Caution!! Reappearance of remimazolam effect after a flumazenil bolus: a larger bolus of flumazenil and a lower total remimazolam clearance are higher risks

Remimazolam: its clinical pharmacology and evolving role in anesthesia and sedation practice

PURPOSE OF REVIEW

Remimazolam is a novel benzodiazepine anesthetic/sedative, designed as a rapidly metabolized carboxylic acid. Since its recent launch, the role of remimazolam in modern anesthesia and sedation practice is still evolving. This review aims to outline the clinical pharmacology and clinical utility of remimazolam to elucidate its potential advantages and limitations.

RECENT FINDINGS

Remimazolam is "short-acting" but not ultra-short-acting compared with propofol based on context-sensitive decrement times. But compared to propofol, the availability of the benzodiazepine antagonist, flumazenil, is considered an advantage, particularly in certain emergency situations such as in patients with difficult airways. However, because flumazenil is shorter acting than remimazolam when remimazolam accumulates or is present in a high concentration, the reappearance of remimazolam sedation may occur after the initial reversal of anesthesia/sedation from flumazenil administration. Although it is beneficial that remimazolam causes less respiratory depression and hypotension than propofol, serious respiratory depression and hypotension can still occur. Remimazolam administration causes minimal or no pain on injection. Remimazolam is associated with less postoperative nausea and vomiting than inhaled anesthetics, but propofol is clearly superior in this regard. The anesthetic/sedative effects may be prolonged by severe hepatic impairment; remimazolam tolerance can occur in long-term benzodiazepine users.

SUMMARY

Remimazolam may be beneficial to use in procedural sedation and general anesthesia for patients with difficult airways or hemodynamic instability. Further clinical studies with remimazolam are warranted to identify the potential benefits in other settings and patient populations.

The clinical role of remimazolam: Protocol for a scoping review

BACKGROUND

Remimazolam, a novel benzodiazepine, shows promise as an alternative to traditional sedatives and hypnotic agents in procedural sedation and general anaesthesia. While preliminary research indicates potential advantages over conventional agents, such as faster onset, predictable duration, and improved safety profile, the extent and quality of existing evidence remain unclear. This scoping review aims to investigate the current clinical role of remimazolam and provide a broad and comprehensive overview.

METHODS

The proposed review will adhere to the JBI methodology for scoping reviews and the Preferred Reporting Items for Systematic Review and Meta-Analysis for Scoping Reviews. A comprehensive search will be conducted across major peer-reviewed databases and grey literature will be sought. All studies involving individuals undergoing procedural sedation or general anaesthesia with remimazolam will be eligible. Data extraction will encompass trial and participant characteristics, intervention details, reported outcomes, comparative efficacy versus midazolam and propofol, patient and operator experience and economic costs.

RESULTS

We will provide a descriptive summary supplemented by statistics, figures and tables where applicable.

CONCLUSION

The outlined scoping review aims to assess the clinical use of remimazolam in procedural sedation and as the hypnotic component of general anaesthesia. The review will map the current body of evidence of remimazolam and identify knowledge gaps, contributing to understanding its clinical implications and guiding future research efforts in procedural sedation and general anaesthesia.

Comparison of remimazolam tosilate and propofol during induction and maintenance of general anesthesia in patients undergoing laparoscopic cholecystectomy: a prospective, single center, randomized controlled trial

BACKGROUND

Remimazolam tosilate (RT) is a new, ultrashort-acting benzodiazepine. Here, we investigated the efficacy and safety of RT for general anesthesia in patients undergoing Laparoscopic Cholecystectomy (LC).

