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

Effect of Enteral Guanfacine on Dexmedetomidine Use in the ICU

Describe the efficacy and safety of guanfacine for dexmedetomidine weaning in critically ill patients.

DESIGN

Retrospective descriptive analysis.

SETTING

Six hundred thirteen-bed academic medical center from October 2020 to October 2021.

PATIENT/SUBJECTS

All Adult patients on IV dexmedetomidine who received at least one dose of guanfacine for sedation or agitation were included.

INTERVENTIONS

Enteral guanfacine.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was discontinuation of dexmedetomidine therapy within 48 hours after guanfacine initiation. Secondary outcomes assessed included adjunctive medication use, rate of dexmedetomidine reinitiation, and safety outcomes. One hundred five patients were included in the analysis. Median age was 59 years old, 66% were male, and median daily dose of guanfacine was 1.5 mg. Dexmedetomidine was discontinued within 48 hours in 58% of patients (n = 61) and within 72 hours in 71% of patients (n = 75). Fifty-five percent of patients (n = 58) required rescue medications for poorly controlled agitation, sedation, or pain while on guanfacine. Dexmedetomidine withdrawal occurred in 2% of patients (n = 2) while on guanfacine. Adverse effects attributed to guanfacine occurred in 8% of patients (n = 8), all experiencing hypotension leading to medication discontinuation.

CONCLUSION

Dexmedetomidine was successfully weaned within 48 hours of guanfacine initiation in 58% of patients with minimal withdrawal or adverse effects. Guanfacine may be an effective and safe enteral option for dexmedetomidine weaning in critically ill patients.

Understanding the roles of central and autonomic activity during sleep in the improvement of working memory and episodic memory

The last decade has seen significant progress in identifying sleep mechanisms that support cognition. Most of these studies focus on the link between electrophysiological events of the central nervous system during sleep and improvements in different cognitive domains, while the dynamic shifts of the autonomic nervous system across sleep have been largely overlooked. Recent studies, however, have identified significant contributions of autonomic inputs during sleep to cognition. Yet, there remain considerable gaps in understanding how central and autonomic systems work together during sleep to facilitate cognitive improvement. In this article we examine the evidence for the independent and interactive roles of central and autonomic activities during sleep and wake in cognitive processing. We specifically focus on the prefrontal-subcortical structures supporting working memory and mechanisms underlying the formation of hippocampal-dependent episodic memory. Our Slow Oscillation Switch Model identifies separate and competing underlying mechanisms supporting the two memory domains at the synaptic, systems, and behavioral levels. We propose that sleep is a competitive arena in which both memory domains vie for limited resources, experimentally demonstrated when boosting one system leads to a functional trade-off in electrophysiological and behavioral outcomes. As these findings inevitably lead to further questions, we suggest areas of future research to better understand how the brain and body interact to support a wide range of cognitive domains during a single sleep episode.

The signaling and selectivity of α-adrenoceptor agonists for the human α2A, α2B and α2C-adrenoceptors and comparison with human α1 and β-adrenoceptors

α2-adrenoceptors, (α2A, α2B and α2C-subtypes), are Gi-coupled receptors. Central activation of brain α2A and α2C-adrenoceptors is the main site for α2-agonist mediated clinical responses in hypertension, ADHD, muscle spasm and ITU management of sedation, reduction in opiate requirements, nausea and delirium. However, despite having the same Gi-potency in functional assays, some α2-agonists also stimulate Gs-responses whilst others do not. This was investigated. Agonist responses to 49 different α-agonists were studied (CRE-gene transcription, cAMP, ERK1/2-phosphorylation and binding affinity) in CHO cells stably expressing the human α2A, α2B or α2C-adrenoceptor, enabling ligand intrinsic efficacy to be determined (binding KD /Gi-IC50 ). Ligands with high intrinsic efficacy (e.g., brimonidine and moxonidine at α2A) stimulated biphasic (Gi-Gs) concentration responses, however for ligands with low intrinsic efficacy (e.g., naphazoline), responses were monophasic (Gi-only). ERK1/2-phosphorylation responses appeared to be Gi-mediated. For Gs-mediated responses to be observed, both a system with high receptor reserve and high agonist intrinsic efficacy were required. From the Gi-mediated efficacy ratio, the degree of Gs-coupling could be predicted. The clinical relevance and precise receptor conformational changes that occur, given the structural diversity of compounds with high intrinsic efficacy, remains to be determined. Comparison with α1 and β1/β2-adrenoceptors demonstrated subclass affinity selectivity for some compounds (e.g., α2:dexmedetomidine, α1:A61603) whilst e.g., oxymetazoline had high affinity for both α2A and α1A-subtypes, compared to all others. Some compounds had subclass selectivity due to selective intrinsic efficacy (e.g., α2:brimonidine, α1:methoxamine/etilefrine). A detailed knowledge of these agonist characteristics is vital for improving computer-based deep-learning and drug design.

Kratom use categories and their associations with co-occurring substance use and mental health disorder symptoms during the COVID-19 pandemic

BACKGROUND

Kratom, a psychoactive substance, use is an evolving research area that needs more studies to augment the limited literature. Our study examines the association between kratom use categories and mental health and substance use disorders in the U.S.

METHODS

We used the 2020 National Survey on Drug Use and Health data (N = 32,893), a cross-sectional survey data, on the U.S. population aged 12 years or older. We used STATA/SE version 16 to perform a multinomial logistic regression analysis to assess our study aims.

RESULTS

Bisexuals, compared to heterosexuals, had higher risks of kratom use within the past 30 days (relative risk ratio [RRR]= 2.47, 95% CI= 1.07, 5.71). Major depressive episode was positively associated with kratom use more than 30 days ago (RRR= 2.04, 95% CI= 1.24, 3.34). This association was also observed for mild (RRR= 2.04, 95% CI= 1.38, 3.02), moderate (RRR= 2.25, 95% CI= 1.13, 4.51), or severe alcohol use disorder (RRR= 1.88, 95% CI= 1.05, 3.36); and mild (RRR= 1.98, 95% CI= 1.27, 3.11), moderate (RRR= 2.38, 95% CI= 1.27, 4.45), or severe marijuana use disorder (RRR= 2.13, 95% CI= 1.02, 4.47). Illicit drug other than marijuana use disorder was associated positively with kratom use more than 30 days ago (RRR= 2.81, 95% CI= 1.85, 4.26) and kratom use within the past 30 days (RRR= 5.48, 95% CI= 1.50, 20.02).

CONCLUSIONS

Our findings suggested that identifying as bisexual, experiencing depression, alcohol use disorder, or illicit drug use disorder increased the risks of kratom use. There is a need to consider mental health and substance use disorders and sexual identity in kratom use interventions and policies geared toward reducing or preventing kratom use.

Propofol and α2-Agonists Attenuate Microglia Activation and Restore Mitochondrial Function in an In Vitro Model of Microglia Hypoxia/Reoxygenation

Cerebrovascular ischemia is a common clinical disease encompassing a series of complex pathophysiological processes in which oxidative stress plays a major role. The present study aimed to evaluate the effects of Dexmedetomidine, Clonidine, and Propofol in a model of hypoxia/reoxygenation injury. Microglial cells were exposed to 1%hypoxia for 3 h and reoxygenated for 3 h, and oxidative stress was measured by ROS formation and the expression of inflammatory process genes. Mitochondrial dysfunction was assessed by membrane potential maintenance and the levels of various metabolites involved in energetic metabolism. The results showed that Propofol and α2-agonists attenuate the formation of ROS during hypoxia and after reoxygenation. Furthermore, the α2-agonists treatment restored membrane potential to values comparable to the normoxic control and were both more effective than Propofol. At the same time, Propofol, but not α2-agonists, reduces proliferation (Untreated Hypoxia = 1.16 ± 0.2, Untreated 3 h Reoxygenation = 1.28 ± 0.01 vs. Propofol hypoxia = 1.01 ± 0.01 vs. Propofol 3 h Reoxygenation = 1.12 ± 0.03) and microglial migration. Interestingly, all of the treatments reduced inflammatory gene and protein expressions and restored energy metabolism following hypoxia/reoxygenation (ATP content in hypoxia/reoxygenation 3 h: Untreated = 3.11 ± 0.8 vs. Propofol = 7.03 ± 0.4 vs. Dexmedetomidine = 5.44 ± 0.8 vs. Clonidine = 7.70 ± 0.1), showing that the drugs resulted in a different neuroprotective profile. In conclusion, our results may provide clinically relevant insights for neuroprotective strategies in intensive care units.

Outcomes of dexmedetomidine versus propofol sedation in critically ill adults requiring mechanical ventilation: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Guidelines have recommended the use of dexmedetomidine or propofol for sedation after cardiac surgery, and propofol monotherapy for other patients. Further outcome data are required for these drugs.

