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

Sexual Incentive Motivation and Copulatory Behavior in Male Rats Treated With the Adrenergic α2-Adrenoceptor Agonists Tasipimidine and Fadolmidine: Implications for Treatment of Premature Ejaculation

BACKGROUND

Premature ejaculation is the most common sexual dysfunction in young men, and it often leads to reduced relationship satisfaction and quality of life.

AIM

To determine the role of central and peripheral α₂-adrenoceptors in the control of ejaculation and sexual incentive motivation in rats.

METHODS

Sexual incentive motivation was studied in a large arena in which a male subject could choose between approaching and remaining close to a sexually receptive female or another male. Sexual behavior was studied in standard observation cages in which a male was allowed to freely interact with a receptive female for 30 minutes. Two highly selective agonists at the α₂-adrenoceptors, tasipimidine and fadolmidine, were administered before the tests. Low peripheral doses of fadolmidine have been reported to have effects mainly outside of the central nervous system, whereas at large doses also the central effects are evident.

OUTCOMES

The time spent close to the receptive female in relation to the time spent with the male and measures of ambulatory activity were obtained from the test for sexual incentive motivation, while the habitual parameters of sexual behavior were recorded with the copulation test.

RESULTS

Tasipimidine prolonged ejaculation latency and the interintromission interval at the dose of 200 µg/kg when data from fast-ejaculating rats were used. No other sexual parameter was modified. A dose of 100 µg/kg was ineffective. There was no consistent effect on sexual incentive motivation, although modest sedation was observed. Fadolmidine, a drug that does not easily penetrate the blood-brain barrier, had no effect on sexual incentive motivation at any of the doses used (3, 30, and 100 µg/kg). The largest dose had clear sedative effects. The lower doses had no systematic effect on sexual behavior, not even when only fast or very fast ejaculating males were analyzed.

CLINICAL TRANSLATION

The findings are relevant to the search for treatments for premature ejaculation that are specific enough to selectively delay ejaculation.

STRENGTHS & LIMITATIONS

The procedures used here are standard in the field and yield the most reliable data. Whether the effects observed in male rats are directly transferrable to men can only be determined through clinical studies.

CONCLUSION

The observation that drugs acting at central but not peripheral α₂-adrenoceptors prolong ejaculation latency without affecting any other parameter of sexual behavior or sexual incentive motivation suggests that this kind of drug may be suitable for treating premature ejaculation. Jyrki L., Elisa V.-A., Xi C., et al. Sexual Incentive Motivation and Copulatory Behavior in Male Rats Treated With the Adrenergic α₂-Adrenoceptor Agonists Tasipimidine and Fadolmidine: Implications for Treatment of Premature Ejaculation. J Sex Med 2021;18:1677-1689.

Comparison of the effects of dexmedetomidine and remifentanil on perioperative hemodynamics and recovery profile of patients undergoing laryngeal microsurgery: A prospective randomized double-blinded study

BACKGROUND

Laryngeal microsurgery (LMS) causes hemodynamic instability and postoperative agitation, cough, pain, nausea, and vomiting. Moreover, because of a short operation time, it is associated with challenging anesthetic management. The aim of this study was to compare the usefulness of continuous administration of dexmedetomidine and remifentanil in inducing general anesthesia in patients undergoing LMS.

METHODS

This is a prospective randomized control design. Continuous intravenous infusion of dexmedetomidine (group D) or remifentanil (group R) was administered from 10 minutes before the induction of anesthesia to the end of surgery. In both groups, 1.5 mg/kg propofol and 0.5 mg/kg rocuronium were administered for the induction of anesthesia, and desflurane were titrated during the measurement of the bispectral index. We recorded hemodynamic data, recovery time, grade of cough, pain score, and analgesic requirements during the perioperative period.

RESULTS

61 patients were finally analyzed (30 for group D, 31 for group R). The incidence of moderate to severe postoperative sore throat was higher in group R than in group D (42% vs 10%, P = .008), and the quantity of rescue fentanyl used in post-anesthesia care unit was significantly higher in group R than in group D (23.2 ± 24.7 mg vs 3.3 ± 8.6 mg; P < .001); however, the time required for eye opening was significantly longer in group D than in group R (599.4 ± 177.9 seconds vs 493.5 ± 103.6 seconds; P = .006). The proportion of patients with no cough or single cough during extubation was comparable between the 2 groups (group D vs group R: 73% vs 70%) as was the incidence of hemodynamic instability.

CONCLUSION

Although there was a transient delay in emergence time, dexmedetomidine reduced postoperative opioid use and the incidence of sore throat. Dexmedetomidine may be used as an alternative agent to opioids in patients undergoing LMS.

Systemic side effects of glaucoma medications

Glaucoma is a progressive loss of retinal ganglion cells leading to visual field loss. Lowering intraocular pressure is currently the only modifiable risk factor to slow glaucoma progression. Intraocular pressure-lowering options include topical and systemic medications, lasers, and surgical procedures. Glaucoma eye drops play a major role in treating this blinding disease. Similar to all medications, the glaucoma medications have their own adverse effects. The majority of glaucoma medications work by stimulating or inhibiting adrenergic, cholinergic, and prostaglandin receptors, which are distributed all over the body. Therefore, the glaucoma medications can affect organs other than the eye. This review will discuss the systemic adverse effects of carbonic anhydrase inhibitors, sympathomimetics, para-sympathomimetics, beta blockers, prostaglandin analogs, hyperosmotic agents, and novel glaucoma medications with a stress on pregnant patients, breastfeeding mothers, and paediatric patients.

Sex differences in hypertension: lessons from spontaneously hypertensive rats (SHR)

Although numerous clinical and experimental studies have clearly identified a sexual dimorphism in blood pressure control, the mechanism(s) underlying gender differences in blood pressure remain unclear. Over the past two decades, numerous laboratories have utilized the spontaneously hypertensive rats (SHR) as an experimental model of essential hypertension to increase our understanding of the mechanisms regulating blood pressure in males and females. Previous work by our group and others have implicated that differential regulation of adrenergic receptors, the renin-angiotensin system, oxidative stress, nitric oxide bioavailability and immune cells contribute to sex differences in blood pressure control in SHR. The purpose of this review is to summarize previous findings to date regarding the mechanisms of blood pressure control in male versus female SHR.

Dexmedetomidine does not compromise neuronal viability, synaptic connectivity, learning and memory in a rodent model

Recent animal studies have drawn concerns regarding most commonly used anesthetics and their long-term cytotoxic effects, specifically on the nervous tissue. It is therefore imperative that the search continues for agents that are non-toxic at both the cellular and behavioural level. One such agent appears to be dexmedetomidine (DEX) which has not only been found to be less neurotoxic but has also been shown to protect neurons from cytotoxicity induced by other anesthetic agents. However, DEX's effects on the growth and synaptic connectivity at the individual neuronal level, and the underlying mechanisms have not yet been fully resolved. Here, we tested DEX for its impact on neuronal growth, synapse formation (in vitro) and learning and memory in a rodent model. Rat cortical neurons were exposed to a range of clinically relevant DEX concentrations (0.05-10 µM) and cellular viability, neurite outgrowth, synaptic assembly and mitochondrial morphology were assessed. We discovered that DEX did not affect neuronal viability when used below 10 µM, whereas significant cell death was noted at higher concentrations. Interestingly, in the presence of DEX, neurons exhibited more neurite branching, albeit with no differences in corresponding synaptic puncta formation. When rat pups were injected subcutaneously with DEX 25 µg/kg on postnatal day 7 and again on postnatal day 8, we discovered that this agent did not affect hippocampal-dependent memory in freely behaving animals. Our data demonstrates, for the first time, the non-neurotoxic nature of DEX both in vitro and in vivo in an animal model providing support for its utility as a safer anesthetic agent. Moreover, this study provides the first direct evidence that although DEX is growth permissive, causes mitochondrial fusion and reduces oxygen reactive species production, it does not affect the total number of synaptic connections between the cortical neurons in vitro.