METHODS

In this study, 122 patients undergoing laparoscopic cholecystectomy were randomly allocated to receive either remimazolam tosilate (Group RT) or propofol group (Group P). RT was administered as a slow bolus of 0.3 mg kg- 1 for induction, followed by 1.0-2.0 mg kg- 1 h- 1 for maintenance of general anesthesia. Propofol was started at 2 mg kg- 1 and followed by 4-10 mg kg- 1 h- 1 until the end of surgery. The primary outcome was the time to bispectral index (BIS) ≤ 60. The secondary outcome included the time to loss of consciousness (LoC), and the time to extubation. Adverse events were also assessed.

RESULTS

A total of 112 patients were recruited for study participation. Among them, the time to BIS ≤ 60 in Group RT was longer than that in Group P (Group RT: 89.3 ± 10.7 s; Group P: 85.9 ± 9.7 s, P > 0.05). While the time to LoC comparing remimazolam and propofol showed no statistical significance (Group RT: 74.4 ± 10.3 s; Group P: 74.7 ± 9.3 s, P > 0.05). The time to extubation in Group RT was significantly longer than that in Group P (Group RT: 16.0 ± 2.6 min; Group P: 8.8 ± 4.3 min, P < 0.001). Remimazolam tosilate had more stable hemodynamics and a lower incidence of hypotension during general anesthesia.

CONCLUSIONS

Remimazolam tosilate can be safely and effectively used for general anesthesia in patients undergoing Laparoscopic Cholecystectomy. It maintains stable hemodynamics during induction and maintenance of general anesthesia compared with propofol. Further studies are needed to validate the findings.

TRIAL REGISTRATION

Chictr.org.cn ChiCTR2300071256 (date of registration: 09/05/2023).

Remimazolam-flumazenil provides fast recovery from general anesthesia compared to propofol during radiofrequency catheter ablation of atrial fibrillation

The optimal anesthetic agent for radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) and its impact on the recovery profiles remain uncertain. We compared the recovery and hemodynamic parameters between the remimazolam-flumazenil and propofol groups during RFCA. Patients were randomized into the remimazolam-flumazenil and propofol groups. The primary outcome measure was the time to eye opening following the discontinuation of anesthetic agents. Secondary outcomes included time to extubation, time to discharge from the operating room, intraprocedural hemodynamic variables and postoperative quality outcomes. Fifty-three patients were included in the final analysis (n = 26 in the remimazolam-flumazenil and n = 27 in the propofol group). The time to eye opening was significantly shorter in the remimazolam-flumazenil group compared to the propofol group (median [interquartile range]: 174 [157-216] vs. 353 [230-483] s, P < 0.001). The mean blood pressure and bispectral index were significantly higher in the remimazolam-flumazenil group compared to the propofol group (mean difference [95% CI], 7.2 [1.7-12.7] mmHg and 6 [3-8]; P = 0.011 and < 0.001, respectively), which were within target ranges in both groups. Other secondary outcomes were comparable between the groups. Consequently, remimazolam emerges as a promising anesthetic agent, characterized by rapid recovery and stable hemodynamics, during RFCA of AF.Trial registration: NCT05397886.

Effect of converting from propofol to remimazolam with flumazenil reversal on recovery from anesthesia in outpatients with mental disabilities: a randomized controlled trial

BACKGROUND

General anesthesia is often necessary for dental treatment of outpatients with mental disabilities. Rapid recovery and effective management of postoperative nausea and vomiting (PONV) are critical for outpatients. This study aimed to investigate the effect of transitioning from propofol to remimazolam with flumazenil reversal administered toward the end of surgery during propofol-based total intravenous anesthesia (TIVA) on recovery.

METHODS

Adults with mental disabilities scheduled to undergo dental treatment were randomly assigned to receive either propofol-based TIVA (Group P) or propofol-remimazolam-based TIVA with flumazenil reversal (Group PR). Propofol was replaced with remimazolam 1 h before the end of surgery in Group PR; moreover, 0.5 mg of flumazenil was administered after the neuromuscular blockade reversal agent. The primary outcome was the duration of stay in the post-anesthesia care unit (PACU). The secondary outcomes included time to eye-opening, time to extubation, occurrence of PONV, and quality of recovery.

