Enhancement of GABAergic activity: neuropharmacological effects of benzodiazepines and therapeutic use in anesthesiology

An ultra-short-acting benzodiazepine in thalamic nucleus reuniens undermines fear extinction via intermediation of hippocamposeptal circuits

Benzodiazepines, commonly used for anxiolytics, hinder conditioned fear extinction, and the underlying circuit mechanisms are unclear. Utilizing remimazolam, an ultra-short-acting benzodiazepine, here we reveal its impact on the thalamic nucleus reuniens (RE) and interconnected hippocamposeptal circuits during fear extinction. Systemic or RE-specific administration of remimazolam impedes fear extinction by reducing RE activation through A type GABA receptors. Remimazolam enhances long-range GABAergic inhibition from lateral septum (LS) to RE, underlying the compromised fear extinction. RE projects to ventral hippocampus (vHPC), which in turn sends projections characterized by feed-forward inhibition to the GABAergic neurons of the LS. This is coupled with long-range GABAergic projections from the LS to RE, collectively constituting an overall positive feedback circuit construct that promotes fear extinction. RE-specific remimazolam negates the facilitation of fear extinction by disrupting this circuit. Thus, remimazolam in RE disrupts fear extinction caused by hippocamposeptal intermediation, offering mechanistic insights for the dilemma of combining anxiolytics with extinction-based exposure therapy.

Extrasynaptic GABAA receptors in central medial thalamus mediate anesthesia in rats

Neuronal depression in the thalamus underlies anesthetic-induced loss of consciousness, while the precise sub-thalamus nuclei and molecular targets involved remain to be elucidated. The present study investigated the role of extrasynaptic GABAA receptors in the central medial thalamic nucleus (CM) in anesthesia induced by gaboxadol (THIP) and diazepam (DZP) in rats. Local lesion of the CM led to a decrease in the duration of loss of righting reflex induced by THIP and DZP. CM microinjection of THIP but not DZP induced anesthesia. The absence of righting reflex in THIP-treated rats was consistent with the increase of low frequency oscillations in the delta band in the medial prefrontal cortex. CM microinjection of GABAA receptor antagonist SR95531 significantly attenuated the anesthesia induced by systemically-administered THIP, but not DZP. Moreover, the rats with declined expression of GABAA receptor δ-subunit in the CM were less responsive to THIP or DZP. These findings explained a novel mechanism of THIP-induced loss of consciousness and highlighted the role of CM extrasynaptic GABAA receptors in mediating anesthesia.

The Rise of Remimazolam: A Review of Pharmacology, Clinical Efficacy, and Safety Profiles

Anesthesiologists often use benzodiazepines (BZDs) due to their remarkable amnestic and anxiolytic capabilities. Because of this, they are perfect for use during the perioperative phase, when patients' anxiety levels are already high. Remimazolam has replaced certain commonly used intravenous (IV) anesthetics due to its excellent safety profile, rapid onset of action, and short half-life. The four classes of BZDs, 2-keto-benzodiazepines, 3-hydroxy-benzodiazepines, triazolobenzodiazepines, and 7-nitro-benzodiazepines based on chemical structure, provide various levels of drowsiness, forgetfulness, and anxiolysis. Based on their elimination half-life, short-acting BZDs typically have a half-life ranging from one to 12 hours, e.g., oxazepam; intermediate-acting BZDs have an average elimination half-life of 12 to 40 hours, e.g., alprazolam; and long-acting BZDs have an average elimination half-life of more than 40 hours, e.g., diazepam. The chloride ion channel is conformationally shifted by the benzodiazepine molecule resulting in central nervous system (CNS) inhibition and hyperpolarization. Each type of benzodiazepine has a favored use. For example, diazepam is used to treat anxiety. Midazolam is used for its anxiolytic and anterograde amnestic effects during the perioperative phase. Anxiety and epilepsy are two conditions that lorazepam effectively treats. There are now phase II and III clinical studies investigating remimazolam. It is not sensitive to alterations in its surroundings and has a brief half-life so that it may be removed rapidly, even after extensive infusion. Being a soft drug means the body easily breaks it down via metabolism, which explains many features. Remimazolam is hydrolyzed into methanol and its carboxylic acid metabolite CNS 7054 by esterase metabolism. Therefore, remimazolam has a shorter onset time and faster recovery than other BZDs. Remimazolam is metabolized independently of any particular organ. Patients with hepatic and renal problems will not see any changes in metabolism or excretion since the drug's ester moiety makes it a substrate for general tissue esterase enzymes. Like its predecessor, midazolam, it has a high potential for addiction. Some side effects that could occur during infusion include headaches and drowsiness. In clinical trials, hypotension, respiratory depression, and bradycardia were noted in participants. BZDs are helpful when used in conjunction with anesthesia. Remimazolam stands out, thanks to its unique pharmacokinetics, pharmacodynamics, safety profile, and potential medical applications. Its desirable properties make it a potential surgical premedication and sedative in the critical care unit. Anesthesiologists and other doctors could have access to more consistent and safer medication. However, additional comprehensive clinical trials are necessary to understand remimazolam's advantages and disadvantages.

The 50% and 95% effective dose of remimazolam tosilate for anaesthesia induction in sleep disorders patients undergoing laparoscopic cholecystectomy: an up-and-down sequential allocation trial

PURPOSE

Previous reports argue that preoperative sleep conditions of patients can influence the dosage of general anaesthesia drugs. Therefore, we aimed to investigate the dose-effect relationship of preoperative sleep disorders on the induction of general anaesthesia with remimazolam tosilate and calculate the Median effective (ED50) and 95% effective (ED95) dosages.

METHODS

Included in our study were 56 patients who underwent laparoscopic cholecystectomy at our hospital. A separate group of 27 patients with sleep disorders (SD group) and 29 patients without sleep disorders (NSD group) using the Pittsburgh Sleep Quality Index (PSQI) were also included. According to the Dixon 'up-and-down' design, patients received remimazolam at preselected concentrations starting at 0.2 mg/kg. After the administration of remimazolam, loss of consciousness was observed. By observing whether consciousness disappeared within a minute, we adjusted the dose of remimazolam by 0.1 mg/kg (up and down) in the following patient. The Median effective dose (ED50), 95% effective dose (ED95), and 95% confidence interval (CI) of remimazolam for effective sedation were calculated.

RESULTS

The ED50 of remimazolam was 0.226 mg/kg (95%CI 0.221-0.232 mg/kg) in the SD group and 0.191 mg/kg (95%CI, 0.183-0.199 mg/kg) in the NSD group. The ED95 of remimazolam was 0.237 mg/kg (95%CI 0.231-0.262 mg/kg) in the SD group and 0.209 mg/kg (95%CI 0.200-0.254 mg/kg) in the NSD group.

CONCLUSIONS

In the SD group, the ED50 and ED95 of remimazolam during anaesthesia induction were 0.226 and 0.237 mg/kg, respectively. The induction dose of remimazolam in the SD group was significantly higher than that in the NSD group.

Remimazolam versus propofol in combination with esketamine for surgical abortion: A double-blind randomized controlled trial

Remimazolam is a new benzodiazepine with a short half-life, good efficacy, and safety profiles in general anesthesia. Combining esketamine with propofol (P + E) could reduce propofol consumption and injection pain. It is, however, unclear if a low dose of remimazolam co-administrated with esketamine (R + E) is comparable to the increasingly used P + E for surgical abortion with general anesthetic. We conducted a double-blind randomized controlled trial to compare the efficacy and safety of R + E and P + E. Two hundred patients scheduled for a surgical abortion were randomized to receive remimazolam 0.3 mg/kg plus esketamine 0.3 mg/kg (R + E), and propofol 2 mg/kg plus esketamine 0.3 mg/kg (P + E). Sedative effectiveness was evaluated by measuring the time to lose consciousness (LOC), recovery time, and successful sedation rate. Safety was assessed by hemodynamics and adverse events during and postoperation. The time to LOC and recovery time in R + E was 5 s shorter and 1 min longer than that in P + E, respectively (both p < 0.001). Success sedation rate did not differ between groups (p = 0.73). Bradycardia incidence and injection site pain were less frequent in the R + E group than that in the P + E group. More rash was observed in the R + E group compared with the P + E group (32% vs. 5%, p < 0.001), but all were mild (only chest rash) and resolved subsequently. Low dose of remimazolam when combined with esketamine has favorable profiles with rapid onset and recovery, but mild hemodynamic side effects and adverse events. It can be used as an alternative for surgical abortion with general anesthetic.