Effects of fadolmidine, an α2 -adrenoceptor agonist, as an adjuvant to spinal bupivacaine on antinociception and motor function in rats and dogs

α2 -Adrenoceptor agonists such as clonidine and dexmedetomidine are used as adjuvants to local anesthetics in regional anesthesia. Fadolmidine is an α2 -adrenoceptor agonist developed especially as a spinal analgesic. The current studies investigate the effects of intrathecally administered fadolmidine with a local anesthetic, bupivacaine, on antinociception and motor block in conscious rats and dogs. The antinociceptive effects of intrathecal fadolmidine and bupivacaine alone or in combination were tested in the rat tail-flick and the dog's skin twitch models. The durations of motor block in rats and in dogs were also assessed. In addition, the effects on sedation, mean arterial blood pressure, heart rate, respiratory rate and body temperature were evaluated in telemetrized dogs. Concentrations of fadolmidine in plasma and spinal cord were determined after intrathecal and intravenous administration in rats. Co-administration of intrathecal fadolmidine with bupivacaine increased the magnitude and duration of the antinociceptive effects and prolonged motor block without hypotension. The interaction of the antinociceptive effect was synergistic in its nature in rats. Concentration of fadolmidine in plasma was very low after intrathecal dosing. Taken together, these studies show that fadolmidine as an adjuvant to intrathecal bupivacaine provides enhanced sensory-motor block and enables a reduction of the doses of both drugs. The results indicate that co-administration of fadolmidine with intrathecal bupivacaine was able to achieve an enhanced antinociceptive effect without hypotension and could thus represent a suitable combination for spinal anesthesia.

The Influence of Xylazine and Clonidine on Lung Ultrasound-Induced Pulmonary Capillary Hemorrhage in Spontaneously Hypertensive Rats

Induction of pulmonary capillary hemorrhage (PCH) by lung ultrasound (LUS) depends not only on physical exposure parameters but also on physiologic conditions and drug treatment. We studied the influence of xylazine and clonidine on LUS-induced PCH in spontaneously hypertensive and normotensive rats using diagnostic B-mode ultrasound at 7.3 MHz. Using ketamine anesthesia, rats receiving saline, xylazine, or clonidine treatment were tested with different pulse peak rarefactional pressure amplitudes in 5 min exposures. Results with xylazine or clonidine in spontaneously hypertensive rats were not significantly different at the three exposure pulse peak rarefactional pressure amplitudes, and thresholds were lower (2.2 MPa) than with saline (2.6 MPa). Variations in LUS PCH were not correlated with mean systemic blood pressure. Similar to previous findings for dexmedetomidine, the clinical drug clonidine tended to increase susceptibility to LUS PCH.

The effects of anaesthetics and sedatives on brain inflammation

Microglia are involved in many dynamic processes in the central nervous system (CNS) including the development of inflammatory processes and neuromodulation. Several sedative, analgesic or anaesthetic drugs, such as opioids, ∝2-adrenergic agonists, ketamine, benzodiazepines and propofol can cause both neuroprotective and harmful effects on the brain. The purpose of this review is to present the main findings on the use of these drugs and the mechanisms involved in microglial activation. Alpha 2-adrenergic agonists, propofol and benzodiazepines have several pro- or anti-inflammatory effects on microglia. Long-term use of benzodiazepines and propofol causes neuroapoptotic effects and α2-adrenergic agonists may attenuate these effects. Conversely, morphine and fentanyl may have proinflammatory effects, causing behavioural changes in patients and changes in cell viability in vitro. Conversely, chronic administration of morphine induces CCL5 chemokine expression in microglial cells that promotes their survival.

Role of α- and β-adrenergic signaling in phenotypic targeting: significance in benign and malignant urologic disease

The urinary tract is highly innervated by autonomic nerves which are essential in urinary tract development, the production of growth factors, and the control of homeostasis. These neural signals may become dysregulated in several genitourinary (GU) disease states, both benign and malignant. Accordingly, the autonomic nervous system is a therapeutic target for several genitourinary pathologies including cancer, voiding dysfunction, and obstructing nephrolithiasis. Adrenergic receptors (adrenoceptors) are G-Protein coupled-receptors that are distributed throughout the body. The major function of α1-adrenoceptors is signaling smooth muscle contractions through GPCR and intracellular calcium influx. Pharmacologic intervention of α-and β-adrenoceptors is routinely and successfully implemented in the treatment of benign urologic illnesses, through the use of α-adrenoceptor antagonists. Furthermore, cell-based evidence recently established the antitumor effect of α1-adrenoceptor antagonists in prostate, bladder and renal tumors by reducing neovascularity and impairing growth within the tumor microenvironment via regulation of the phenotypic epithelial-mesenchymal transition (EMT). There has been a significant focus on repurposing the routinely used, Food and Drug Administration-approved α1-adrenoceptor antagonists to inhibit GU tumor growth and angiogenesis in patients with advanced prostate, bladder, and renal cancer. In this review we discuss the current evidence on (a) the signaling events of the autonomic nervous system mediated by its cognate α- and β-adrenoceptors in regulating the phenotypic landscape (EMT) of genitourinary organs; and (b) the therapeutic significance of targeting this signaling pathway in benign and malignant urologic disease. Video abstract.

Methadone, Buprenorphine, and Clonidine Attenuate Mitragynine Withdrawal in Rats

Background: Kratom or Mitragyna speciosa Korth has been widely used to relieve the severity of opioid withdrawal in natural settings. However, several studies have reported that kratom may by itself cause dependence following chronic consumption. Yet, there is currently no formal treatment for kratom dependence. Mitragynine, is the major psychoactive alkaloid in kratom. Chronic mitragynine treatment can cause addiction-like symptoms in rodent models including withdrawal behaviour. In this study we assessed whether the prescription drugs, methadone, buprenorphine and clonidine, could mitigate mitragynine withdrawal effects. In order to assess treatment safety, we also evaluated hematological, biochemical and histopathological treatment effects. Methods: We induced mitragynine withdrawal behaviour in a chronic treatment paradigm in rats. Methadone (1.0 mg/kg), buprenorphine (0.8 mg/kg) and clonidine (0.1 mg/kg) were i.p. administered over four days during mitragynine withdrawal. These treatments were stopped and withdrawal sign assessment continued. Thereafter, toxicological profiles of the treatments were evaluated in the blood and in organs. Results: Chronic mitragynine treatment caused significant withdrawal behaviour lasting at least 5 days. Methadone, buprenorphine, as well as clonidine treatments significantly attenuated these withdrawal signs. No major effects on blood or organ toxicity were observed. Conclusion: These data suggest that the already available prescription medications methadone, buprenorphine, and clonidine are capable to alleviate mitragynine withdrawal signs rats. This may suggest them as treatment options also for problematic mitragynine/kratom use in humans.

Ligands of Adrenergic Receptors: A Structural Point of View

Adrenergic receptors are G protein-coupled receptors for epinephrine and norepinephrine. They are targets of many drugs for various conditions, including treatment of hypertension, hypotension, and asthma. Adrenergic receptors are intensively studied in structural biology, displayed for binding poses of different types of ligands. Here, we summarized molecular mechanisms of ligand recognition and receptor activation exhibited by structure. We also reviewed recent advances in structure-based ligand discovery against adrenergic receptors.

Comparative Study of the Adverse Events Associated With Adjuvant Use of Dexmedetomidine and Clonidine in Local Anesthesia

Background: Although clonidine and dexmedetomidine are used as alpha-2 agonists to improve the quality and duration of blockade induced by local anesthetics, no study has been reported to compare their associated adverse events in local anesthesia. The aim of this study is to compare the adverse events associated with the adjuvant use of dexmedetomidine and clonidine in local anesthesia.

Methods: A comprehensive search was performed to retrieve any reported adverse event associated with adjuvant use of dexmedetomidine and clonidine in local anesthesia from published literature up to 1 July 2020. Assessment of the quality of included studies was performed by the Jadad score. A comparison of any reported adverse event was made between interventions by pooling data from studies using a direct meta-analysis technique. Dichotomous outcomes were summarized as risk ratios. The review was performed according to PRISMA guideline.

