Population pharmacokinetic/pharmacodynamic modeling for remimazolam in the induction and maintenance of general anesthesia in healthy subjects and in surgical subjects

Remimazolam inhibits postoperative cognitive impairment after cardiopulmonary bypass by alleviating neuroinflammation and promoting microglia M2 polarization

Postoperative cognitive impairment (POCD) is a complication of cardiopulmonary bypass (CPB). Remimazolam is an ultra-short acting benzodiazepine that can be used for anesthesia or sedation during surgery. This study investigated the role of remimazolam in inflammasome activation and microglia polarization using CPB rat model and lipopolysaccharide (LPS)-induced microglia model. The cognitive function of rats was evaluated by Morris water maze. TUNEL assay was performed to detect apoptosis. Inflammatory cytokines concentration were analyzed by enzyme-linked immunosorbent assay. Reverse transcription-polymerase chain reaction was used to assess the expression of inflammasome and M1/M2-related microglia markers. Flow cytometry was performed to evaluate the expression of CD16/32 and CD206 in microglia. The results showed that remimazolam improved the memory and learning abilities in CPB rats. CPB rats and LPS-treated microglia showed increased apoptosis, pro-inflammatory cytokines level, and inflammasome expression as well as decreased microglia activation, while the results were reversed after remimazolam treatment. Besides, remimazolam treatment promoted the expression of M2-related markers in LPS-treated microglia. Nigericin treatment reversed the increased M2-related mRNA levels and the decreased apoptosis and inflammatory responses induced by remimazolam treatment. In conclusion, remimazolam attenuated POCD after CPB through regulating neuroinflammation and microglia M2 polarization, suggesting a new insight into the clinical treatment of POCD after CPB.

Comparative Analysis of the Performance of Electroencephalogram Parameters for Monitoring the Depth of Sedation During Remimazolam Target-Controlled Infusion

BACKGROUND

The changes in hypnotic indicators in remimazolam sedation remain unclear. We investigated the correlation of the electroencephalogram (EEG) parameters with the effect-site remimazolam concentration and the depth of sedation in patients receiving a target-controlled infusion of remimazolam.

METHODS

This prospective observational study enrolled 35 patients (32 analyzed) who underwent lower extremity varicose vein surgery or lower extremity orthopedic surgery under spinal anesthesia. We administered remimazolam by target-controlled infusion using the pharmacokinetic model introduced by Schüttler et al. The EEG data were continuously recorded, including the bispectral index (BIS), patient state index (PSI), spectral edge frequency (SEF), and raw EEG signals. The relative beta ratio (RBR), defined as log (spectral power [30-47 Hz]/spectral power [11-20 Hz]), was obtained by analyzing raw EEG. The level of sedation corresponding to each effect-site remimazolam concentration was assessed using the Modified Observer's Assessment of Alertness/Sedation (MOAA/S). The prediction probability (Pk) and Spearman's correlation coefficients (R) were calculated between effect-site remimazolam concentration, MOAA/S, and EEG parameters.

RESULTS

BIS and PSI showed significantly higher Pk for effect-site remimazolam concentration (Pk = 0.76 [0.72-0.79], P < .001 for BIS; Pk = 0.76 [0.73-0.79], P < .001 for PSI) compared to RBR (Pk = 0.71 [0.68-0.74], P < .001) and SEF (Pk = 0.58 [0.53-0.63], P = .002). BIS, PSI, and RBR showed significantly higher correlation coefficients for effect-site remimazolam concentration (R = -0.70 [-0.78 to -0.63], P < .001 for BIS; R = -0.72 [-0.79 to -0.66], P < .001 for PSI; R = -0.61 [-0.69 to -0.54], P < .001 for RBR) compared to SEF (R = -0.22 [-0.36 to -0.08], P = .002). BIS and PSI also had significantly higher Pk and correlation coefficients for MOAA/S (Pk = 0.81 [0.79-0.83], P < .001; R = 0.84 [0.81-0.88], P < .001 for BIS) (Pk = 0.80 [0.78-0.83], P < .001; R = 0.82 [0.78-0.87], P < .001 for PSI) compared to RBR (Pk = 0.74 [0.72-0.77], P < .001; R = 0.72 [0.65-0.78], P < .001) and SEF (Pk = 0.55 [0.50-0.59], P = .041; R = 0.13 [-0.01 to 0.27], P = .067).

CONCLUSIONS

BIS, PSI, and RBR showed an acceptable correlation with the effect-site remimazolam concentration and depth of sedation in this study, suggesting that these EEG-derived parameters are potentially reliable hypnotic indicators during remimazolam sedation. BIS and PSI showed superior performance as hypnotic indicators to RBR and SEF in patients receiving target-controlled infusion of remimazolam.

Comparison of Remimazolam Tosilate and Propofol Sedation on the Early Postoperative Quality of Recovery in Patients Undergoing Day Surgery: A Prospective Randomized Controlled Trial

Purpose

Remimazolam tosilate is a novel ultrafast-acting benzodiazepine that has a rapid emergence even after continuous infusion when using flumazenil. So far, relatively few articles are still focusing on the quality of recovery after general anesthesia with remimazolam, especially in day surgery. This study aimed to compare the early postoperative quality of recovery of remimazolam tosilate with flumazenil and propofol in patients undergoing day surgery.

Patients and Methods

137 patients scheduled for day surgery were randomly divided into the remimazolam tosilate or propofol group. The primary endpoint was the incidence of overall recovery assessed with the early postoperative quality of recovery scale (PostopQRS) on postoperative day 1 (POD 1). The Richmond Agitation-Sedation Scale (RASS) scores in the post-anesthesia care unit (PACU), extubation time, postoperative recovery profiles, and perioperative data were documented. Any adverse events were recorded.

Results

The incidence of overall recovery on POD1 was 47.7% in the remimazolam tosilate group and 65.1% in the propofol group (odds ratio, 0.52; 95% confidence interval (CI) 0.26 to 1.06; P = 0.072). In general, the overall recovery of the PostopQRS increased over time, and its interaction between time and group was significant (P = 0.003). Among the five dimensions of PostopQRS, there exist statistical differences between groups including emotional state and cognitive recovery. Upon arrival at the PACU, the remimazolam group was more sedated and took longer to recover to a RASS score similar to propofol. The frequency of application of vasoactive drugs during anesthesia was similar in both groups (P = 0.119). Despite rapid emergence with remimazolam after flumazenil reversal, re-sedation (10.8%) or somnolence (60%) in the PACU was observed, and the length of PACU stay in patients treated with remimazolam tosilate was longer than that of the propofol (35 min vs 30 min, P<0.001).

