomidine progressively de-recruited sympathetic APs beginning with the largest AP clusters (12 ± 3 to 7 ± 2 clusters, P = 0.002). Despite de-recruiting large AP clusters with shorter latencies, dexmedetomidine reduced AP latency across remaining clusters (1.18 ± 0.12 to 1.13 ± 0.13 s, P = 0.002). A subset of six participants performed a Valsalva manoeuvre (20 s, 40 mmHg) during baseline and the dexmedetomidine infusion. Compared to baseline, AP discharge (Δ 361 ± 292 to Δ 113 ± 155 AP 100 beats-1, P = 0.011) and AP cluster recruitment elicited by the Valsalva manoeuvre were lower during dexmedetomidine (Δ 2 ± 1 to Δ 0 ± 2 AP clusters, P = 0.041). The reduction in sympathetic AP latency elicited by the Valsalva manoeuvre was not affected by dexmedetomidine (Δ -0.09 ± 0.07 to Δ -0.07 ± 0.14 s, P = 0.606). Dexmedetomidine reduced baroreflex gain, most strongly for medium-sized APs (normalized cluster 2: -6.0 ± 5 to -1.6 ± 2 % mmHg-1; P = 0.008). These data suggest that α2-adrenergic mechanisms within the central nervous system modulate sympathetic postganglionic neuronal discharge, recruitment and latency strategies in humans. KEY POINTS: Sympathetic postganglionic neuronal subpopulations innervating the human circulation exhibit complex patterns of discharge, recruitment and latency. However, the central neural mechanisms governing sympathetic postganglionic discharge remain unclear. This microneurographic study investigated the impact of a dexmedetomidine infusion (α2-adrenergic receptor agonist) on muscle sympathetic postganglionic action potential (AP) discharge, recruitment and latency patterns. Dexmedetomidine infusion inhibited the recruitment of large and fast conducting sympathetic APs and attenuated the discharge of medium sized sympathetic APs that fired during resting conditions and the Valsalva manoeuvre. Dexmedetomidine infusion elicited shorter sympathetic AP latencies during resting conditions but did not affect the reductions in latency that occurred during the Valsalva manoeuvre. These data suggest that α2-adrenergic mechanisms within the central nervous system modulate sympathetic postganglionic neuronal discharge, recruitment and latency strategies in humans.

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.

Assessment of the molecular mechanism in fish using eugenol as anesthesia based on network pharmacology

Eugenol is a commonly used fish anesthetic, but its mechanism of action is not fully understood. This study employed network pharmacology, molecular docking, and molecular dynamics simulation to explore the anesthetic targets of eugenol in fish. Initially, 63 potential targets for eugenol anesthesia were identified using databases such as SwissTarget, TargetNet, GeneCards, OMIM, and TTD. The DAVID database was utilized to analyze the GO functions and KEGG pathways of these targets, revealing 384 GO enrichment terms and 43 KEGG pathways. These terms involved neuroactive ligand-receptor interaction, calcium signaling pathway, and synaptic transmission. Subsequently, AutodockTools software facilitated molecular docking with targets in the KEGG pathway for "neuroactive ligand-receptor interaction." The results showed that eugenol had a strong affinity with these proteins. Concurrently, molecular dynamics simulations were conducted on the proteins with the top four lowest binding energies (Cnr1, Oprk1, Nr3c1, and Chrm5a) in the presence of eugenol. The eugenol-protein complexes remained stable and equilibrated within the dynamic environment. The results indicated that eugenol-anesthesia might affect membrane receptors, neurotransmitters, and ion signaling. This study elucidates the anesthetic mechanism of eugenol, enriches the primary data on fish anesthesia, and offers new analytical tools for understanding the action mechanisms of fishery drugs.

A combination treatment based on drug repurposing demonstrates mutation-agnostic efficacy in pre-clinical retinopathy models

Inherited retinopathies are devastating diseases that in most cases lack treatment options. Disease-modifying therapies that mitigate pathophysiology regardless of the underlying genetic lesion are desirable due to the diversity of mutations found in such diseases. We tested a systems pharmacology-based strategy that suppresses intracellular cAMP and Ca2+ activity via G protein-coupled receptor (GPCR) modulation using tamsulosin, metoprolol, and bromocriptine coadministration. The treatment improves cone photoreceptor function and slows degeneration in Pde6βrd10 and RhoP23H/WT retinitis pigmentosa mice. Cone degeneration is modestly mitigated after a 7-month-long drug infusion in PDE6A-/- dogs. The treatment also improves rod pathway function in an Rpe65-/- mouse model of Leber congenital amaurosis but does not protect from cone degeneration. RNA-sequencing analyses indicate improved metabolic function in drug-treated Rpe65-/- and rd10 mice. Our data show that catecholaminergic GPCR drug combinations that modify second messenger levels via multiple receptor actions provide a potential disease-modifying therapy against retinal degeneration.