Results: From 121 articles retrieved from the search finally 14 articles including 1,120 patients had eligibility criteria for including in the meta-analysis. No significant difference was observed between bradycardia/hypotension (OR = 1.17; 95 % CI = 0.66–2.10; P = 0.580; I² = 53.78 %, P = 0.027), nausea/vomiting (OR = 0.91; 95% CI = 0.59-1.42; P = 0.706; I² = 0.0 %, P = 0.940) dizziness/headache (OR = 1.10; 95% CI = 0.44–2.75; P = 0.831; I² = 0.0 %, P = 0.882) shivering (OR = 0.95 % CI = 0.50–1.66; P = 0.831; I² = 0.0 %, P = 0.920) and dry mouth (OR = 1.00; 95 % CI = 0.50–1.96; P = 0.996; I² = 0.0%, P = 0.900). No significant difference was observed in subgroup comparison of adverse events in the intravenous or local adjuvant use of the study drugs (p > 0.05).

Conclusion: There is no difference in adverse events associated with the intravenous or local adjuvant use of dexmedetomidine and clonidine in local anesthesia.

Evidence-based pharmacological treatment options for ADHD in children and adolescents

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity, causing functional impairment. Its prevalence lies at approximately 5% in children and adolescents and at approximately 2.5% in adults. The disorder follows a multifactorial etiology and shows a high heritability. Patients show a high interindividual and intraindividual variability of symptoms, with executive deficits in several cognitive domains. Overall, ADHD is associated with high rates of psychiatric comorbidities, and insufficient treatment is linked to adverse long-term outcomes. Current clinical guidelines recommend an individualized multimodal treatment approach including psychoeducation, pharmacological interventions, and non-pharmacological interventions. Available medications include stimulants (methylphenidate, amphetamines) and non-stimulants (atomoxetine, guanfacine, clonidine). While available pharmacological treatment options for ADHD show relatively large effect sizes (in short-term trials) and overall good tolerability, there is still a need for improvement of current pharmacotherapeutic strategies and for the development of novel medications. This review summarizes available pharmacological treatment options for ADHD in children and adolescents, identifies current issues in research and evidence gaps, and provides an overview of ongoing efforts to develop new medications for the treatment of ADHD in children and adolescents by means of a systematic cross-sectional analysis of the clinical trials registry www.clinicaltrials.gov.

Lighting Up the Plasma Membrane: Development and Applications of Fluorescent Ligands for Transmembrane Proteins

Despite the fact that transmembrane proteins represent the main therapeutic targets for decades, complete and in-depth knowledge about their biochemical and pharmacological profiling is not fully available. In this regard, target-tailored small-molecule fluorescent ligands are a viable approach to fill in the missing pieces of the puzzle. Such tools, coupled with the ability of high-precision optical techniques to image with an unprecedented resolution at a single-molecule level, helped unraveling many of the conundrums related to plasma proteins' life-cycle and druggability. Herein, we review the recent progress made during the last two decades in fluorescent ligand design and potential applications in fluorescence microscopy of voltage-gated ion channels, ligand-gated ion channels and G-coupled protein receptors.

Neurotoxicity of Olindias sambaquiensis and Chiropsalmus quadrumanus extracts in sympathetic nervous system

Cnidarians are equipped with nematocysts, which are specialized organelles used to inoculate venom during prey capturing and defense. Their venoms are rich in toxins and a potential source of bioactive compounds, however, poorly explored so far. In this work, the activity of the methanolic extracts from the hydromedusa Olindias sambaquiensis and the cubozoan jellyfish Chiropsalmus quadrumanus were studied in sympathetic neurotransmission. For that, bisected rat vas deferens - a classic model of sympathetic neurotransmission - were incubated with the extracts for further myographic and histopathological analysis. The O. sambaquiensis extract, at 0.1 μg/mL, facilitated the neurogenic contractions of the noradrenergic-rich epididymal portion, while reducing the noradrenaline (NA) potency, which suggests an interaction with postsynaptic α₁-adrenoceptors. On the other hand, a higher concentration (1 μg/mL) leads to time- and frequency-dependent blockade of nerve-evoked contractions without significantly changing the response to exogenous NA. In turn, the C. quadrumanus extract at 0.1 μg/mL induced blockade of nerve-evoked noradrenergic contractions while reducing the potency to exogenous NA. Both extracts did not affect the purinergic neurotransmission or induce muscle damages. Our results demonstrate that O. sambaquiensis and C. quadrumanus extracts significantly interfere with the noradrenergic neurotransmission without altering purinergic response or smooth muscle structure on rat vas deferens. Such results bring to light the pharmacological potential of O. sambaquiensis and C. quadrumanus molecules for therapeutics focusing on noradrenergic neurotransmission.

Dexmedetomidine as an Analgesic Agent with Neuroprotective Properties: Experimental and Clinical Aspects

Dexmedetomidine (Dexdor or Precedex®) is considered as a sedative agent which is widely used as an adjuvant in general anesthesia and critical care practice. There is extensive evidence indicating its neuroprotective properties especially in various ischemic and hemorrhagic brain injury models of animals. Clinical trials have shown that dexmedetomidine (DEX) can improve the outcome of intensive care unit (ICU) patients. Also, DEX is appropriate as a non-opioid analgesic therapy whenever minimizing opioid-related side effects is necessary. The present article reviews the recent advances in the use of DEX as a neuroprotective agent in both animal and human studies including newest findings about the mechanism of the drug as well as analgesic efficacy of this drug at all perioperative stages. In spite of the beneficial effects of the drug on the nervous system, there are potential adverse effects, such as hypotension and bradycardia, which can be treated pharmacologically and must be taken into consideration by clinicians.

Delirium and abnormal autonomic nervous system response to head-up tilt testing

BACKGROUND

Delirium is a common condition with poorly understood pathophysiology. Various theories have been proposed including that delirious patients have reduced cerebral blood flow. We hypothesised that patients with delirium could have abnormal autonomic nervous system function, as assessed by tilt table testing, which would explain the alteration in blood flow.

METHODS

A prospective cohort study of medical inpatients aged 65 years and older was undertaken. Delirium was assessed using DRS-R98 and DSM-IV criteria. Beat-to-beat blood pressure (BP) was recorded during tilt testing. Differences in BP changes between the two groups (those with delirium and those without) were explored. The association between severity of delirium and magnitude of BP changes was also examined.

RESULTS

64 participants were recruited during hospitalisation. 29 completed follow-up Head-Up Tilt testing. The mean age of participants was 80.8 years (SD 6.2 years). The control group (n = 12) had a median decrease in systolic BP of 17.5 mmHg (IQR 20.75). The delirium group (n = 17) had a median decrease in systolic BP of 1 mmHg (IQR 38.5), p = 0.04. As delirium severity scores increased, systolic BP change during tilting also increased (r_s = 0.42, p = 0.03).

CONCLUSION

Participants in the delirium group showed different BP responses to tilt test which may represent abnormal sympathetic response. This would be consistent with other features of delirium such as treatment response to centrally acting alpha-2 blockers. Equity of access to research for older, frail and delirious cohorts is essential but feasibility and acceptability needs to be optimised and factored into study design.

Efficacy of perioperative intravenous dexmedetomidine administration for the prevention of postoperative sore throat: a meta-analysis

Objective

Postoperative sore throat (POST) is an undesirable intubation-related complication after surgery. Several studies have investigated the efficacy of perioperative intravenous dexmedetomidine administration for the prevention of POST, but the results have been inconsistent. We aimed to summarize all existing evidence and draw a more precise conclusion to guide future clinical work.

Methods

PubMed, Cochrane Library, EMBASE and China National Knowledge Infrastructure databases were comprehensively searched for all randomized controlled trials published before 1 February 2021 that investigated the efficacy of dexmedetomidine for the prevention of POST.

Results

Nine studies involving 400 patients were included in our meta-analysis. Compared with the control groups (i.e., saline and anesthetic drugs), perioperative intravenous use of dexmedetomidine significantly reduced the incidence of POST [risk ratio (RR): 0.56; 95% confidence interval (CI): 0.40–0.77; I² = 0%) and coughing on the tube during extubation (RR: 0.58; 95% CI: 0.41–0.82; I² = 0%). Additionally, patients in the dexmedetomidine group were more likely to develop bradycardia (RR: 2.46; 95% CI: 1.28–4.71; I² = 0%) and hypotension (RR: 3.26; 95% CI: 1.14–9.33; I² = 0%) during the administration of dexmedetomidine than those in the control group.

Conclusion

Perioperative intravenous administration of dexmedetomidine has a positive effect on the prevention of POST.