Conclusion

General anesthesia with remimazolam tosilate in conjunction with flumazenil reversal permits rapid recovery of consciousness in day surgery, but there was a notable occurrence of re-sedation or somnolence observed in PACU.

Rocuronium Can Trigger a Hypertensive Crisis in a Patient With Paraganglioma: A Case Report

We present a case of rocuronium-induced hypertensive crises that occurred twice in a patient with paraganglioma. An 86-year-old woman was first scheduled for laminectomy for lumbar spinal stenosis. Five minutes after intravenous induction of anesthesia using fentanyl, propofol, rocuronium, and remifentanil, the patient's blood pressure (BP) and heart rate (HR) suddenly increased with no stimuli. Surgery was postponed because the patient was suspected of having pheochromocytoma. After that, paraganglioma was diagnosed, and surgery for removal of the paraganglioma was scheduled after the commencement of alpha-blocker therapy. The patient's hemodynamic parameters remained stable when anesthesia was induced with an infusion of remimazolam. Subsequently, immediately after rocuronium was administered as an intravenous bolus, the patient's arterial BP and HR increased, and plasma concentrations of noradrenaline and rocuronium had markedly increased. Ten minutes after the administration of rocuronium, the patient's BP and HR gradually and fully recovered without any intervention. The plasma concentrations of both noradrenaline and rocuronium also concurrently decreased. We conclude that simultaneous increases in BP, HR, and plasma concentration of noradrenaline revealed a direct correlation with rocuronium.

Target-controlled infusion of remimazolam effect-site concentration for total intravenous anesthesia in patients undergoing minimal invasive surgeries

Background

Although pharmacokinetic and pharmacodynamic models of remimazolam have been developed, their clinical application remains limited. This study aimed to administer a target-controlled infusion (TCI) of remimazolam at the effect-site concentration (Ce) in patients undergoing general anesthesia and to investigate the relationship of the remimazolam Ce with sedative effects and with recovery from general anesthesia.

Methods

Fifty patients aged 20-75 years, scheduled for minimally invasive surgery under general anesthesia for less than 2 h, were enrolled. Anesthesia was induced and maintained using Schüttler's model for effect-site TCI of remimazolam. During induction, the remimazolam Ce was increased stepwise, and sedation levels were assessed using the Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale and bispectral index (BIS). Following attainment of MOAA/S scale 1, continuous infusion of remifentanil was commenced, and rocuronium (0.6 mg/kg) was administered for endotracheal intubation. The target Ce of remimazolam and the remifentanil infusion rate were adjusted to maintain a BIS between 40 and 70 and a heart rate within 20% of the baseline value. Approximately 5 min before surgery completion, the target Ce of remimazolam was reduced by 20-30%, and anesthetic infusion ceased at the end of surgery. Nonlinear mixed-effects modeling was employed to develop pharmacodynamic models for each sedation level as well as emergence from anesthesia.

Results

The remimazolam Ces associated with 50% probability (Ce50) of reaching MOAA/S scale ≤4, 3, 2, and 1 were 0.302, 0.397, 0.483, and 0.654 μg/mL, respectively. The Ce50 values for recovery of responsiveness (ROR) and endotracheal extubation were 0.368 and 0.345 μg/mL, respectively. The prediction probabilities of Ce and BIS for detecting changes in sedation level were 0.797 and 0.756, respectively. The sedation scale significantly correlated with remimazolam Ce (r = -0.793, P < 0.0001) and BIS (r = 0.914, P < 0.0001). Age significantly correlated with Ce at MOAA/S1 and ROR.

Conclusion

Effect-site TCI of remimazolam was successfully performed in patients undergoing general anesthesia. The remimazolam Ce significantly correlated with sedation depth. The Ce50 for MOAA/S scale ≤1 and ROR were determined to be 0.654 and 0.368 μg/mL, respectively.

Anaesthetic efficacy and postinduction hypotension with remimazolam compared with propofol: a multicentre randomised controlled trial

Remimazolam, a short-acting benzodiazepine, may be used for induction and maintenance of total intravenous anaesthesia, but its role in the management of patients with multiple comorbidities remains unclear. In this phase 3 randomised controlled trial, we compared the anaesthetic efficacy and the incidence of postinduction hypotension during total intravenous anaesthesia with remimazolam vs. propofol. A total of 365 patients (ASA physical status 3 or 4) scheduled for elective surgery were assigned randomly to receive total intravenous anaesthesia with remimazolam (n = 270) or propofol (n = 95). Primary outcome was anaesthetic effect, quantified as the percentage of time with Narcotrend® Index values ≤ 60, during surgery (skin incision to last skin suture), with a non-inferiority margin of -10%. Secondary outcome was the incidence of postinduction hypotensive events. Mean (SD) percentage of time with Narcotrend Index values ≤ 60 during surgery across all patients receiving remimazolam (93% (20.7)) was non-inferior to propofol (99% (4.2)), mean difference (97.5%CI) -6.28% (-8.89-infinite); p = 0.003. Mean (SD) number of postinduction hypotension events was 62 (38.1) and 71 (41.1) for patients allocated to the remimazolam and propofol groups, respectively; p = 0.015. Noradrenaline administration events (requirement for a bolus and/or infusion) were also lower in patients allocated to remimazolam compared with propofol (14 (13.5) vs. 20 (14.6), respectively; p < 0.001). In conclusion, in patients who were ASA physical status 3 or 4, the anaesthetic effect of remimazolam was non-inferior to propofol.

Safety and efficacy comparison of remimazolam and propofol for intravenous anesthesia during gastroenteroscopic surgery of older patients: A meta-analysis

BACKGROUND

Remimazolam is characterized by rapid action and inactive metabolites. It is used as the general anesthetic for many clinical surgeries. In this study, we performed a meta-analysis to evaluate whether remimazolam is superior to propofol for gastroenteroscopy in older patients.

AIM

To compare the adverse events and efficacy of remimazolam and propofol during gastroenteroscopy in older adults.

METHODS

The PubMed, Web of Science, the Cochrane Library databases were queried for the relevant key words "remimazolam," "and propofol," "and gastrointestinal endoscopy or gastroscopy." The search scope was "Title and Abstract," and the search was limited to human studies and publications in English. Seven studies wherein remimazolam and propofol were compared were included for the meta-analysis.