Symptomatic bradycardia associated with topical brimonidine gel (Mirvaso) administration: a case report

Background

Bradycardia can have a number of different aetiologies, including as a side effect of medications. Brimonidine is a rare, but recognized, cause of bradycardia. Brimonidine is indicated in the treatment of facial erythema in rosacea when given as topical brimonidine gel (Mirvaso). It may also be administered as eye drops for raised intraocular pressure in open-angle glaucoma and ocular hypertension. Brimonidine is an alpha-2 agonist, which if systemically absorbed can present with bradycardia, hypotension, and dizziness. The authors are unaware of any other case reports regarding topical administration of Mirvaso in an adult and symptomatic bradycardia.

Case summary

We present the case of a 78-year-old man with a background of rosacea, benign prostatic hyperplasia, and hypertension who had two separate admissions with symptomatic bradycardia. Electrocardiograms showed sinus bradycardia with AV block first degree, with rate recorded as low as 31 b.p.m. during a syncopal episode. These episodes of symptomatic bradycardia were intermittent and had a temporal association with topical administration of Mirvaso. He had no further episodes of bradycardia on discontinuation of Mirvaso and has remained symptom free for over 6 months.

Discussion

The topical administration of Mirvaso should be avoided to broken or inflamed skin. This is owing to the increased risk of systemic absorption, which as in this case report, may present with bradycardia. This case reiterates the importance of completing a full medication history including all topical and parenteral medications in patients with arrhythmia.

Role of Dexmedetomidine and Clonidine With Hyperbaric Ropivacaine in Subarachnoid Block: A Comprehensive Review

Subarachnoid block (SAB), a fundamental technique in regional anesthesia, offers efficient anesthesia for various surgical procedures with advantages including rapid onset, reliable anesthesia, and reduced systemic effects compared to general anesthesia. Hyperbaric ropivacaine, a long-acting local anesthetic, has gained popularity due to its favorable pharmacokinetic profile and safety profile. However, to extend the duration and enhance the quality of anesthesia provided by hyperbaric ropivacaine, adjuvants such as dexmedetomidine and clonidine are frequently employed. This comprehensive review explores the roles of dexmedetomidine and clonidine as adjuvants to hyperbaric ropivacaine in SAB. It examines their pharmacological mechanisms, clinical efficacy, safety profiles, and comparative effectiveness in prolonging analgesia and enhancing anesthesia. The review synthesizes evidence from clinical studies to delineate the synergistic effects of these adjuvants, their impact on patient outcomes, and their potential advantages over traditional anesthesia techniques. Through a detailed analysis of current literature and clinical practices, this review aims to provide insights into optimizing the use of dexmedetomidine and clonidine in SAB protocols. It discusses clinical implications, offers recommendations for practice, and identifies future research directions to further enhance the efficacy and safety of SAB using these adjuvants.

Centhaquine Increases Stroke Volume and Cardiac Output in Patients with Hypovolemic Shock

Introduction: Centhaquine is a resuscitative agent that acts on α2B adrenergic receptors. Its effect on cardiac output in hypovolemic shock patients has not been reported. Methods: This pilot study was conducted in 12 hypovolemic shock patients treated with centhaquine who participated in an open-label phase IV study (NCT05956418). Echocardiography was utilized to measure stroke volume (SV), cardiac output (CO), left ventricular outflow tract velocity time integral (LVOT-VTI) and diameter (LVOTd), heart rate (HR), left ventricular ejection fraction (LVEF) and fractional shortening (LVFS), and inferior vena cava (IVC) diameter before (0 min) and 60, 120, and 300 min after centhaquine (0.01 mg/kg) iv infusion for 60 min. Results: SV was significantly increased after 60, 120, and 300 min. CO increased significantly after 120 and 300 min despite a decrease in HR. IVC diameter and LVOT-VTI at these time points significantly increased, indicating the increased venous return. LVEF and LVFS did not change, while the mean arterial pressure (MAP, mmHg) increased after 120 and 300 min. Positive correlations between IVC diameter and SV (R2 = 0.9556) and between IVC diameter and MAP (R2 = 0.8928) were observed, which indicated the effects of an increase in venous return on SV, CO, and MAP. Conclusions: Centhaquine-mediated increase in venous return is critical in enhancing SV, CO, and MAP in patients with hypovolemic shock; these changes could be pivotal for reducing shock-mediated circulatory failure, promoting tissue perfusion, and improving patient outcomes. Trial Registration: CTRI/2021/01/030263 and NCT05956418.

Ingestion of Fluids of the Ocular Surface Containing Eye Drops of Imidazole Derivatives-Alpha Adrenergic Receptor Agonists as Paragons

Accidental poisonings by ingesting conjunctival fluid mixed with eye drops commonly involve alpha-2 adrenergic receptor agonists and tetrahydrozoline. These substances are recognized in commonly reported ingestions. Victims of all ages, otherwise in good health, often present as pale and lethargic to the emergency department (ED) after unintentionally ingesting topical eye medication. While eye drop poisoning cases in childhood include accidents during the play and poisonings in adults mean either suicide attempts or side effects caused by the systemic absorption of the substance, fluid of the ocular surface is a risk to all age groups. With this in mind, this study aimed to summarize data in the literature on tetrahydrozoline and alpha-2 adrenergic receptor agonists as dangerous medications, even when administered in low-bioavailability forms, such as eye drops. With this aim, a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant systematic review of relevant studies was conducted. A search of PubMed, Scopus, Web of Science, and EBSCOhost yielded nine studies that met the rigorous inclusion criteria. The primary studies were subject to a meta-analysis once a quality appraisal of the studies and a narrative synthesis of the extracted data had been conducted. The author hopes that this information will provide observations that will lead to better designs for over-the-counter eye drops, off-label drug usage policies, and parental attention.