The effects of clonidine and yohimbine in the tail flick and hot plate tests in the naked mole rat (Heterocephalus glaber)

Objective

The naked mole rat (NMR) (Heterocephalus glaber) is increasingly considered an important biomedical research model for various conditions like hypoxic brain injury, cancer and nociception. This study was designed to investigate the effects of clonidine and yohimbine, an alpha-2 (α₂) adrenoceptor agonist and antagonist respectively in the tail flick and hot plate tests.

Results

A significant difference in tail flick latency was noted between saline control and 30 µg/kg clonidine, which was reduced after administration of 30 µg/kg yohimbine. A significant difference in hot plate latency was also noted between saline control and 30 µg/kg clodinine during the periods 30, 45, 60, 75 and 90 min after administration, and between saline control and 10 µg/kg clonidine during 30 min after administration. The hot plate latency by 30 µg/kg clonidine was also reduced by 30 µg/kg yohimbine during 30 min after administration. Since the tail-flick and hot plate tests mediate the effects at spinal and supraspinal levels respectively, the present study indicates the presence and involvement of noradrenergic receptors in thermal antinociception at spinal and supraspinal levels of the NMR, similar to what has been found in other mammals.

Effects of dexmedetomidine on neurocognitive disturbance after elective non-cardiac surgery in senile patients: a systematic review and meta-analysis

OBJECTIVE

Senile patients often experience neurocognitive disturbance after non-cardiac surgery. Several clinical trials have investigated if the perioperative intravenous use of dexmedetomidine has a positive effect on the prevention of neurocognitive dysfunction, but the results have been inconsistent. We performed a meta-analysis to investigate the effects of dexmedetomidine on neurocognitive disturbance after elective non-cardiac surgery in senile patients.

METHODS

The PubMed, Cochrane Library, EMBASE and China National Knowledge Infrastructure databases were comprehensively searched for all randomized controlled trials published before 1 February 2020 that investigated the efficacy of dexmedetomidine in the prevention of postoperative delirium (POD) or postoperative cognitive dysfunction (POCD).

RESULTS

Sixteen studies involving 4376 patients were included in this meta-analysis. Compared with the control (i.e., saline), the perioperative intravenous use of dexmedetomidine significantly reduced the incidence of POD and POCD. However, patients in the dexmedetomidine group were more likely to develop bradycardia and hypotension during the administration of dexmedetomidine than patients in the control group. There were no differences between the two groups in the incidence of nausea and vomiting or mortality rate.

CONCLUSION

Dexmedetomidine has a positive effect on the prevention of neurocognitive disturbance in senile patients after elective non-cardiac surgery.

Molecular toxicological alterations in the mouse hearts induced by sub-chronic thiazolidinedione drugs administration

Thiazolidinediones are well-known anti-diabetic drugs. However, they are not widely used due to their cardiotoxic effects. Therefore, in this study, we aimed to determine the molecular toxicological alterations induced in the mouse hearts after thiazolidinedione administration. Balb/c mice received doses clinically equivalent to those given to humans of the most commonly used thiazolidinediones, pioglitazone, and rosiglitazone for 30 days. After that, RNA samples were isolated from the hearts. The mRNA expression of cytochrome (cyp) p450 genes that synthesize the cardiotoxic 20-hydroxyeicosatetraenoic acid (20-HETE) in addition to 92 cardiotoxicity biomarker genes were analyzed using quantitative polymerase chain reaction array technique. The analysis demonstrated that thiazolidinediones caused a significant upregulation (p < 0.5) of the mRNA expression of cyp1a1, cyp4a12, itpr1, ccl7, ccr1, and b2 m genes. In addition, thiazolidinediones caused a significant (p < 0.05) downregulation of the mRNA expression of adra2a, bsn, col15a1, fosl1, Il6, bpifa1, plau, and reg3b genes. The most affected gene was itpr1 gene, which was upregulated by pioglitazone and rosiglitazone by sevenfold and 3.5-fold, respectively. In addition, pioglitazone caused significant upregulation of (p < 0.05) hamp, ppbp, psma2, sik1, timp1, and ucp1 genes, which were not affected significantly (p > 0.05) by rosiglitazone administration. In conclusion, this study showed that thiazolidinediones induce toxicological molecular alterations in the mouse hearts, such as the induction of cyp450s that synthesize 20-HETE, chemokine activation, inflammatory responses, blood clotting, and oxidative stress. These findings may help us understand the mechanism of cardiotoxicity involved in thiazolidinedione administration.

Novel Approaches, Drug Candidates, and Targets in Pain Drug Discovery

Because of the problems associated with opioids, drug discovery efforts have been employed to develop opioids with reduced side effects using approaches such as biased opioid agonism, multifunctional opioids, and allosteric modulation of opioid receptors. Receptor targets such as adrenergic, cannabinoid, P2X3 and P2X7, NMDA, serotonin, and sigma, as well as ion channels like the voltage-gated sodium channels Nav1.7 and Nav1.8 have been targeted to develop novel analgesics. Several enzymes, such as soluble epoxide hydrolase, sepiapterin reductase, and MAGL/FAAH, have also been targeted to develop novel analgesics. In this review, old and recent targets involved in pain signaling and compounds acting at these targets are summarized. In addition, strategies employed to reduce side effects, increase potency, and efficacy of opioids are also elaborated. This review should aid in propelling drug discovery efforts to discover novel analgesics.

Current State of Analgesia and Sedation in the Pediatric Intensive Care Unit

Critically ill pediatric patients often require complex medical procedures as well as invasive testing and monitoring which tend to be painful and anxiety-provoking, necessitating the provision of analgesia and sedation to reduce stress response. Achieving the optimal combination of adequate analgesia and appropriate sedation can be quite challenging in a patient population with a wide spectrum of ages, sizes, and developmental stages. The added complexities of critical illness in the pediatric population such as evolving pathophysiology, impaired organ function, as well as altered pharmacodynamics and pharmacokinetics must be considered. Undersedation leaves patients at risk of physical and psychological stress which may have significant long term consequences. Oversedation, on the other hand, leaves the patient at risk of needing prolonged respiratory, specifically mechanical ventilator, support, prolonged ICU stay and hospital admission, and higher risk of untoward effects of analgosedative agents. Both undersedation and oversedation put critically ill pediatric patients at high risk of developing PICU-acquired complications (PACs) like delirium, withdrawal syndrome, neuromuscular atrophy and weakness, post-traumatic stress disorder, and poor rehabilitation. Optimal analgesia and sedation is dependent on continuous patient assessment with appropriately validated tools that help guide the titration of analgosedative agents to effect. Bundled interventions that emphasize minimizing benzodiazepines, screening for delirium frequently, avoiding physical and chemical restraints thereby allowing for greater mobility, and promoting adequate and proper sleep will disrupt the PICU culture of immobility and reduce the incidence of PACs.

Cardiac Arrest Upon Induction of General Anesthesia

There are numerous causes of cardiac arrest in the perioperative period, including hypoxia, hypovolemia, and vagal response to medications or procedures during routine anesthetics. Initiation of adequate cardiopulmonary resuscitation, administration of epinephrine, and application of a defibrillator, with shocking when applicable, are all essential steps in achieving return of spontaneous circulation. Knowledge and utilization of monitoring equipment can alert the provider to problems leading to cardiac arrest as well as ensure proper resuscitative efforts during the event. Polypharmacy is quite common with many of today's special needs patients. It is important to understand the medications they are taking as well as the potential interactions that may occur with drugs given during sedation and general anesthesia. The following is a case report of cardiac arrest including asystole and pulseless electrical activity in a 27-year-old man with autism and behavioral problems who presented for restorative dentistry under general anesthesia in the ambulatory surgery setting.