Chemical, Pharmacological, and Structural Characterization of Novel Acrylamide-Derived Modulators of the GABAA Receptor

Acrylamide-derived compounds have been previously shown to act as modulators of members of the Cys-loop transmitter-gated ion channel family, including the mammalian GABAA receptor. Here we have synthesized and functionally characterized the GABAergic effects of a series of novel compounds (termed "DM compounds") derived from the previously characterized GABAA and the nicotinic α7 receptor modulator (E)-3-furan-2-yl-N-p-tolyl-acrylamide (PAM-2). Fluorescence imaging studies indicated that the DM compounds increase apparent affinity to the transmitter by up to 80-fold in the ternary αβγ GABAA receptor. Using electrophysiology, we show that the DM compounds, and the structurally related (E)-3-furan-2-yl-N-phenylacrylamide (PAM-4), have concurrent potentiating and inhibitory effects that can be isolated and observed under appropriate recording conditions. The potentiating efficacies of the DM compounds are similar to those of neurosteroids and benzodiazepines (ΔG ∼ -1.5 kcal/mol). Molecular docking, functionally confirmed by site-directed mutagenesis experiments, indicate that receptor potentiation is mediated by interactions with the classic anesthetic binding sites located in the transmembrane domain of the intersubunit interfaces. Inhibition by the DM compounds and PAM-4 was abolished in the receptor containing the α1(V256S) mutation, suggestive of similarities in the mechanism of action with that of inhibitory neurosteroids. Functional competition and mutagenesis experiments, however, indicate that the sites mediating inhibition by the DM compounds and PAM-4 differ from those mediating the action of the inhibitory steroid pregnenolone sulfate. SIGNIFICANCE STATEMENT: We have synthesized and characterized the actions of novel acrylamide-derived compounds on the mammalian GABAA receptor. We show that the compounds have concurrent potentiating effects mediated by the classic anesthetic binding sites, and inhibitory actions that bear mechanistic resemblance to but do not share binding sites with, the inhibitory steroid pregnenolone sulfate.

Non-Opioid Anesthetics Addiction: A Review of Current Situation and Mechanism

Drug addiction is one of the major worldwide health problems, which will have serious adverse consequences on human health and significantly burden the social economy and public health. Drug abuse is more common in anesthesiologists than in the general population because of their easier access to controlled substances. Although opioids have been generally considered the most commonly abused drugs among anesthesiologists and nurse anesthetists, the abuse of non-opioid anesthetics has been increasingly severe in recent years. The purpose of this review is to provide an overview of the clinical situation and potential molecular mechanisms of non-opioid anesthetics addiction. This review incorporates the clinical and biomolecular evidence supporting the abuse potential of non-opioid anesthetics and the foreseeable mechanism causing the non-opioid anesthetics addiction phenotypes, promoting a better understanding of its pathogenesis and helping to find effective preventive and curative strategies.

Comparison of the recovery profile of remimazolam with flumazenil and propofol anesthesia for open thyroidectomy

BACKGROUND

Previous studies have consistently reported a slower recovery of consciousness following remimazolam-based total intravenous anesthesia without flumazenil than with propofol. This study aimed to compare the reversal effect of flumazenil on the recovery of consciousness after remimazolam-based total intravenous anesthesia with the propofol recovery profile.

METHODS

This prospective, single-blinded, randomized trial included 57 patients undergoing elective open thyroidectomy at a tertiary university hospital. Patients were randomly allocated to receive either remimazolam- or propofol-based total intravenous anesthesia (remimazolam group: 28 patients, propofol group: 29 patients). The primary outcome was the time from the end of general anesthesia to first eye opening (min). The secondary outcomes were the time from the end of the general anesthesia to extubation (min), initial modified Aldrete score measured at the post-anesthesia care unit, length of stay at the post-anesthesia care unit (min), occurrence of postoperative nausea and vomiting during the first 24 h postoperatively, and Korean version of Quality of Recovery-15 score at 24 h postoperatively.

RESULTS

The remimazolam group showed significantly faster first eye opening time (2.3 [interquartile range, IQR: 1.8-3.3] min vs. 5.0 [IQR: 3.5-7.8] min, median difference:-2.7 [95% confidence interval, CI: -3.7 to -1.5] min, P < 0.001) and extubation time (3.2 [IQR: 2.4-4.2] min vs. 5.7 [IQR: 4.7-8.3] min, median difference: -2.7 [97.5% CI: -5.0 to -1.6] min, P < 0.001). There were no significant differences in other postoperative outcomes.

CONCLUSIONS

The planned incorporation of flumazenil with remimazolam-based total intravenous anesthesia provided rapid and reliable recovery of consciousness.

The use of remimazolam versus propofol for induction and maintenance of general anesthesia: A systematic review and meta-analysis

Background: The primary objective of this study was to compare the risk of hypotension, as well as the induction and recovery characteristics between remimazolam and propofol in patients receiving surgery under general anesthesia. Methods: The Embase, Medline, Google scholar, and the Cochrane Library databases were searched from inception to March 2022 for randomized controlled trials The primary outcome was the risk of post-induction hypotension between the two agents, while the secondary outcomes included anesthetic depth, induction efficacy, time to loss of consciousness (LOC), hemodynamic profiles, time to eye opening, extubation time as well as the incidence of injection pain and postoperative nausea/vomiting (PONV). Results: Meta-analysis of eight studies published from 2020 to 2022 involving 738 patients revealed a significantly lower risk of post-induction hypotension with the use of remimazolam compared to that with propofol [risk ratio (RR) = 0.57, 95% confidence interval (CI): 0.43 to 0.75, p < 0.0001, I2 = 12%, five studies, 564 patients]. After anesthetic induction, the anesthetic depth measured by bispectral index (BIS) was lighter in the remimazolam group than that in the propofol group (MD = 9.26, 95% confidence interval: 3.06 to 15.47, p = 0.003, I2 = 94%, five studies, 490 patients). The time to loss of consciousness was also longer in the former compared to the latter (MD = 15.49 s, 95%CI: 6.53 to 24.46, p = 0.0007, I2 = 61%, three studies, 331 patients). However, the use of remimazolam correlated with a lower risk of injection pain (RR = 0.03, 95%CI: 0.01 to 0.16, p < 0.0001, I2 = 0%, three studies, 407 patients) despite comparable efficacy of anesthetic induction (RR = 0.98, 95%CI: 0.9 to 1.06, p = 0.57, I2 = 76%, two studies, 319 patients). Our results demonstrated no difference in time to eye opening, extubation time, and risk of PONV between the two groups. Conclusion: Remimazolam was associated with a lower risk of post-induction hypotension after anesthetic induction compared with propofol with similar recovery characteristics. Further studies are required to support our findings. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/; Identifier: CRD42022320658.

Diazepam induces retrograde facilitation of object recognition and object location memory in male mice

Benzodiazepines are widely prescribed for patients suffering from anxiety and insomnia. Although amnesic effects of benzodiazepines are commonly known as side effects, it has also been reported that these drugs improve memory for information learned before drug intake, a phenomenon called retrograde facilitation. However, the retrograde effects of benzodiazepines on cognitive performances in rodents remain controversial. It should be considered that studies on diazepam-induced retrograde facilitation in humans have been conducted using a recall paradigm focused on short-term memory, whereas these studies in rodents have been conducted using memory tasks that mainly target long-term memory and/or require negative or positive reinforcers. In the current study, we investigated whether diazepam, a benzodiazepine, induces retrograde facilitation for object recognition memory and spatial memory in mice, using a novel object recognition test and an object location test, respectively. These tests are available for short-term memory and do not require any reinforcer. The mice treated with diazepam retained object recognition memory for at least 180 min and spatial memory for at least 150 min. In contrast, vehicle-treated control mice retained object recognition memory for 120 min but not 150 min or longer, and spatial memory for 90 min but not 120 min or longer. These data clearly demonstrated diazepam-induced retrograde facilitation for both object recognition and spatial memories in mice. The present study is expected to contribute to the elucidation of the neural basis of retrograde facilitation.

Remimazolam: An Updated Review of a New Sedative and Anaesthetic

Remimazolam (CNS7056) is a novel benzodiazepine for intravenous sedation; it has an ultra-short duration of action and was recently approved for use in procedural sedation and general anaesthesia. It acts on γ-aminobutyric acid type A receptors and is rapidly converted into an inactive metabolite by tissue esterase enzymes. Remimazolam has been successfully used in endoscopic inspection or surgery and general anaesthesia induction and maintenance with fast and predictable onset and recovery times, high procedure success rates, and minor respiratory and hemodynamic fluctuations and without serious drug-related adverse reactions. If needed, the effects of remimazolam can be reversed by flumazenil, which allows prompt termination of sedation. Although remimazolam has great potential for sedation in patients admitted to intensive care units, future studies are needed to evaluate its efficacy and safety in patients requiring sedation for a long period, and numerous studies are warranted to explore the optimal dose in different application scenarios. The review aimed to provide an introduction to the process of remimazolam synthesis and its current clinical uses and future clinical developments.