Cannabinoid Analgesia in Postoperative Pain Management: From Molecular Mechanisms to Clinical Reality

Postoperative pain (POP) is a challenging clinical phenomenon that affects the majority of surgical patients and demands effective management to mitigate adverse outcomes such as persistent pain. The primary goal of POP management is to alleviate suffering and facilitate a seamless return to normal function for the patient. Despite compelling evidence of its drawbacks, opioid analgesia remains the basis of POP treatment. Novel therapeutic approaches rely on multimodal analgesia, integrating different pharmacological strategies to optimize efficacy while minimizing adverse effects. The recognition of the imperative role of the endocannabinoid system in pain regulation has prompted the investigation of cannabinoid compounds as a new therapeutic avenue. Cannabinoids may serve as adjuvants, enhancing the analgesic effects of other drugs and potentially replacing or at least reducing the dependence on other long-term analgesics in pain management. This narrative review succinctly summarizes pertinent information on the molecular mechanisms, clinical therapeutic benefits, and considerations associated with the plausible use of various cannabinoid compounds in treating POP. According to the available evidence, cannabinoid compounds modulate specific molecular mechanisms intimately involved in POP. However, only two of the eleven clinical trials that evaluated the efficacy of different cannabinoid interventions showed positive results.

Evaluation of the efficacy of silymarin and dexmedetomidine on kidney and lung tissue in the treatment of sepsis in rats with cecal perforation

Sepsis is a systemic inflammatory response syndrome that develops in the host against microorganisms. This response develops away from the primary infection site and results in end-organ damage. The present study aimed to investigate the protective and therapeutic effects on lung and kidney tissue of silymarin (S) and dexmedetomidine (DEX) applied 1 h before and after sepsis induced by the cecal ligation and puncture (CLP) method in rats. A total of 62 rats was randomly divided into eight groups: i) Control (n=6); ii) cecal perforation (CLP; n=8); iii) S + CLP (n=8; S + CLP; S administered 1 h before CPL); iv) CLP + S (n=8; S administered 1 h after CLP); v) DEX + CLP (n=8; D + CLP; DEX administered 1 h before CLP); vi) CLP + D (n=8; DEX administered 1 h after CLP); vii) SD + CLP (n=8; S and DEX administered 1 h before CLP) and viii) CLP + SD (n=8; S and DEX administered 1 h after CLP). After the cecum filled with stool, it was tied with 3/0 silk under the ileocecal valve and the anterior surface of the cecum was punctured twice with an 18-gauge needle. A total of 100 mg/kg silymarin and 100 µg/kg DEX were administered intraperitoneally to the treatment groups. Lung and kidney tissue samples were collected to evaluate biochemical and histopathological parameters. In the histopathological examination, all parameters indicating kidney injury; interstitial edema, peritubular capillary dilatation, vacuolization, ablation of tubular epithelium from the basement membrane, loss of brush border in the proximal tubule epithelium, cell swelling and nuclear defragmentation; were increased in the CLP compared with the control group. Silymarin administration increased kidney damage, including ablation of tubular epithelium from the basement membrane, compared with that in the CLP group. DEX significantly reduced kidney damage compared with the CLP and silymarin groups. The co-administration of DEX + silymarin decreased kidney damage, although it was not as effective as DEX-alone. To conclude, intraperitoneal DEX ameliorated injury in CLP rats. DEX + silymarin partially ameliorated injury but silymarin administration increased damage. As a result, silymarin has a negative effects with this dosage and DEX has a protective effect. In the present study, it was determined that using the two drugs together had a greater therapeutic effect than silymarin and no differences in the effects were not observed any when the application times of the agents were changed.

Resting and activated bovine neutrophils and eosinophils differ in their responses to adrenergic agonists

Polymorphonuclear cells (PMN) provide a rapid response to infection and tissue damage and stress can modify these critical innate immune defences. The study of adrenergic receptor (AR) expression and function in bovine PMNs is limited but both neutrophils and eosinophils express numerous AR genes but differ significantly in their expression of individual AR genes. A flow cytometric technique was developed to differentiate between bovine neutrophils and eosinophils so both neutrophil and eosinophil responses to adrenergic agonists could be analysed. Neutrophils and eosinophils displayed significantly different changes in CD11b, L-selectin, and CD44 expression when activated by bovine serum opsonized zymosan and recombinant bovine interferon gamma. The responses of activated and resting neutrophils and eosinophils were then compared following stimulation with endogenous adrenergic agonists, epinephrine (E) norepinephrine (NE), and synthetic agonists targeting α1-, α2-, or β-ARs. Both resting and activated neutrophils and eosinophils displayed differences in iROS, CD44, and L-selectin expression following stimulation with E and NE. Resting neutrophils displayed pro-inflammatory responses to both E and NE, while resting eosinophils displayed a pro-inflammatory response to only NE. No single synthetic adrenergic agonist fully recapitulated responses observed with either E or NE and responses to adrenergic agonists were dose-dependent. In conclusion, bovine eosinophils and neutrophils responded to multiple adrenergic agonists by altering expression of proteins involved in immune surveillance and pro-inflammatory responses. Significant differences in neutrophil and eosinophil responses to adrenergic agonists are consistent with their differences in AR gene expression. This highlights the importance of analysing separately these two PMN subpopulations when investigating the effects of either endogenous or synthetic AR agonists.