METHODS

This systematic review and meta-analysis was prospectively registered on PROSPERO. The primary outcome was ICU length of stay. Secondary outcomes included duration of mechanical ventilation, ICU delirium, all-cause mortality, and haemodynamic effects. Intensive care patients were analysed separately as cardiac surgical, medical/noncardiac surgical, those with sepsis, and patients in neurocritical care. Subgroup analyses based on age and dosage were conducted.

RESULTS

Forty-one trials (N=3948) were included. Dexmedetomidine did not significantly affect ICU length of stay across any ICU patient subtype when compared with propofol, but it reduced the duration of mechanical ventilation (mean difference -0.67 h; 95% confidence interval: -1.31 to -0.03 h; P=0.041; low certainty) and the risk of ICU delirium (risk ratio 0.49; 95% confidence interval: 0.29-0.87; P=0.019; high certainty) across cardiac surgical patients. Dexmedetomidine was also associated with a greater risk of bradycardia across a variety of ICU patients. Subgroup analyses revealed that age might affect the incidence of haemodynamic side-effects and mortality among cardiac surgical and medical/other surgical patients.

CONCLUSION

Dexmedetomidine did not significantly impact ICU length of stay compared with propofol, but it significantly reduced the duration of mechanical ventilation and the risk of delirium in cardiac surgical patients. It also significantly increased the risk of bradycardia across ICU patient subsets.

Xylazine and Overdoses: Trends, Concerns, and Recommendations

Xylazine is a nonopioid veterinary anesthetic and sedative that is increasingly detected in the illicit drug supply in the United States. Data indicate a striking prevalence of xylazine among opioid-involved overdose deaths. The emergence of xylazine in the illicit drug supply poses many unknowns and potential risks for people who use drugs. The public health system needs to respond by increasing testing to determine the prevalence of xylazine, identifying its potential toxicity at various exposure levels, and taking mitigating action to prevent harms. Currently, there is little testing capable of identifying xylazine in drug supplies, which limits the possibility of public health intervention, implementation of harm reduction strategies, or development of novel treatment strategies. (Am J Public Health. 2022;112(8):1212-1216. https://doi.org/10.2105/AJPH.2022.306881).

Guanabenz ameliorates disease in vanishing white matter mice in contrast to sephin1

OBJECTIVE

Vanishing white matter (VWM) is a leukodystrophy, characterized by stress-sensitive neurological deterioration and premature death. It is currently without curative treatment. It is caused by bi-allelic pathogenic variants in the genes encoding eukaryotic initiation factor 2B (eIF2B). eIF2B is essential for the regulation of the integrated stress response (ISR), a physiological response to cellular stress. Preclinical studies on VWM mouse models revealed that deregulated ISR is key in the pathophysiology of VWM and an effective treatment target. Guanabenz, an α2-adrenergic agonist, attenuates the ISR and has beneficial effects on VWM neuropathology. The current study aimed at elucidating guanabenz's disease-modifying potential and mechanism of action in VWM mice. Sephin1, an ISR-modulating guanabenz analog without α2-adrenergic agonistic properties, was included to separate effects on the ISR from α2-adrenergic effects.

METHODS

Wild-type and VWM mice were subjected to placebo, guanabenz or sephin1 treatments. Effects on clinical signs, neuropathology, and ISR deregulation were determined. Guanabenz's and sephin1's ISR-modifying effects were tested in cultured cells that expressed or lacked the α2-adrenergic receptor.

RESULTS

Guanabenz improved clinical signs, neuropathological hallmarks, and ISR regulation in VWM mice, but sephin1 did not. Guanabenz's effects on the ISR in VWM mice were not replicated in cell cultures and the contribution of α2-adrenergic effects on the deregulated ISR could therefore not be assessed.

INTERPRETATION

Guanabenz proved itself as a viable treatment option for VWM. The exact mechanism through which guanabenz exerts its ameliorating impact on VWM requires further studies. Sephin1 is not simply a guanabenz replacement without α2-adrenergic effects.

A Disproportionality Analysis of Drug-Drug Interactions of Tizanidine and CYP1A2 Inhibitors from the FDA Adverse Event Reporting System (FAERS)

INTRODUCTION

Tizanidine is primarily metabolized via cytochrome P450 (CYP) 1A2 and therefore medications that inhibit the enzyme will affect the clearance of tizanidine, leading to increased plasma concentrations of tizanidine and potentially serious adverse events.

OBJECTIVES

Our aim was to study the occurrence of adverse events reported in the FDA Adverse Event Reporting System (FAERS) involving the combination of tizanidine and drugs that inhibit the metabolic activity of CYP1A2.

METHODS

A disproportionality analysis of FAERS reports from 2004 quarter 1 through 2020 quarter 3 was conducted to calculate the reporting odds ratio (ROR) of reports mentioning tizanidine in a suspect or interacting role or having any role, a CYP1A2 inhibitor, and the following adverse events: hypotension, bradycardia, syncope, shock, cardiorespiratory arrest, and fall or fracture.

RESULTS

A total of 89 reports were identified mentioning tizanidine, at least one CYP1A2 inhibitor, and one of the adverse events of interest. More than half of the reports identified tizanidine as having a suspect or interacting role (n = 59, 66.3%), and the reports more frequently involved women (n = 58, 65.1%). The median age was 56.1 years (standard deviation 17.1). Some of the important safety signals included interactions between tizanidine in a suspect or interacting role and ciprofloxacin (ROR for hypotension 28.1, 95% confidence interval [CI] 19.2-41.2) or fluvoxamine (ROR for hypotension 36.9, 95% CI 13.1-103.4), and also when reported in "any role" with ciprofloxacin (ROR for hypotension 6.3, 95% CI 4.7-8.5), fluvoxamine (ROR for hypotension 11.4, 95% CI 4.5-28.8), and zafirlukast (ROR for falls 16.0, 95% CI 6.1-42.1).

CONCLUSIONS

Reports involving tizanidine and a CYP1A2 inhibitor have higher odds of reporting hypotension. This study suggests that concurrent use of tizanidine with CYP1A2 inhibitors may lead to serious health consequences associated with low blood pressure such as falls and fractures.

MC4R biased signalling and the conformational basis of biological function selections

The MC4R, a GPCR, has long been a major target for obesity treatment. As the most well‐studied melanocortin receptor subtype, the evolutionary knowledge pushes the drug development and structure–activity relationship (SAR) moving forward. The past decades have witnessed the evolution of scientists' view on GPCRs gradually from the control of a single canonical signalling pathway via a bilateral ‘active‐inactive’ model to a multi‐state alternative model where the ligands' binding affects the selection of the downstream signalling. This evolution brings the concept of biased signalling and the beginning of the next generation of peptide drug development, with the aim of turning from receptor subtype specificity to signalling pathway selectivity. The determination of the value structures of the MC4R revealed insights into the working mechanism of MC4R activation upon binding of agonists. However, new challenge has risen as we seek to unravel the mystery of MC4R signalling selection. Thus, more biased agonists and ligands with representative biological functions are needed to solve the rest of the puzzle.

The Neuromodulatory Role of the Noradrenergic and Cholinergic Systems and Their Interplay in Cognitive Functions: A Focused Review

The noradrenergic and cholinergic modulation of functionally distinct regions of the brain has become one of the primary organizational principles behind understanding the contribution of each system to the diversity of neural computation in the central nervous system. Decades of work has shown that a diverse family of receptors, stratified across different brain regions, and circuit-specific afferent and efferent projections play a critical role in helping such widespread neuromodulatory systems obtain substantial heterogeneity in neural information processing. This review briefly discusses the anatomical layout of both the noradrenergic and cholinergic systems, as well as the types and distributions of relevant receptors for each system. Previous work characterizing the direct and indirect interaction between these two systems is discussed, especially in the context of higher order cognitive functions such as attention, learning, and the decision-making process. Though a substantial amount of work has been done to characterize the role of each neuromodulator, a cohesive understanding of the region-specific cooperation of these two systems is not yet fully realized. For the field to progress, new experiments will need to be conducted that capitalize on the modular subdivisions of the brain and systematically explore the role of norepinephrine and acetylcholine in each of these subunits and across the full range of receptors expressed in different cell types in these regions.

THE effect of general anesthetics on genetic absence epilepsy in WAG/Rij rats

AIM

To establish safe and straightforward anesthesia used in experiments, we examined the effect of ketamine, ketamine/xylazine, urethane, chloral hydrate, pentobarbital, isoflurane, dexmedetomidine, and dexmedetomidine/ketamine on epileptiform activity in genetic absence epilepsy (WAG\Rij) rats.

MATERIALS AND METHOD

Sixty-three male WAG/Rij rats weighing (170-190 g) were used. Tripolar electrodes were inserted into the skull. After ECoG activities were recorded for each animal for 2 hours as controls, , the anesthetic substances were administered and the recording continued for another 2 hours. All the anesthetic substances were administered intraperitoneally except isoflurane, which was administered by inhalation.The PowerLab system was used for electrophysiological activity recording and analysis.