Moderate sedation by total intravenous remimazolam-alfentanil vs. propofol-alfentanil for third molar extraction: A prospective randomized controlled trial

Background

Oral dental treatment cause anxiety, fear, and physical stress. This study aimed to investigate the efficacy and safety of moderate sedation by remimazolam with alfentanil vs. propofol with alfentanil in third molar extraction.

Methods

This single-center, randomized, single-blind clinical trial included 100 adults who underwent third molar ambulatory extraction. All patients had continuous infusion of Alfentanil 0.2 μg/kg/min. Group remimazolam with alfentanil (group RA) had an induction dose of 80 μg/kg and maintenance dosage of 5 μg/kg/min. In group propofol with alfentanil (PA group), propofol was infused at an initial concentration of 1.8 μg/mL under target controlled infusion (TCI) mode and a maintenance concentration of 1.5 μg/mL. The incidence rates of adverse effects were recorded and compared. Depth of sedation was assessed using the modified observer alertness/sedation assessment (MOAA/S) and entropy index. Recovery characteristics were recorded and complications observed for next 24 h.

Results

The incident of adverse events 6 (12%) in the group RA was lower than the group PA 25 (50%) [Mean difference 0.136 (95%CI, 0.049–0.377); P &lt; 0.05], with no serious adverse events during the sedation procedure. The incidence of injection pain in group RA was significantly lower than that in group PA [4 vs. 26%, mean difference 0.119 (95%CI, 0.025–0.558); P = 0.004]. Before starting local anesthesia, the mean arterial pressure, heart rate, and respiratory rate of the PA group were lower than those of the RA group. None of the patients required further treatments for a decreased heart rate, blood pressure, or low SpO2. The rate of moderate sedation success was 100% in both groups. The MOAA/S score was similar between the groups indicating that the depth of sedation was effective. Group RA had significantly shorter recovery and discharge times than those of group PA.

Conclusions

Remimazolam with alfentanil is a safer and more effective alternative for ambulatory sedation and can reduce recovery and discharge time and the incidence of perioperative adverse events compare with propofol.

Clinical trial registration

http://www.chictr.org.cn/index.aspx, identifier: ChiCTR2200058106.

Sedative effect of remimazolam combined with alfentanil in colonoscopic polypectomy: a prospective, randomized, controlled clinical trial

Background

Remimazolam is a newer benzodiazepine with properties of rapid onset, short duration of action, and fast recovery. Our study was to evaluate the effects of different doses of remimazolam combined with alfentanil in colonoscopic polypectomy.

Methods

One hundred twenty patients were randomly divided into four groups: alfentanil and propofol (AP) group, alfentanil and remimazolam 0.1 mg/kg (AR1 group), 0.15 mg/kg (AR2 group), or 0.2 mg/kg (AR3 group). Patients in the four groups received alfentanil 10 μg/kg, followed by propofol 2 mg/kg and three dosages of remimazolam. Modified Observer's Assessment of Alertness and Sedation (MOAA/S) scale, heart rate (HR), oxygen saturation (SpO₂), respiratory rate (RR), bispectral index (BIS) values and mean arterial pressure (MAP) were collected at intervals of 5 min and analyzed at different time points: before anesthesia (T0), 5 min (T1), 10 min (T2), 15 min after anesthesia (T3) and at the end of surgery (T4). The average MAP was calculated utilizing the average of all MAP values. The primary outcome was the success rate of sedation. Secondary outcomes included time to full alert and adverse events.

Results

The success rate of sedation was 100% among the four groups. The incidence of hypotension was significantly decreased (all P < 0.05) and the average MAP was higher in AR1-AR3 groups than AP group (all P < 0.001). None of the patients developed bradycardia or hypertension during surgery in all study groups. BIS values were higher (all P < 0.001) and the time to full alert was statistically shorter in AR1-AR3 groups (all P < 0.05) compared with the AP group. The MOAA/S score in AR1 was higher than AR2 (P < 0.05) and the AR3 group (P < 0.05) at T1 and BIS values in the AR1 group were significantly higher than AR3 group (P < 0.05) at T4.

Conclusions

Remimazolam combined with alfentanil have a non-inferior sedative effect than propofol during the colonoscopic polypectomy. Moreover, this combination of two short-acting drugs might be a safer alternative.

Trial registration

The clinical trial was registered on (16/05/2021, ChiCTR2100046492).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01805-3.

Investigation of [3H]diazepam derivatives as allosteric modulators of GABAA receptor α1β2γ2 subtypes: combination of molecular docking/dynamic simulations, pharmacokinetics/drug-likeness prediction, and QSAR analysis

In this paper, a data set of [³H] diazepam derivatives was analyzed using various computational methods: molecular docking/dynamic simulations, and QSAR analysis. The main aims of these studies are to understand the binding mechanisms by which benzodiazepines allosterically modulate GABA_A receptor α₁β₂γ₂ subtypes, from inducing neuronal inhibition at lower doses to the anesthetic effect at higher doses, and also, to define the structural requirements that contribute to improving the response of GABA_A/α₁β₂γ₂ receptor to benzodiazepine drugs. The results of the molecular docking study allowed selecting Ro12-6377 and proflazepam as the best modulators for the four binding sites simultaneously. Subsequently, the stability of the selected complexes was investigated by performing molecular dynamics simulation. The latter confirmed the features of both modulators to exert direct effects on the chloride-channel lining residues. Pharmacokinetics and drug-likeness profile were assessed through in silico tool. Furthermore, a QSAR analysis was conducted using an improved vemolecular dynamics simulations proposed byrsion of PLS regression. The goodness of fit and the predictive power of the resulting PLS model were estimated according to internal and external validation parameters: R² = 0.632, R²_adj = 0.584, F = 12.806; p-value = 6.2050e − 07, Q²_loo = 0.639, and Q²_F3 = 0.813. Clearly, the obtained results ensure the predictive ability of the developed QSAR model for the design of new high-potency benzodiazepine drugs.

Hippocampal Inhibitory Synapsis Deficits Induced by α5-Containing GABAA Receptors Mediate Chronic Neuropathic Pain-Related Cognitive Impairment

Chronic neuropathic pain often leads to cognitive impairment, but the exact mechanism remains unclear. Gamma-aminobutyric acid A receptors (GABA_ARs) are the major inhibitory receptors in the brain, of which the α5-containing GABA_ARs (GABA_ARs-α5) are implicated in a range of neuropsychiatric disorders with cognitive deficits. However, whether GABA_ARs-α5 are involved in chronic neuropathic pain-related cognitive impairment remains unknown. In this study, the rats with chronic neuropathic pain induced by right sciatic nerve ligation injury (SNI) exhibited cognitive impairment with declined spontaneous alternation in Y-maze test and discrimination index in novel object recognition test. The GABA_ARs-α5 expressing on parvalbumin and somatostatin interneurons increased remarkably in hippocampus, resulting in decreased mean frequency of spontaneous inhibitory postsynaptic currents in hippocampal pyramidal neurons. Significantly, antagonizing the GABA_ARs-α5 by L655708 rescued weakened inhibitory synaptic transmission and cognitive impairment induced by chronic neuropathic pain. Taken together, these data suggest that the GABA_ARs-α5 play a crucial role in chronic neuropathic pain-induced cognitive impairment by weakening inhibitory synaptic transmission, which may provide insights into the pharmacologic treatment of chronic neuropathic pain-related cognitive impairment.

Efficacy of Remimazolam for Procedural Sedation in American Society of Anesthesiologists (ASA) I to IV Patients Undergoing Colonoscopy: A Systematic Review and Meta-Analysis

Remimazolam is made by combining midazolam and remifentanil as an alternative to conventional sedatives. To evaluate the efficacy of remimazolam for sedation in patients undergoing colonoscopy, we conducted a systematic review and meta-analysis of the available randomized controlled trials (RCTs) comparing remimazolam and midazolam. A search was conducted using PubMed, Cochrane Library, and clinicaltrial.gov from inception till December 26, 2021, for RCTs that investigated the efficacy of remimazolam during the above-mentioned procedure. There was no restriction of language. A quality assessment was performed using the Cochrane Risk-of-Bias tool. The data were pooled, and a meta-analysis was completed. The systemic review was conducted in accordance with the Preferred Reporting Items for Systemic Reviews and Meta-Analysis (PRISMA) guideline statement. Three randomized controlled trials involving 539 patients were included in the meta-analysis. Compared with midazolam during colonoscopy, remimazolam results in reduced need for top-up doses (RR= 3.45, 95% CI=1.07 to 11.14; P=0.04, I²=84%). The need for rescue medication was reduced with remimazolam as compared to midazolam (RR=2.42, 95%CI=1.04 to 5.61; P=0.04, I²=96%). There was no significant difference observed between the two drugs on completion of colonoscopy and the overall procedural sedation, but the sensitivity analysis favored remimazolam over midazolam for procedural sedation (RR=4.08, 95%CI=2.35 to 7.09; P<0.00001, I²=39%). This analysis demonstrates the advantages of remimazolam over other agents and sets a platform for relevant future studies.