Dexmedetomidine Versus Fentanyl on Time to Extubation in Patients with Morbid Obesity Undergoing Laparoscopic Sleeve Gastrectomy

Background

Sleeve gastrectomy (SG) is an effective method for managing obesity. While opioids are used for their hemodynamic stability and their ability to reduce intraoperative stress, they also have reported side effects. Dexmedetomidine (DEX), an α2 adrenergic receptor agonist, is noted for its analgesic and anesthetic-sparing effects, leading to a higher quality of recovery.

Objectives

The study aims to compare the effects of fentanyl and dexmedetomidine (DEX) on the recovery of morbidly obese patients following laparoscopic sleeve gastrectomy (SG).

Methods

This randomized, double-blind study involved 64 patients, equally divided into two groups. The Dexmedetomidine group (Group D) received an intravenous (IV) loading dose of dexmedetomidine (1 μg/kg) over 15 minutes before anesthesia induction, followed by a 10 mL saline 0.9% infusion over 60 seconds during induction. Post-intubation, dexmedetomidine was administered at 0.5 μg/kg/h. The Fentanyl group (Group F) received a volume-matched saline 0.9% IV over 15 minutes pre-induction and fentanyl (1 μg/kg) diluted in 10 ml saline 0.9% IV over 60 seconds during induction. After intubation, a continuous fentanyl infusion was maintained at a rate of 1 μg/kg/hr.

Results

Extubation time was significantly shorter in the Dexmedetomidine group (Group D) at 8.25 ± 2.7 minutes compared to the Fentanyl group (Group F) at 10.47 ± 2.17 minutes, with a P-value of 0.001. Intraoperative heart rate and mean arterial blood pressure were also significantly lower in Group D than in Group F. Visual analogue scale (VAS) pain scores were significantly lower in Group D compared to Group F upon arrival at the post-anesthesia care unit and at 2 hours postoperatively (P-value < 0.05). Additionally, the morphine dose consumed in the first 12 hours after surgery was significantly lower in Group D (5.75 ± 2.20 mg) compared to Group F (8 ± 2.38 mg), with a P-value of 0.001.

Conclusions

For morbidly obese patients undergoing laparoscopic sleeve gastrectomy, dexmedetomidine (DEX) proves to be an effective anesthetic choice. It not only reduces extubation time but also lowers early postoperative visual analogue scale (VAS) pain scores and opioid consumption within the first 12 hours following surgery.

Opioid requirement and pain intensity after mandibular surgeries with dexmedetomidine administration in two ways: intraoperative infusion versus bolus injection

PURPOSE

The purpose of this study is to compare the opioid requirement and pain intensity after surgeries of mandibular fractures with administration of dexmedetomidine by two approaches of infusion and single bolus.

METHODS

In this double-blind clinical trial, the participants were randomized and matched in terms of age and gender in two groups (infusion and bolus). In both groups, the amount of narcotic used, hemodynamic indices, oxygen saturation, and pain intensity were collected based on the ten-point Visual Analogue Scale (VAS) at 7 time points for 24 h. SPSS version 24 software was used for data analysis. A significance level of less than 5% was considered.

RESULTS

A total of 40 patients were included in the study. There was no significant difference between the two groups in terms of gender, age, ASA class, and duration of surgery (P>0.05). There was no significant difference between the two groups in terms of nausea and vomiting and subsequently receiving anti-nausea medication (P>0.05). The need for opioid consumption after surgery was not different in two groups (P>0.05). Infusion of dexmedetomidine reduced postoperative pain more rapidly than its single bolus dose (P<0.05). However, over time, there was no significant difference between the two groups in terms of changes in oxygen saturation variables (P>0.05). Homodynamic indices including heart rate, systolic blood pressure, and diastolic blood pressure in the bolus group were significantly lower than the infusion group (P<0.05).

CONCLUSION

Administration of dexmedetomidine in the form of infusion can reduce postoperative pain better than bolus injection, with less probability of hypotension and bradycardia.

Alpha Alert: Utilization of Transdermal Clonidine for Refractory Agitation

Alpha-2 agonists are under-recognized for their class effects yet offer potential benefit in specialty palliative care via decreasing sympathetic output, inducing sedation, and modulating pain. Especially in clinical contexts where agitation predominates and patients are intolerant of oral medication route, transdermal medication delivery is advantageous. We report a case of agitated behaviors in setting of mixed Alzheimer/vascular-type dementia limiting hospital discharge to nursing facility that were ameliorated with transdermal clonidine. We suggest palliative clinicians routinely conceptualize the seemingly disparate alpha-2 agonists as a class for effective symptom palliation especially as new clinical evidence becomes available.