Dexmedetomidine protects against degeneration of dopaminergic neurons and improves motor activity in Parkinson's disease mice model

Parkinson’s disease (PD) is the result of dopaminergic (DA) neuronal death in the substantianigra pars compacta (SNc). Current treatments for PD such as L-dopa are limited in effectiveness and fail to address the cause. Targeted anti-inflammatory therapies, particularly directed at nuclear factor kappa B (NF‐κB) activity in alleviating degeneration of DA-neurons is of evolving interest. In the present study, we hypothesised that dexmedetomidine (DEX), an alpha-2 receptor adrenergic agonist, suppress the inflammatory responses associated with PD and restores dopaminergic levels by alleviating substantia nigral degeneration. Male mice (C57Bl/10, 8–11 months old and of 34–40 g of weight) were divided into: the control, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and MPTP + dexmedetomidine (MPTP + DEX) (n = 26 each group). Dex restored dopamine levels in SNpc of MPTP-induced PD mice model. Results of immunohisto staining revealed that Dex treatment post-MPTP induction restored TH-positive cells, with only 12.37% increase (^##p < 0.01 vs MPTP) on the third day and a steep 55% increase (^###p < 0.001 vs MPTP) following the seventh day of Dex treatment. Moreover, the expressions of proinflammatory markers regulated by NF-κB were diminished in Dex + MPTP group. In addition, cylinder test revealed that Dex treatment improved asymmetric limb usage pattern in MPTP induced mice over the course of 7 days. Hence, in this study, we provided insight on the effect of Dex in the inhibition of NF-κB1 regulated proinflammatory mediators to improve dopamine levels and reduce SNpc dopaminergic neuronal degeneration.

Cardiac cAMP-PKA Signaling Compartmentalization in Myocardial Infarction

Under physiological conditions, cAMP signaling plays a key role in the regulation of cardiac function. Activation of this intracellular signaling pathway mirrors cardiomyocyte adaptation to various extracellular stimuli. Extracellular ligand binding to seven-transmembrane receptors (also known as GPCRs) with G proteins and adenylyl cyclases (ACs) modulate the intracellular cAMP content. Subsequently, this second messenger triggers activation of specific intracellular downstream effectors that ensure a proper cellular response. Therefore, it is essential for the cell to keep the cAMP signaling highly regulated in space and time. The temporal regulation depends on the activity of ACs and phosphodiesterases. By scaffolding key components of the cAMP signaling machinery, A-kinase anchoring proteins (AKAPs) coordinate both the spatial and temporal regulation. Myocardial infarction is one of the major causes of death in industrialized countries and is characterized by a prolonged cardiac ischemia. This leads to irreversible cardiomyocyte death and impairs cardiac function. Regardless of its causes, a chronic activation of cardiac cAMP signaling is established to compensate this loss. While this adaptation is primarily beneficial for contractile function, it turns out, in the long run, to be deleterious. This review compiles current knowledge about cardiac cAMP compartmentalization under physiological conditions and post-myocardial infarction when it appears to be profoundly impaired.

Cerebrovascular and neurological perspectives on adrenoceptor and calcium channel modulating pharmacotherapies

Adrenoceptor and calcium channel modulating medications are widely used in clinical practice for acute neurological and systemic conditions. It is generally assumed that the cerebrovascular effects of these drugs mirror that of their systemic effects - and this is reflected in how these medications are currently used in clinical practice. However, recent research suggests that there are distinct cerebrovascular-specific effects of these medications that are related to the unique characteristics of the cerebrovascular anatomy including the regional heterogeneity in density and distribution of adrenoceptor subtypes and calcium channels along the cerebrovasculature. In this review, we critically evaluate existing basic science and clinical research to discuss known and putative interactions between adrenoceptor and calcium channel modulating pharmacotherapies, the neurovascular unit, and cerebrovascular anatomy. In doing so, we provide a rationale for selecting vasoactive medications based on lesion location and lay a foundation for future investigations that will define neuroprotective paradigms of adrenoceptor and calcium channel modulating therapies to improve neurological outcomes in acute neurological and systemic disorders.

Emerging therapies and management for neonatal encephalopathy-controversies and current approaches

Neonatal encephalopathy (NE) continues to have a major impact on newborn survival and neurodevelopmental outcomes worldwide. In high-income settings, therapeutic hypothermia is the only established standard treatment for neonates with moderate-to-severe NE, with compelling evidence that cooling reduces mortality and major neurodevelopmental impairment in survivors. Despite therapeutic hypothermia, a significant proportion of cooled infants continue to suffer long-term disability from brain injury. Innovative therapies offer the possibility of further improving neurodevelopmental outcomes by working synergistically with therapeutic hypothermia to decrease hypoxia-ischemia-induced excitotoxicity, prevent progression to secondary energy failure, and in some cases, promote neuroregeneration in the developing neonatal brain. This review discusses emerging NE therapies currently under investigation, offers insight into controversies surrounding various approaches to clinical care during therapeutic hypothermia, and identifies ongoing knowledge deficits that hinder attainment of optimal outcomes for neonates with NE.

The addition of clonidine to ropivacaine in rectus sheath nerve blocks for pediatric patients undergoing laparoscopic appendectomy: A double blinded randomized prospective study

STUDY OBJECTIVE

The primary goal of this study was to determine if the addition of clonidine to ropivacaine prolonged periumbilical numbness compared to ropivacaine alone in pediatric patients receiving ultrasound guided rectus sheath nerve blocks for laparoscopic appendectomy. The secondary goals were to evaluate differences in perioperative pain scores, analgesic consumption, sedation, anxiolysis, and hemodynamic effects from clonidine.

DESIGN

This was a single center, randomized, double-blinded prospective study.

SETTING

This study was conducted within the pediatric operating rooms at the Children's Hospital of Pittsburgh, a large university-based academic medical center.

PATIENTS

Fifty pediatric patients (ages 10-17 years old) without pre-existing cognitive impairment, developmental delay or chronic pain undergoing laparoscopic appendectomy during weekday hours were enrolled and randomized to control versus intervention groups.

INTERVENTION

Ultrasound guided rectus sheath nerve block injections were performed at the beginning of surgery with either ropivacaine 0.5% plus normal saline or ropivacaine 0.5% plus clonidine (2 mcg/kg, maximum of 100 mcg).

MEASUREMENTS

The duration of periumbilical numbness, Numeric Pain Rating Scale scores, University of Michigan Sedation Scale, State-Trait Anxiety Inventory for Children, analgesic consumption, heart rate, blood pressure, and mean arterial pressures, were recorded for each patient at several time points in the perioperative setting.

MAIN RESULTS

There were no significant differences in demographic characteristics between groups. The median duration of periumbilical numbness did not significantly differ between the ropivacaine only and the ropivacaine plus clonidine groups 540.0 minutes [360.0 -1015.0] (median [interquartile range (IQR)]) versus 823.5 minutes [509.5- 1080.0], p = 0.451. There were no significant differences in perioperative analgesic consumption, pain and anxiety scores, PACU sedation, or hemodynamic instability.

CONCLUSIONS

The addition of clonidine did not significantly prolong rectus sheath nerve block duration and was well tolerated in pediatric patients. Perioperative analgesia, hemodynamics, anxiety, and PACU sedation did not differ between groups.

TRIAL REGISTRATION

Clinical Trials NCT02439281.

Rapid Recovery and Short Duration Anesthesia after Low Dose Ketamine and High Dose Dexmedetomidine in Rhesus Macaques (Macaca mulatta)

Anesthesia in rhesus macaques is required for many procedures. Although ketamine is the backbone of most anesthetic protocols, tolerance to the drug can develop, resulting in the need for higher doses to provide sufficient restraint. Combination with other drugs, such as α-agonists, can be ketamine-sparing, providing for sufficient restraint at lower ketamine doses. In addition, because α-agonists are reversible, recovery from anesthesia has the potential to be much shorter. We hypothesized that use of a low dose of ketamine with a high dose of dexmedetomidine, an α2 receptor selective agonist, in male and female rhesus macaques less than 15 y of age would provide adequate anesthesia for short procedures and that recovery would be faster than in macaques given a higher dose of ketamine (10 mg/kg) alone. We found that the combination, in conjunction with atipamezole for reversal, provided smooth induction of anesthesia and significantly shorter recovery time than did ketamine alone, with no significant effects of sex. The combination of low dose ketamine and high dose dexmedetomidine also provided a 30-min window of anesthesia with analgesia sufficient for mild to moderately painful procedures.

