Association between Early Guanfacine Discontinuation and Somnolence for Attention-Deficit/Hyperactivity Disorder.

Guanfacine, used as a medication for attention-deficit/hyperactivity disorder (ADHD), leads to a high incidence of somnolence, in contrast to methylphenidate, which leads to a high incidence of insomnia. The impact of somnolence on continuing guanfacine treatment is unclear. Therefore, we investigated the reasons for discontinuing guanfacine and analyzed the factors associated with discontinuation caused by somnolence. We surveyed 96 patients under guanfacine from July 2017 to December 2021 at the Saga University Hospital. Patients who discontinued guanfacine by the end date of our study were divided into a median early and late group. We compared the reasons for discontinuation in both groups. Of all patients, 47 continued and 49 discontinued guanfacine. A higher percentage of patients discontinued guanfacine caused by somnolence for ≤70 d than for >70 d of treatment (44.0 vs. 8.3%; p = 0.008). When stratified by the concomitant use of other ADHD drugs, somnolence resulted in a higher discontinuation rate for ≤70 d than for >70 d of treatment without concomitant use (55.0 vs. 7.1%; p = 0.009). Nonetheless, concomitant use resulted in no difference. In conclusion, somnolence affects the early discontinuation of guanfacine as an ADHD drug. The combination of methylphenidate or atomoxetine may decrease withdrawal caused by somnolence.

Record Setting Temperatures in the Setting of SARS-CoV-2 Suggests Dexmedetomidine Drug-Induced Fever: A Case Report.

Patients infected with COVID-19 can develop coinfections or acute respiratory disorder that result in ventilation. Dexmedetomidine is a common medication used to sedate ventilated patients in the intensive care unit and for nonintubated patients prior to a surgical procedure. As a highly selective alpha-2 agonist, dexmedetomidine provides sedation while reducing the need for anxiolytics or opioids. However, previous case reports suggest dexmedetomidine can induce fever in a variety of conditions. The purpose of this case report is to describe a patient who acquired a fever of 42.6°C in the setting of COVID-19 after administration of dexmedetomidine.

Dexmedetomidine alleviates acute postoperative anxiety in rats by suppressing the NF-ĸB pathway.

Evidence suggests that surgical procedures can effect the central nervous system and lead to changes in mood and behavior, rarely understood about the role of acute inflammation in promoting acute anxiety postoperatively. This study was designed to explore the possible mechanism of dexmedetomidine (DEX, a2-adrenergic receptor agonist) for reducing acute postoperative anxiety, which may be related to the activation of nuclear factor kappa B (NF-κB) and downstream signal pathway in the hippocampus. Experiments were conducted with rat, the elevated plus-maze and open field test were performed to evaluate anxiety-like behavior. Inhibit DEX with Atipamezole (AT, α2-adrenergic receptor antagonist) and inhibit NF-κB with Pyrrolidinedithiocarbamate (PDTC, inhibit phosphorylation of IκB, prevent the activation of NF-κB), the level of interleukin-6 (IL-6), IL-1ß, IL-10 and Tumor necrosis factor-α (TNF-α); the nuclear translocation of NF-κB in the hippocampus and anxiety-like behavior were measured. Rats exhibited anxiety-like behavior at 6h and 12h after surgery. Preoperative administration of DEX significantly alleviated postoperative anxiety-like behavior. DEX premedication inhibited the nuclear translocation of NF-κB alleviate acute postoperative anxiety. These findings are the first to show that acute postoperative anxiety may be related to NF-κB nuclear translocation in the hippocampus in rats, which can be alleviated by DEX premedication.

Giant T waves and QT interval prolongation associated with guanfacine toxicity.

INTRODUCTION: Guanfacine is a central α2-adrenergic receptor agonist that produces drowsiness, bradycardia, hypotension, and occasionally QT interval prolongation. We discuss giant T waves associated with guanfacine toxicity. CASE SUMMARIES: Three patients presented to the hospital with histories and physical findings compatible with guanfacine toxicity. Supratherapeutic concentrations were confirmed in two of them. All three developed QT interval prolongation and giant T waves on the electrocardiogram. Giant T waves occur commonly in patients with acute myocardial infarct and hyperkalemia, as well as rarely with a number of other cardiac and non-cardiac causes. CONCLUSION: Guanfacine toxicity may cause the novel electrocardiographic finding of 'giant T wave with QT interval prolongation'. Further studies are warranted to investigate the association between the novel electrocardiographic finding and guanfacine toxicity, as well as its diagnostic utility in such cases.