Sedation for Colonoscopy Procedures Using Dexmedetomidine Versus Propofol-Fentanyl Infusions: A Prospective Randomized Controlled Trial

Objective

Different anaesthetists for sedation or monitored anaesthesia care have been used for colonoscopy. The target of this research was the ability to perform colonoscopy under a painless degree of sedation and the prevalence of undesired proceedings.

Methods

A total of 60 patients were randomly divided into two groups: Group D received dexmedetomidine and Group PF received propofol-fentanyl. Patients in both groups received the same infusion ratio. The minimum infusion amount of dexmetatomidine is (0.1 to 0.4 μg kg-1 h-1) in Group D, whereas fentanyl is administered at a rate of 0.01 to 0.05 μg kg-1 min-1 in the PF group during the approximately 45-min colonoscopy.

Results

Group D exhibited significantly lower modified Observer's Assessment of Alertness/Sedation (OAA/S) scores at intraoperative time points T1-T12. Group D also exhibited significantly lower visual analog scale scores for pain at intraoperative time points T4 and T7. The mean arterial pressure was significantly lower in Group D at intraoperative times T6-T8 and T11-T12, as well as upon admission to the post-anaesthesia care unit (PACU) and 30 min after admission to the PACU. The results of the ANOVA tests revealed a significantly lower heart rate in Group D. The respiratory rate exhibited a notable decrease during time intervals T8 and T10 in the PF group.

Conclusion

The administration of dexmetatomidine and propofol-fentanyl during colonoscopy was found to be safe. In addition, dexmetatomidine may present significant benefits in this context because of its lower occurrence of adverse respiratory events.

Not Carfentanil-A Case of Unexpected Xylazine Detection

Historically, xylazine has been utilized in veterinary medicine for decades as an anesthetic and analgesic sedative to facilitate safe handling, diagnostic testing, and surgical procedures in large animals. Currently, xylazine is an emerging threat to human health. It has been detected in the illicit drug supply chain, often as an adulterant. It has been more commonly added to illicit substances, most notably fentanyl, by drugmakers to enhance drug effect. End users are often unaware of its presence. This is alarming given the large number of xylazine-involved overdose deaths while laboratory detections are deficient and reversal agents are absent. Herein, we present the first documented case of xylazine identified via gas chromatography-tandem mass spectrometry at University of California Davis Health despite a peculiarly mild clinical presentation. We hope to increase awareness of this potentially fatal adulterant that is often missed in evaluation and engender further opportunities to study this ongoing issue.

Rosacea in Older Adults and Pharmacologic Treatments

Rosacea is a chronic inflammatory skin condition that is often more severe in older patients. The main clinical features are erythema, telangiectasia, and inflammatory lesions of the face. The pathogenesis of this condition is not fully understood but certainly multifaceted. Immune and inflammatory dysregulation, genetics, neurogenic dysregulation, microbiome dysbiosis, and systemic disease have all been implicated in rosacea pathogenesis. As we better understand the various pathways that lead to rosacea, we acknowledge that the different symptoms may have unique underlying triggers and mechanisms. Aging also impacts rosacea diagnosis and treatment. Older adults have more severe rosacea symptoms while also having more sensitive and fragile skin than younger patients; therefore, rosacea treatments for older patients require a balance between delivering adequate potency while also minimizing skin irritation and other adverse effects. Until recently, rosacea diagnoses were based on concrete subtypes that did not necessarily capture each patient's manifestation of rosacea. There is now an emphasis on more personalized phenotype-based diagnoses and treatments, which allows for more emphasis on treating individual symptoms and accounting for the unique characteristics of older patients. Centrofacial erythema is best treated with brimonidine and oxymetazoline, while phymatous change and telangiectasia are best treated with surgery and laser ablation. Treatment for rosacea papules and pustules ranges from topicals, such as azelaic acid, ivermectin, metronidazole, minocycline, and encapsulated benzoyl peroxide, to systemics, such as doxycycline and isotretinoin. It is important to understand these treatments in relation to adverse effects and drug interactions that may specifically arise in older populations to provide optimal care. As we advance in understanding rosacea's pathogenesis and adopt personalized phenotype-based approaches, optimizing care for older patients becomes crucial. Continued research into novel treatments is essential to address their unique needs.

Pharmacokinetics and pharmacodynamics of intravenous dexmedetomidine (2 μg∙kg-1) in dogs