RESULTS

We selected seven randomized controlled trials involving 1445 cases for the analysis. Remimazolam reduced the hypotension (relative risk, RR = 0.44, 95%CI: 0.29-0.66, P = 0.000), respiratory depression (RR = 0.46, 95%CI: 0.30-0.70, P = 0.000), injection pain (RR = 0.12, 95%CI: 0.05-0.25, P = 0.000), bradycardia (RR = 0.37, 95%CI: 0.24-0.58, P = 0.000), and time to discharge [weighted mean difference (WMD) = -0.58, 95%CI: -0.97 to -0.18, P = 0.005], compared to those after propofol administration. No obvious differences were observed for postoperative nausea and vomiting (RR = 1.09, 95%CI: 0.97-1.24, P = 0.151), dizziness (RR = 0.77, 95%CI: 0.43-1.36, P = 0.361), successful sedation rate (RR = 0.96, 95%CI: 0.93-1.00, P = 0.083), or the time to become fully alert (WMD = 0.00, 95%CI: -1.08-1.08, P = 0.998).

CONCLUSION

Remimazolam appears to be safer than propofol for gastroenteroscopy in older adults. However, further studies are required to confirm these findings.

Efficacy of remimazolam tosilate versus propofol for total intravenous anaesthesia in urological surgery: A randomised clinical trial

BACKGROUND

Remimazolam is a novel ultra-short-acting benzodiazepine sedative that acts on the gamma-aminobutyric acid type A receptor (GABAAR).

OBJECTIVE

To compare the efficacies of remimazolam (RMZ), and propofol (PROP) combined with remifentanil and cisatracurium for total intravenous anaesthesia (TIVA) in patients undergoing urological surgery.

DESIGN

A prospective, single-blind, randomised, noninferiority clinical trial.

SETTING

Single centre from 1 January 2022 to 30 March 2022.

PATIENTS

A total of 146 adult patients undergoing elective urological surgery.

INTERVENTION

Patients were randomly allocated in a 1 : 1 ratio to the PROP or RMZ groups. In the PROP group, anaesthesia was induced with propofol at 100 mg min -1 to reach a bispectral index score (BIS) of 40 to 60. After loss of consciousness (LOC), intravenous fentanyl 3 μg kg -1 was administered, followed by cisatracurium 0.3 mg kg -1 . Patients were intubated 3 min after cisatracurium administration. Anaesthesia was maintained with the combination of propofol (plasma concentration: 2.5 to 4 μg ml -1 ) and remifentanil (plasma concentration: 2.5 to 4 ng ml -1 ). In the RMZ group, anaesthesia was induced with remimazolam tosilate starting at 10 mg kg -1  h -1 to reach a BIS of 40 to 60 and maintained between 0.2 and 2 mg kg -1  h -1 . After LOC, fentanyl and cisatracurium were administered and intubation was performed as in the PROP group. Anaesthesia was maintained with a combination of remimazolam (0.2 to 2 mg kg -1  h -1 ) and remifentanil (plasma concentration: 2.5 to 4 ng ml -1 ).

MAIN OUTCOME MEASURES

The primary outcome was the TIVA success rate. The predefined noninferiority margin considered an absolute difference of 6% in the primary outcome between the groups. The secondary outcomes were vital signs, anaesthesia and surgery characteristics, and adverse events.

RESULTS

All patients completed the trial. The success rates of TIVA with remimazolam and propofol were 100 and 98.6%, respectively. The incidence of hypotension during anaesthesia was lower in the RMZ group (26%) than in the PROP group (46.6%) ( P  = 0.016). The median [IQR] total consumption of ephedrine during anaesthesia was higher in the PROP group 10 [0 to 12.5] mg than in the RMZ group 0 [0 to 10] mg ( P  = 0.0002). The incidence of injection pain was significantly higher in the PROP group (76.7%) than in the RMZ group (0; P  < 0.001). No significant differences in the controllability of the anaesthesia depth, anaesthesia and surgery characteristics, or vital signs were observed between the groups.

CONCLUSION

Remimazolam demonstrated noninferior efficacy to propofol combined with remifentanil and cisatracurium for TIVA in patients undergoing urological surgery.

TRIAL REGISTRATION

Chictr.org.cn, identifier: ChiCTR2100050923.

CLINICAL REGISTRATION

The study was registered in the Chinese Clinical Trial Registry (ChiCTR2100050923, Principal investigator: Xuehai Guan, Date of registration: 8 November 2021, https://www.chictr.org.cn/showproj.html?proj=133466 ).

Target-controlled Infusion of Remimazolam in Healthy Volunteers Shows Some Acute Tolerance

BACKGROUND

Remimazolam exhibits sedative properties by binding to γ-aminobutyric acid type A receptors. Remimazolam is administered as a bolus dose or continuous infusion, but has not been studied using target-controlled infusion (TCI). The study quantified the relationship between the remimazolam concentration, Modified Observer's Assessment of Alertness and Sedation (MOAAS) score, and bispectral index (BIS) using TCI.

METHODS

The authors performed a three-period, crossover, dose-ranging clinical trial in 24 healthy volunteers using age and sex stratification. Data collected in the first period, where remimazolam was administered alone using a step-up and step-down TCI protocol, were used for this analysis. Remimazolam concentrations, MOAAS scores, and BIS values were collected at each step at steady state. Data were analyzed using nonlinear mixed-effects modeling methodology.

RESULTS

The relationship between remimazolam, BIS, and MOAAS differed between step-up and step-down infusions at similar remimazolam target concentrations. Tolerance, driven by remimazolam or CNS7054, significantly improved overall model fit (P < 0.01) for both BIS and MOAAS models. After 30 min of repeated bolus dosing, mimicking the regimen in the label for procedural sedation, the BIS and probability of MOAAS 2/3 were predicted to be 54 (95% prediction interval, 44 to 67) and 2% (95% prediction interval, 0 to 32%) versus 58 (95% prediction interval, 48 to 70) and 8% (95% prediction interval, 0 to 36%) in a model without and with tolerance, respectively. After 60 min of continuous infusion, mimicking the regimen in the label for general anesthesia, the BIS and probability of MOAAS 0 were predicted to be 40 (95% prediction interval, 33 to 50) and 87% (95% prediction interval, 18 to 100%) versus 50 (95% prediction interval, 41 to 60) and 59% (95% prediction interval, 6 to 99%) in a model without and with tolerance, respectively.

CONCLUSIONS

In this study, it was shown that remimazolam-induced sedation is prone to tolerance development, which is potentially mediated by the CNS7054 concentration. The clinical consequences are, however, limited in situations where remimazolam is titrated to effect.

EDITOR’S PERSPECTIVE

Population pharmacokinetic/pharmacodynamic modeling and exposure-response analysis of ciprofol in the induction and maintenance of general anesthesia in patients undergoing elective surgery: A prospective dose optimization study

AIM

This study aimed to establish a population pharmacokinetic and pharmacodynamic (PK-PD) model to explore the optimal maintenance dose and appropriate starting time of maintenance dose after induction of ciprofol and investigate the efficacy and safety of ciprofol for general anesthesia induction and maintenance in patients undergoing elective surgery.