A Comparative Study of the Antiemetic Effects of α2-Adrenergic Receptor Agonists Clonidine and Dexmedetomidine against Diverse Emetogens in the Least Shrew (Cryptotis parva) Model of Emesis.

In contrast to cats and dogs, here we report that the α2-adrenergic receptor antagonist yohimbine is emetic and corresponding agonists clonidine and dexmedetomidine behave as antiemetics in the least shrew model of vomiting. Yohimbine (0, 0.5, 0.75, 1, 1.5, 2, and 3 mg/kg, i.p.) caused vomiting in shrews in a bell-shaped and dose-dependent manner, with a maximum frequency (0.85 ± 0.22) at 1 mg/kg, which was accompanied by a key central contribution as indicated by increased expression of c-fos, serotonin and substance P release in the shrew brainstem emetic nuclei. Our comparative study in shrews demonstrates that clonidine (0, 0.1, 1, 5, and 10 mg/kg, i.p.) and dexmedetomidine (0, 0.01, 0.05, and 0.1 mg/kg, i.p.) not only suppress yohimbine (1 mg/kg, i.p.)-evoked vomiting in a dose-dependent manner, but also display broad-spectrum antiemetic effects against diverse well-known emetogens, including 2-Methyl-5-HT, GR73632, McN-A-343, quinpirole, FPL64176, SR141716A, thapsigargin, rolipram, and ZD7288. The antiemetic inhibitory ID50 values of dexmedetomidine against the evoked emetogens are much lower than those of clonidine. At its antiemetic doses, clonidine decreased shrews' locomotor activity parameters (distance moved and rearing), whereas dexmedetomidine did not do so. The results suggest that dexmedetomidine represents a better candidate for antiemetic potential with advantages over clonidine.

Alpha 2 agonists for sedation to produce better outcomes from critical illness (A2B trial): protocol for a mixed-methods process evaluation of a randomised controlled trial.

INTRODUCTION: An association between deep sedation and adverse short-term outcomes has been demonstrated although this evidence has been inconsistent. The A2B (alpha-2 agonists for sedation in critical care) sedation trial is designed to determine whether the alpha-2 agonists clonidine and dexmedetomidine, compared with usual care, are clinically and cost-effective. The A2B intervention is a complex intervention conducted in 39 intensive care units (ICUs) in the UK. Multicentre organisational factors, variable cultures, perceptions and practices and the involvement of multiple members of the healthcare team add to the complexity of the A2B trial. From our pretrial contextual exploration it was apparent that routine practices such as type and frequency of pain, agitation and delirium assessment, as well as the common sedative agents used, varied widely across the UK. Anticipated challenges in implementing A2B focused on the impact of usual practice, perceptions of risk, ICU culture, structure and the presence of equipoise. Given this complexity, a process evaluation has been embedded in the A2B trial to uncover factors that could impact successful delivery and explore their impact on intervention delivery and interpretation of outcomes. METHODS AND ANALYSIS: This is a mixed-methods process evaluation guided by the A2B intervention logic model. It includes two phases of data collection conducted during and at the end of trial. Data will be collected using a combination of questionnaires, stakeholder interviews and routinely collected trial data. A framework approach will be used to analyse qualitative data with synthesis of data within and across the phases. The nature of the relationship between delivery of the A2B intervention and the trial primary and secondary outcomes will be explored. ETHICS AND DISSEMINATION: All elements of the A2B trial, including the process evaluation, are approved by Scotland A Research Ethics Committee (Ref. 18/SS/0085). Dissemination will be via publications, presentations and media engagement. TRIAL REGISTRATION NUMBER: NCT03653832.

Dexmedetomidine Pretreatment Confers Myocardial Protection and Reduces Mechanical Ventilation Duration for Patients Undergoing Cardiac Valve Replacement under Cardiopulmonary Bypass.