This study assessed the pharmacokinetics and pharmacodynamics of low-dose dexmedetomidine after IV bolus in dogs. Six healthy adult dogs (6.8 ± 3.0 kg) received dexmedetomidine (2 μg.kg-1 IV) over 2 min, using an infusion pump. Blood samples were collected totaling 5 h of monitoring. A validated UHPLC-MS/MS method was used to determine the plasma concentration of dexemedetomidine. For pharmacodynamics, HR, RR, oscillometric MBP, Grint END sedation score were evaluated at baseline (T0), every 3 min (T3 to T21), and after 30 (T30) and 60 (T60) minutes, with p < 0.05. T1/2 was 28.28 ± 6.14 min; the area under the curve was 467.44 ± 60.42 ng/mL/min. The total clearance was 5.46 ± 0.41 mL/min/kg, the Vdss was 146.19 ± 21.04 mL/kg, and the C max was 3.13 ± 1.15 ng/mL. HR (bpm) decreased significantly from T6 (79 ± 21) to T21 (78 ± 31) compared to T0 (116 ± 28). RR(mpm) decreased from T3 (43 ± 44) to T60 (41 ± 23), with T0 being 70 ± 48. The MBP (mmHg) increased at T18 (151 ± 34), T21 (152 ± 35), and T30 (140 ± 27), compared to T0 (111 ± 22). Sedation occurred at all times post-bolus, with a maximum peak at T12 (END 8 ± 6). The low dose of dexmedetomidine provided sedation in all animals, characterizing rapid metabolization and elimination. However, cardiovascular effects still may have negative repercussions in dogs with hemodynamic comorbidities, highlighting the caution and individualization of its use in certain patients.

Comparison between dexmedetomidine and lidocaine for attenuation of cough response during tracheal extubation: A systematic review and meta-analysis

Background and Aims

Tracheal extubation often causes cardiovascular and airway responses, potentially resulting in hazardous consequences. It remains unknown whether dexmedetomidine or lidocaine is more effective for cough suppression. Hence, we conducted a systematic review and meta-analysis of randomised controlled trials to compare the effectiveness and safety of dexmedetomidine and lidocaine in reducing cough response after tracheal extubation in adult patients.

Methods

A thorough search of electronic databases, including PubMed, Embase, Cochrane Library, and Web of Science, was conducted to identify relevant studies (from inception to 31 January 2023). Randomised controlled trials comparing intravenous (IV) dexmedetomidine versus IV lidocaine administration during emergence from anaesthesia to prevent tracheal extubation response in adult patients under general anaesthesia were included. The primary outcome was the incidence of post-extubation cough. Secondary outcomes included emergence time, extubation time, residual sedation, and incidences of bradycardia. Statistical analysis was conducted using RevMan software. The Cochrane risk of bias tool was used to evaluate the potential risk for bias.

Results

In total, seven studies with 450 participants were included. There was no statistically significant difference in the incidence of cough between dexmedetomidine and lidocaine groups [Risk Ratio = 0.76; 95% Confidence Interval: 0.46, 1.24]. Emergence and extubation times were not significantly different between the two groups. Meta-analysis revealed a higher incidence of bradycardia and residual sedation in dexmedetomidine compared to the lidocaine group.

Conclusion

This meta-analysis found no difference in cough, emergence, and extubation time between dexmedetomidine and lidocaine after tracheal extubation. However, residual sedation and bradycardia were more significant in dexmedetomidine than in lidocaine.

Ferroptosis and circular RNAs: new horizons in cancer therapy

Cancer poses intricate challenges to treatment due to its complexity and diversity. Ferroptosis and circular RNAs (circRNAs) are emerging as innovative therapeutic avenues amid the evolving landscape of cancer therapy. Extensive investigations into circRNAs reveal their diverse roles, ranging from molecular regulators to pivotal influencers of ferroptosis in cancer cell lines. The results underscore the significance of circRNAs in modulating molecular pathways that impact crucial aspects of cancer development, including cell survival, proliferation, and metastasis. A detailed analysis delineates these pathways, shedding light on the molecular mechanisms through which circRNAs influence ferroptosis. Building upon recent experimental findings, the study evaluates the therapeutic potential of targeting circRNAs to induce ferroptosis. By identifying specific circRNAs associated with the etiology of cancer, this analysis paves the way for the development of targeted therapeutics that exploit vulnerabilities in cancer cells. This review consolidates the existing understanding of ferroptosis and circRNAs, emphasizing their role in cancer therapy and providing impetus for ongoing research in this dynamic field. See also the graphical abstract(Fig. 1).

Impact of anesthetics on rat hippocampus and neocortex: A comprehensive proteomic study based on label-free mass spectrometry

Anesthesia is regarded as an important milestone in medicine. However, the negative effect on memory and learning has been observed. In addition, the impact of anesthetics on postoperative cognitive functions is still discussed. In this work, in vivo experiment simulating a general anesthesia and ICU sedation was designed to assess the impact of two intravenous (midazolam, dexmedetomidine) and two inhalational (isoflurane, desflurane) agents on neuronal centers for cognition (neocortex), learning, and memory (hippocampus). More than 3600 proteins were quantified across both neocortex and hippocampus. Proteomic study revealed relatively mild effects of anesthetics, nevertheless, protein dysregulation uncovered possible different effect of isoflurane (and midazolam) compared to desflurane (and dexmedetomidine) to neocortical and hippocampal proteins. Isoflurane induced the upregulation of hippocampal NMDAR and other proteins of postsynaptic density and downregulation of GABA signaling, whereas desflurane and dexmedetomidine rather targeted mitochondrial VDAC isoforms and protein regulating apoptotic activity.