RESULTS

The administration of ketamine (90 mg/kg), ketamine/xylazine (90/10 mg/kg), urethane (1.25 g/kg), chloral hydrate (175 mg/kg), pentobarbital (50-90 mg/kg), isoflurane (induction 5%, maintaining 3-4%), dexmedetomidine (0.5-1 mg/kg), and dexmedetomidine/ketamine (50/90 mg/kg), significantly decreased the total number of SWD, the total number of spikes, and the SWD duration (p < 0,05). The mean duration of SWD was not affected in pentobarbital (50-90 mg/kg), isoflurane (induction 5%, maintaining 3-4%), dexmedetomidine (0.5-1 mg/kg), and Dexmedetomidine/ketamine (50/90 mg/kg) groups (p > 0.05). Time scale showed a significant decrease in the total number of SWD in the first 20 minutes (P < 0.001) for all groups except dexmedetomidine (0.5-1 mg/kg), and dexmedetomidine/ketamine (50/90 mg/kg) groups (p > 0.05).

CONCLUSION

The anesthetics we used significantly reduced the epileptiform activity immediately after the administration, except dexmedetomidine and dexmedetomidine/ketamine groups, so we recommend using dexmedetomidine and Dexmedetomidine/ketamine in electrophysiological studies accompanied by anesthetics.

High-Dose Dexmedetomidine for Severe Hyperactive Delirium Secondary to Intravenous Levetiracetam on Two Separate Occasions in the Same Patient

We describe the case of a 5-year-old male who developed severe hyperactive delirium with aggressive violent behavior following the administration of IV levetiracetam for the treatment of status epilepticus on two occasions. The child's symptoms ranged from attacking his parents and the intensive care staff. Risperidone was given without any improvement in symptoms. A high-dose continuous infusion of IV dexmedetomidine was administered, and his violent behavior and delirium significantly improved. The two episodes of hyperactive delirium following IV levetiracetam administration occurred at ages 3 and 5, resulting in extensive work up including laboratory testing and cranial imaging, along with cerebral spinal fluid analysis and were normal. IV dexmedetomidine provided rapid symptom relief to prevent harm for the child, staff, and family on both occasions.

Comparing Efficacy of Intravenous Dexmedetomidine and Lidocaine on Perioperative Analgesic Consumption in Patients Undergoing Laparoscopic Surgery

Background

Perioperative pain management is a major challenge for anaesthesiologists. IV lidocaine and dexmedetomidine have been utilised for peri-operative pain management.

Aims and Objectives

To analyse the effects of intraoperative intravenous lignocaine/dexmedetomidine on pain relief, opioid consumption, peri-operative hemodynamic and side-effect profiles/unique interactions in patients undergoing laparoscopic surgeries.

Materials and Methods

Prospective, interventional, single-centric, double-blind, randomised, active-controlled, Helsinki protocol-compliant clinical study was conducted on 90 ASA I/II class patients aged 18-60 yrs. This Patients were block-randomised to Group-L (2% Lignocaine), Group-D (dexmedetomidine) and Group C (Control/Placebo/0.9% normal saline). Hemodynamic were noted at pre-defined time frames intra-/post-operatively. Post-operative VAS score and Richmond Agitation Sedation Score monitoring was done.

Results

Demographic parameters of were comparable. Mean intra-operative fentanyl consumption amongst the three groups were 20.5 ± 20.05 mcg, 26.5 ± 17.57 mcg and 46.83 + 21.31 mcg (Group-L, Group-D, Group-C; P value Group-L vs Group-D:0.22, Group L/D vs Group C: <0.0001). Group-D exhibited the lower heart rates and MAP (P < 0.05). Extubation- First rescue analgesic phase was comparable for the Group-C and Group-L (59.17 ± 46.224 min vs 61.64 ± 53.819 min) and significantly greater in Group-D (136.07 + 55.350 min; P < 0.0001).

Conclusion

Both Dexmedetomidine and lignocaine can be useful intra-operative pain relief adjuncts. Dexmedetomidine delayed First rescue analgesic and total analgesic consumption more than lignocaine. Dexmedetomidine patients exhibited bradycardia intraoperatively more than the other groups. we recommend, Dexmedetomidine in the intra-operative phase and lignocaine in the post-operative phase can be an alternative in patients who are poor candidates for post-operative opioids/sedation/contraindicated regional anaesthesia regimes.

Comparative Study of the Sedative and Anti-nociceptive Effects of Sacrococcygeal Epidural Administration of Romifidine, Lidocaine, and Romifidine/Lidocaine in the Dromedary Camel

In a randomized prospective study, comparative sedative and anti-nociceptive effects of epidural administration of romifidine (RO), lidocaine (LD), and a combination of romifidine-lidocaine (ROLD) in camel were evaluated. Eighteen healthy adult dromedary camels were assigned randomly to three treatment groups (n = 6), each receiving 50 μg/kg of RO, 0.30 mg/kg of LD, or a combination of both RO and LD. All treatments were expanded in 0.9% sterile normal saline solution to a final dose volume of 20 ml and administered directly into the sacrococcygeal space. After epidural injection of each treatment, the onset time, duration, anatomical extension of anti-nociception, and sedation were documented. Anti-nociception was tested at different areas using a pinprick test and artery forceps pinching at the perineum and inguinal area. RO and ROLD treatments resulted in mild to severe sedation and complete bilateral analgesia with loss of sensation in the tail, perineum, scrotum in males, vulva in females, the caudal aspect skin of the upper hind limb, and inguinal region (udder in females and the prepuce in males). The anatomic extent of anti-nociception reached the chest cranially and the footpad distally. Camels who received LD showed the shortest duration (P &lt; 0.001) to the onset of perineal anti-nociception (3.67 ± 0.33 min) followed by those who received RO LD (4.00 ± 0.37 min) and RO (6.67 ± 0.33 min), respectively. RO and ROLD resulted in significantly (P &lt; 0.001) longer periods of analgesia (158.33 ± 4.01 min and 165 ± 3.87 min, respectively) than LD (75.83 ± 3.27). An epidural RO and ROLD would appear to produce a very effective and acceptable anti-nociceptive effect in the perineal and inguinal regions of camels.

Researching Mitigation of Alcohol Binge Drinking in Polydrug Abuse: KCNK13 and RASGRF2 Gene(s) Risk Polymorphisms Coupled with Genetic Addiction Risk Severity (GARS) Guiding Precision Pro-Dopamine Regulation

Excessive alcohol intake, e.g., binge drinking, is a serious and mounting public health problem in the United States and throughout the world. Hence the need for novel insights into the underlying neurobiology that may help improve prevention and therapeutic strategies. Therefore, our group employed a darkness-induced alcohol intake protocol to define the reward deficiency domains of alcohol and other substance use disorders in terms of reward pathways' reduced dopamine signaling and its restoration via specifically-designed therapeutic compounds. It has been determined that KCNK13 and RASGRF2 genes, respectively, code for potassium two pore domain channel subfamily K member 13 and Ras-specific guanine nucleotide-releasing factor 2, and both genes have important dopamine-related functions pertaining to alcohol binge drinking. We present a hypothesis that identification of KCNK13 and RASGRF2 genes' risk polymorphism, coupled with genetic addiction risk score (GARS)-guided precision pro-dopamine regulation, will mitigate binge alcohol drinking. Accordingly, we review published reports on the benefits of this unique approach and provide data on favorable outcomes for both binge-drinking animals and drunk drivers, including reductions in alcohol intake and prevention of relapse to drinking behavior. Since driving under the influence of alcohol often leads to incarceration rather than rehabilitation, there is converging evidence to support the utilization of GARS with or without KCNK13 and RASGRF2 risk polymorphism in the legal arena, whereby the argument that "determinism" overrides the "free will" account may be a plausible defense strategy. Obviously, this type of research is tantamount to helping resolve a major problem related to polydrug abuse.

A multiparametric calcium signal screening platform using iPSC-derived cortical neural spheroids

Discovery of therapeutics for neurological diseases is hampered by the lack of predictive in vitro and in vivo models. Traditionally, in vitro assays rely on engineered cell lines grown two-dimensionally (2D) outside a physiological tissue context, which makes them very amenable for large scale drug screening but reduces their relevance to in vivo neurophysiology. In recent years, three-dimensional (3D) neural cell culture models derived from human induced pluripotent stem cells (iPSCs) have been developed as an in vitro assay platform to investigate brain development, neurological diseases, and for drug screening. iPSC-derived neural spheroids or organoids can be developed to include complex neuronal and glial cell populations and display spontaneous, synchronous activity, which is a hallmark of in vivo neural communication. In this report we present a proof-of-concept study evaluating 3D iPSC-derived cortical neural spheroids as a physiologically- and pharmacologically-relevant high-throughput screening (HTS) platform and investigate their potential for use for therapeutic development. To this end, a library of 687 neuroactive compounds were tested in a phenotypic screening paradigm which measured calcium activity as a functional biomarker for neural modulation through fluctuations in calcium fluorescence. Pharmacological responses of cortical neural spheroids were analyzed using a multi-parametric approach, whereby seven peak characteristics from the calcium activity in each well were quantified and incorporated into principal component analysis and Sammon mapping to measure compound response. Here, we describe the implementation of the 687-compound library screen and data analysis demonstrating that iPSC-derived cortical spheroids are a robust and information-rich assay platform for HTS.