Gastroscopy sedation: clinical trial comparing propofol and sufentanil with or without remimazolam

BACKGROUND

Propofol-sufentanil is often used in clinical anesthesia for patients undergoing sedative gastroscopy, but there are still adverse events such as longer recovery time, respiratory depression and higher doses of propofol etc. This study was to evaluate the sedative effect of remimazolam-propofol-sufentanil in sedative gastroscopy.

METHODS

Patients who were going to have gastroscopy examination were randomly divided into two groups: Group RM (remimazolam-propofol-sufentanil group) and group PR (propofol-sufentanil group). Patients of each group were anesthetized according to the corresponding anesthesia procedure, and all observation indices were recorded.

RESULTS

In the RM group, there were only small and unsignificant changes in the values of SBP, HR, RR and SpO2 after anesthesia(P>0.05), while the values of SBP, HR, RR and SpO2 in the PR group at each time point after anesthesia were significantly lower than those at T0, and the values of SBP and RR at T2, T3 and T4 were also significantly lower than those at T1（P<0.05). The dosage of propofol (38±9 mg) in the RM group was significantly less than that (115±15 mg) in the PR group, meanwhile the anesthesia time (8.4±1.6 min), awakening time (2.9±0.8 min), discharge time (6.7±3.1 min) of the RM group were also significantly shorter than those of the PR group (14.5±3.3, 8.7±1.9, 12.4±3.6 min)（P<0.05), but there was no statistical significance between the two groups in other indices（P>0.05).

CONCLUSIONS

In clinical practice, remimazolam-propofol-sufentanil sedative scheme has more advantages than propofol-sufentanil sedative scheme.

Missing a case of nitrous oxide toxicity

Nitrous oxide is a highly lipid-soluble molecule, which can produce euphoria and calming effects through noncompetitive antagonism of the N-methyl-D-aspartate (NMDA) glutamate receptor and agonism of the y-aminobutyric acid (GABA) A receptor. It can also produce toxicities likely through inactivation of methylcobalamin (vitamin B12) with subsequent neurological, psychiatric, and other sequelae that may be mistaken for other clinical entities. We present a classic presentation of nitrous oxide toxicity, which was missed and urgently referred to infectious diseases with concerns for an infectious neuromyelitis. Knowing the constellation of symptoms and findings and maintaining a high index of suspicion are key to diagnosing nitrous oxide toxicity, which can otherwise easily be missed. Cessation of use, B12 supplementation, and supportive measures such as occupational and physical therapy are helpful for maximizing long-term beneficial outcomes.

Anesthesia-Induced Oxidative Stress: Are There Differences between Intravenous and Inhaled Anesthetics?

Agents used for the induction of anesthesia have been shown to either promote or mitigate oxidative stress. A fine balance between the presence of reactive oxygen species (ROS) and antioxidants is crucial for the proper normal functioning of the cell. A basal concentration of ROS is essential for the manifestation of cellular functions, whereas disproportionate levels of ROS cause damage to cellular macromolecules such as DNA, lipids, and proteins, eventually leading to necrosis and apoptosis. Increased ROS has been linked with numerous illnesses, such as cardiovascular, immune system, liver, and kidney, and has been shown to promote cancer and accelerate aging. Knowledge of the various pharmacologic agents that increase or reduce oxidative stress may promote a safer way of inducing anesthesia. Furthermore, surgery itself leads to increased ROS production and ischemia/reperfusion injury. Indeed, increased perioperative oxidative stress has been correlated with increased postoperative complications and prolonged recovery. Anesthesiologists care for patients during the whole spectrum of perioperative care and thus are in a unique position to deliver countermeasures to oxidative stress. Using preferentially an induction agent which reduces oxidative stress might lead to better clinical outcomes and fewer postoperative complications. Propofol has been shown in several studies to reduce oxidative stress, which reduces postoperative complications and leads to a faster recovery, and thus might represent the preferred induction agent in the right clinical setting.

Remimazolam alleviates neuropathic pain via regulating bradykinin receptor B1 and autophagy

OBJECTIVES

Neuropathic pain (NP) represents a broad scope of various pathological ramifications of the nervous system. Remimazolam is a proved sedative in treating neuropathic pain. Considering the Bradykinin receptor's vital role and the potentials of Bradykinin receptor B1 (BDKRB1) in the neuropathic pain-signalling pathway, we nominated them as a primary target for remimazolam.

METHODS

In this study, rats were injected with complete freund's adjuvant (CFA) to construct NP models in vivo. BV2 microglia cells were treated with LPS to establish NP model in vitro. qRT-PCR, ELISA, western blot and immunofluorescence were applied to determine gene expression.

KEY FINDINGS

Our findings revealed that BDKRB1 was overexpressed in NP models in vivo, while R715 (an antagonist of BDKRB1) suppressed the levels of BDKRB1 and inhibited the hyperpathia induced by spinal nerve litigation surgery. Moreover, remimazolam inactivated BDKRB1 signalling via suppressing NF-κB translocation and decreased the release of pro-inflammatory cytokines. Additionally, remimazolam suppressed the translocation of NF-κB, and inhibited autophagic lysosome formation in vivo and in vitro. However, R838 (an agonist of BDKRB1) reversed the effects of remimazolam.

CONCLUSIONS

Remimazolam downregulated BDKRB1, inhibited BDKRB1/RAS/MEK signalling pathway and regulated the autophagic lysosome induction, exhibiting a better outcome in the NP.

Immediate retrograde amnesia induced by midazolam: A prospective, non-randomised cohort study

BACKGROUND

Midazolam, a short-acting benzodiazepine, has sedative, anxiolytic, amnestic and anticonvulsant effects. Given its advantages of rapid onset, short duration and low toxicity, midazolam is optimal for any procedural sedation. Midazolam is known to cause anterograde amnesia; however, the possibility of retrograde amnesia has also been raised. This prospective cohort, non-randomised study evaluated the presence and extent of retrograde amnesia induced by midazolam during caesarean delivery.

METHODS

One hundred parturients scheduled for elective caesarean delivery under spinal anaesthesia were enrolled. As soon as giving birth, six picture cards were shown to the patients in 1-min intervals, and then midazolam (0.1 mg/kg) was given or not according to the patients' preference. This overall retrograde recall rate of six cards was the primary outcome of our study, which was asked by a blinded investigator.

RESULTS

The overall retrograde card recall rate was lower in the midazolam group compared with the control group (77.0 ± 13.4 vs. 87.7 ± 3.9%, P < .001), especially at 1 minute before midazolam administration (58% vs. 88%, P < .001). Decreased memory trend was observed as time progressed towards midazolam administration in the midazolam group (P = .035). More patients answered 'yes' to the factitious event in the midazolam group than in the control group (26% vs. 4%, P = .004).

CONCLUSION

Intravenous midazolam could cause a brief-period retrograde amnesia in visual and event memory. Moreover, there were more spurious reports of intraoperative factitious events in the midazolam group, implying that episodic memories were also affected by midazolam.

Effect of remimazolam besylate compared with propofol on the incidence of delirium after cardiac surgery: study protocol for a randomized trial

Background

Delirium is an acute cognitive disorder that presents with fluctuation in cognition, apathy, and non-organized thinking, resulting in increased morbidity, mortality, intensive care unit (ICU) stay, and total healthcare costs. In patients undergoing cardiac surgery, delirium also increases the risk of postoperative complications, such as respiratory insufficiency, sternum instability, and need for re-operation of the sternum. This study aims to understand the incidence of delirium in patients after cardiac surgery in patients sedated with remimazolam besylate versus propofol.

Methods

In this prospective, double-blind, randomized controlled clinical trial, we aim to recruit 200 patients undergoing cardiac surgery between January 1, 2021, and December 31, 2021, who will be randomized to receive either remimazolam besylate or propofol infusions postoperatively, until they are extubated. The primary outcome is the incidence of delirium within 5 days after surgery. Secondary outcomes include the time of delirium onset, duration of delirium, ICU length of stay, hospital length of stay, and mechanical ventilation time.

Discussion

The key objective of this study is to assess whether remimazolam besylate reduces the incidence of delirium in patients after cardiac surgery compared to propofol sedation. In this preliminary randomized controlled clinical trial, we will test the hypothesis that the use of remimazolam besylate lowers the incidence of delirium when compared to propofol in patients undergoing cardiac surgery.