PURPOSE: The study aims to assess the effects of dexmedetomidine (Dex) pretreatment on patients during cardiac valve replacement under cardiopulmonary bypass. METHODS: For patients in the Dex group (n = 52), 0.5 µg/kg Dex was given before anesthesia induction, followed by 0.5 µg/kg/h pumping injection before aortic occlusion. For patients in the control group (n = 52), 0.125 ml/kg normal saline was given instead of Dex. RESULTS: The patients in the Dex group had longer time to first dose of rescue propofol than the control group (P = 0.003). The Dex group required less total dosage of propofol than the control group (P = 0.0001). The levels of cardiac troponin I (cTnI), creatine kinase isoenzyme MB (CK-MB), malondialdehyde (MDA), and tumor necrosis factor-α (TNF-α) were lower in the Dex group than the control group at T4, 8 h after the operation (T5), and 24 h after the operation (T6) (P <0.01). The Dex group required less time for mechanical ventilation than the control group (P = 0.003). CONCLUSION: The study suggests that 0.50 µg/kg Dex pretreatment could reduce propofol use and the duration of mechanical ventilation, and confer myocardial protection without increased adverse events during cardiac valve replacement.

Xylazine does not enhance fentanyl reinforcement in rats: A behavioral economic analysis.

The adulteration of illicit fentanyl with the alpha-2 agonist xylazine has been designated an emerging public health threat. The clinical rationale for combining fentanyl with xylazine is currently unclear, and the inability to study fentanyl/xylazine interactions in humans warrants the need for preclinical research. We studied fentanyl and xylazine pharmacodynamic and pharmacokinetic interactions in male and female rats using drug self-administration behavioral economic methods. Fentanyl, but not xylazine, functioned as a reinforcer under both fixed-ratio and progressive-ratio drug self-administration procedures. Xylazine combined with fentanyl at three fixed dose-proportion mixtures did not significantly alter fentanyl reinforcement as measured using behavioral economic analyses. Xylazine produced a proportion-dependent decrease in the behavioral economic Q0 endpoint compared to fentanyl alone. However, xylazine did not significantly alter fentanyl self-administration at FR1. Fentanyl and xylazine co-administration did not result in changes to pharmacokinetic endpoints. The present results demonstrate that xylazine does not enhance the addictive effects of fentanyl or alter fentanyl plasma concentrations. The premise for why illicitly manufacture fentanyl has been adulterated with xylazine remains to be determined.

Dexmedetomidine attenuates lipopolysaccharide-induced renal cell fibrotic phenotypic changes by inhibiting necroinflammation via activating α2-adrenoceptor: A combined randomised animal and in vitro study.

BACKGROUND: Acute kidney injury (AKI) was reported to be one of the initiators of chronic kidney disease (CKD) development. Necroinflammation may contribute to the progression from AKI to CKD. Dexmedetomidine (Dex), a highly selective α2-adrenoreceptor (AR) agonist, has cytoprotective and "anti-" inflammation effects. This study was designed to investigate the anti-fibrotic properties of Dex in sepsis models. METHODS: C57BL/6 mice were randomly treated with an i.p. injection of lipopolysaccharides (LPS) (10 mg/kg) alone, LPS with Dex (25 µg/kg), or LPS, Dex and Atipamezole (Atip, an α2-adrenoreceptor antagonist) (500 µg/kg) (n=5/group). Human proximal tubular epithelial cells (HK2) were also cultured and then exposed to LPS (1 µg/ml) alone, LPS and Dex (1 µM), transforming growth factor-beta 1 (TGF-ß1) (5 ng/ml) alone, TGF-ß1 and Dex, with or without Atip (100 µM) in culture media. Epithelial-mesenchymal transition (EMT), cell necrosis, necroptosis and pyroptosis, and c-Jun N-terminal kinase (JNK) phosphorylation were then determined. RESULTS: Dex treatment significantly alleviated LPS-induced AKI, myofibroblast activation, NLRP3 inflammasome activation, and necroptosis in mice. Atip counteracted its protective effects. Dex attenuated LPS or TGF-ß1 induced EMT and also prevented necrosis, necroptosis, and pyroptosis in response to LPS stimulation in the HK2 cells. The anti-EMT effects of Dex were associated with JNK phosphorylation. CONCLUSIONS: Dex reduced EMT following LPS stimulation whilst simultaneously inhibiting pyroptosis and necroptosis via α2-AR activation in the renal tubular cells. The "anti-fibrotic" and cytoprotective properties and its clinical use of Dex need to be further studied.