Minimizing Motion Artifacts in Intravital Microscopy Using the Sedative Effect of Dexmedetomidine

Among intravital imaging instruments, the intravital two-photon fluorescence excitation microscope has the advantage of enabling real-time 3D fluorescence imaging deep into cells and tissues, with reduced photobleaching and photodamage compared with conventional intravital confocal microscopes. However, excessive motion of organs due to involuntary movement such as breathing may result in out-of-focus images and severe fluorescence intensity fluctuations, which hinder meaningful imaging and analysis. The clinically approved alpha-2 adrenergic receptor agonist dexmedetomidine was administered to mice during two-photon fluorescence intravital imaging to alleviate this problem. As dexmedetomidine blocks the release of the neurotransmitter norepinephrine, pain is suppressed, blood pressure is reduced, and a sedation effect is observed. By tracking the quality of focus and stability of detected fluorescence in two-photon fluorescence images of fluorescein isothiocyanate-sensitized liver vasculature in vivo, we demonstrated that intravascular dexmedetomidine can reduce fluorescence fluctuations caused by respiration on a timescale of minutes in mice, improving image quality and resolution. The results indicate that short-term dexmedetomidine treatment is suitable for reducing involuntary motion in preclinical intravital imaging studies. This method may be applicable to other animal models.

The Role of miRNAs in Dexmedetomidine's Neuroprotective Effects against Brain Disorders

There are limited neuroprotective strategies for various central nervous system conditions in which fast and sustained management is essential. Neuroprotection-based therapeutics have become an intensively researched topic in the neuroscience field, with multiple novel promising agents, from natural products to mesenchymal stem cells, homing peptides, and nanoparticles-mediated agents, all aiming to significantly provide neuroprotection in experimental and clinical studies. Dexmedetomidine (DEX), an α2 agonist commonly used as an anesthetic adjuvant for sedation and as an opioid-sparing medication, stands out in this context due to its well-established neuroprotective effects. Emerging evidence from preclinical and clinical studies suggested that DEX could be used to protect against cerebral ischemia, traumatic brain injury (TBI), spinal cord injury, neurodegenerative diseases, and postoperative cognitive disorders. MicroRNAs (miRNAs) regulate gene expression at a post-transcriptional level, inhibiting the translation of mRNA into functional proteins. In vivo and in vitro studies deciphered brain-related miRNAs and dysregulated miRNA profiles after several brain disorders, including TBI, ischemic stroke, Alzheimer's disease, and multiple sclerosis, providing emerging new perspectives in neuroprotective therapy by modulating these miRNAs. Experimental studies revealed that some of the neuroprotective effects of DEX are mediated by various miRNAs, counteracting multiple mechanisms in several disease models, such as lipopolysaccharides induced neuroinflammation, β-amyloid induced dysfunction, brain ischemic-reperfusion injury, and anesthesia-induced neurotoxicity models. This review aims to outline the neuroprotective mechanisms of DEX in brain disorders by modulating miRNAs. We address the neuroprotective effects of DEX by targeting miRNAs in modulating ischemic brain injury, ameliorating the neurotoxicity of anesthetics, reducing postoperative cognitive dysfunction, and improving the effects of neurodegenerative diseases.

Acute Cannabigerol Administration Lowers Blood Pressure in Mice

Cannabigerol is a cannabinoid compound synthesized by Cannabis sativa, which in its acid form acts as the substrate for both Δ⁹-tetraydrocannabinol and cannabidiol formation. Given its lack of psychoactive effects, emerging research has focused on cannabigerol as a potential therapeutic for health conditions including algesia, epilepsy, anxiety, and cancer. While cannabigerol can bind to classical cannabinoid receptors, it is also an agonist at α2-adrenoreceptors (α2AR) which, when activated, inhibit presynaptic norepinephrine release. This raises the possibility that cannabigerol could activate α2AR to reduce norepinephrine release to cardiovascular end organs to lower blood pressure. Despite this possibility, there are no reports examining cannabigerol cardiovascular effects. In this study, we tested the hypothesis that acute cannabigerol administration lowers blood pressure. Blood pressure was assessed via radiotelemetry at baseline and following intraperitoneal injection of cannabigerol (3.3 and 10 mg/kg) or vehicle administered in a randomized crossover design in male C57BL/6J mice. Acute cannabigerol significantly lowered mean blood pressure (-28 ± 2 mmHg with 10 mg/kg versus -12 ± 5 mmHg vehicle, respectively; p = 0.018), with no apparent dose responsiveness (-22 ± 2 mmHg with 3.3 mg/kg). The depressor effect of cannabigerol was lower in magnitude than the α2AR agonist guanfacine and was prevented by pretreatment with the α2AR antagonist atipamezole. These findings suggest that acute cannabigerol lowers blood pressure in phenotypically normal mice likely via an α2AR mechanism, which may be an important consideration for therapeutic cannabigerol administration.

Protective Effect of Nalbuphine Combined With Dexmedetomidine on the Lungs of Children With Atelectasis and Foreign Body in the Bronchus During the Perioperative Period

Objective: The present study aims to explore the protective effect of nalbuphine combined with dexmedetomidine on the lungs of children with atelectasis who have a foreign body in a bronchus during the perioperative period.

Methods: A total of 180 patients whose computed tomography scan showed atelectasis and a foreign body in a bronchus were randomly divided into three groups: group C (conventional anesthesia group), group D (dexmedetomidine group), and group N + D (nalbuphine combined with the dexmedetomidine group). The following indicators were recorded: 1) heart rate (HR) and mean arterial pressure (MAP) prior to induction (T0), at bronchoscope placement (T1), at intubation after surgery (T2), at tube removal (T3), 10 min after tube removal (T4), 20 min after tube removal (T5), and at awaking (T6); 2) monocyte toll-like receptors (TLRs) TLR⁃2, TLR⁃4, tumor necrosis factor α, interleukin 6, oxygenation index, and the B-line sum at T0, T3, 2 h (T7), and 24 h (T8) after tube removal; and 3) hospital stay after surgery.

Results: Compared with group C, in group D and group N + D, 1) the HR and MAP at T1∼T6 were lower; 2) the inflammatory factor indicator and B-line sum were lower, and the oxygenation index was higher at T7 and T8; 3) the agitation and cough scores were decreased during tube removal; and 4) the Ramsay sedation score was higher, and ventilator weaning time was shortened at T4∼T6 (p &lt; 0.05). Compared with group D, in group N + D, 1) the inflammatory factor indicator and B-line sum were lower at T8; 2) the oxygenation index was higher (p &lt; 0.05). Compared with groups C and D, in group N + D, the length of hospital stay was decreased (p &lt; 0.05).

Conclusion: In patients with atelectasis and a foreign body in a bronchus during the perioperative period, nalbuphine combined with dexmedetomidine may be capable of reducing the oxidative stress response, improving the oxygenation index, decreasing the pulmonary fluid content, protecting the lung, and facilitating postoperative recovery.

A Concise and Useful Guide to Understand How Alpha1 Adrenoceptor Antagonists Work

Adrenoceptors are the receptors for the catecholamines, adrenaline and noradrenaline. They are divided in α (α1 and α2) and β (β1, β2 and β3). α1-Adrenoceptors are subdivided in α1A, α1B and α1D. Most tissues express mixtures of α1-adrenoceptors subtypes, which appear to coexist in different densities and ratios, and in most cases their responses are probably due to the activation of more than one type. The three subtypes of α1-adrenoceptors are G-protein-coupled receptors (GPCR), specifically coupled to Gq/11. Additionally, the activation of these receptors may activate other signaling pathways or different components of these pathways, which leads to a great variety of possible cellular effects. The first clinically used α1 antagonist was Prazosin, for Systemic Arterial Hypertension (SAH). It was followed by its congeners, Terazosin and Doxazosin. Nowadays, there are many classes of α-adrenergic antagonists with different selectivity profiles. In addition to SAH, the α1-adrenoceptors are used for the treatment of Benign Prostatic Hyperplasia (BPH) and urolithiasis. This antagonism may be part of the mechanism of action of tricyclic antidepressants. Moreover, the activation of these receptors may lead to adverse effects such as orthostatic hypotension, similar to what happens with the antidepressants and with some antipsychotic. Structure-activity relationships can explain, in part, how antagonists work and how selective they can be for each one of the subtypes. However, it is necessary to develop new molecules which antagonize the α1-adrenoceptors or make chemical modifications in these molecules to improve the selectivity, pharmacokinetic profile and/or reduce the adverse effects of known drugs.