Optimizing Pain Control and Minimizing Opioid Use in Trauma Patients

Adverse effects of opioids and the ongoing crisis of opioid abuse have prompted providers to reduce prescribing opioids and increase use of multiple nonpharmacologic therapies, nonopioid analgesics, and co-analgesics for pain management in trauma patients. Nonopioid agents, including acetaminophen, nonsteroidal anti-inflammatory drugs, gabapentinoids, ketamine, central α2 agonists, and lidocaine, can be used as adjuncts or alternatives to opioids in the trauma population. Complementary therapies such as acupuncture, virtual reality, and mirror therapy are modalities that also may be helpful in reducing pain. Performing pain assessments is fundamental to identify pain and evaluate treatment effectiveness in the critically ill trauma patient. The efficacy, safety, and availability of opioid-sparing therapies and multimodal pain regimens are reviewed.

Effects of an Intraoperative Intravenous Bolus Dose of Dexmedetomidine on Remifentanil-Induced Postinfusion Hyperalgesia in Patients Undergoing Thyroidectomy: A Double-Blind Randomized Controlled Trial

BACKGROUND

Consecutive exposure to high-dose remifentanil during anesthesia may induce remifentanil-induced postinfusion hyperalgesia (RPH). Dexmedetomidine, a highly selective α2-adrenergic receptor agonist, may have synergistic effects with opioids and aid in perioperative pain management. In this study, we hypothesized that an intraoperative bolus dose of intravenous dexmedetomidine could alleviate RPH in patients undergoing thyroidectomy under general anesthesia.

METHODS

Ninety patients undergoing thyroidectomy were randomly assigned to 1 of 3 groups: placebo, normal saline (group P); low-dose dexmedetomidine 0.2 μg·kg-1 (group LD); or high-dose dexmedetomidine 0.5 μg·kg-1 (group HD). Remifentanil was infused at a rate of 0.30 μg·kg-1·minute-1. Mechanical pain thresholds were measured using an Electronic von Frey device preoperatively and at 30 minutes, 6 hours, 24 hours, and 48 hours after surgery and were analyzed with 2-way repeated-measures analysis of variance (ANOVA) followed by Bonferroni post hoc comparison. We also recorded postoperative pain scores, the incidence of receiving rescue analgesics, and side effects up to 48 hours after surgery.

RESULTS

The mechanical pain thresholds around the skin incision were significantly higher in group LD compared to group P 30 minutes and 6 hours after surgery (mean ± standard deviation: [65.0 ± 25.2] vs [49.6 ± 24.4] g, mean difference [95% confidence interval]: 15.4 [0.3-30.5] g, P = .045 at 30 minutes; [65.9 ± 24.5] vs [49.3 ± 26.1] g, 16.6 [1.1-32.1] g, P = .032 at 6 hours). The pain thresholds around the skin incision were significantly higher in group HD compared to group P 30 minutes and 6 hours after surgery ([67.8 ± 21.7] vs [49.6 ± 24.4] g, 18.2 [3.1-33.3] g, P = .013 at 30 minutes; [68.3 ± 22.5] vs [49.3 ± 26.1] g, 19.0 [3.5-34.5] g, P = .011 at 6 hours). The incidence of hyperalgesia around the skin incision was lower in group HD than in group P 30 minutes and 6 hours after surgery (4 [13%] vs 14 [48%], P = .012 at 30 minutes, 4 [13%] vs 12 [41%], P = .045 at 6 hours), although no significant difference was observed between group LD and group P. Postoperative pain scores, the incidence of rescue analgesic demand, and postoperative side effects were not significantly different between the groups.

CONCLUSIONS

An intraoperative intravenous bolus dose of dexmedetomidine 0.5 μg·kg-1 alleviates remifentanil-induced hyperalgesia in patients undergoing thyroidectomy without a significant difference in side effects.

Acute Kidney Injury in Cardiac Surgery

Acute kidney injury (AKI) occurs frequently after cardiac surgery and is associated with high morbidity and mortality. Although the number of cardiac surgical procedures is constantly growing worldwide, incidence of cardiac surgery-associated AKI is still around 40% and has a significant impact on global health care costs. Numerous trials attempted to identify strategies to prevent AKI and attenuate its detrimental consequences. Effective options remained elusive. Current evidence supports a multimodal risk-stratification approach with biomarker-guided management of high-risk patients, perioperative administration of dexmedetomidine, and implementation of a care bundle as recommended by the Kidney Disease: Improving Global Outcomes group.

Management of Musculoskeletal Pain: An Update with Emphasis on Chronic Musculoskeletal Pain

Musculoskeletal pain is a challenging condition for both patients and physicians. Many adults have experienced one or more episodes of musculoskeletal pain at some time of their lives, regardless of age, gender, or economic status. It affects approximately 47% of the general population. Of those, about 39–45% have long-lasting problems that require medical consultation. Inadequately managed musculoskeletal pain can adversely affect quality of life and impose significant socioeconomic problems. This manuscript presents a comprehensive review of the management of chronic musculoskeletal pain. It briefly explores the background, classifications, patient assessments, and different tools for management according to the recently available evidence. Multimodal analgesia and multidisciplinary approaches are fundamental elements of effective management of musculoskeletal pain. Both pharmacological, non-pharmacological, as well as interventional pain therapy are important to enhance patient’s recovery, well-being, and improve quality of life. Accordingly, recent guidelines recommend the implementation of preventative strategies and physical tools first to minimize the use of medications. In patients who have had an inadequate response to pharmacotherapy, the proper use of interventional pain therapy and the other alternative techniques are vital for safe and effective management of chronic pain patients.

Effects of topical application of tramadol with/without dexmedetomidine and proparacaine on corneal sensitivity in rats

PURPOSE

To evaluate the corneal anesthetic effect following topical application of tramadol alone and in combination with dexmedetomidine, and compare it to proparacaine, in clinically healthy rats.

METHODS

A randomized, crossover study was performed. Twenty Wistar albino rats (n = 40 eyes) were used. Corneal touch threshold (CTT) measurements (in mm) were obtained using a Cochet-Bonnet aesthesiometer. CTT measurements were obtained at baseline, 1-min following application of the topical anesthetic agent, and repeated at 5-min intervals up to 75 min. The topical protocol involved 3 treatment conditions, separated by a 2-week washout period: proparacaine, tramadol alone, and tramadol in combination with dexmedetomidine.

RESULTS

CTT values were significantly decreased compared to baseline at each timepoint until completion of the 75-min evaluation in all treated eyes, regardless of the assigned treatment (p < 0.0083). With tramadol, complete corneal anesthesia (CTT = 0) was achieved within 1-5 min in 18 eyes and ranged from 5 to 25 min. Co-administration of dexmedetomidine to tramadol resulted in significantly increased CTT values from 5 to 20 min following topical application, compared to tramadol alone (p < 0.0083), and complete corneal anesthesia was achieved in only 14 out of 20 treated eyes.

CONCLUSION

Tramadol might be a useful alternative to topical anesthetic agents, providing a dose-related corneal anesthetic effect. Co-administration of dexmedetomidine does not potentiate its anesthetic effect. The underlying mechanism(s) of drug antagonism between tramadol and dexmedetomidine remains to be determined.

Injection of Lidocaine Alone versus Lidocaine plus Dexmedetomidine in Impacted Third Molar Extraction Surgery, a Double-Blind Randomized Control Trial for Postoperative Pain Evaluation

Objectives

Administration of medications such as dexmedetomidine as a topical anesthetic has been suggested in the pain control in dentistry. This double-blind randomized control trial study evaluated postoperative pain and associated factors following impacted third molar extraction surgery. Lidocaine alone was taken as the control and lidocaine plus dexmedetomidine as the intervention.

Materials and Methods

Forty patients undergoing mandibular third molar extraction entered the study and were randomly allocated to the control and interventional groups. 0.15 ml of dexmedetomidine was added to each lidocaine cartridge and the drug concentration was adjusted to 15 μg for the intervention group while only lidocaine was used in the control group. A visual analog scale was used to measure and record pain levels at the end of the surgery and 6, 12, and 24 hours after the surgery and number of painkillers taken by the patients after the surgery was also recorded.

Results

Pain scores of the intervention group decreased significantly during the surgery and also 6, 12, and 24 hours after the surgery compared to the control group. The pain score was correlated significantly with our intervention during the surgery and also 6 and 12 hours after that (all P value < 0.05). There was a nonsignificant reduction in the number of painkillers taken by the patients at 6, 12, and 24 hours after surgery (all P value > 0.05).

Conclusion

In patients undergoing molar surgery, administration of a combination of dexmedetomidine and lidocaine is beneficial for the pain control. Clinical Relevance. Compared to the injection of lidocaine alone, combination of dexmedetomidine and lidocaine can be used for a better pain control in molar surgeries.