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.

Resolving neuroinflammatory and social deficits in ASD model mice: Dexmedetomidine downregulates NF-κB/IL-6 pathway via α2AR.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that severely affects individuals' daily life and social development. Unfortunately, there are currently no effective treatments for ASD. Dexmedetomidine (DEX) is a selective agonist of α2 adrenergic receptor (α2AR) and is widely used as a first-line medication for sedation and hypnosis in clinical practice. In recent years, there have been reports suggesting its potential positive effects on improving emotional and cognitive functions. However, whether dexmedetomidine has therapeutic effects on the core symptoms of ASD, namely social deficits and repetitive behaviors, remains to be investigated. In the present study, we employed various behavioral tests to assess the phenotypes of animals, including the three-chamber, self-grooming, marble burying, open field, and elevated plus maze. Additionally, electrophysiological recordings, western blotting, qPCR were mainly used to investigate and validate the potential mechanisms underlying the role of dexmedetomidine. We found that intraperitoneal injection of dexmedetomidine in ASD model mice-BTBR T+ Itpr3tf/J (BTBR) mice could adaptively improve their social deficits. Further, we observed a significant reduction in c-Fos positive signals and interleukin-6 (IL-6) expression level in the prelimbic cortex (PrL) of the BTBR mice treated with dexmedetomidine. Enhancing or inhibiting the action of IL-6 directly affects the social behavior of BTBR mice. Mechanistically, we have found that NF-κB p65 is a key pathway regulating IL-6 expression in the PrL region. In addition, we have confirmed that the α2AR acts as a receptor switch mediating the beneficial effects of dexmedetomidine in improving social deficits. This study provides the first evidence of the beneficial effects of dexmedetomidine on core symptoms of ASD and offers a theoretical basis and potential therapeutic approach for the clinical treatment of ASD.

A randomized, double-blind, dose-controlled study of the use of dexmedetomidine alone for procedural sedation of children and adolescents undergoing MRI scans.

BACKGROUND: Dexmedetomidine is a selective α2-adrenergic agonist originally approved for sedation of adults in the intensive care unit and subsequently approved for procedural sedation in adults undergoing medical procedures. Dexmedetomidine is widely used off-label for procedural sedation in children. AIMS: To evaluate efficacy and safety of monotherapy dexmedetomidine for magnetic resonance imaging procedural sedation of children ≥1month-<17years across three ascending doses. METHODS: Randomized, double-blind, dose-ranging study of procedural sedation recruited patients at USA and Japanese sites from February 2020 to November 2021. Patients were stratified into Cohort A (≥1month-<2years) or Cohort B (≥2-<17years). Cohort A loading doses/maintenance infusions: 0.5 mcg/kg/0.5 mcg/kg/h, 1.0 mcg/kg/1.0 mcg/kg/h, and 1.5 mcg/kg/1.5 mcg/kg/h. Cohort B loading doses/maintenance infusions: 0.5 mcg/kg/0.5 mcg/kg/h, 1.2 mcg/kg/1.0 mcg/kg/h, and 2.0 mcg/kg/1.5 mcg/kg/h. Primary endpoint was percentage of overall patients completing MRI without rescue propofol at the high versus low dose. Key secondary endpoint was percentage in each age cohort who did not require propofol at the high versus low dose. RESULTS: One hundred twenty-two patients received high- (n = 38), middle- (n = 42), or low-dose (n = 42) dexmedetomidine. A greater percentage completed MRI without propofol rescue, while receiving high- versus low-dose dexmedetomidine (24/38 [63.2%] vs. 6/42 [14.3%]) (odds ratio: 10.29, 95% confidence interval: 3.47-30.50, p < .001). Similar results were seen in both age cohorts. The most common adverse events were bradypnea, bradycardia, hypertension, and hypotension, and the majority were of mild-to-moderate severity. CONCLUSIONS: Dexmedetomidine was well tolerated. The high dose was associated with meaningfully greater efficacy compared with lower doses. Based on these results, the recommended starting dose for procedural sedation in children ≥1month-<2years is loading dose 1.5 mcg/kg/maintenance infusion 1.5 mcg/kg/h; children ≥2-<17years is loading dose 2.0 mcg/kg/maintenance infusion 1.5 mcg/kg/h.