Trial registration

chictr.org.cn ChiCTR2000038976. Registered on October 11, 2020

Adverse reactions after orange essential oil administration to lambs

The major compound in orange essential oil (OEO) is limonene, which has in vitro anthelmintic properties; however, a safe in vivo dose has not been defined for animals. Therefore, a pilot study was conducted to evaluate the effect of an OEO formulation for the control of gastrointestinal nematodes in sheep and to investigate adverse reactions in lambs after OEO administration. A total of 17 lambs received an oral OEO formulation at a concentration of 600 mg/mL, in doses of 200, 300, and 600 mg/kg. The most common clinical signs observed were head shaking (88.8%), backward head movement (51.1%), and ataxia (74.4%). Lambs treated with 600 mg/kg of OEO showed more severe combined clinical signs and longer duration of symptoms, presenting adverse reactions for up to 2 h after OEO administration. Testing of different doses and formulations with slower release of the active ingredient is recommended to minimize or eliminate these effects.

Difference between remimazolam toluenesulfonic acid and propofol in waking quality and conscious state after general anesthesia

Objective

To explore the difference of anesthesia recovery and postoperative conscious state between remimazolam toluenesulfonic acid and propofol after induction and maintenance of general anesthesia.

Methods

104 patients undergoing elective tracheal intubation general anesthesia in our hospital were randomly divided into 2 groups: Remimazolam Toluenesulfonic acid group (Group R) and Propofol group (Group P). MOAA/S score, the modified Aldrete score, recovery index, time point, a state of consciousness, interpretative vital signs and adverse events were monitored at different time.

Results

Compared with the Group P, the extubation time and orientation recovery time of the Group R were significantly shorter. When the operation time was less than 1 hour, the MOAA/S score of the Group R was shorter than that of Group P at 5 min and 15 min after the operation. To compare with the Group P, the score of MOAA/S in the Group R increased at 5 min, 20 min and 30 min after the operation. When the operation time was less than or equal to 1 h, the modified Aldrete score in the Group R was slightly higher than that in the Group P at 30 min after extubation. There was no injection pain in the the Group R, and the incidence of hypotension was lower than that of propofol.

Conclusion

Compared with Propofol, when the operation time of general anesthesia is more than 1 hour, recovery time of Remimazolam Toluenesulfonic acid is shorter, with more complete and higher-quality recovery.

Remimazolam: Non-Clinical and Clinical Profile of a New Sedative/Anesthetic Agent

A program to identify novel intravenous sedatives with a short and predictable duration of action was initiated in the late 1990's by Glaxo Wellcome. The program focussed on the identification of ester-based benzodiazepine derivatives that are rapidly broken down by esterases. Remimazolam was identified as one of the lead compounds. The project at Glaxo was shelved for strategic reasons at the late lead optimization stage. Via the GSK ventures initiative, the program was acquired by the small biotechnology company, TheraSci, and, through successive acquisitions, developed as the besylate salt at CeNeS and PAION. The development of remimazolam besylate has been slow by industry standards, primarily because of the resource limitations of these small companies. It has, however, recently been approved for anesthesia in Japan and South Korea, procedural sedation in the United States, China, and Europe, and for compassionate use in intensive care unit sedation in Belgium. A second development program of remimazolam was later initiated in China, using a slightly different salt form, remimazolam tosylate. This salt form of the compound has also recently been approved for procedural sedation in China. Remimazolam has the pharmacological profile of a classical benzodiazepine, such as midazolam, but is differentiated from other intravenous benzodiazepines by its rapid conversion to an inactive metabolite resulting in a short onset/offset profile. It is differentiated from other intravenous hypnotic agents, such as propofol, by its low liability for cardiovascular depression, respiratory depression, and injection pain. The benzodiazepine antagonist flumazenil can reverse the effects of remimazolam in case of adverse events and further shorten recovery times. The aim of this review is to provide an analysis of, and perspective on, published non-clinical and clinical information on 1) the pharmacology, metabolism, pharmacokinetics, and pharmacodynamic profile of remimazolam, 2) the profile of remimazolam compared with established agents, 3) gaps in the current understanding of remimazolam, 4) the compound's discovery and development process and 5) likely future developments in the clinical use of remimazolam.

Synthetic Approaches to the New Drugs Approved during 2019

New drugs introduced to the market are privileged structures having affinities for biological targets implicated in human diseases and conditions. These new chemical entities (NCEs), particularly small molecules and antibody-drug conjugates, provide insight into molecular recognition and simultaneously function as leads for the design of future medicines. This review is part of a continuing series presenting the most likely process-scale synthetic approaches to 40 NCEs approved for the first time anywhere in the world in 2019.

Remimazolam Has Low Oral Bioavailability and No Potential for Misuse in Drug-Facilitated Sexual Assaults, with or Without Alcohol: Results from Two Randomised Clinical Trials

BACKGROUND AND OBJECTIVES

Remimazolam is a new ultra-short-acting benzodiazepine currently being developed for intravenous use in procedural sedation, general anaesthesia, and intensive care unit sedation. Benzodiazepines represent a drug class associated with drug-facilitated sexual assaults, especially in combination with alcohol. Two clinical trials were designed to evaluate the oral bioavailability and pharmacokinetics/pharmacodynamics of remimazolam and to assess the potential for remimazolam misuse in drug-facilitated sexual assaults via oral ingestion.

METHODS

Trial 1 was conducted in 14 healthy volunteers to evaluate the oral bioavailability of remimazolam. Part 1 of trial 2 was conducted in 21 healthy female volunteers to find the minimal biologically active dose of oral remimazolam. Part 2 of trial 2 was conducted in 11 healthy female volunteers to evaluate the pharmacokinetics/pharmacodynamics of oral remimazolam in combination with alcohol.

RESULTS

Remimazolam undergoes rapid and extensive first-pass metabolism upon oral administration. The oral bioavailability of remimazolam was negligible (2.2% based on total systemic exposure and 1.2% based on maximum plasma concentration). Plasma clearance of both remimazolam and its metabolite was fast (elimination half-life 20‒40 min and 1.75‒2 h, respectively). Alcohol did not appear to inhibit the rapid first-pass metabolism of remimazolam. No clear sedative effects were observed for remimazolam without alcohol. Significant sedation was observed in one of ten subjects after remimazolam 360 mg (18 drug product vials) + 40% v/v alcohol.

CONCLUSION

The oral bioavailability of remimazolam is negligible, which-together with its distinct bitter taste-suggests no meaningful potential for misuse in drug-facilitated sexual assaults via oral ingestion, with or without alcohol.

CLINICAL TRIAL REGISTRATION NUMBERS

Trial 1 (NCT04113564) and trial 2 (NCT04113343) both retrospectively registered on 2 October 2019.

Interaction between GABAA receptor α1 and β2 subunits at the N-terminal peripheral regions is crucial for receptor binding and gating

Pentameric ligand gated ion channels (pLGICs) are crucial in electrochemical signaling but exact molecular mechanisms of their activation remain elusive. So far, major effort focused on the top-down molecular pathway between the ligand binding site and the channel gate. However, recent studies revealed that pLGIC activation is associated with coordinated subunit twisting in the membrane plane. This suggests a key role of intersubunit interactions but the underlying mechanisms remain largely unknown. Herein, we investigated a "peripheral" subunit interface region of GABA_A receptor where structural modeling indicated interaction between N-terminal α₁F14 and β₂F31 residues. Our experiments underscored a crucial role of this interaction in ligand binding and gating, especially preactivation and opening, showing that the intersubunit cross-talk taking place outside (above) the top-down pathway can be strongly involved in receptor activation. Thus, described here intersubunit interaction appears to operate across a particularly long distance, affecting vast portions of the macromolecule.

Role of Oxidative Stress in Hepatic and Extrahepatic Dysfunctions during Nonalcoholic Fatty Liver Disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is a pathology that contains a broad liver dysfunctions spectrum. These alterations span from noninflammatory isolated steatosis until nonalcoholic steatohepatitis (NASH), a more aggressive form of the disease characterized by steatosis, inflammatory status, and varying liver degrees fibrosis. NAFLD is the most prevalent chronic liver disease worldwide. The causes of NAFLD are diverse and include genetic and environmental factors. The presence of NASH is strongly associated with cirrhosis development and hepatocellular carcinoma, two conditions that require liver transplantation. The liver alterations during NAFLD are well described. Interestingly, this pathological condition also affects other critical tissues and organs, such as skeletal muscle and even the cardiovascular, renal, and nervous systems. Oxidative stress (OS) is a harmful state present in several chronic diseases, such as NAFLD. The purpose of this review is to describe hepatic and extrahepatic dysfunctions in NAFLD. We will also review the influence of OS on the physiopathological events that affect the critical function of the liver and peripheral tissues.