RESULTS

Fifty-four patients were included in this study. The duration of stay in the PACU in Group PR was significantly shorter than that in Group P (mean difference, 8.7 min; confidence interval [95% CI], 3.3-14.2; P = 0.002). Group PR exhibited a shorter time to eye opening (mean difference, 5.4 min; 95% CI, 3.3-8.1; P < 0.001) and time to extubation (mean difference, 5.5 min; 95% CI, 3.6-7.9; P < 0.001) than Group P. Neither group required the administration of rescue analgesics, and the incidence of PONV was not reported.

CONCLUSIONS

Transitioning from propofol to remimazolam 1 h before the end of surgery followed by flumazenil reversal reduced the duration of stay in the PACU and the time to eye opening and extubation without affecting the incidence of PONV and quality of recovery.

TRIAL REGISTRATION NUMBER

Clinical Research Information Service (KCT0007794), Clinical trial first registration date: 12/10/2022.

Remimazolam Pilot for Office-Based Dental Sedation: Adverse Events, Awareness and Outcomes

In recent years, remimazolam has gained approval for use in adult procedural sedation in both the United Kingdom and the United States, potentially offering an alternative to conventional sedatives like propofol and midazolam for procedural sedation. However, there is a limited body of literature that systematically reviews the outcomes of a remimazolam-alfentanil combination protocol for routine office-based dental procedures. The primary objective of this pilot study was to assess the occurrence of significant adverse events associated with the use of a remimazolam-alfentanil sedation protocol for adult dental procedures. Secondary outcomes included evaluating physiological responses, sedation effectiveness, patient and clinician satisfaction and the incidence of intraprocedural awareness. Notably, no significant adverse events were reported among the 25 adult subjects who received remimazolam and alfentanil, and all dental procedures were successfully completed. Patients and clinicians expressed high levels of satisfaction, and patients did not report any distressing memories associated with the dental procedure. These findings suggest that in a limited cohort, the remimazolam-alfentanil regimen appears to be well tolerated and effective for office-based dental procedures in adult patients, with a low risk of adverse events, acceptable hemodynamic effects, rapid onset and recovery and minimal intraoperative awareness. This study provides valuable insights into the potential use of the remimazolam-alfentanil combination in dental sedation practice.

Comparison of propofol vs. remimazolam on emergence profiles after general anesthesia: A randomized clinical trial

STUDY OBJECTIVE

The emergence profiles in patients undergoing total intravenous anesthesia with either propofol or remimazolam with flumazenil reversal were compared.

DESIGN

A prospective, double-blind, randomized trial.

SETTING

An operating room and a post-anesthesia care unit (PACU).

PATIENTS

Adult patients (n = 100) having American Society of Anesthesiologists (ASA) physical status of I-III undergoing general anesthesia were enrolled and randomly assigned to the propofol or the remimazolam group.

INTERVENTIONS

The propofol group received target-controlled infusion of propofol, and the remimazolam group received continuous infusion of remimazolam. Continuous infusion of remifentanil was used in both groups. For emergence, flumazenil was used in increments of 0.2 mg in the remimazolam group.

MEASUREMENTS

The primary outcome was the time required for the patient to obey verbal commands. The secondary outcomes included the time to bispectral index (BIS) over 80, the time to laryngeal mask airway (LMA) removal, the Richmond Agitation-Sedation Scale (RASS) scores in the PACU, and adverse events throughout the study period.

MAIN RESULTS

The time taken to obey verbal commands was significantly longer in the propofol group than the remimazolam group (14 [9, 19]) vs. 5 [3, 7]) minutes, P < 0.001; median difference -9, 95% confidence interval -11 to -6). The times to BIS over 80 and to LMA removal were also significantly longer in the propofol group. In addition, the RASS score upon arrival to the PACU differed significantly between the two groups (P = 0.006). Re-sedation in the PACU was observed in 11 (22%) of the patients in the remimazolam group.