METHOD

A total of 334 subjects with 3092 concentration measurements from nine clinical trials and 115 subjects with 5640 bispectral index (BIS) measurements from two clinical trials were used in the population PK-PD analysis. Exposure-response relationships for both efficacy endpoints (duration of anesthesia successful induction, time to recovery from anesthesia, time to respiratory recovery, and time from discontinuation to the 1st/3rd consecutive Aldrete score ≥ 9) and safety variables (hypotension, bradycardia, and injection site pain) were evaluated based on the data gathered from 115 subjects in two clinical trials.

RESULT

Ciprofol pharmacokinetics (PK) were adequately described by a three-compartment model with first-order elimination from the central compartment and redistribution from the deep and shallow peripheral compartments. An inhibitory sigmoidal Emax model best described the relationship between ciprofol effect-site concentrations and BIS measurements. Body weight, age, sex, blood sampling site, and study type (short-term infusion vs long-term infusion) were identified as statistically significant covariates on the PK of ciprofol. No covariates were found to have a significant effect on the pharmacodynamic (PD) parameters. The PK-PD simulation results showed that the optimal maintenance dose was 0.8 mg/kg/h and the appropriate time to start the maintenance dose was 4-5 mins after the induction dose of ciprofol. Within the exposure range of this study, no meaningful correlations between ciprofol exposures and efficacy or safety endpoints were observed.

CONCLUSION

A population PK-PD model was successfully developed to describe the ciprofol PK and BIS changes. Efficacy was consistent across the exposure range with a well-tolerated safety profile indicating no maintenance dose adjustment is required for patients undergoing elective surgery.

The Effect of Sex on the Remimazolam Dosage Required for Successful i-gel Supraglottic Airway Insertion with Remifentanil in Non-Paralyzed Patients: An Up-and-Down Sequential Allocation Trial

(1) Background: The physiological and pharmacological variations between men and women are known to influence drug efficacy. The objective of this study was to determine the 50% and 95% effective doses (ED50 and ED95) of remimazolam required for i-gel supraglottic airway (ISA) insertion under remifentanil infusion without neuromuscular blocking agents (NMBAs) in both males and females. (2) Methods: Patients aged 19-65 years, scheduled for general anesthesia using ISA, were enrolled in this study. Patients were divided into two groups based on their sex. The anesthesia process began with a remifentanil infusion targeting an effect-site concentration of 3.0 ng/mL, accompanied by a remimazolam injection. The initial remimazolam dose was 0.25 mg/kg, and it was adjusted with a step size of 0.05 mg/kg based on the outcome of ISA insertion in the preceding patient. (3) Results: The ED50 of remimazolam (mean ± standard error) was 0.28 ± 0.02 mg/kg in the male group and 0.18 ± 0.02 mg/kg in the female group (p < 0.001). Additionally, ED95, which was calculated using the isotonic regression method, was significantly comparable between the male and female groups (male: 0.35 mg/kg, 95% confidence interval [CI] = 0.34-0.35; female: 0.29 mg/kg, 95% CI = 0.25-0.30). (4) Conclusions: This study showed that both the ED50 and the ED95 of remimazolam for successful ISA insertion was higher for men than that for women. Therefore, while using remimazolam alongside remifentanil infusion without NMBAs for ISA insertion, one should consider the patient's sex for appropriate dosing.

Safety and efficacy of remimazolam for general anesthesia in elderly patients undergoing laparoscopic cholecystectomy: a randomized controlled trial

Introduction

There is insufficient evidence regarding the efficacy and safety of remimazolam in elderly patients. Therefore, this study evaluated the differences in the anesthesia characteristics and perioperative hemodynamic profiles of elderly patients receiving total intravenous anesthesia with remimazolam or propofol.

Methods

Eighty-four patients aged >65 years with an American Society of Anesthesiologists physical status of I-III were randomly assigned to Group R (receiving remimazolam, n = 42) or Group P (receiving propofol, n = 42). In Group R, remimazolam was initiated at a rate of 6 mg/kg/h until loss of consciousness (LOC) was achieved and maintained at 1 mg/kg/h subsequently. In Group P, 1.0-1.5 mg/kg of propofol was injected for 1 min and maintained at 100 μg/kg/min subsequently. The maintenance infusion rate was adjusted to maintain an appropriate depth of anesthesia until the end of the surgery. The primary outcome was the time to LOC. The depth of anesthesia scores and hemodynamic profiles were recorded perioperatively.

Results

The time to LOC was significantly longer in Group R (120 s) than in Group P (60 s) (p < 0.001). The time to eye-opening (Group R, 10 min; Group P, 10 min; p = 0.056), the incidence of maintenance of hemodynamic changes within 20% of the peri-anesthetic values, and treatments for hemodynamic instability did not differ significantly between the groups. The depth of anesthesia scores did not differ significantly between the groups; however, the scores were higher in Group R than those in Group P before endotracheal intubation. The hemodynamic parameters did not differ significantly at any time point. The time to extubation was longer in Group R (12 min) than that in Group P (10 min) (p = 0.007). Similarly, the time to discharge from the operating room was significantly longer in Group R (15 min) compared to Group P (12 min) (p = 0.018).

Conclusion

Remimazolam does not exhibit a comparable effect to propofol in terms of anesthesia induction and recovery. However, it demonstrates a similar effect to propofol regarding intraoperative anesthesia depth and hemodynamic profile in elderly patients undergoing remifentanil-based total intravenous anesthesia.

Comparison of 95% effective dose of remimazolam besylate and propofol for gastroscopy sedation on older patients: A single-centre randomized controlled trial

AIMS

Advanced age is an important risk factor for adverse events during procedural sedation. Remimazolam is safe and effective in gastroscopic sedation. However, the ideal dose and application for older patients are not well known. We aim to investigate its 95% effective dose (ED95) for older patients undergoing gastroscopy and to assess its safety and efficacy, with propofol as the comparison.

METHODS

The trial consists of 2 parts, patients aged >65 years and scheduled for outpatient painless gastroscopy were enrolled. In the first part, Dixon's up-and-down methodology was used to determine the ED95 of remimazolam besylate and propofol for gastroscopic insertion, in combination with 0.2 μg/kg remifentanil. In the second part, patients in each group received 0.2 μg/kg remifentanil and ED95 dose of the study drugs for sedation induction, supplemental doses were added to maintain sedation depth when necessary. The primary outcome was the incidence of adverse events. The secondary outcome was the recovery time.