Dexmedetomidine and Other Analgosedatives Alter Pupil Characteristics in Critically Ill Patients

In critically ill patients with neurologic disease, pupil examination abnormalities can signify evolving intracranial pathology. Analgesic and sedative medications (analgosedatives) target pupillary pathways, but it remains unknown how analgosedatives alter pupil findings in the clinical care setting. We assessed dexmedetomidine and other analgosedative associations with pupil reactivity and size in a heterogeneous cohort of critically ill patients with acute intracranial pathology.

DESIGN

Retrospective cohort study.

SETTING

Two neurologic ICUs between 2016 and 2018.

PATIENTS

Critically ill adult patients with pupil measurements within 60 minutes of analgosedative administration. Patients with a history of intrinsic retinal pathology, extracranial injury, inaccessible brain imaging, or no Glasgow Coma Scale (GCS) data were excluded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We used mixed-effects linear regression accounting for intrapatient correlations and adjusting for sex, age, GCS score, radiographic mass effect, medication confounders, and ambient light. We tested the association between an initiation or increased IV infusion of dexmedetomidine and pupil reactivity (Neurologic Pupil Index [NPi]) and resting pupil size (mm) obtained using NeurOptics NPi-200 (NeurOptics, Irvine, CA) pupillometer. Of our 221 patients with 9,897 pupil observations (median age, 60 [interquartile range, 50-68]; 59% male), 37 patients (166 pupil observations) were exposed to dexmedetomidine. Dexmedetomidine was associated with higher average NPi (β = 0.18 per 1 unit increase in rank-normalized NPi ± 0.04; p < 0.001) and smaller pupil size (β = -0.25 ± 0.05; p < 0.001). Exploratory analyses revealed that acetaminophen was associated with higher average NPi (β = 0.04 ± 0.02; p = 0.02) and that most IV infusion analgosedatives including propofol, fentanyl, and midazolam were associated with smaller pupil size.

CONCLUSIONS

Dexmedetomidine is associated with higher pupil reactivity (high NPi) and smaller pupil size in a cohort of critically ill patients with neurologic injury. Familiarity with expected pupil changes following analgosedative administration is important for accurate interpretation of pupil examination findings, facilitating optimal management of patients with acute intracranial pathology.

Influence of Receptor Polymorphisms on the Response to α-Adrenergic Receptor Blockers in Pheochromocytoma Patients

Background: Presurgical treatment with an α-adrenergic receptor blocker is recommended to antagonize the catecholamine-induced α-adrenergic receptor mediated vasoconstriction in patients with pheochromocytoma or sympathetic paraganglioma (PPGL). There is, however, a considerable interindividual variation in the dose-response relationship regarding the magnitude of blood pressure reduction or the occurrence of side effects. We hypothesized that genetically determined differences in α-adrenergic receptor activity contribute to this variability in dose-response relationship. Methods: Thirty-one single-nucleotide polymorphisms (SNPs) of the α1A, α1B, α1D adrenoreceptor (ADRA1A, ADRA1B, ADRA1D) and α2A, α2B adrenoreceptor (ADRA2A, ADRA2B) genes were genotyped in a group of 116 participants of the PRESCRIPT study. Haplotypes were constructed after determining linkage disequilibrium blocks. Results: The ADRA1B SNP rs10515807 and the ADRA2A SNPs rs553668/rs521674 were associated with higher dosages of α-adrenergic receptor blocker (p < 0.05) and with a higher occurrence of side effects (rs10515807) (p = 0.005). Similar associations were found for haplotype block 6, which is predominantly defined by rs10515807. Conclusions: This study suggests that genetic variability of α-adrenergic receptor genes might be associated with the clinically observed variation in beneficial and adverse therapeutic drug responses to α-adrenergic receptor blockers. Further studies in larger cohorts are needed to confirm our observations.

The State-of-the-art Pharmacotherapeutic Options for the Treatment of Chronic Non-Cancer Pain

INTRODUCTION

Pharmacotherapeutic options continue to expand for the treatment of chronic non-cancer pain. There has been an increasing emphasis on multimodal analgesia. This strategy employs use of multiple analgesic medications each with a distinct mechanism of action, which when administered concomitantly may provide profound analgesia.

AREAS COVERED

The authors describe evidence from randomized controlled trials and systematic reviews on a variety of established medications including anti-inflammatory agents, opioids, anti-convulsants, anti-depressants, N-methyl-D-aspartate receptor antagonists, sodium channel blockers, cannabinoids, and alpha-2-receptor blockers. Furthermore, they provide developing evidence on more novel pharmacotherapeutics including alpha lipoic acid, acetyl-L-carnitine, low dose naltrexone, calcitonin gene-related peptide antagonists, targeted toxin therapy, Nav1.7 inhibitors, neurotensin agonists, purinoceptor antagonists, and sigma-1 receptor antagonists. Furthermore, the authors review the safety and adverse effect profile for these agents.

EXPERT OPINION

In this era of the opioid epidemic, clinicians should first offer non-opioid analgesics and employ a multimodal analgesic strategy. Current guidelines recommend a personalized approach to the chronic pain treatment, in each case accounting for type, location, severity, and chronicity of pain. Clinicians should also carefully consider the risk-to-benefit ratio to the patient based on the drug side effect profile, patient age, and comorbidities.

Synthesis and Evaluation of Novel Tetrahydronaphthyridine CXCR4 Antagonists with Improved Drug-like Profiles

Our first-generation CXCR4 antagonist TIQ15 was rationally modified to improve drug-like properties. Introducing a nitrogen atom into the aromatic portion of the tetrahydroisoquinoline ring led to several heterocyclic variants including the 5,6,7,8-tetrahydro-1,6-naphthyridine series, greatly reducing the inhibition of the CYP 2D6 enzyme. Compound 12a demonstrated the best overall properties after profiling a series of isomeric tetrahydronaphthyridine analogues in a battery of biochemical assays including CXCR4 antagonism, CYP 2D6 inhibition, metabolic stability, and permeability. The butyl amine side chain of 12a was substituted with various lipophilic groups to improve the permeability. These efforts culminated in the discovery of compound 30 as a potent CXCR4 antagonist (IC50 = 24 nM) with diminished CYP 2D6 activity, improved PAMPA permeability (309 nm/s), potent inhibition of human immunodeficiency virus entry (IC50 = 7 nM), a cleaner off-target in vitro safety profile, lower human ether a-go-go-related gene channel activity, and higher oral bioavailability in mice (% FPO = 27) compared to AMD11070 and TIQ15.

Structural insights into ligand recognition, activation, and signaling of the α2A adrenergic receptor

The α_2A adrenergic receptor (α_2AAR) is a G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor that mediates important physiological functions in response to the endogenous neurotransmitters norepinephrine and epinephrine, as well as numerous chemically distinct drugs. However, the molecular mechanisms of drug actions remain poorly understood. Here, we report the cryo-electron microscopy structures of the human α_2AAR-GoA complex bound to norepinephrine and three imidazoline derivatives (brimonidine, dexmedetomidine, and oxymetazoline). Together with mutagenesis and functional data, these structures provide important insights into the molecular basis of ligand recognition, activation, and signaling at the α_2AAR. Further structural analyses uncover different molecular determinants between α_2AAR and βARs for recognition of norepinephrine and key regions that determine the G protein coupling selectivity. Overall, our studies provide a framework for understanding the signal transduction of the adrenergic system at the atomic level, which will facilitate rational structure-based discovery of safer and more effective medications for α_2AAR.

17β-Estradiol Concentration and Direct β2-Adrenoceptor Inhibition Determine Estrogen-Mediated Reversal of Adrenergic Immunosuppression

Background:

Sympathetic innervation of lymphoid organs, and the presence of 17β-estradiol (estrogen or E2) and adrenergic receptors (ARs) on lymphocytes, suggests that sympathetic stimulation and hormonal activation may influence immune functions.

Purpose:

Modeling and simulating these pathways may help to understand the dynamics of neuroendocrine-immune modulation at the cellular and molecular levels.

Methods:

Dose- and receptor-dependent effects of E2 and AR subtype-specific agonists were established in vitro on lymphocytes from young male Sprague-Dawley rats and were modeled in silico using the MATLAB Simbiology toolbox. Kinetic principles were assigned to define receptor–ligand dynamics, and concentration/time plots were obtained using Ode15s solvers at different time intervals for key regulatory molecules. Comparisons were drawn between in silico and in vitro data for validating the constructed model with sensitivity analysis of key regulatory molecules to assess their individual impacts on the dynamics of the system. Finally, docking studies were conducted with key ligands E2 and norepinephrine (NE) to understand the mechanistic principles underlying their interactions.

Results:

Adrenergic activation triggered proapoptotic signals, while E2 enhanced survival signals, showing opposing effects as observed in vitro. Treatment of lymphocytes with E2 shows a 10-fold increase in survival signals in a dose-dependent manner. Cyclic adenosine monophosphate (cAMP) activation is crucial for the activation of survival signals through extracellular signal-regulated kinase (p-ERK) and cAMP responsive element binding (p-CREB) protein. Docking studies showed the direct inhibition of ERK by NE and β2-AR by E2 explaining how estrogen signaling overrides NE-mediated immunosuppression in vitro.