Effects of alpha-2-adrenoceptor agonism and antagonism on equine blood insulin and glucose concentrations after oral carbohydrate load.

Alpha-2-adrenoceptor agonist detomidine is a commonly used sedative agent in horses. In addition to the sedative effect, detomidine has been reported to elicit changes in energy metabolism such as hypoinsulinaemia and hyperglycaemia. This study aimed to investigate the effects of detomidine with and without peripherally acting alpha-2-adrenoceptor antagonist vatinoxan on insulin and blood glucose (BG) concentrations in horses after a standard dose of oral carbohydrates. Sixteen horses were assigned to four intravenous treatments in a randomised cross-over design: saline (SAL), detomidine (0.02 mg/kg; DET), vatinoxan (0.2 mg/kg; VAT), and a combination of detomidine and vatinoxan (DET+VAT). Horses were administered corn syrup (0.45 mL/kg) immediately before each treatment. Blood samples were collected until 360 min. The differences between treatments were evaluated with repeated measures analysis of covariance and change from baseline was used as a response. P<0.05 was considered significant. After oral carbohydrate load, DET reduced insulin (median 30 min nadir 3.7, min-max 0.6-7.4 µIU/mL) significantly compared with SAL (P<0.0001; 17.4, 9.3-65.4 µIU/mL) and DET+VAT (P=0.0005; 6.4, 2.9-12.9 µIU/mL). BG increased significantly after DET (peak; 130.5, 8.8-15.8 mmol/L) compared with SAL (P<0.0001; 8.7, 6.9-12.4 mmol/L) and DET+VAT (P<0.0001; 8.5, 6.8-10.6 mmol/L). Vatinoxan alone reduced BG (peak median 7.6, 7.0-9.9 mmol/L) compared with SAL (P=0.02) and delayed insulin responses to carbohydrates. In conclusion, vatinoxan alleviated the detomidine-induced changes (DET+VAT compared to DET) in insulin and BG after oral carbohydrate load. Additionally, vatinoxan is potentially able to modulate BG concentration and insulin response after oral carbohydrate administration in horses, but more research is warranted.

PERK modulation, with GSK2606414, Sephin1 or salubrinal, failed to produce therapeutic benefits in the SOD1G93A mouse model of ALS.

Amyotrophic lateral sclerosis (ALS) has been linked to overactivity of the protein kinase RNA-like ER kinase (PERK) branch of the unfolded protein response (UPR) pathway, both in ALS patients and mouse models. However, attempts to pharmacologically modulate PERK for therapeutic benefit have yielded inconsistent and often conflicting results. This study sought to address these discrepancies by comprehensively evaluating three commonly used, CNS-penetrant, PERK modulators (GSK2606414, salubrinal, and Sephin1) in the same experimental models, with the goal of assessing the viability of targeting the PERK pathway as a therapeutic strategy for ALS. To achieve this goal, a tunicamycin-challenge assay was developed using wild-type mice to monitor changes in liver UPR gene expression in response to PERK pathway modulation. Subsequently, multiple dosing regimens of each PERK modulator were tested in standardized, well-powered, gender-matched, and litter-matched survival efficacy studies using the SOD1G93A mouse model of ALS. The alpha-2-adrenergic receptor agonist clonidine was also tested to elucidate the results obtained from the Sephin1, and of the previously reported guanabenz studies, by comparing the effects of presence or absence of α-2 agonism. The results revealed that targeting PERK may not be an ideal approach for ALS treatment. Inhibiting PERK with GSK2606414 or activating it with salubrinal did not confer therapeutic benefits. While Sephin1 showed some promising therapeutic effects, it appears that these outcomes were mediated through PERK-independent mechanisms. Clonidine also produced some favorable therapeutic effects, which were unexpected and not linked to the UPR. In conclusion, this study highlights the challenges of pharmacologically targeting PERK for therapeutic purposes in the SOD1G93A mouse model and suggests that exploring other targets within, and outside, the UPR may be more promising avenues for ALS treatment.