RESULTS

The ED95 of remimazolam besylate and propofol induction were 0.2039 (95% confidence interval 0.1753-0.3896) mg/kg and 1.9733 (95% confidence interval 1.7346-3.7021) mg/kg respectively. Adverse events were reported in 26 (40.6%) patients in the remimazolam group and 54 (83.1%) in the propofol group (P < .0001), whereas the remimazolam group presented a higher incidence of hiccups (P = .0169). Besides, the median time to awakening was approximately 1 min shorter with remimazolam than with propofol (P < .05).

CONCLUSION

For older patients undergoing gastroscopy, the ED95 dose of remimazolam is a safer alternative than propofol when inducing the same sedation depth.

Comparison of Remimazolam and Propofol for Drug-Induced Sleep Endoscopy: A Randomized Clinical Trial

OBJECTIVE

To compare the efficacy and safety of remimazolam with those of propofol for drug-induced sleep endoscopy (DISE) in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).

STUDY DESIGN

A prospective, single-center, randomized clinical trial.

SETTING

Xiangya Hospital of Central South University.

METHODS

Patients with OSAHS receiving DISE were randomly assigned to either the remimazolam or propofol group. The primary outcome was the incidence of hypoxemia (pulse oxygen saturation [SpO2 ] < 90%) during DISE. The secondary outcomes were the incidence of severe hypoxemia (SpO2  < 80%), the minimal value of SpO2 , sedation success rate (completion of DISE according to the medication regimen), and incidence of events of interest (including injection pain, bradycardia, and decreased respiratory rate).

RESULTS

Sixty-four patients were included in this study. The incidence of hypoxemia was significantly lower in the remimazolam than in the propofol group (25.00% vs 62.50%, respectively; relative risk, 0.40; 95% confidence interval [CI], 0.20-0.74; p < .01). There was no significant difference in the sedation success rate between the remimazolam and propofol groups (96.88% vs 81.25%, respectively; relative risk, 1.19; 95% CI, 1.01-1.50; p = .10). The incidence of at least 1 event of interest was lower in the remimazolam than in the propofol group (43.75% vs 96.88%, respectively; relative risk, 0.45; 95% CI, 0.29-0.63; p < .01).

CONCLUSION

Remimazolam can present satisfactory sedative efficacy in DISE, with a lower incidence of hypoxemia and a higher safety profile than propofol.

Propofol Versus Remimazolam on Cognitive Function, Hemodynamics, and Oxygenation During One-Lung Ventilation in Older Patients Undergoing Pulmonary Lobectomy: A Randomized Controlled Trial

OBJECTIVES

To investigate the effects of remimazolam on postoperative cognitive function, intraoperative hemodynamics, and oxygenation in older patients undergoing lobectomy.

DESIGN

A prospective, double-blind, randomized, controlled study.

SETTING

A university hospital.

PARTICIPANTS

Eighty-four older patients with lung cancer who underwent lobectomy, aged ≥65 years.

INTERVENTIONS

Patients were divided randomly into the remimazolam (group R) and propofol (group P) groups. Group R underwent remimazolam anesthesia induction and maintenance, whereas group P underwent propofol anesthesia induction and maintenance. Cognitive function was assessed with neuropsychological tests 1 day before surgery and 7 days after surgery. The Clock Drawing Test, Verbal Fluency Test (VFT), Digit Symbol Switching Test (DSST), and Auditory Verbal Learning Test-Huashan (AVLT-H) assessed visuospatial ability, language function, attention, and memory, respectively. The systolic blood pressure (SBP), heart rate, mean arterial pressure (MAP), and cardiac index were recorded 5 minutes before induction of anesthesia (T0), 2 minutes after sedation (T1), 5 minutes after intubation with two-lung ventilation (T2), 30 minutes after one-lung ventilation (OLV) (T3), 60 minutes after OLV (T4), and at the end of surgery (T5), and the incidences of hypotension and bradycardia were recorded. The PaO2, oxygenation index (OI), and intrapulmonary shunt (Qs/Qt) were assessed at T0, T2, T3, T4, and T5. The levels of S-100β and interleukin 6 were measured by enzyme-linked immunosorbent assay at T0, T5, 24 hours after surgery (T6), and on day 7 after surgery (T7).

MEASUREMENTS AND MAIN RESULTS

The VFT, DSST, immediate recall AVLT-H, and short-delayed recall AVLT-H scores were significantly higher in group R than in group P on day 7 after surgery (p < 0.05). The SBP and MAP at T2 to T5 were significantly higher in group R than in group P, the incidence of hypotension was significantly lower in group R (9.5%) than in group P (35.7%) (p = 0.004), and remimazolam significantly reduced the dose of phenylephrine used (p < 0.05). The PaO2 and OI at T4 were significantly higher in group R than in group P, and Qs/Qt was significantly lower in group R than in group P. The levels of S-100β at T5 were significantly lower in group R than in group P (p < 0.05).

CONCLUSION

The results showed that remimazolam (versus propofol) may lessen the degree of short-term postoperative cognitive dysfunction measured by standard neuropsychological tests, better optimize intraoperative hemodynamics, and lead to improved oxygenation during OLV.

Remimazolam for Pediatric Procedural Sedation: Results of an Institutional Pilot Program

Remimazolam, an ultra-short-acting benzodiazepine sedative, was first approved in 2020 in Japan as a general anesthetic for adults. However, its utilization in pediatric settings remains unexplored and, to date, is confined to isolated case reports due to a lack of specific pediatric labeling. The primary objective of our study was to evaluate the safety profile of remimazolam when used for procedural sedation in children following dosages established in adult protocols. Additional parameters, including dosage per kg of body weight, duration of the procedure, efficacy (measured as successful completion of the procedure), the necessity for supplemental medications, and changes in physiological parameters, such as the heart rate (HR) and mean arterial blood pressure (MAP), were assessed. Our study encompassed 48 children with an average age of 7.0 years. The objective Tracking and Reporting Outcomes of Procedural Sedation tool indicated no adverse events. In our cohort, propofol and ketamine were used as adjunctive treatments in 8 and 39 patients, respectively, with successful completion of all procedures. Notable hemodynamic variability was observed, with 88.4% of patients experiencing a ≥20% change (increase or decrease) and 62.8% experiencing a ≥30% change in MAP. Additionally, a ≥20% change in HR was observed in 54.3% of patients, and a ≥30% change was observed in 34.8% of patients. Nevertheless, none of the patients required pharmacological intervention to manage these hemodynamic fluctuations. Our findings suggest that remimazolam, when supplemented with propofol or ketamine, could offer a safe and effective pathway for administering procedural sedation in pediatric populations.