Recent Developments in Drugs for GI Endoscopy Sedation

Providing sedation for patients undergoing gastrointestinal (GI) endoscopy continues to be a debated topic in both anesthesia and gastroenterology circles. Sedation approaches are widely varied across the globe. While propofol administration is embraced by more endoscopists and patients, its administration evolves controversy. Whereas trained nurses and gastroenterologists are allowed to administer propofol for GI endoscopy sedation in Europe and Asia, it is the sole privilege of anesthesia providers in the USA. However, the costs of anesthesia providers are significant and threaten to derail the screening colonoscopy practice. Efforts were made by both drug and device manufacturers to find alternatives. Fospropofol was one such effort that did not live up to the expectations due to respiratory depressant properties that were similar to propofol. Use of a new tool to administer propofol in the form of Sedasys® was the next experiment that tried to find alternative to anesthesia providers. The device did not succeed due to inadequate sedation. The latest effort is remimazolam, a new benzodiazepine that has quicker recovery profile. In the interim, many drug combinations such as propofol-dexmedetomidine and propofol-ketamine are improving the safety without compromising the quality of sedation. This review attempts to discuss the new drug innovations and drug combinations of existing sedatives for the benefit of readers.

Efficacy and safety of remimazolam in procedural sedation and analgesia: A protocol for systematic review and meta analysis

BACKGROUND

Remimazolam is a newly developed benzodiazepine as an alternative of conventional sedatives in the procedure of anesthesia. For the purpose of evaluating the efficacy and safety of remimazolam sedation during an endoscopy, we will perform a systematic review and meta-analysis of randomized controlled trials that compared remimazolam with midazolam and/or placebo.

METHODS

We will search PubMed, Embase, Web of Science, and the Cochrane Controlled Register of Trials (CENTRAL) from inception to December 2019 for randomized controlled trials that investigated efficacy and safety of remimazolam during an endoscopy. The job will be performed without language restriction. Experimental groups will include the interventions of remimazolam, while control groups will involve midazolam, placebo, or no controls. The primary outcome will be the onset time, followed by the secondary outcomes of the recovery time, the incidence of hypotension, the incidence of hypoxia and the incidence of bradycardia. Relative ratio or standardized mean difference will be used to measure the effect size of remimazolam. We will use I statistics to assess the between-study heterogeneity in each meta-analysis, Eager's test to detect publication bias.

RESULTS

The results of this study will be published in a peer-reviewed journal.

ETHICS AND DISSEMINATION

There is no need for ethical approval because all data used in this meta-analysis have been published. In addition, all data will be analyzed anonymously during the review process.

PROTOCOL REGISTRATION NUMBER

CRD42020170745.

Associations between prescribed benzodiazepines, overdose death and buprenorphine discontinuation among people receiving buprenorphine

BACKGROUND AND AIMS

Benzodiazepines are commonly prescribed to patients with opioid use disorder receiving buprenorphine treatment, yet may increase overdose risk. However, prescribed benzodiazepines may improve retention in care by reducing buprenorphine discontinuation and thus may prevent relapse to illicit opioid use. We aimed to test the association between benzodiazepine prescription and fatal opioid overdose, non-fatal opioid overdose, all-cause mortality and buprenorphine discontinuation.

DESIGN AND SETTING

This was a retrospective cohort study using five individually linked data sets from Massachusetts, United States government agencies.

PARTICIPANTS

We studied 63 389 Massachusetts residents aged 18 years or older who received buprenorphine treatment between January 2012 and December 2015.

MEASUREMENTS

Filled benzodiazepine prescription during buprenorphine treatment was the main independent variable. The primary outcome was time to fatal opioid overdose. Secondary outcomes were time to non-fatal opioid overdose, all-cause mortality and buprenorphine discontinuation. We defined buprenorphine discontinuation as having a 30-day gap without another prescription following the end date of the previous prescription. We used Cox proportional hazards models to calculate hazards ratios that tested the association between receipt of benzodiazepines and all outcomes, restricted to periods during buprenorphine treatment.

FINDINGS

Of the 63 345 individuals who received buprenorphine, 24% filled at least one benzodiazepine prescription during buprenorphine treatment. Thirty-one per cent of the 183 deaths from opioid overdose occurred when individuals received benzodiazepines during buprenorphine treatment. Benzodiazepine receipt during buprenorphine treatment was associated with an increased risk of fatal opioid overdose adjusted hazard ratio (HR) = 2.92, 95% confidence interval (CI) = 2.10-4.06, non-fatal opioid overdose, adjusted HR = 2.05, 95% CI, 1.68-2.50, all-cause mortality, adjusted HR = 1.90, 95% CI, 1.48-2.44 and a decreased risk of buprenorphine discontinuation, adjusted HR = 0.87, 95% CI, 0.85-0.89.

CONCLUSIONS

Benzodiazepine receipt appears to be associated with both increased risk of opioid overdose and all-cause mortality and decreased risk of buprenorphine discontinuation among people receiving buprenorphine.

Medical, Political, and Economic Considerations for the Use of MAC for Endoscopic Sedation: Big Price, Little Justification?

The last few decades of gastrointestinal (GI) endoscopy have seen phenomenal growth. In many aspects, GI endoscopy has led the field of nonsurgical interventional medicine. In many aspects, this growth is facilitated by advancements in sedation-both drugs and techniques. Unfortunately, the topic of GI endoscopy sedation is also mired in many controversies, mainly emanating from the cost of anesthesia providers. While no one debates their role in the majority of advanced endoscopic procedures, the practice of universal propofol sedation in the USA, delivered by anesthesia providers, needs a closer look. In this review, medical, political, and economic considerations of this important topic are discussed in a very frank and honest way. While such ubiquitous propofol use has increased satisfaction of both patients and gastroenterologists, there is little justification. More importantly, going by the evidence, there is even less justification for the mandated anesthesia providers use for such delivery. Unfortunately, the FDA could not be convinced otherwise. The new drug fospropofol met the same fate. Approval of SEDASYS^®, the first computer-assisted personalized sedation system, was a step in the right direction, nevertheless an insufficient step that failed to takeoff. As a result, in spite of years of research and efforts of many august societies, the logjam of balancing cost and justification of propofol sedation has continued. We hope that recent approval of remimazolam, a novel benzodiazepine, and potential approval of oliceridine, a novel short-acting opioid, might be able to contain the cost without compromising the quality of sedation.

GABAa receptor subunits expression in silver catfish (Rhamdia quelen) brain and its modulation by Nectandra grandiflora Nees essential oil and isolated compounds

Studies using silver catfish (Rhamdia quelen) as experimental models are often applied to screen essential oils (EO) with GABAergic-mediated effects. However, the expression of GABAa receptors in the silver catfish brain remains unknown. Thus, we assessed whether silver catfish express GABAa receptor subunits associated with sedation/anesthetic process and/or neurological diseases. Additionally, we evaluated the brain expression of GABAa receptor subunits in fish sedated with Nectandra grandiflora EO and its isolated compounds, the fish anesthetic (+)-dehydrofukinone (DHF), and dehydrofukinone epoxide (DFX), eremophil-11-en-10-ol (ERM) and selin-11-en-4-α-ol (SEL), which have GABAa-mediated anxiolytic-like effects in mice. The expression of the subunits gabra1, gabra2, gabra3, gabrb1, gabrd and gabrg2 in the silver catfish brain were assessed after a 24h-sedation bath by real time PCR. Since qPCR data rarely describes mechanisms of action, which are usually found through interactions with receptors, we also performed an antagonist-driven experiment using flumazenil (FMZ). Real-time PCR detected the mRNA expression of all targeted genes in R. quelen brain. The expression of gabra1 was decreased in fish sedated with ERM; EO increased gabra2, gabra3, gabrb1 and gabrg2 expression; SEL increased gabrb1, gabrd and gabrg2 expression. EO and compounds DFX, SEL and ERM induced sustained sedation in fish and FMZ-bath prompted the recovery from ERM- and DFX-induced sedation. Our results suggest that the EO, SEL, ERM and DFX sedative effects involve interaction with the GABAergic system. Our findings support the use of the silver catfish as robust and reliable experimental model to evaluate the efficacy of drugs with putative GABAergic-mediated effects.

Safety, pharmacokinetic and pharmacodynamic properties of single ascending dose and continuous infusion of remimazolam besylate in healthy Chinese volunteers

PURPOSE

The aim of the present study was to evaluate the safety, pharmacokinetic (PK) and pharmacodynamic (PD) properties of remimazolam besylate following single ascending dose (SAD) and continuous infusion in healthy Chinese volunteers.

METHODS

This was a randomized phase I study conducted in two parts. Part I was a double-blind, placebo- and midazolam-controlled, SAD study among healthy Chinese participants with a remimazolam dose of 0.025-0.4 mg/kg. Part II was an open-label, midazolam-controlled, continuous infusion study. Bispectral index (BIS) monitoring and Modified Observers Assessment of Alertness and Sedation (MOAA/S) score assessment were used to assess the PD properties.

RESULTS

The half-life range of remimazolam was from 34.1 ± 8.1 to 59.8 ± 20.5 min in the SAD study. The sedation function was initially observed at the dose of 0.05 mg/kg remimazolam. Doses of ≥ 0.075 mg/kg exerted a peak sedation effect within 1-2 min after injection, resulting in a deeper and more rapid sedation. In the 2 h continuous infusion, remimazolam showed a deeper sedation and more rapid recovery than midazolam. For general anesthesia, an induction dosage of 0.2 mg/kg/min and a maintenance dosage of 1 mg/kg/h can achieve a satisfactory efficacy effect.