LC-derived excitatory synaptic transmission to dorsal raphe serotonin neurons is inhibited by activation of alpha2-adrenergic receptors.

In the central nervous system, noradrenaline transmission controls the degree to which we are awake, alert, and attentive. Aberrant noradrenaline transmission is associated with pathological forms of hyper- and hypo-arousal that present in numerous neuropsychiatric disorders often associated with dysfunction in serotonin transmission. In vivo, noradrenaline regulates the release of serotonin because noradrenergic input drives the serotonin neurons to fire action potentials via activation of excitatory α1-adrenergic receptors (α1-AR). Despite the critical influence of noradrenaline on the activity of dorsal raphe serotonin neurons, the source of noradrenergic afferents has not been resolved and the presynaptic mechanisms that regulate noradrenaline-dependent synaptic transmission have not been described. Using an acute brain slice preparation from male and female mice and electrophysiological recordings from dorsal raphe serotonin neurons, we found that selective optogenetic activation of locus coeruleus terminals in the dorsal raphe was sufficient to produce an α1-AR-mediated excitatory postsynaptic current (α1-AR-EPSC). Activation of inhibitory α2-adrenergic receptors (α2-AR) with UK-14,304 eliminated the α1-AR-EPSC via presynaptic inhibition of noradrenaline release, likely via inhibition of voltage-gated calcium channels. In a subset of serotonin neurons, activation of postsynaptic α2-AR produced an outward current through activation of GIRK potassium conductance. Further, in vivo activation of α2-AR by systemic administration of clonidine reduced the expression of c-fos in the dorsal raphe serotonin neurons, indicating reduced neural activity. Thus, α2-AR are critical regulators of serotonin neuron excitability.

M1 polarization of macrophages promotes stress-induced hair loss via interleukin-18 and interleukin-1ß.

Stress-induced hair loss is a prevalent health concern, with mechanisms that remain unclear, and effective treatment options are not yet available. In this study, we investigated whether stress-induced hair loss was related to an imbalanced immune microenvironment. Screening the skin-infiltrated immune cells in a stressed mouse model, we discovered a significant increase in macrophages upon stress induction. Clearance of macrophages rescues mice from stress-induced hair shedding and depletion of hair follicle stem cells (HFSCs) in the skin, demonstrating the role of macrophages in triggering hair loss in response to stress. Further flow cytometry analysis revealed a significant increase in M1 phenotype macrophages in mice under stressed conditions. In searching for humoral factors mediating stress-induced macrophage polarization, we found that the hormone Norepinephrine (NE) was elevated in the blood of stressed mice. In addition, in-vivo and in-vitro studies confirm that NE can induce macrophage polarization toward M1 through the ß-adrenergic receptor, Adrb2. Transcriptome, enzyme-linked immunosorbent assay (ELISA), and western blot analyses reveal that the NLRP3/caspase-1 inflammasome signaling and its downstream effector interleukin 18 (IL-18) and interleukin 1 beta (IL-1ß) were significantly upregulated in the NE-treated macrophages. However, inhibition of the NE receptor Adrb2 with ICI118551 reversed the upregulation of NLRP3/caspase-1, IL-18, and IL-1ß. Indeed, IL-18 and IL-1ß treatments lead to apoptosis of HFSCs. More importantly, blocking IL-18 and IL-1ß signals reversed HFSCs depletion in skin organoid models and attenuated stress-induced hair shedding in mice. Taken together, this study demonstrates the role of the neural (stress)-endocrine (NE)-immune (M1 macrophages) axis in stress-induced hair shedding and suggestes that IL-18 or IL-1ß may be promising therapeutic targets.

QT-Interval Prolongation Associated with Supratherapeutic Guanfacine Concentration: A Case Report.