Case of tizanidine withdrawal showing hallucination, decorticate posture and tremor, with hypersympathetic vital signs

Tizanidine, an α2-adrenergic receptor agonist commonly prescribed as a muscle relaxant, has been associated with limited cases of acute intoxication or withdrawal. Here, we present a case of tizanidine withdrawal in a woman in her 40s who presented with an unusual combination of systemic and neurological symptoms. These included hallucinations, decorticate posture, limb and eyelid tremors, along with hypertension, tachycardia and tachypnoea. The diagnosis of tizanidine withdrawal was established by a comprehensive assessment of the patient's medical history and the systematic exclusion of other potential diseases. Our approach to managing the withdrawal symptoms was to initiate symptomatic treatment with a combination of a beta-blocker and a calcium channel blocker. Remarkably, this intervention successfully resolved both vital signs and neurological manifestations by the following day. In conclusion, tizanidine withdrawal is associated with a distinct and diagnostically significant neurological syndrome characterised by hallucinations, decorticate posture, tremors and hypersympathetic vital signs.

The role of perioperative sedative anesthetics in preventing postoperative delirium: a systematic review and network-meta analysis including 6679 patients

OBJECTIVE

Postoperative delirium is a common and debilitating complication that significantly affects patients and their families. The purpose of this study is to investigate whether there is an effective sedative that can prevent postoperative delirium while also examining the safety of using sedatives during the perioperative period.

METHODS

The net-meta analysis was used to compare the incidence of postoperative delirium among four sedatives: sevoflurane, propofol, dexmedetomidine, and midazolam. Interventions were ranked according to their surface under the cumulative ranking curve (SUCRA).

RESULTS

A total of 41 RCT studies involving 6679 patients were analyzed. Dexmedetomidine can effectively reduce the incidence of postoperative delirium than propofol (OR 0.47 95% CI 0.25-0.90), midazolam (OR 0.42 95% CI 0.17-1.00), normal saline (OR 0.42 95% CI 0.33-0.54) and sevoflurane (OR 0.39 95% CI 0.18-0.82). The saline group showed a significantly lower incidence of bradycardia compared to the group receiving dexmedetomidine (OR 0.55 95% CI 0.37-0.80). In cardiac surgery, midazolam (OR 3.34 95%CI 2.04-5.48) and normal saline (OR 2.27 95%CI 1.17-4.39) had a higher rate of postoperative delirium than dexmedetomidine, while in non-cardiac surgery, normal saline (OR 1.98 95%CI 1.44-2.71) was more susceptible to postoperative delirium than dexmedetomidine.

CONCLUSION

Our analysis suggests that dexmedetomidine is an effective sedative in preventing postoperative delirium whether in cardiac surgery or non-cardiac surgery. The preventive effect of dexmedetomidine on postoperative delirium becomes more apparent with longer surgical and extubation times. However, it should be administered with caution as it was found to be associated with bradycardia.

Naphazoline intoxication managed with minimally invasive cardiac output monitoring

Naphazoline, a nonspecific alpha-adrenoceptor stimulant, is a potent vasoconstrictor used in nasal sprays, eye drops, and over-the-counter antiseptics. Naphazoline intoxication increases afterload by constricting the peripheral arteries, which can lead to complications including multiple organ failure. Although phentolamine, a nonselective alpha-adrenoceptor antagonist, and nicardipine, a calcium channel blocker, are used for the treatment of naphazoline intoxication, no established administration protocols currently exist. We present the case of a 32-year-old male with depression who ingested 150 mL of an antiseptic containing 0.1% naphazoline (equivalent to 150 mg of naphazoline). Five hours after ingestion, the patient was admitted to hospital exhibiting signs of naphazoline intoxication, such as bradycardia (46 beats/min), blood pressure of 166/122 mmHg, and peripheral cyanosis. We used the FloTrac™/EV1000™ system (Edwards Lifesciences, Irvine, CA, USA), a minimally invasive cardiac output monitoring system, to monitor systemic vascular resistance. The systemic vascular resistance index (SVRI) was elevated (4457 dyne.s/cm5/m2; nomal range: 1970-2390 dyne.s/cm5/m2) upon admission and initial treatment with continuous intravenous infusion of phentolamine led to SVRI normalization within 2 h. With the goal of maintaining SVRI normalization, continuous infusion with nicardipine was then started. At 10 h after treatment initiation, the nicardipine dose peaked at 9 mg/h (1.9 μg/kg/min). Treatment was discontinued 8 h later, and the patient was discharged on the fourth day without sequelae. In conclusion, the use of a minimally invasive cardiac output monitoring system to track vascular resistance can effectively guide the dosing of phentolamine or nicardipine in the treatment of naphazoline intoxication.

Retrospective Analysis of Perioperative Dexmedetomidine Use in Retina Surgeries: Impact on Postanesthesia Care

BACKGROUND AND OBJECTIVE

Dexmedetomidine (Precedex®) has been linked to depressive hemodynamic effects and increased length of stay in the post-anesthesia care unit (PACU) when used in ambulatory phacoemulsification procedures. We aimed to determine the prevalence and impact of dexmedetomidine use during ambulatory vitreoretinal procedures.