Elements not Graded in the Cardiac Enhanced Recovery After Surgery Guidelines Might Improve Postoperative Outcome: A Comprehensive Narrative Review

Enhanced Recovery Programs (ERPs) are protocols involving the whole patient surgical journey. These protocols are based on multimodal, multidisciplinary, evidence-based, and patient-centered approaches aimed at improving patient recovery after a surgical intervention. Such programs have shown striking positive results in different surgical specialties. However, only a few research groups have incorporated preoperative, intraoperative, and postoperative evidence-based interventions in bundles used to standardize care and build cardiac surgery ERPs. The Enhanced Recovery After Surgery Society recently published evidence-based recommendations for perioperative care in cardiac surgery. Their recommendations included 22 perioperative interventions that may be part of any cardiac ERP. However, various components integrated in already-published cardiac ERPs were neither graded nor reported in these recommendations. The goals of the current review are to present published cardiac ERPs and their effects on patient outcomes and reported components incorporated into these ERPs and to discuss the objectives and scope of cardiac ERPs.

Centrally acting antihypertensives change the psychogenic cardiovascular reactivity

Clonidine (CL) and Rilmenidine (RI) are among the most frequently prescribed centrally acting antihypertensives. Here, we compared CL and RI effects on psychogenic cardiovascular reactivity to sonant, luminous, motosensory, and vibrotactile stimuli during neurogenic hypertension. The femoral artery and vein of Wistar (WT - normotensive) and spontaneously hypertensive rats (SHR) were catheterized before (24 h interval) i.p. injection of vehicle (NaCl 0.9%, control - CT group), CL (10 µg/kg), or RI (10 µg/kg) and acute exposure to luminous (5000 lm), sonant (75 dB sudden tap), motor (180° cage twist), and air-jet (10 L/min - restraint and vibrotactile). Findings showed that: (i) CL or RI reduced the arterial pressure of SHR, without affecting basal heart rate in WT and SHR; (ii) different stimuli evoked pressor and tachycardic responses; (iii) CL and RI reduced pressor response to sound; (iv) CL or RI reduced pressor responses to luminous stimulus without a change in peak tachycardia in SHR; (v) cage twist increased blood pressure in SHR, which was attenuated by CL or RI; (vi) air-jet increased pressure and heart rate; (vii) CL or RI attenuated the pressor responses to air-jet in SHR while RI reduced the chronotropic reactivity in both strains. Altogether, both antihypertensives relieved the psychogenic cardiovascular responses to different stimuli. The RI elicited higher cardioprotective effects through a reduction in air-jet-induced tachycardia.

Particulate matter inhalation and the exacerbation of cardiopulmonary toxicity due to metabolic disease

Particulate matter is a significant public health issue in the United States and globally. Inhalation of particulate matter is associated with a number of systemic and organ-specific adverse health outcomes, with the pulmonary and cardiovascular systems being particularly vulnerable. Certain subpopulations are well-recognized as being more susceptible to inhalation exposures, such as the elderly and those with pre-existing respiratory disease. Metabolic syndrome is becoming increasingly prevalent in our society and has known adverse effects on the heart, lungs, and vascular systems. The limited evaluations of individuals with metabolic syndromehave demonstrated that theymay compose a sensitive subpopulation to particulate exposures. However, the toxicological mechanisms responsible for this increased vulnerability are not fully understood. This review evaluates the currently available literature regarding how the response of an individual's pulmonary and cardiovascular systems is influenced by metabolic syndrome and metabolic syndrome-associated conditions such as hypertension, dyslipidemia, and diabetes. Further, we will discuss potential therapeutic agents and targets for the alleviation and treatment of particulate-matter induced metabolic illness. The information reviewed here may contribute to the understanding of metabolic illness as a risk factor for particulate matter exposure and further the development of therapeutic approaches to treat vulnerable subpopulations, such as those with metabolic diseases.

Phentolamine Mesylate Ophthalmic Solution Provides Lasting Pupil Modulation and Improves Near Visual Acuity in Presbyopic Glaucoma Patients in a Randomized Phase 2b Clinical Trial

PURPOSE

Phentolamine mesylate ophthalmic solution (PMOS), applied to the eye topically, was shown previously to have beneficial effects in patients with dim light vision disturbances (DLD), including decreased pupil diameter (PD), improved best-corrected distance visual acuity (BCDVA), as well as lower intraocular pressure (IOP). The ORION-1 trial evaluated the long-term safety and efficacy of PMOS in a glaucomatous, presbyopic population.

PATIENTS AND METHODS

In this randomized, double-masked, multi-center, placebo-controlled, multiple-dose Phase 2b trial, 39 patients with elevated IOP were randomized to receive one evening dose of study medication or placebo for 14 days. The primary outcome measure was mean change in diurnal IOP, and the key secondary outcome measures included changes in PD, distance-corrected near visual acuity (DCNVA), and conjunctival hyperemia.

RESULTS

Use of 1% PMOS did not lead to a statistically significant decrease in diurnal IOP compared to placebo (P = 0.89) but trended toward a greater decrease in patients with lower IOP baselines. PMOS produced a statistically significant mean 20% PD reduction under both photopic and mesopic conditions that was sustained for 36 hours post-dosing. A statistically significant number of patients with PMOS compared to placebo demonstrated ≥1 line of improvement in photopic DCNVA at day 8 (P = 0.0018), day 15 (P = 0.0072), and day 16 (P = 0.0163), with a trend for 2- and 3-line improvements at all time points. There was no statistical difference in conjunctival hyperemia compared to placebo.

CONCLUSION

Although mean IOP was not lowered significantly, daily evening dosing of 1% PMOS was found to be well tolerated with no daytime conjunctival redness and demonstrated improvement in DCNVA with sustained PD reduction in a glaucomatous and presbyopic population. Smaller pupil size can have beneficial effects in improving symptoms of presbyopia and DLD, which will be the focus of further studies.

Ligand- and Structure-Based Analysis of Deep Learning-Generated Potential α2a Adrenoceptor Agonists

The α2a adrenoceptor is a medically relevant subtype of the G protein-coupled receptor family. Unfortunately, high-throughput techniques aimed at producing novel drug leads for this receptor have been largely unsuccessful because of the complex pharmacology of adrenergic receptors. As such, cutting-edge in silico ligand- and structure-based assessment and de novo deep learning methods are well positioned to provide new insights into protein-ligand interactions and potential active compounds. In this work, we (i) collect a dataset of α2a adrenoceptor agonists and provide it as a resource for the drug design community; (ii) use the dataset as a basis to generate candidate-active structures via deep learning; and (iii) apply computational ligand- and structure-based analysis techniques to gain new insights into α2a adrenoceptor agonists and assess the quality of the computer-generated compounds. We further describe how such assessment techniques can be applied to putative chemical probes with a case study involving proposed medetomidine-based probes.

Experimental research in rats on the reactivity of new corneal blood vessels to adrenaline

Aim: The purpose of this experimental study was to evaluate the existence of adrenergic receptors in ketamine-induced corneal blood vessels in rat pups. Methods: The study of corneal neovascularization motricity was performed on 45-day-old Wistar rats in which, starting from the 15th day of life, corneal blood vessels were obtained by injecting intraperitoneal ketamine at a dose of 150 mg/ kg body weight, a total of 5 successive doses. The examination of the neovascularization was done with the help of a Nikon stereomicroscope connected to a video camera and a computer, the total magnification being 400X. The reactivity of the new corneal blood vessels to the administration in conjunctival instillations of a 1.5 mmol/L adrenaline solution was tested. The parameters followed were represented by variations in the caliber of corneal blood vessels. The data were analyzed using Microsoft Office Excel. Results: Administration of distilled water did not produce statistically significant changes in corneal blood vessels, while adrenaline produced a statistically significant constriction of vascular diameter (p=0.01 at T9, p=0.004 at T10, p=0.019 at time T11 of examinations). Conclusions: The results showed that adrenaline produces vasoconstriction in the new corneal blood vessels, which allows us to assume that they contain α-adrenergic receptors. However, we cannot say that corneal pathological vessels do not contain β2-type adrenergic receptors, because the effect of adrenaline may be an algebraic sum between vasoconstriction produced by stimulating α-adrenergic receptors and vasodilation produced by stimulating β2-adrenergic receptors, but in which the vasodilating effect may be masked by the vasoconstrictor effect given by a higher density of α-adrenergic receptors. Abbreviations: A= adrenaline, DNM = non-measurable diameter, NA= noradrenaline, Std.Er.= Standard error.