CONCLUSIONS

Remimazolam was safe and well tolerated in healthy Chinese participants. Based on the phase I clinical study, we suggest that remimazolam besylate demonstrates greater sedation and quicker recovery from sedation than midazolam.

Anesthetics influence concussive head injury induced blood-brain barrier breakdown, brain edema formation, cerebral blood flow, serotonin levels, brain pathology and functional outcome

Several lines of evidences show that anesthetics influence neurotoxicity and neuroprotection. The possibility that different anesthetic agents potentially influence the pathophysiological and functional outcome following neurotrauma was examined in a rat model of concussive head injury (CHI). The CHI was produced by an impact of 0.224N on the right parietal bone by dropping a weight of 114.6g from a 20cm height under different anesthetic agents, e.g., inhaled ether anesthesia or intraperitoneally administered ketamine, pentobarbital, equithesin or urethane anesthesia. Five hour CHI resulted in profound volume swelling and brain edema formation in both hemispheres showing disruption of the blood-brain barrier (BBB) to Evans blue and radioiodine. A marked decrease in the cortical CBF and a profound increase in plasma or brain serotonin levels were seen at this time. Neuronal damages were present in several parts of the brain. These pathological changes were most marked in CHI under ether anesthesia followed by ketamine (35mg/kg, i.p.), pentobarbital (50mg/kg, i.p.), equithesin (3mL/kg, i.p.) and urethane (1g/kg, i.p.). The functional outcome on Rota Rod performances or grid walking tests was also most adversely affected after CHI under ether anesthesia followed by pentobarbital, equithesin and ketamine. Interestingly, the plasma and brain serotonin levels strongly correlated with the development of brain edema in head injured animals in relation to different anesthetic agents used. These observations suggest that anesthetic agents are detrimental to functional and pathological outcomes in CHI probably through influencing the circulating plasma and brain serotonin levels, not reported earlier. Whether anesthetics could also affect the efficacy of different neuroprotective agents in CNS injuries is a new subject that is currently being examined in our laboratory.

Midazolam Sedation Induces Upper Limb Coordination Deficits That Are Reversed by Flumazenil in Patients with Eloquent Area Gliomas

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

Midazolam has been found to exacerbate or unmask limb motor dysfunction in patients with brain tumors. This study aimed to determine whether the exacerbated upper limb motor-sensory deficits are mediated through benzodiazepine sites by demonstrating reversibility by flumazenil in patients with gliomas in eloquent areas.

Methods

This was an interventional, parallel assignment, nonrandomized trial. Study subjects were admitted in the operating room. Patients with supratentorial eloquent area gliomas and volunteers of similar age without neurologic disease were sedated with midazolam, but still responsive and cooperative. Motor and sensory functions for upper extremities were evaluated by the Nine-Hole Peg Test before and after midazolam, as well as after flumazenil reversal.

Results

Thirty-two cases were included: 15 in the glioma group and 17 in the control group. The total dose of midazolam and flumazenil were comparable between the groups. In the glioma group, the times to task completion after midazolam in the contralateral hand (P = 0.001) and ipsilateral hand (P = 0.002) were 26.5 (95% CI, 11.3 to 41.7) and 13.7 (95% CI, 5.0 to 22.4) seconds slower than baseline, respectively. After flumazenil reversal, the contralateral hand (P = 0.99) and ipsilateral hand (P = 0.187) performed 1.2 (95% CI, −3.3 to 5.8) and 1.5 (95% CI, −0.5 to 3.5) seconds slower than baseline, respectively. In the control group, the dominant (P &lt; 0.001) and nondominant hand (P = 0.006) were 2.9 (95% CI, 1.4 to 4.3) and 1.7 (95% CI, 0.5 to 2.9) seconds slower than baseline, respectively. After flumazenil, the dominant hand (P = 0.99) and nondominant hand (P = 0.019) performed 0.2 (95% CI, −0.7 to 1.0) and 1.3 (95% CI, −0.2 to 2.4) seconds faster than baseline, respectively.

Conclusions

In patients with eloquent area gliomas, mild sedation with midazolam induced motor coordination deficits in upper limbs. This deficit was almost completely reversed by the benzodiazepine antagonist flumazenil, suggesting that this is a reversible abnormality linked to occupation of the receptor by midazolam.

Ketamine-induced hypnosis and neuroplasticity in mice is associated with disrupted p-MEK/p-ERK sequential activation and sustained upregulation of survival p-FADD in brain cortex: Involvement of GABAA receptor

Ketamine (KET) is an antidepressant and hypnotic drug acting as an antagonist at excitatory NMDA glutamate receptors. The working hypothesis postulated that KET-induced sleep in mice results in dysregulation of mitogen-activated protein kinases (MAPK) MEK-ERK sequential phosphorylation and upregulation of survival p-FADD and other neuroplastic markers in brain. Low (5-15 mg/kg) and high (150 mg/kg) doses of KET on target proteins were assessed by Western immunoblot in mouse brain cortex. During the time course of KET (150 mg/kg)-induced sleep (up to 50 min) p-MEK was increased (up to +79%) and p-ERK decreased (up to -46%) indicating disruption of MEK to ERK signal. Subhypnotic KET (5-15 mg/kg) also revealed uncoupling of p-MEK (+13-81%) to p-ERK (unchanged content). KET did not alter contraregulatory MAPK mechanisms such as inactivated p-MEK1 (ERK dampening) and phosphatases MKP1/2/3 (ERK dephosphorylation). As other relevant findings, KET (5, 15 and 150 mg/kg) upregulated p-FADD in a dose-dependent manner, and for the hypnotic dose the effect paralleled the time course of sleep which resulted in increased p-FADD/FADD ratios. KET (150 mg/kg) also increased NF-κΒ and PSD-95 neuroplastic markers. Flumazenil (a neutral allosteric antagonist at GABA_A receptor) prolonged KET sleep and blocked p-MEK upregulation, indicating the involvement of this receptor as a negative modulator. SL-327 (a MEK inhibitor) augmented KET sleep, further indicating the relevance of reduced p-ERK1/2 in KET-induced hypnosis. These findings suggest that hypnotic and subhypnotic doses of KET inducing uncoupling of p-MEK to p-ERK signal and regulation of p-ERK (downregulation) and p-FADD (upregulation) may participate in the expression of some of its adverse effects (e.g. amnesia, dissociative effects).

Pentobarbital and other anesthetic agents induce opposite regulations of MAP kinases p-MEK and p-ERK, and upregulate p-FADD/FADD neuroplastic index in brain during hypnotic states in mice

Midazolam and ketamine-induced anesthesia were recently shown to induce a disruption of MEK/ERK sequential phosphorylation with parallel upregulation of p-FADD in the mouse brain. The present study was designed to assess whether other structurally diverse anesthetic agents (pentobarbital, ethanol, chloral hydrate, isoflurane) also impair brain p-MEK to p-ERK signal and increase p-FADD during the particular time course of 'sleep' in mice. Pentobarbital (50 mg/kg)-, ethanol (4000 mg/kg)-, chloral hydrate (400 mg/kg)-, and isoflurane (2% in O₂)-induced anesthesia (range: 24-60 min) were associated with unaltered or increased p-MEK1/2 (up to +155%) and decreased p-ERK1/2 (up to -60%) contents, revealing disruption of MEK to ERK activation in mouse brain cortex. These anesthetic agents also upregulated cortical p-FADD (up to +110%), but not total FADD (moderately decreased), which resulted in increased neuroplastic/survival p-FADD/FADD ratios (up to +2.8 fold). The inhibition of pentobarbital metabolism with SKF525-A (a cytochrome P450 inhibitor) augmented barbiturate anesthesia (2.6 times) and induced a greater and sustained upregulation of p-MEK with p-ERK downregulation, as well as prolonged increases of p-FADD content and p-FADD/FADD ratio (effects lasting for more than 240 min). Pentobarbital also upregulated significantly the cortical contents of other markers of neuroplasticity such as the ERK inhibitor p-PEA-15 (up to +46%), the transcription factor NF-κB (up to +27%) and the synaptic density protein PSD-95 (up to +20%) during 'sleep'. The results reveal a paradoxical stimulation of p-MEK without the concomitant (canonical) activation of p-ERK (e.g. with pentobarbital and isoflurane), for which various molecular mechanisms are discussed. The downregulation of brain p-ERK may participate in the manifestations of adverse effects displayed by most hypnotic/anesthetic agents in clinical use (e.g. amnesia).

Should Benzodiazepines and Anticonvulsants Be Used During Electroconvulsive Therapy?: A Case Study and Literature Review

OBJECTIVE

This study aims to investigate the clinical effects of benzodiazepines or anticonvulsant use during a course of electroconvulsive therapy (ECT).