Bibliometric Analysis of Global Trends in Remimazolam-Related Research Over the Past 15 Years: Compared with Propofol

Purpose

Although remimazolam is a popular novel anesthetic, there is a lack of data in the literature about current and future trends. Therefore, the aim of this study was to explore emerging trends and potential hotspots of remimazolam research over the past 15 years through bibliometric methods.

Methods

Relevant articles on remimazolam published from 2007 to 2022 and propofol from 1997 to 2001 were retrieved from the Web of Science Core Collection database. Data were collected using Microsoft Excel and graphs were generated with the Bibliometrix package in R software. Visual bibliometric maps were created using VOS viewer and CiteSpace software.

Results

In total, 184 articles were included for analysis. Remimazolam-related research tended to increase, especially from 2020 to 2022. China produced the most publications (327), whereas the USA dominated in quality (h-index = 16). Among institutions, PAION Deutschland GmbH produced the most articles (Np = 21). Similar to initial research and development of propofol, the hotspots of remimazolam research have extended beyond pharmacokinetics and pharmacodynamics to adverse reactions, clinical scenarios, specific populations, and compatible regimens, as confirmed by high numbers of common references and keywords.

Conclusion

Remimazolam research has developed rapidly over the past two years. Remimazolam can achieve faster onset and recovery, and more stable hemodynamics than midazolam or propofol, enabling gradual piloting of applications from endoscopy and general anesthesia to sedation of critical care patients; foreseeing specific population (patients with hepatic or renal impairment and reduced cardiovascular reserve, the elderly, and children) through compatible anesthetics regimens to more optimal and safe. Future studies of remimazolam are likely to include adverse reactions, effects on different organ systems, and identification of monitoring indicators.

Comparison of the effects of remimazolam and dexmedetomidine on early postoperative cognitive function in elderly patients with gastric cancer

Purpose

To compare the effects of remimazolam and dexmedetomidine on early postoperative cognitive dysfunction (POCD) in aged gastric cancer patients.

Methods

From June to December 2022, 104 elderly patients (aged 65-80 years) received laparoscopic radical resection of gastric cancer at the First Affiliated Hospital of Nanchang University. Using the random number table approach, the patients were separated into three groups: remimazolam (Group R), dexmedetomidine (Group D), and saline (Group C). The primary outcome was the incidence of POCD, and secondary outcomes included TNF-α and S-100β protein concentrations, hemodynamics, VAS scores, anesthesia recovery indicators, and the occurrence of adverse events within 48 h postoperatively.

Results

At 3 and 7 days after surgery, there were no statistically significant differences in the incidence of POCD, the MMSE and MoCA scores between groups R and D (p > 0.05). However, compared to the saline group, both groups had higher MMSE and MoCA scores and decreased incidences of POCD. These differences were statistically significant (p < 0.05). Between group R and group D, there were no statistically significant changes (p > 0.05) in the levels of TNF-α and S-100β protein at the three time points (at the end of the surgery, 1 day later, and 3 days later). Even though neither group's concentration of the two factors was as high as that of the saline group, the differences were statistically significant (p < 0.05). At all three time points-following induction (T₂), 30 min into the operation (T₃), and at the conclusion of the surgery (T₄)-the heart rate and blood pressure in group R were greater than those in groups D and C. Statistics showed that the differences were significant (p < 0.05). The incidence of intraoperative hypotension was highest in group D and lowest in group R (p < 0.05). The dose of propofol and remifentanil, group C > group R > group D. Extubation and PACU residence times did not differ statistically significantly (p > 0.05) between the three groups. There was no significant difference in VAS scores between groups R and D after 24 h postoperatively (p > 0.05), although both had lower scores than group C, and the difference was statistically significant (p < 0.05). The VAS scores between the three groups at 72 h (T₆) and 7 days (T₇) were not statistically significant (p > 0.05). Adverse reactions such as respiratory depression, hypotension, bradycardia, agitation, drowsiness, and nausea and vomiting had the lowest incidence in group R and the highest incidence in group C (p < 0.05).

Conclusion

Remimazolam is similarly beneficial as dexmedetomidine in lowering the incidence of early POCD in aged patients after radical gastric cancer resection, probably due to reduced inflammatory response.

Safety and effectiveness of the combination of remimazolam tosilate and propofol in gastroscopy: a multicenter, randomized controlled, single-blind clinical trial

Remimazolam tosilate (RT) is a new short-acting γ-aminobutyric acid A (GABAA) receptors agonist. However, its optimal use mode and dosage still remain unclear. This study aimed to examine the safety and effectiveness of the combination of RT and propofol in gastroscopy. This was a prospective, single-blind, randomized, multicenter, parallel-group study. All eligible 256 patients were randomized into the following 3 groups. Patients were anesthetized with propofol (Group P), RT (Group R) or the combination of RT and propofol (Group RP). The primary efficacy endpoints were: body movement score; satisfaction of gastroscopy doctors; success rate of sedation and effects on sleep status. Sedation induction time, time to be fully alert and adverse events were also recorded. The probability of complete immobility was lower in group R (33.73%) than in group P (86.67%) and RP (83.13%). The rate of doctors' satisfaction was much lower in group R (28.92%) than in group P (77.78%) and RP (72.29%). The success rate of sedation and sleep outcome score has no difference in the three groups. The time to adequate sedation was longer in group RP (77.27 ± 18.63 s) than in group P (64.47 ± 24.36 s), but much shorter than that in group R (102.84 ± 46.43s). The time to be fully alert was shorter in group R (6.30 ± 1.52 min) and RP (6.54 ± 1.13 min) than in group P (7.87 ± 1.08 min). The proportion of sedative hypotension was significantly higher in group P (41.11%) than in group R (1.20%) and group RP (3.61%) (p < 0.001). The incidence of respiratory depression was much higher in group P (17.78%) than in group R (no patient) and group RP (1.2%). The incidence of adverse events was lower in groups R (4.82%) and RP (9.64%) than in group P (31.11%). The combination of RT and propofol takes effect quickly, makes patients alert quickly, provides a sufficient depth of sedation, reduces body movement, does not inhibit circulation and respiratory function, does not affect sleep, and is the preferred mode for gastroscopy doctors and anesthesiologists.

Comparison of the effects of remimazolam tosylate and propofol on postoperative delirium among older adults undergoing major non-cardiac surgery: protocol for a randomised controlled trial

INTRODUCTION

Postoperative delirium (POD) is a common cognitive disturbance in elderly individuals that is characterised by acute and fluctuating impairments in attention and awareness. Remimazolam tosylate is a novel, ultrashort-acting benzodiazepine, and there is limited evidence of its correlation with the incidence of early POD. The aim of this study is to evaluate the incidence of POD after anaesthesia induction and maintenance with remimazolam tosylate or propofol in elderly patients undergoing major non-cardiac surgery.