Clonidine as a strategy for discontinuing dexmedetomidine sedation in critically ill patients: A narrative review

PURPOSE

To review the efficacy and safety of transitioning from dexmedetomidine to clonidine to facilitate weaning of patients from sedation with dexmedetomidine. There is a paucity of data describing dexmedetomidine withdrawal syndrome (DWS) as well as clonidine's place in therapy for DWS. This review will describe and analyze current literature to provide clinical recommendations.

SUMMARY

A MEDLINE literature search was performed to identify original research articles describing DWS and/or transitioning from dexmedetomidine to clonidine for the purpose of weaning patients from sedation with dexmedetomidine. Four case reports describing DWS, 3 case reports describing the use of clonidine to treat DWS, and 3 observational studies describing the use of clonidine to facilitate dexmedetomidine weaning were identified. The incidence of and risk factors for DWS are unknown; factors including patient age and dexmedetomidine infusion rate, loading dose, and discontinuation strategy have inconsistent associations with DWS. All cases of DWS have been associated with infusion durations greater than 72 hours. While there are limited data describing clonidine use for the treatment of dexmedetomidine withdrawal, clonidine appears to be beneficial for dexmedetomidine weaning and its use for that purpose has been well described. Clonidine dosages that have been assessed for discontinuing dexmedetomidine vary from 0.1 to 0.3 mg orally or enterally every 6 to 8 hours; one study assessed use of transdermal clonidine (100 µg/24 h patch). Patients with extensive cardiac comorbidities may be more susceptible to adverse effects of clonidine, which may limit the drug's use for DWS intervention.

CONCLUSION

Despite limited supportive data, clonidine provides a promising option for sedation management in adult ICU patients, with successful transitions from dexmedetomidine reported within 24 hours after clonidine initiation.

Beyond Amitriptyline: A Pediatric and Adolescent Oriented Narrative Review of the Analgesic Properties of Psychotropic Medications for the Treatment of Complex Pain and Headache Disorders

Children and adolescents with recurrent or chronic pain and headache are a complex and heterogenous population. Patients are best served by multi-specialty, multidisciplinary teams to assess and create tailored, individualized pain treatment and rehabilitation plans. Due to the complex nature of pain, generalizing pharmacologic treatment recommendations in children with recurrent or chronic pains is challenging. This is particularly true of complicated patients with co-existing painful and psychiatric conditions. There is an unfortunate dearth of evidence to support many pharmacologic therapies to treat children with chronic pain and headache. This narrative review hopes to supplement the available treatment options for this complex population by reviewing the pediatric and adult literature for analgesic properties of medications that also have psychiatric indication. The medications reviewed belong to medication classes typically described as antidepressants, alpha 2 delta ligands, mood stabilizers, anti-psychotics, anti-sympathetic agents, and stimulants.

Which idea is better with regard to immune response? Opioid anesthesia or opioid free anesthesia

The stress of surgery is characterized by an inflammatory response with immune suppression resulting from many factors, including the type of surgery and the kind of anesthesia, linked with the drugs that are used and the underlying disease of the patient. The trauma of surgery triggers a cascade of reactions involving the immune response and nociception. As strong analgesics, opioids provide the analgesic component of general anesthesia with bi-directional effect on the immune system. Opioids influence almost all aspects of the immune response in regards to leukocytes, macrophages, mast cells, lymphocytes, and NK cells. The suppressive effect of opioids on the immune system is limiting their use, especially in patients with impaired immune response, so the possibility of using multimodal anesthesia without opioids, known as opioid-free anesthesia (OFA), is gaining more and more sympathizers. The idea of OFA is to eliminate opioid analgesia in the treatment of acute pain and to replace it with drugs from other groups that are assumed to have a comparable analgesic effect without affecting the immune system. Here, we present a review on the impact of anesthesia, with and without the use of opioids, on the immune response to surgical stress.

Evaluation of dexmedetomidine withdrawal in critically ill adults

BACKGROUND

Dexmedetomidine (DEX) withdrawal syndrome has been reported in the pediatric population, but literature describing DEX withdrawal in critically ill adults is limited. The purpose of this study was to determine the incidence of DEX withdrawal in adult patients and to identify factors associated with DEX withdrawal syndrome.

METHODS

A retrospective chart review was performed in the adult intensive care units of two tertiary medical centers. Eligible patients were at least 18 years of age and received DEX for 24 h or more. Patients were excluded if they presented with a primary neurologic diagnosis, had a history of substance abuse, or received any other α2-agonists 24 h before discontinuation of DEX. The primary outcome was the percentage of patients who developed withdrawal as defined by the presence of two or more symptoms (tachycardia, hypertension, vomiting, agitation) within the 24 h following DEX discontinuation.

RESULTS

Of the 165 patients included, 50 patients experienced withdrawal (30.3%), lasting a median of two days. The incidence of withdrawal was higher in surgical (40%) compared to medical (28%) or cardiac (32%) patients (p = 0.004). Median duration of infusion was 52.5 h (interquartile range [IQR], 37.8 to 102.8) in the withdrawal group and 52 h (IQR, 41 to 87) in the non-withdrawal group (p = 0.887). Median DEX dose was 0.56 μg/kg/h (IQR, 0.39 to 0.83) in the withdrawal group and 0.48 μg/kg/h (0.36 to 0.65) in the non-withdrawal group (p = 0.12). Weaning did not reduce the incidence of withdrawal as compared to abrupt discontinuation (p = 0.68). The withdrawal group was more likely to have concomitantly discontinued opioids (54% vs 12.2%) and benzodiazepines (36% vs 0%) at the time of DEX discontinuation compared to the non-withdrawal group (p = 0.004).

CONCLUSION

Development of DEX-associated withdrawal occurred in approximately 30% of adult patients, comparable to rates reported in pediatric literature. There appeared to be no correlation between dose, exposure, and weaning in the occurrence of withdrawal, but concomitant discontinuation of opioids or benzodiazepines as well as ICU admission type could highlight cases requiring closer monitoring.

Impact of Dexmedetomidine Infusion on Postoperative Acute Kidney Injury in Elderly Patients Undergoing Major Joint Replacement: A Retrospective Cohort Study

Purpose

Postoperative acute kidney injury (AKI) is a frequent complication in elderly patients that increases morbidity and mortality. Approximately 1.7 million people die from AKI worldwide every year. Dexmedetomidine (Dex) is often used as an adjunct to multimodal analgesia. Our study investigated whether Dex could safely decrease the incidence of AKI in elderly patients undergoing major joint replacement.

Methods

A single-center retrospective study was conducted in patients aged >65 years undergoing major joint replacement. Propensity score–matching analysis was used, and a total of 1,006 patients were matched successfully. The primary outcome was the incidence of postoperative AKI. Secondary outcomes included perioperative adverse complications, opioid consumption, time to extubation, and length of hospital stay.

Results

Among the 1,006 patients included, postoperative AKI occurred in 9.3% (n=94). The Dex group (perioperative Dex infusion) had lower incidence of postoperative AKI than the control group (7.2% vs 11.5%, P=0.017). Compared with the control group, the Dex group had less opioid consumption (P<0.05), reduced time to extubation (P=0.004), and shorter length of hospital stay (P=0.001). The Dex group also showed higher incidence of bradycardia (20.1% vs 15.1%, P=0.038). There were no differences in intraoperative hypotension (19.5% vs 17.5%), postoperative nausea and vomiting (4.2% vs 5.4%), time in PACU (45.0±6.4 vs 45.5±6.2 minutes), or rate of ICU admission (9.7% vs 11.1%) between the Dex group and control group (All P>0.05).

Conclusion

This retrospective study showed Dex infusion in elderly patients undergoing major joint replacement was associated with lower incidence of postoperative AKI, less opioid consumption, and shorter extubation time and hospital stay. However, the Dex group had higher incidence of bradycardia. We found no statistical differences in other perioperative adverse complications between the groups.