INTRODUCTION: Guanfacine, an alpha-2 adrenergic agonist, is used to treat attention deficit hyperactivity disorder (ADHD). Although cardiovascular effects including hypotension and bradycardia are common adverse effects of guanfacine, the effect of guanfacine on QT intervals remains unclear. The association between the serum concentration of guanfacine and its toxicity has also not been fully investigated. CASE REPORT: This is a case of a 21-year-old woman with ADHD who developed repeated presyncope 1 day before admission. She was taking 3 mg of extended-release guanfacine and 50 mg of sertraline. On admission, she had bradycardia and hypotension. An electrocardiogram (ECG) showed a QT interval of 0.68 s and a QTcF interval of 0.648 s. The QT intervals were manually measured and corrected by the Fridericia formula (QTcF = QT/RR1/3). Although she denied taking an overdose of guanfacine and other drugs, we suspected guanfacine toxicity. The serum guanfacine concentration was 13.0 ng/mL on admission and decreased to 3.2 ng/mL on day 1 and 0.4 ng/mL on day 2. Changes in QTcF intervals and her vital signs correlated with serum guanfacine concentrations. CONCLUSION: Supratherapeutic serum guanfacine concentrations may induce QT prolongation.

Dexmedetomidine and clonidine in palliative medicine: multicentric qualitative evaluation.

OBJECTIVES: Alpha-2 agonists have analgesic and sedative properties that can prove interesting in palliative care. The main objective of this study was to describe the use of clonidine and dexmedetomidine in palliative care units (PCU). The secondary objective was to identify physicians' perspectives and attitudes toward alpha-2-agonists. METHODS: International multicentric qualitative survey of prescribing characteristics and attitudes towards alpha-2 agonist. All 159 PCUs in France, Belgium and French-speaking Switzerland were contacted, and 142 physicians answered the questionnaire (31% participation). RESULTS: 20% of the practitioners surveyed prescribe these molecules are mainly for analgesic and sedative indications. There was considerable heterogeneity in the modalities and dosages of administration. The use of clonidine is more frequent and common in Belgium, while dexmedetomidine is only used in France. There is a high level of satisfaction among practitioners who use these molecules, with the desire of the majority of respondents to obtain additional studies and information on alpha-2-agonists. CONCLUSION: Alpha-2 agonists are little known and little prescribed by French-speaking palliative care physicians but are of interest because of their potential in this field. Phase 3 studies could justify the use of these molecules in palliative situations and would contribute to harmonising professional practices.

The effects of dexmedetomidine on intraoperative neurophysiologic monitoring modalities during corrective scoliosis surgery in pediatric patients: A systematic review.

BACKGROUND: During scoliosis surgery, motor evoked potentials (MEP), and somatosensory evoked potentials (SSEP) have been reported to be affected by the use of higher doses of anesthetic agents. Dexmedetomidine, a sympatholytic agent, an alpha-2 receptor agonist, has been used as an adjunctive agent to lower anesthetic dose. However, there is conflicting evidence regarding the effects of dexmedetomidine on the intraoperative neurophysiological monitoring of MEP and SSEP during surgery, particularly among pediatric patients. OBJECTIVES: This systematic review aimed to determine whether, during spinal fusion surgery in pediatric patients with scoliosis, dexmedetomidine alters MEP amplitude or SSEP latency and amplitude and, if so, whether different doses of dexmedetomidine display different effects (PROSPERO registration number CRD42022300562). METHODS: We searched PubMed, Scopus, and Cochrane Library on January 1, 2022 and included randomized controlled trials, observational cohort and case-control studies and case series investigating dexmedetomidine in the population of interest and comparing against a standardized anesthesia regimen without dexmedetomidine or comparing multiple doses of dexmedetomidine. Animal and in vitro studies and conference abstracts were excluded. RESULTS: We found substantial heterogeneity in the risk of bias (per Cochrane-preferred tools) of the included articles (n = 5); results are summarized without meta-analysis. Articles with the lowest risk of bias indicated that dexmedetomidine was associated with MEP loss and that higher doses of dexmedetomidine increased risk. In contrast, articles reporting no association between dexmedetomidine and MEP loss suffered from higher risk of bias, including suspected or confirmed problems with confounding, outcome measurement, participant selection, results reporting, and lack of statistical transparency and power. CONCLUSION: Given the limitations of the studies available in the literature, it would be advisable to conduct rigorous randomized controlled trials with larger sample sizes to assess the effects of dexmedetomidine use of in scoliosis surgery in pediatric patients.