CONCLUSIONS

Remimazolam-based total intravenous anesthesia with flumazenil reversal may be effective in reducing emergence time, but a significant incidence of re-sedation was observed in the PACU. Further studies are needed to determine adequate dose and timing of routine flumazenil use and minimize the risk of re-sedation.

Remimazolam and serious adverse events: A scoping review

Remimazolam is anticipated to be an interesting anaesthetic and sedative. It combines the pharmacodynamic properties of midazolam with pharmacokinetic properties similar to remifentanil. However, worrisome case reports of anaphylaxis, delayed emergence and re-sedation have emerged recently and necessitate further investigation.PubMed (including MEDLINE) and EMBASE were searched for all studies reporting serious adverse events where remimazolam was administered for sedation or anaesthesia.Thirty-six case reports and 73 trials were identified, involving a total of 6740 patients who received remimazolam. Hypotension was reported in 911 cases, delayed emergence in 68 cases, anaphylaxis in 10 cases and re-sedation in 8 cases. The incidence of hypotension seems to be lower compared with other anaesthetics, even in high-risk patients.Delayed emergence might be related to the metabolism of remimazolam through carboxylesterase 1 (CES1), a tissue esterase predominant in the liver. There is significant interindividual variation, and it is inhibited by flavonoids, fatty acids and alcohol. Individual benzodiazepine sensitivity has also been reported. A higher BMI, older age and low plasma albumin concentration are risk factors for delayed emergence. Anaphylaxis might be related to a non-IgE-mediated effect of the excipient dextran-40 or a partially IgE-mediated reaction to remimazolam itself. Resedation has been reported after flumazenil reversal and is explained by the specific pharmacokinetic properties of flumazenil and remimazolam. Reversal by flumazenil should be reserved for and used carefully in patients with delayed emergence.

VISUAL ABSTRACT

http://links.lww.com/EJA/A864 .

Comparative Study About Different Doses of Remimazolam in Short Laparoscopic Surgery: A Randomized Controlled Double-Blind Trial

Objective

To study the efficacy and safety of different doses of remimazolam used for induction and maintenance in short laparoscopic surgery.

Methods

A randomized controlled trial was conducted between May 2021 and May 2022 on patients underwent laparoscopic surgery for 30 minutes to an hour. Based on the drug used and the infusion rate, included patients were allocated into the Low-group of remimazolam (using a constant infusion rate of 6.0 mg/kg/h for induction and the rate of 1 mg/kg/h for maintenance), the Median-group (9.0 mg/kg/h for induction, 2 mg/kg/h for maintenance), the High-group (12.0 mg/kg/h for induction, 3.0 mg/kg/h for maintenance), and the Propofol group. The postoperative extubation time was used as the primary outcome.

Results

A total of 192 patients were included in the study, with 47, 48, 48, and 49 patients in the Low-, Median-, High-, and Propofol group, respectively. There was a significant difference in postoperative extubation time, with the High-group having the highest duration of 15.21±2.34 minutes compared to the Median-group (13.17±1.71 minutes, p<0.001), Low- group (12.72±1.31 minutes, p<0.001), and the Propofol group (12.24±1.23 minutes, p<0.001). No significant difference was found between the Low-group and the Propofol group, while the Median-group still showed higher postoperative extubation time compared to the Propofol group (p=0.008).

Conclusion

Compared to propofol, total intravenous induction and maintenance with high and median dosages of remimazolam may prolong postoperative extubation time. Remimazolam can be safely used for induction and maintenance at various doses while not increasing the likelihood of adverse events.