Conclusion:

The cross-talk between E2 and adrenergic signaling pathways determines lymphocyte functions in a receptor subtype and coactivation-dependent manner in health and disease.

Research on Mechanism of miR-106a Nanoparticles Carrying Dexmedetomidine in Regulating Recovery and Metabolism of Nerve Cells in Hypoxia-Reoxygenation Injury

We studied the mechanism of miR-106a nanoparticles carrying dexmedetomidine (DEX) in regulating the recovery and metabolism of nerve cells in hypoxia-reoxygenation injury. Hippocampus neuron model in hypoxia-reoxygenation injury was prepared in vitro. Study groups were randomly divided into control set, ischemic reperfusion (IR) set, dexmedetomidine (DEX) set, miR-106a-nanoparticles (NPs) set and set of dexmedetomidine (DEX) and miR-106a-NPs. We studied miR-106a expression, proliferative and apoptotic activity, secretion of IL-6 and tumor necrosis factor (TNF)-α, quantity of Phosphocreatine (PCr), adenosine triphosphate (ATP) and total adenine nucleotide, and also content of reactive oxygen species (ROS) and superoxide dismutases (SOD). Expressions of of Bax, Bcl-2 and NF-κB were also detected. Results showed that the expression of miR-106a in hippocampus neuron was reduced, while proliferation was reduced and apoptotic activity was increased. The secretions of IL-6 and TNF-α were increased, while the quantities of Phosphocreatine (PCr), adenosine triphosphate (ATP) and total adenine nucleotide were reduced. Bax expression was also increased and Bcl-2 expression was reduced. Moreover, ROS content was increased and SOD activity was reduced, while the NF-κB presentation was increased. The above-mentioned changes could be reversed in IR set, DEX set and miR-106a-NPs set. The action was more notable in the DEX and miR-106a-NPs sets. Finally, the proliferation in hippocampus neuron in hypoxia-reoxygenation injury could be prompted and apoptosis could be restrained by DEX and miR-106a-NPs. The secretion of inflammatory factors could be restrained through restraining the inflammatory pathway and oxidative stress. The energy metabolism could therefore be improved effectively and recovery of nerve cells in HBI could be improved.

Adrenergic receptor gene expression in bovine leukocytes

The α- and β-adrenergic receptors (ARs) bind the stress hormones epinephrine (E), norepinephrine (NE), and dopamine and activate diverse physiological responses. A lack of information on AR gene expression in leukocytes limits our understanding of how stress alters immune function. Quantitative analyses of AR gene expression was completed for bovine leukocytes. Individual leukocyte lineages and subpopulations within lineages were isolated with high-speed cell sorting to facilitate a targeted analysis of AR gene expression. These analyses confirmed all 9 AR genes were expressed in bovine leukocytes with marked differences in AR gene expression when comparing among leukocyte lineages. Furthermore, separation of polymorphonuclear cells into neutrophils and eosinophils revealed these key innate immune cells also differ significantly in AR gene expression. This study provides the first comprehensive survey of AR gene expression in immune cells of any mammalian species and provides insight into conflicting reports that stress can either activate or suppress immune function.

Mitragyna Species as Pharmacological Agents: From Abuse to Promising Pharmaceutical Products

Mitragyna is a genus belonging to the Rubiaceae family and is a plant endemic to Asia and Africa. Traditionally, the plants of this genus were used by local people to treat some diseases from generation to generation. Mitragyna speciosa (Korth.) Havil. is a controversial plant from this genus, known under the trading name “kratom”, and contains more than 40 different types of alkaloids. Mitragynine and 7-hydroxymitragynine have agonist morphine-like effects on opioid receptors. Globally, Mitragyna plants have high economic value. However, regulations regarding the circulation and use of these commodities vary in several countries around the world. This review article aims to comprehensively examine Mitragyna plants (mainly M. speciosa) as potential pharmacological agents by looking at various aspects of the plants. A literature search was performed and information collected using electronic databases including Scopus, ScienceDirect, PubMed, directory open access journal (DOAJ), and Google Scholar in early 2020 to mid-2021. This narrative review highlights some aspects of this genus, including historical background and botanical origins, habitat, cultivation, its use in traditional medicine, phytochemistry, pharmacology and toxicity, abuse and addiction, legal issues, and the potential of Mitragyna species as pharmaceutical products.

The Association of an Alpha-2 Adrenergic Receptor Agonist and Mortality in Patients With COVID-19

There is a need for treatments to reduce coronavirus disease 2019 (COVID-19) mortality. Alpha-2 adrenergic receptor (α₂ AR) agonists can dampen immune cell and inflammatory responses as well as improve oxygenation through physiologic respiratory parameters. Therefore, α₂ AR agonists may be effective in reducing mortality related to hyperinflammation and acute respiratory failure in COVID-19. Dexmedetomidine (DEX) is an α₂ AR agonist used for sedation. We performed a retrospective analysis of adults at Rush University System for Health hospitals between March 1, 2020 and July 30, 2020 with COVID-19 requiring invasive mechanical ventilation and sedation (n = 214). We evaluated the association of DEX use and 28-day mortality from time of intubation. Overall, 28-day mortality in the cohort receiving DEX was 27.0% as compared to 64.5% in the cohort that did not receive DEX (relative risk reduction 58.2%; 95% CI 42.4–69.6). Use of DEX was associated with reduced 28-day mortality on multivariable Cox regression analysis (aHR 0.19; 95% CI 0.10–0.33; p < 0.001). Adjusting for time-varying exposure to DEX also demonstrated that DEX was associated with reduced 28-day mortality (aHR 0.51; 95% CI 0.28–0.95; p = 0.03). Earlier DEX use, initiated <3.4 days from intubation, was associated with reduced 28-day mortality (aHR 0.25; 95% CI 0.13–0.50; p < 0.001) while later DEX use was not (aHR 0.64; 95% CI 0.27–1.50; p = 0.30). These results suggest an α₂ AR agonist might reduce mortality in patients with COVID-19. Randomized controlled trials are needed to confirm this observation.

Beneficial Extracardiac Effects of Cardiovascular Medications

Cardiovascular diseases are the most common cause of death worldwide, with cardiovascular medications being amongst the most common medications prescribed. These medications have diverse effects on the heart, vascular system, as well as other tissues and organ systems. The extra cardiovascular effects have been found to be of use in the treatment of non-cardiovascular diseases and pathologies. Minoxidil is used to manage systemic hypertension with its well-known side effect of hirsutism used to treat alopecia and baldness. Sildenafil was originally investigated as a treatment option for systemic hypertension; however, its side effect of penile erection led to it being widely used for erectile dysfunction. Alpha-1 blockers such as terazosin are indicated to treat systemic hypertension but are more commonly used for benign prostatic hyperplasia and post-traumatic stress disorder. Beta blockers are the mainstay treatment for congestive heart failure and systemic hypertension but have been found useful to help in patients with intention tremors as well as prophylaxis of migraines. Similarly, calcium channel blockers are indicated in medical expulsion therapy for ureteric calculi in addition to their cardiovascular indications. Thiazides are commonly used for treating systemic hypertension and as diuretics. Thiazides can cause hypocalciuria and hypercalcemia. This side effect has led to thiazides being used to treat idiopathic hypercalciuria and associated nephrolithiasis. Spironolactone is commonly utilized in treating heart failure and as a diuretic for edema. It's well described anti-androgen side effects have been used for acne vulgaris and hirsutism in polycystic ovarian syndrome. This review article discusses how the various extracardiovascular effects of commonly used cardiovascular medications are put to use in managing non-cardiovascular conditions.

Nonopioid analgesics for analgesia in critically ill patients: Friends, enemies, or collaborators

Patients in intensive care units (ICUs) experience pain, which they describe as a significant cause of stress during treatment. It can progress to chronic pain and significantly affect the quality of life. Opioids have long been the backbone of ICU pain therapy. The consequences of their long-term use are known today, such as prolonged ICU stay and mechanical ventilation, resulting in increased treatment costs. Additionally, abstinence syndrome is a consequence of abrupt opioid withdrawal. Also, there is a risk of tolerance and hyperalgesia after prolonged opioid use. Globally, opioid dependence after hospital opioid treatment is alarming, although there is still a lack of data on its incidence after ICU. Multimodal analgesia enables comfort to the patient, opioid-sparing, and avoidance of side effects of non-opioid analgesics. Nonsteroidal anti-inflammatory drugs (NSAIDs) are a broad group of drugs recommended with paracetamol to treat mild to moderate acute postoperative pain. Although often prescribed by intensivists, their use in treating painful conditions in ICU is controversial due to the possible consequences on the organs of critically ill patients. Due to the inhibition of cyclooxygenases, NSAIDs indirectly cause vasoconstriction of the renal arteries and arterioles, leading to kidney damage. NSAIDs inhibit platelet aggregation and may predispose to bleeding. Analgesia of a critically ill patient is a important part of their treatment, however it can be challenging in certain patients. Numerous combinations of pharmacological and non-pharmacological approaches can be adapted to the patient's current characteristics.