METHODS AND ANALYSIS

This is a single-centre, randomised controlled trial. 636 elderly patients undergoing major non-cardiac surgery will be enrolled and randomised at a 1:1 ratio to receive total intravenous anaesthesia with either remimazolam tosylate or propofol. The primary outcome is the incidence of POD within 5 days after surgery. Delirium will be assessed twice daily by the 3 min Diagnostic Interview for the Confusion Assessment Method or the Confusion Assessment Method for the intensive care unit (ICU) for ICU patients. Secondary outcomes are the onset and duration of delirium, cognitive function at discharge and within 1-year postoperatively, postoperative analgesia within 5 days, chronic pain at 3 months, quality of recovery and postoperative inflammatory biomarker levels.

ETHICS AND DISSEMINATION

The study was approved by the institutional ethics committee of the National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences (approval No. 22/520-3722). Written informed consent will be obtained from each patient before enrolment. The results of this trial will be presented at scientific conferences and in peer-reviewed scientific journals.

TRIAL REGISTRATION NUMBER

ChiCTR2300067368.

Comparison of the Incidence of Postoperative Acute Kidney Injury Following the Administration of Remimazolam or Sevoflurane in Elderly Patients Undergoing Total Knee Arthroplasty: A Randomized Controlled Trial

BACKGROUND

We evaluated the incidence of postoperative acute kidney injury (AKI) and complications when remimazolam (RMMZ) or sevoflurane (SEVO) were used in elderly patients undergoing total knee arthroplasty.

METHODS

Seventy-eight participants aged ≥65 were randomly allocated to either the RMMZ or SEVO group. The primary outcome was the incidence of AKI on postoperative day (POD) 2. The secondary outcomes included intraoperative heart rate (HR), blood pressure (BP), total drug administered, emergence time, postoperative complications on POD 2, and hospital length of stay (HLOS).

RESULTS

The incidence of AKI was comparable between the RMMZ and SEVO groups. The doses of intraoperative remifentanil, vasodilators, and additional sedatives were significantly higher in the RMMZ group than in the SEVO group. Overall intraoperative HR and BP tended to remain higher in the RMMZ group. The emergence time in the operating room was significantly faster in the RMMZ group; however, the time required for an Aldrete score ≥ 9 was comparable between the RMMZ and SEVO groups. Postoperative complications and HLOS were comparable between the RMMZ and SEVO groups.

CONCLUSION

RMMZ may be recommended for patients who are expected to decrease in intraoperative vital signs. However, stable hemodynamics with RMMZ were not sufficient to influence the prevention of AKI.

Randomized controlled trial for anesthesia during gastroscopy: interactions between remimazolam and propofol in combination with sufentanil

BACKGROUND

Remimazolam is a new short-duration anesthetic currently used for gastroscopy and can be mixed with propofol and potent opioids.

AIM

The study aimed to investigate the synergistic interaction between remimazolam and propofol after sufentanil administration and to determine the appropriate dose ratios between remimazolam and propofol.

METHOD

This study used a randomized controlled design. Patients scheduled for gastrointestinal endoscopy were included and randomized into five groups. The randomized block design was applied at a randomization ratio of 1:1. Patients in each group received sufentanil (0.1 μg/kg) and the calculated doses of remimazolam and propofol. Using the up and down method, the median effective dose (ED₅₀) and the 95% confidence interval (CI) were determined based on whether the eyelash reflex disappeared in each treatment group. Isobolographic analysis was used to analyze the presence of drug interactions. The interaction coefficient and the dose ratio between remimazolam and propofol were calculated by algebraic analysis. Statistical analysis was performed using interval estimates and 95% CI for statistical attributes.

RESULTS

Cross-sectional analysis of the isobologram showed a clinically significant synergistic effect between remimazolam and propofol. When 0.016, 0.032, and 0.047 mg/kg of remimazolam were combined with 0.477, 0.221, and 0.131 mg/kg of propofol, the interaction coefficients were 1.04, 1.21, and 1.06, respectively. The dose ratio of remimazolam to propofol was approximately 1:7.

CONCLUSION

Remimazolam and propofol have synergistic clinical effects. A strong synergistic effect was observed when the remimazolam and propofol dose ratio was 1:7 (mg/kg).

CLINICAL TRIAL

The study protocol was registered at the Chinese Clinical Trial Registry (ChiCTR2100052425).

The safety and efficacy of remimazolam tosylate for induction and maintenance of general anesthesia in pediatric patients undergoing elective surgery: Study protocol for a multicenter, randomized, single-blind, positive-controlled clinical trial

Introduction: Remimazolam is an ultra-short-acting benzodiazepine sedative agent commonly used in general anesthesia, procedural sedation, and intensive care unit (ICU) sedation. This study aimed to explore the efficacy and safety of remimazolam versus propofol for the induction and maintenance of general anesthesia in preschool-age children undergoing elective surgery. Methods and analysis: In this multicenter, randomized, single-blind, positive-controlled non-inferior clinical trial, one hundred ninety-two children aged 3-6 years will be randomly allocated as a 3:1 ratio into two groups: Group R with an intravenous dose of remimazolam 0.3 mg/kg for the induction of anesthesia followed by a constant infusion rate of remimazolam 1-3 mg/kg/h to maintain anesthesia, and Group P with an intravenous dose of propofol 2.5 mg/kg for the induction of anesthesia followed by a constant infusion rate of propofol 4-12 mg/kg/h to maintain anesthesia. The primary outcome will be the rate of the successful induction and maintenance of anesthesia. The secondary outcomes will include the time to LoC, the Bispectral Index (BIS) value, awakening time, extubation time, post-anesthesia care unit (PACU) discharge time, usage of additional sedative drugs during the induction period, usage of remedial drugs in PACU, emergence delirium, pain in PACU, behavior scores at day 3 after surgery, parental and anesthesiologists' satisfaction, and adverse events. Ethics and dissemination: This study has been approved by the ethics review boards at all participating hospitals. The Ethics Committee of the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University (Reference No. LCKY 2020-380, November 13, 2020) is the central ethics committee.

Effect of Remimazolam on Postoperative Delirium in Older Adult Patients Undergoing Orthopedic Surgery: A Prospective Randomized Controlled Clinical Trial

Background

Postoperative delirium is common in older adult patients and associated with a poor prognosis. The use of benzodiazepine was identified as an independent risk factor for delirium, but there is no randomized controlled trial regarding the relationship between remimazolam, a new ultra-short acting benzodiazepine, and postoperative delirium. We designed a randomized controlled trial to evaluate if remimazolam increases the incidence of postoperative delirium compared with propofol in older adult patients undergoing orthopedic surgery with general anesthesia.