METHOD

A case report study of a patient who received ECT with and without concomitant flurazepam and pregabalin is presented. The literature on the use of benzodiazepines and anticonvulsants during ECT is reviewed.

RESULTS

A woman with treatment resistant depression received a course of ECT while taking flurazepam and pregabalin, but seizures were of short duration and symptomatic improvement was minimal. After discontinuation of flurazepam and pregabalin, a course of right unilateral ultrabrief ECT was associated with adequate seizures and remission of depression and suicidal ideation. Our literature review suggests that benzodiazepines decrease seizure duration, but most evidence shows no association with increased seizure threshold. One prospective RCT and 3 large retrospective studies found that benzodiazepines compromise the efficacy of unilateral but not bilateral ECT. Regarding anticonvulsants, several studies had varied and contradictory results on their effect on seizure duration and seizure threshold. Of the 2 large retrospective studies and 3 RCTs, only 1 retrospective study showed that anticonvulsants decrease the efficacy of ECT.

CONCLUSIONS

Judicious assessment of all medications used in combination with ECT is recommended. Overall, published studies suggest that benzodiazepines and anticonvulsants impact the clinical outcomes of ECT less than what would be expected given their pharmacologic effects. However, there are significant gaps in the literature, including a lack of study on suprathreshold stimulation of right unilateral ECT and the possibility of a greater effect with higher medication doses.

Neurochemical and neuropharmacological characterization of ASP2905, a novel potent selective inhibitor of the potassium channel KCNH3

KCNH3 (BEC1) is a member of the ether-à-go-go (KCNH) family of voltage-gated K⁺ channels. The aim of this study was to determine the pharmacological profiles in vitro and in vivo of a KCNH3 inhibitor N-(4-fluorophenyl)-N'-phenyl-N''-(pyrimidin-2-ylmethyl)-1,3,5-triazine-2,4,6-triamine (ASP2905). We analyzed the effects of ASP2905 on channel activity in vitro and its neuropharmacological properties in young and aged rats as well as in mice. ASP2905 potently inhibited potassium currents in CHO cells expressing KCNH3 (IC₅₀ = 9.0nM). In contrast, ASP2905 (≤ 10μM) minimally bound with low affinities to 55 transmembrane proteins. ASP2905 (0.1µM, 1µM) decreased the frequency of spontaneous inhibitory postsynaptic currents in cultured rat hippocampal neurons. In mice, ASP2905 reversed the disruption of spontaneous alternation behavior induced by MK-801 and scopolamine (minimum effective dose of ASP2905: 0.0625mg/kg, po). ASP2905 ameliorated the cognitive deficits of aged rats in step-through passive avoidance (0.0313 and 0.0625mg/kg, po) and Morris water-maze tasks (0.01mg/kg, po) and effectively penetrated the brain. The mean plasma and brain concentrations of ASP2905 reached their maxima (C_max = 0.399ng/ml and 1.77ng/g, respectively) 1h after a single oral administration and then decreased (t_1/2 = 1.5-1.6h) (brain plasma ratio = 2.7-4.9). The present study suggests that ASP2905 is a selective, orally administered inhibitor of KCNH3, which can enhance cognitive performance.

Disruption of brain MEK-ERK sequential phosphorylation and activation during midazolam-induced hypnosis in mice: Roles of GABAA receptor, MEK1 inactivation, and phosphatase MKP-3

Midazolam is a positive allosteric modulator at GABA_A receptor that induces a short hypnosis and neuroplasticity, in which the sequential phosphorylation of MEK1/2 and ERK1/2 was shown to play a role. This study investigated the parallel activation of p-MEK and p-ERK and regulatory mechanisms induced by midazolam through the stimulation of GABA_A receptors in the mouse brain. During the time course of midazolam (60mg/kg)-induced sleep in mice (lasting for about 2h) p-Ser217/221 MEK1/2 was increased (+146% to +258%) whereas, unexpectedly, p-Tyr204/Thr202 ERK1/2 was found decreased (-16% to -38%), revealing uncoupling of MEK to ERK signals in various brain regions. Midazolam-induced p-MEK1/2 upregulation was prevented by pretreatment (30min) with flumazenil (10mg/kg), indicating the involvement of GABA_A receptors. Also unexpectedly, midazolam-induced p-ERK1/2 downregulation was not prevented by flumazenil (10 or 30mg/kg). Notably, during midazolam-induced sleep the content of inactivated p-Thr286 MEK1, which can dampen ERK1/2 activation, was increased (+33% to +149%) through a mechanism sensitive to flumazenil (10mg/kg). Midazolam also increased MKP-3 (+13% to +73%) content and this upregulation was prevented by flumazenil (10mg/kg); an effect suggesting ERK inactivation because MKP-3 is the phosphatase selective for ERK1/2 dephosphorylation. The results indicate that during midazolam-induced sleep in mice there is an uncoupling of p-MEK (increased) to p-ERK (decreased) signals. p-ERK1/2 downregulation (not involving GABA_A receptors) is the result of increased inactivated MEK1 and phosphatase MKP-3 (both effects involving GABA_A receptors). These findings are relevant for the neurobiology and clinical use of benzodiazepines.

Impact of pharmaceutical care on pain and agitation in a medical intensive care unit in Thailand

Background Currently, a lack of pharmaceutical care exists concerning pain and agitation in medical intensive care units (MICU) in Thailand. Pharmaceutical care focusing on analgesics/sedatives would improve clinical outcomes. Objective To investigate the impact of pharmaceutical care of pain and agitation on ICU length of stay (LOS), hospital LOS, ventilator days and mortality. Setting The MICU of a university hospital. Method A before/after study was conducted on mechanically ventilated patients receiving analgesics/sedatives. Medical chart reviews and data collection were conducted in the retrospective group (no pharmacists involved). In the prospective group, pharmacists involved with the critical care team helped select analgesics/sedatives for individual patients. Main outcome measure ICU LOS Results In total, 90 and 66 patients were enrolled in retrospective and prospective groups, respectively. The median duration of ICU LOS was reduced from 10.00 (2.00-72.00) in the retrospective group to 6.50 days (2.00-30.00) in the prospective group (p = 0.002). The median hospital stay was reduced from 30.50 days (2.00-119.00) in the retrospective group to 17.50 days (2.00-110.00) in the prospective group (p < 0.001). Also, the median ventilator days was reduced from 14.00 days (2.00-90.00) to 8.50 days (1.00-45.00), p = 0.008. Mortality was 53.03% in the prospective group and 46.67% in the retrospective group (p = 0.432). Conclusion Pharmacist participation in a critical care team resulted in a significant reduction in the duration of ICU LOS, hospital LOS and ventilator days, but not mortality.

A Review of Agents for Palliative Sedation/Continuous Deep Sedation: Pharmacology and Practical Applications

Continuous deep sedation at the end of life is a specific form of palliative sedation requiring a care plan that essentially places and maintains the patient in an unresponsive state because their symptoms are refractory to any other interventions. Because this application is uncommon, many providers may lack practical experience in this specialized area and resources they can access are outdated, nonspecific, and/or not comprehensive. The purpose of this review is to provide an evidence- and experience-based reference that specifically addresses those medications and regimens and their practical applications for this very narrow, but vital, aspect of hospice care. Patient goals in a hospital and hospice environments are different, so the manner in which widely used sedatives are dosed and applied can differ greatly as well. Parameters applied in end-of-life care that are based on experience and a thorough understanding of the pharmacology of those medications will differ from those applied in an intensive care unit or other medical environments. By recognizing these different goals and applying well-founded regimens geared specifically for end-of-life sedation, we can address our patients' symptoms in a more timely and efficacious manner.

The Relationship Between Cortical Inhibition and Electroconvulsive Therapy in the Treatment of Major Depressive Disorder

Dysfunctional cortical inhibition (CI) is postulated as a key neurophysiological mechanism in major depressive disorder. Electroconvulsive therapy (ECT) is the treatment of choice for resistant depression and ECT has been associated with enhanced CI. The objective of this study was to evaluate the relationship between CI and ECT response in resistant depression. Twenty-five patients with treatment resistant depression underwent an acute course of ECT. CI was indexed by the cortical silent period (CSP) and short-interval cortical inhibition (SICI), through TMS-EMG. CI and clinical response was measured prior to beginning an acute ECT course and within 48 hours of the last ECT treatment in the course. Clinical response to ECT was assessed by HDRS-17 before and after an acute course of ECT. We found that there was a significant difference in CSP at baseline between responder and non-responder groups (p = 0.044). Baseline CSP predicted therapeutic response to ECT with sensitivity of 80% and specificity of 60%. There were no changes in CSP or SICI after administration of the ECT course. Our findings suggest that duration of pre-treatment CSP may be a useful predictor of therapeutic response to ECT in patients with TRD.