Comparative evaluation of intrathecal dexmedetomidine and fentanyl as an adjuvant for combined spinal–epidural analgesia for labor

Background:

Combined spinal–epidural technique is a widely accepted and popular modality for labor analgesia. Opioids are being used as adjuvants since long time. Dexmedetomidine is a new drug that is being used as an intrathecal adjuvant.

Aim:

The study aims to compare the safety and efficacy of fentanyl and dexmedetomidine as intrathecal adjuvants in labor analgesia.

Settings and Design:

This was a continuous, prospective, randomized controlled trial with 120 parturients.

Materials and Methods:

After ethical approval and written consent, participants were divided randomly into two groups: Group A – bupivacaine 2.5 mg (0.5 mL diluted to 2 mL) + 20 μg of dexmedetomidine in 1 mL saline intrathecally (total volume: 3 mL) and Group B – bupivacaine 2.5 mg (0.5 mL diluted to 2 mL) + 15 μg of fentanyl in 1 mL saline intrathecally (total volume: 3 mL). Primary outcomes were satisfactory analgesia, mode of delivery, and neonatal outcome. Participants were monitored for the onset and duration of analgesia, degree of motor block, and maternal and fetal side effects.

Results:

A total of 108 parturients reported sufficient analgesia (Group A: 57; Group B: 51), and 74 patients delivered vaginally (Group A: 41; Group B: 44). The rates of normal vaginal delivery were higher in Group B. Group A reported earlier onset of analgesia (61.26 ± 18.23 s) that lasted for longer duration (124.16 ± 26.23 min) than in Group B. There were no serious side effects in any of the groups. Fetal ultrasound revealed attenuation of fetal heart rate variability. The heart rate of newborns was also found to be low in Group A.

Conclusion:

Chances of vaginal delivery are higher with intrathecal fentanyl as an adjuvant. Intensity and duration of analgesia are better with intrathecal dexmedetomidine.

Pharmacological and clinical implications of local anaesthetic mixtures: a narrative review

Various techniques have been explored to prolong the duration and improve the efficacy of local anaesthetic nerve blocks. Some of these involve mixing local anaesthetics or adding adjuncts. We did a literature review of studies published between 01 May 2011 and 01 May 2021 that studied specific combinations of local anaesthetics and adjuncts. The rationale behind mixing long- and short-acting local anaesthetics to hasten onset and extend duration is flawed on pharmacokinetic principles. Most local anaesthetic adjuncts are not licensed for use in this manner and the consequences of untested admixtures and adjuncts range from making the solution ineffective to potential harm. Pharmaceutical compatibility needs to be established before administration. The compatibility of drugs from the same class cannot be inferred and each admixture requires individual review. Precipitation on mixing (steroids, non-steroidal anti-inflammatory drugs) and subsequent embolisation can lead to serious adverse events, although these are rare. The additive itself or its preservative can have neurotoxic (adrenaline, midazolam) and/or chondrotoxic properties (non-steroidal anti-inflammatory drugs). The prolongation of block may occur at the expense of motor block quality (ketamine) or block onset (magnesium). Adverse effects for some adjuncts appear to be dose-dependent and recommendations concerning optimal dosing are lacking. An important confounding factor is whether studies used systemic administration of the adjunct as a control to accurately identify an additional benefit of perineural administration. The challenge of how best to prolong block duration while minimising adverse events remains a topic of interest with further research required.

Peripheral Voltage-Gated Cation Channels in Neuropathic Pain and Their Potential as Therapeutic Targets

The persistence of increased excitability and spontaneous activity in injured peripheral neurons is imperative for the development and persistence of many forms of neuropathic pain. This aberrant activity involves increased activity and/or expression of voltage-gated Na+ and Ca2+ channels and hyperpolarization activated cyclic nucleotide gated (HCN) channels as well as decreased function of K+ channels. Because they display limited central side effects, peripherally restricted Na+ and Ca2+ channel blockers and K+ channel activators offer potential therapeutic approaches to pain management. This review outlines the current status and future therapeutic promise of peripherally acting channel modulators. Selective blockers of Nav1.3, Nav1.7, Nav1.8, Cav3.2, and HCN2 and activators of Kv7.2 abrogate signs of neuropathic pain in animal models. Unfortunately, their performance in the clinic has been disappointing; some substances fail to meet therapeutic end points whereas others produce dose-limiting side effects. Despite this, peripheral voltage-gated cation channels retain their promise as therapeutic targets. The way forward may include (i) further structural refinement of K+ channel activators such as retigabine and ASP0819 to improve selectivity and limit toxicity; use or modification of Na+ channel blockers such as vixotrigine, PF-05089771, A803467, PF-01247324, VX-150 or arachnid toxins such as Tap1a; the use of Ca2+ channel blockers such as TTA-P2, TTA-A2, Z 944, ACT709478, and CNCB-2; (ii) improving methods for assessing "pain" as opposed to nociception in rodent models; (iii) recognizing sex differences in pain etiology; (iv) tailoring of therapeutic approaches to meet the symptoms and etiology of pain in individual patients via quantitative sensory testing and other personalized medicine approaches; (v) targeting genetic and biochemical mechanisms controlling channel expression using anti-NGF antibodies such as tanezumab or re-purposed drugs such as vorinostat, a histone methyltransferase inhibitor used in the management of T-cell lymphoma, or cercosporamide a MNK 1/2 inhibitor used in treatment of rheumatoid arthritis; (vi) combination therapy using drugs that are selective for different channel types or regulatory processes; (vii) directing preclinical validation work toward the use of human or human-derived tissue samples; and (viii) application of molecular biological approaches such as clustered regularly interspaced short palindromic repeats (CRISPR) technology.

Comparison of two injectable anaesthetic techniques on induction and subsequent anaesthesia in pigs

Pig experiments often require anaesthesia, and a rapid stress-free induction is desired. Induction drugs may alter the subsequent anaesthesia. Therefore, the aim of the present study was to compare, in pigs, the effects of two different injectable anaesthetic techniques on the induction and on the physiological variables in a subsequent eight hours of total intravenous anaesthesia (TIVA). Twelve domestic castrates (Swedish Landrace/Yorkshire) 27‒31 kg were used. The pigs were randomly assigned to different induction drug combinations of zolazepam-tiletamine and medetomidine intramuscularly (ZTMe) or midazolam, ketamine intramuscularly and fentanyl intravenously (MiKF). Time from injection to unconsciousness was recorded and the ease of endotracheal intubation assessed. The TIVA infusion rate was adjusted according to the response exhibited from the nociceptive stimulus delivered by mechanically clamping the dewclaw. The time from injection to unconsciousness was briefer and intubation was easier in the ZTMe group. Results from the recorded heart rate, cardiac index and arterial blood pressure variables were satisfactorily preserved and cardiovascular function was maintained in both groups. Shivering was not observed in the ZTMe group, but was observed in four of the pigs in the MiKF group. The requirement of TIVA was lower in the ZTMe group. In conclusion, ZTMe had better results than MiKF in areas such as shorter induction time, better intubation scoring results and less adjustment and amount of TIVA required up to six hours of anaesthesia. The results may have been due to a greater depth of anaesthesia achieved with the ZTMe combination at the dose used.

Effect of dexmedetomidine on opioid consumption and pain control after laparoscopic cholecystectomy: a meta-analysis of randomized controlled trials

Introduction

The clinical evidence on dexmedetomidine (DEX) for postoperative pain scores and opioid consumption remains unclear in laparoscopic cholecystectomy (LC).

Aim

To evaluate whether DEX could reduce opioid consumption and pain control after LC.

Material and methods

A meta-analysis search of EMBASE, PubMed and Cochrane CENTRAL databases was performed and randomized controlled trials (RCTs) comparing DEX with control for adult patients undergoing LC were searched. The primary outcome was opioid consumption in the first 24 h after the operation. The secondary outcomes were the time of first request of analgesia, visual analogue scale (VAS) scores 24 h after the operation, the incidence of patients’ need for rescue analgesics, opioid-related adverse effects, DEX-related adverse effects and other complications.

Results

There were fourteen aspects of twelve trials and 967 patients included in the analysis. DEX use significantly reduced the opioid consumption in the first 24 h after the operation (weighted mean difference (WMD), –19.17; 95% confidence interval (CI), –30.29 to –8.04; p = 0.0007), lengthened the time of first request of analgesia (WMD = 38.90; 95% CI: 0.88–76.93; p = 0.04) and lowered post-operative nausea or vomiting (PONV) (odds ratio (OR) = 0.49; 95% CI: 0.27–0.89; p = 0.02).

Conclusions

Intravenous DEX infusion significantly improved the duration of the analgesic effect and reduced postoperative opioid consumption. Moreover, lower incidence of post-operative nausea or vomiting was found in the DEX group.