PATIENTS AND METHODS

This retrospective cohort study involved 9,666 adult vitrectomies. Cases were divided into groups by anesthesia type: general anesthesia (GA) and monitored anesthesia care (MAC). For each group, various factors were compared between those who did and did not receive dexmedetomidine. Chi-squared and t tests were used for comparisons.

RESULTS

Changes in mean arterial pressure in the MAC group were -1.69 ± 0.23 mmHg for no dexmedetomidine patients and -6.31 ± 0.39 mmHg for dexmedetomidine patients (P < 0.01). In the GA group, mean arterial pressure was -6.1 ± 0.35 mmHg for no dexmedetomidine patients and -11.18 ± 0.88 mmHg for dexmedetomidine patients (P < 0.01). PACU Phase II time in the MAC group was 36.93 ± 0.37 minutes and 40.67 ± 0.86 minutes for no dexmedetomidine and dexmedetomidine patients, respectively (P < 0.01). In the GA group, PACU Phase II time was 58.63 ± 0.95 minutes and 65.19 ± 2.38 minutes for no dexmedetomidine and dexmedetomidine patients, respectively (P < 0.01).

CONCLUSIONS

Dexmedetomidine use in vitrectomies was associated with significant PACU delays. These delays may stem from adverse hemodynamic effects. [Ophthalmic Surg Lasers Imaging Retina 2024;55:86-91.].

Low dose lofexidine for medically directed outpatient opioid tapering in adults with chronic pain: a prospective case series

BACKGROUND

In adults with chronic pain, mild-to-moderate withdrawal symptoms during medically directed opioid tapering in the outpatient setting may not be accompanied by hypertension or tachycardia. This clinical scenario could limit the use of lofexidine at dosages reported in clinical trials of opioid withdrawal precipitated by abrupt opioid discontinuation. Thus, the primary aim of this prospective case series is to describe the use of low dose lofexidine for opioid withdrawal in patients with chronic pain undergoing medically directed opioid tapering in an outpatient setting.

METHODS

Six patients (white 5, Latino 1) admitted to an outpatient interdisciplinary pain rehabilitation program met inclusion and exclusion criteria. Patients self-selected to undergo medically directed opioid tapering, and the medication the patients were prescribed upon admission was used in the taper schedule. Upon initiation of the opioid taper, patients received 0.18 mg of lofexidine every 6 hours.

RESULTS

Five of the six patients were women, and the median morphine milligram equivalents at baseline were 36.9. The median taper duration was 15 days, and the median duration of lofexidine administration was 14 days. Withdrawal scores were mild throughout the taper in four patients, and two patients with fibromyalgia experienced single episodes of moderately severe withdrawal symptoms at the median morphine milligram equivalent midpoint of the taper. No hypotension or sustained bradycardia were observed, and no adverse effects related to lofexidine were reported.

CONCLUSION

The observations from this prospective case series suggest that low-dose lofexidine may be a feasible adjunct medication to attenuate withdrawal symptoms in adults with chronic pain undergoing outpatient opioid tapering.

Presynaptic Adrenoceptors

Presynaptic α2-adrenoceptors are localized on axon terminals of many noradrenergic and non-noradrenergic neurons in the peripheral and central nervous systems. Their activation by exogenous agonists leads to inhibition of the exocytotic release of noradrenaline and other transmitters from the neurons. Most often, the α2A-receptor subtype is involved in this inhibition. The chain of molecular events between receptor occupation and inhibition of the exocytotic release of transmitters has been determined. Physiologically released endogenous noradrenaline elicits retrograde autoinhibition of its own release. Some clonidine-like α2-receptor agonists have been used to treat hypertension. Dexmedetomidine is used for prolonged sedation in the intensive care; It also has a strong analgesic effect. The α2-receptor antagonist mirtazapine increases the noradrenaline concentration in the synaptic cleft by interrupting physiological autoinhibion of release. It belongs to the most effective antidepressive drugs. β2-Adrenoceptors are also localized on axon terminals in the peripheral and central nervous systems. Their activation leads to enhanced transmitter release, however, they are not activated by endogenous adrenaline.

Genetic Variants of Adrenoceptors

Adrenoceptors are class A G-protein-coupled receptors grouped into three families (α1-, α2-, and β-adrenoceptors), each one including three members. All nine corresponding adrenoceptor genes display genetic variation in their coding and adjacent non-coding genomic region. Coding variants, i.e., nucleotide exchanges within the transcribed and translated receptor sequence, may result in a difference in amino acid sequence thus altering receptor function and signaling. Such variants have been intensely studied in vitro in overexpression systems and addressed in candidate-gene studies for distinct clinical parameters. In recent years, large cohorts were analyzed in genome-wide association studies (GWAS), where variants are detected as significant in context with specific traits. These studies identified two of the in-depth characterized 18 coding variants in adrenoceptors as repeatedly statistically significant genetic risk factors - p.Arg389Gly in the β1- and p.Thr164Ile in the β2-adrenoceptor, along with 56 variants in the non-coding regions adjacent to the adrenoceptor gene loci, the functional role of which is largely unknown at present. This chapter summarizes current knowledge on the two coding variants in adrenoceptors that have been consistently validated in GWAS and provides a prospective overview on the numerous non-coding variants more recently attributed to adrenoceptor gene loci.