Monitored Anesthesia Care Under a Combination of Low-Dose Remimazolam Infusion and Flumazenil Antagonism: A Case Report

Remimazolam is a novel benzodiazepine known for its short-acting properties. The safe use of flumazenil antagonism following remimazolam infusion remains a subject of debate. We present a case of monitored anesthesia care managed to be safe through low-dose remimazolam infusion and flumazenil antagonism. Pharmacokinetic simulations revealed that low-dose remimazolam was practically useful as one of the components of multimodal sedation/analgesia. Subsequent sedation with the readministration of remimazolam after a dose of flumazenil could also be attained.

Remimazolam Compared to Propofol for Total Intravenous Anesthesia with Remifentanil on the Recovery of Psychomotor Function: A Randomized Controlled Trial

INTRODUCTION

This study aimed to compare remimazolam to propofol in psychomotor recovery after total intravenous anesthesia (TIVA) using the Trieger dot test.

METHODS

Sixty-six patients who were scheduled to undergo endoscopic sinus surgery with American Society of Anesthesiologists (ASA) physical status I or II were randomly allocated to the remimazolam (group R) or propofol group (group P). In group R, all patients received flumazenil postoperatively. After discontinuation of anesthetic agents, the time to eye opening, response to verbal commands, extubation, and discharge from the operation room were measured. Psychomotor recovery was assessed using the Trieger dot test before induction and at 0, 30, 60, 90, 120, 150, and 180 min after anesthesia.

RESULTS

The time to eye opening, response to verbal commands, extubation, and discharge from the operation room were significantly longer in group P compared to group R (group P: 9.8 ± 3.2 min, 11.5 ± 3.4 min, 12.7 ± 3.4 min, 18.1 ± 4.2 min; group R: 6.5 ± 2 min, 7.3 ± 2.6 min, 8.4 ± 2.9 min, 13.2 ± 3.2 min; respectively, p < 0.05). In the Trieger dot test, the number of dots missed was significantly increased in group R compared to group P at 30, 60, 90, and 120 min after discharge from the operation room (group R: 20.5 ± 9.3, 16 ± 8.8, 14.9 ± 11.1, 14.3 ± 10.8; group P: 14.6 ± 7.8, 10 ± 7.1, 8.7 ± 7.3, 7.3 ± 5.7; respectively, p < 0.05). The maximum distance of dots missed was significantly increased in group R compared to group P at 30 min after discharge from the operation room (group R: 3.9 ± 2.8; group P: 2.7 ± 1.6; p < 0.05).

CONCLUSION

Our results suggest that remimazolam with flumazenil leads to rapid recovery following anesthesia; however, it may cause delayed psychomotor decline.

CLINICAL TRIAL REGISTRATION

This trial is registered with the University Hospital Medical Information Network (registration number UMIN000044900).

Antidotes in Clinical Toxicology-Critical Review

Poisoning and overdose are very important aspects in medicine and toxicology. Chemical weapons pose a threat to civilians, and emergency medicine principles must be followed when dealing with patients who have been poisoned or overdosed. Antidotes have been used for centuries and modern research has led to the development of new antidotes that can accelerate the elimination of toxins from the body. Although some antidotes have become less relevant due to modern intensive care techniques, they can still save lives or reduce the severity of toxicity. The availability of antidotes is crucial, especially in developing countries where intensive care facilities may be limited. This article aims to provide information on specific antidotes, their recommended uses, and potential risks and new uses. In the case of poisoning, supportive therapies are most often used; however, in many cases, the administration of an appropriate antidote saves the patient's life. In this review, we reviewed the literature on selected antidotes used in the treatment of poisonings. We also characterised the antidotes (bio)chemically. We described the cases in which they are used together with the dosage recommendations. We also analysed the mechanisms of action. In addition, we described alternative methods of using a given substance as a drug, an example of which is N-acetylcysteine, which can be used in the treatment of COVID-19. This article was written as part of the implementation of the project of the Polish Ministry of Education and Science, "Toxicovigilance, poisoning prevention, and first aid in poisoning with xenobiotics of current clinical importance in Poland", grant number SKN/SP/570184/2023.