Dexmedetomidine versus Propofol in Combination with Fentanyl for Sedation-Analgesia in Colonoscopy Procedures: A Randomized Prospective Study

BACKGROUND Colonoscopy is an uncomfortable and short procedure needing brief sedation with fast emergence. METHODS This research is going to measure intravenous dexmedetomidine against propofol-fentanyl combination in terms of sedation-analgesia and hemodynamic changes in non-obligatory colonoscopy procedures. 70 colonoscopy candidates aged between 20 to 70 years were enrolled in this study while separated into two random equal-sized groups (p stands for propofol- & D stands for dexmedetomidine groups). All patients were premedicated with 0.03 mg/kg midazolam and 1 µ/kg fentanyl, 10 minutes and 5 minutes before the colonoscopy process, respectively. 0.5-1 mg/kg propofol for the P group and 1 µ/kg dexmedetomidine for the D group were infused in one minute before the initiation of the procedure following by normal saline as maintenance liquid and boluses of 25-50 µg fentanyl as needed. RESULTS These variables were entered into a datasheet: hemodynamic changes, sedation-analgesia level throughout the procedure, and patients' and physicians' contentment. The mean arterial pressure changes were similar and insignificant in the two groups (82.44±12.34 vs. 87.63±22.45 p=0.2). The D group had lower heart rates in comparison with the P group (72.51±16.7 vs. 81.56±15.71 p=0.001). The P group was deeply to moderately sedated and required a significantly lower doses of fentanyl rescue treatment (71.02±25.63 vs. 91.45±38.62 µg p=0.003). The P group was associated with a high incidence of apnea and was significantly superior to the D group in the matter of satisfaction (43% against 77%). CONCLUSION Colonoscopists' contentment rates were identical in both groups. Propofol infusion is more satisfactory yet having more respiratory depression possibility in comparison with dexmedetomidine infusion in colonoscopy candidates.

Comparison of hypotensive properties of dexmedetomidine versus clonidine for induced hypotension during functional endoscopic sinus surgery: A randomised, double-blind interventional study

Background and Aims

Excessive bleeding is a major concern in functional endoscopic sinus surgery (FESS) under general anaesthesia; this can be decreased by various hypotensive agents. This study was conducted to compare the hypotensive effectiveness and haemodynamic stability of dexmedetomidine and clonidine in patients undergoing elective FESS.

Methods

In this prospective double-blinded interventional study, 70 adult patients of either sex, 20-50 years of age, posted for elective FESS were randomly assigned to two groups. Group A received a loading dose of intravenous (IV) dexmedetomidine 1 μg/kg, followed by infusion of 1 μg/kg/h, and group B received a loading dose of IV clonidine 2 μg/kg, followed by 1 μg/kg/h infusion. Surgical field quality, emergence time, sedation score, visual analogue score, recovery profile and haemodynamic parameters were recorded. Statistical analysis was done by Student's unpaired t-test to evaluate the significance of normally distributed variables, whereas Mann-Whitney test and Chi-square test were used for ordinal data and categorical variables and proportions, respectively.

Results

In both the groups, target mean arterial pressure (MAP) of 65-70 mmHg and improved surgical field quality were achieved. MAP and heart rate (HR) were statistically significantly lower in the dexmedetomidine group with a longer duration of post-operative analgesia (P = 0.001). None of the groups showed any statistically significant adverse effects.

Conclusions

Both dexmedetomidine and clonidine can be used for controlled hypotension to improve surgical field quality in FESS. Dexmedetomidine provides more haemodynamic stability and an additional benefit of post-operative analgesia and conscious sedation.

Impact of chronic medications in the perioperative period: mechanisms of action and adverse drug effects (Part I)

Background: This review article discusses the pharmacology of the most commonly used chronic medications in patients undergoing elective surgical procedures. The mechanism of action and adverse side effects of cardiovascular medications (e.g., beta blockers, alpha-2 agonist, calcium channel blockers, ACE inhibitors, diuretics), lipid-lowering drugs, gastrointestinal medications (H2-blockers, proton pump inhibitors), pulmonary medications (inhaled β-agonists, anticholinergics,), antibiotics (tetracyclines, clindamycin and macrolide, linezolid), opioids and non-opioids analgesics (NSAIDs, COX-2 inhibitors, acetaminophen), gabapentanoids, erectile dysfunction (ED) drugs, and psychotropic drugs (tricyclic antidepressants [TCAs], monoamine oxidase inhibitors [MAOI], selective serotonin reuptake inhibitors [SSRIs], serotonin norepinephrine reuptake inhibitors [SNRIs], and cannabinol-containing drugs) will be reviewed.Materials and Methods: An online search was conducted from January 2000 through February 2021 with the Medline database through PubMed and Google Scholar using the following search terms/keywords: "chronic medications in the perioperative period", and "chronic medications and anesthetic implications." In addition, we searched for anesthetic side effects associated with the major drug groups.Results and Conclusions: An understanding of the pharmacology and pharmacokinetics of most used chronic medications is important to avoid untoward outcomes in the perioperative period. These drug interactions may result in altered efficacy and toxicity of the anesthetic medications administered during surgery. These drug-drug interactions can also effect the morbidity, mortality, and recovery time of surgical patients. Part I of this two-part review article focuses on the mechanisms of action and adverse side effects of the chronic medications most commonly taken by surgical patients in the preoperative period.

Caffeine, genetic variation and anaerobic performance in male athletes: a randomized controlled trial

PURPOSE

The effect of caffeine on anaerobic performance is unclear and may differ depending on an individual's genetics. The goal of this study was to determine whether caffeine influences anaerobic performance in a 30 s Wingate test, and if 14 single nucleotide polymorphisms (SNPs) in nine genes, associated with caffeine metabolism or response, modify caffeine's effects.

METHODS

Competitive male athletes (N = 100; 25 ± 4 years) completed the Wingate under three conditions: 0, 2, or 4 mg of caffeine per kg of body mass (mg kg^-1), using a double-blinded, placebo-controlled design. Using saliva samples, participants were genotyped for the 14 SNPs. The outcomes were peak power (Watts [W]), average power (Watts [W]), and fatigue index (%).

RESULTS

There was no main effect of caffeine on Wingate outcomes. One significant caffeine-gene interaction was observed for CYP1A2 (rs762551, p = 0.004) on average power. However, post hoc analysis showed no difference in caffeine's effects within CYP1A2 genotypes for average power performance. No significant caffeine-gene interactions were observed for the remaining SNPs on peak power, average power and fatigue index.

CONCLUSION

Caffeine had no effect on anaerobic performance and variations in several genes did not modify any effects of caffeine.

TRIAL REGISTRATION

This study was registered with clinicaltrials.gov (NCT02109783).

GPCR Pharmacological Profiling of Aaptamine from the Philippine Sponge Stylissa sp. Extends Its Therapeutic Potential for Noncommunicable Diseases

We report the first isolation of the alkaloid aaptamine from the Philippine marine sponge Stylissa sp. Aaptamine possessed weak antiproliferative activity against HCT116 colon cancer cells and inhibited the proteasome in vitro at 50 µM. These activities may be functionally linked. Due to its known, more potent activity on certain G-protein coupled receptors (GPCRs), including α-adrenergic and δ-opioid receptors, the compound was profiled more broadly at sub-growth inhibitory concentrations against a panel of 168 GPCRs to potentially reveal additional targets and therapeutic opportunities. GPCRs represent the largest class of drug targets. The primary screen at 20 µM using the β-arrestin functional assay identified the antagonist, agonist, and potentiators of agonist activity of aaptamine. Dose-response analysis validated the α-adrenoreceptor antagonist activity of aaptamine (ADRA2C, IC₅₀ 11.9 µM) and revealed the even more potent antagonism of the β-adrenoreceptor (ADRB2, IC₅₀ 0.20 µM) and dopamine receptor D4 (DRD4, IC₅₀ 6.9 µM). Additionally, aaptamine showed agonist activity on selected chemokine receptors, by itself (CXCR7, EC₅₀ 6.2 µM; CCR1, EC₅₀ 11.8 µM) or as a potentiator of agonist activity (CXCR3, EC₅₀ 31.8 µM; CCR3, EC₅₀ 16.2 µM). These GPCRs play a critical role in the treatment of cardiovascular disease, diabetes, cancer, and neurological disorders. The results of this study may thus provide novel preventive and therapeutic strategies for noncommunicable diseases (NCDs).

Sedation and Anesthesia for the Adolescent Dental Patient

This article focuses on sedation/anesthesia of adolescent patients in the dental setting. Preoperative evaluation, treatment planning, monitoring, and management are critical components to successful sedation. The authors discuss commonly administered agents and techniques to adolescents, including nitrous oxide/oxygen analgesia. The levels and spectrum of sedation and anesthesia are reviewed. Common comorbidities are also presented as they relate to sedation of the adolescent dental patient.