Patients and Methods

We enrolled 320 patients aged more than 60 with American Society of Anesthesiologists physical status I-III who underwent orthopedic surgery. Patients were randomized to two groups to receive intraoperative remimazolam or propofol, respectively. Our primary outcome was the incidence of delirium within 3 days after surgery. Secondary outcome was emergence quality including the incidence of emergence agitation, extubation time, and length of post-anesthesia care unit (PACU) stay. Adverse events were also recorded.

Results

The incidence of postoperative delirium was 15.6% in the remimazolam group and 12.4% in the propofol group (Risk ratio, 1.26; 95% CI, 0.72 to 2.21; Risk difference, 3.2%; 95% CI, -4.7% to 11.2%; P = 0.42). No significant differences were observed for time of delirium onset, duration of delirium, and delirium subtype between the two groups. Patients in remimazolam group had a lower incidence of hypotension after induction and consumed less vasoactive drugs intraoperatively, but had a longer postoperative extubation time and PACU stay.

Conclusion

General anesthesia with remimazolam was not associated with an increased incidence of postoperative delirium compared with propofol in older adult patients undergoing orthopedic surgery.

The difference in mean arterial pressure induced by remimazolam compared to etomidate in the presence of fentanyl at tracheal intubation: A randomized controlled trial

Background: Combined use of hypnotic and opioids during anesthesia inductions decreases blood pressure. Post-induction hypotension (PIHO) is the most common side effect of anesthesia induction. We aimed to compare the difference in mean arterial pressure (MAP) induced by remimazolam with that induced by etomidate in the presence of fentanyl at tracheal intubation. Methods: We assessed 138 adult patients with American Society of Anesthesiologists physical status I-II who underwent elective urological surgery. Patients were randomly allocated to receive either remimazolam or etomidate as alterative hypnotic in the presence of fentanyl during anesthesia induction. Comparable BIS values were achieved in both groups. The primary outcome was the difference in the MAP at tracheal intubation. The secondary outcomes included the characteristics of anesthesia, surgery, and adverse effects. Results: The MAP was higher in the etomidate group than in the remimazolam group at tracheal intubation (108 [22] mmHg vs. 83 [16] mmHg; mean difference, -26; 95% confidence interval [CI], -33 to -19; p < 0.0001). Heart rate was significantly higher in the etomidate group than in the remimazolam group at tracheal intubation. The patients' condition warranted the administration of ephedrine more frequently in the remimazolam group (22%) than in the etomidate group (5%) (p = 0.0042) during anesthesia induction. The remimazolam group had a lower incidence of hypertension (0% vs. 9%, p = 0.0133), myoclonus (0% vs. 47%, p < 0.001), and tachycardia (16% vs. 35%, p = 0.0148), and a higher incidence of PIHO (42% vs. 5%, p = 0.001) than the etomidate group during anesthesia induction. Conclusion: Remimazolam was associated with lower MAP and lower heart rate compared to etomidate in the presence of fentanyl at tracheal intubation. Patients in the remimazolam group had a higher incidence of PIHO, and their condition warranted the administration of ephedrine more frequently than in the etomidate group during anesthesia induction.

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.

Remimazolam besylate for the sedation of postoperative patients undergoing invasive mechanical ventilation in the ICU: a prospective dose‒response study

This single-center study aimed to determine the effective dose and safety of remimazolam besylate for the sedation of postoperative patients undergoing invasive mechanical ventilation in the intensive care unit (ICU). Mechanically ventilated patients admitted to the ICU after surgery were included. The Narcotrend index (NTI) was used to assess the depth of sedation, and the Richmond Agitation-Sedation Scale (RASS) score was also recorded. Remimazolam besylate was administered initially at a loading dose of 0.02 mg/kg, followed by a gradual increase of 0.005 mg/kg each time until the targeted depth of sedation was achieved (NTI 65-94). A maintenance dose of remimazolam besylate was administered starting at 0.2 mg/kg/h, followed by increments or subtractions of 0.05 mg/kg/h each time until a satisfactory depth of sedation was achieved and maintained for at least 30 min. The demographic data, anesthesia, surgery types, hemodynamics and respiratory parameters were recorded. Adverse events and adverse drug reactions were monitored for safety. Twenty-three patients were eventually included in this study covering a period of 1 year. A satisfactory depth of sedation was achieved by a single intravenous infusion of remimazolam besylate at a loading dose of 0.02-0.05 mg/kg followed by a maintenance dose of 0.20-0.35 mg/kg/h. There were no significant changes in hemodynamic and respiratory parameters within 10 min after the administration of remimazolam besylate. In addition, a significant correlation was observed between the NTI and the RASS score for assessing sedation (r = 0.721, P < 0.001). The NTI showed a predictive probability for a RASS score of 0.817. Remimazolam besylate was effective for mild/moderate sedation of invasively mechanically ventilated postoperative patients in the ICU while maintaining excellent respiratory and hemodynamic stability. The NTI can be used as a good tool for the objective evaluation of the depth of sedation and agitation.

Efficacy and safety of remimazolam besylate in bronchoscopy for adults: A multicenter, randomized, double-blind, positive-controlled clinical study

Background: With the development of fiberoptic bronchoscopy in the diagnosis and treatment of various pulmonary diseases, the anesthesia/sedation requirements are becoming more demanding, posing great challenges for patient safety while ensuring a smooth examination/surgery process. Remimazolam, a brand-new ultra-short-acting anesthetic, may compensate for the shortcomings of current anesthetic/sedation strategies in bronchoscopy.

Methods: This study was a prospective, multicenter, randomized, double-blind, parallel positive controlled phase 3 clinical trial. Subjects were randomized to receive 0.2 mg/kg remimazolam besylate or 2 mg/kg propofol during bronchoscopy to evaluate the efficacy and safety of remimazolam.

Results: A total of 154 subjects were successfully sedated in both the remimazolam group and the propofol group, with a success rate of 99.4% (95%CI of the adjusted difference −6.7 × 10%–6% to −5.1 × 10%–6%). The sedative effect of remimazolam was noninferior to that of propofol based on the prespecified noninferiority margin of −5%. Compared with the propofol group, the time of loss of consciousness in the remimazolam group (median 61 vs. 48s, p < 0.001), the time from the end of study drug administration to complete awakening (median 17.60 vs. 12.80 min, p < 0.001), the time from the end of bronchoscopy to complete awakening (median 11.00 vs. 7.00 min, p < 0.001), the time from the end of study drug administration to removal of monitoring (median 19.50 vs. 14.50 min, p < 0.001), and the time from the end of bronchoscopy to removal of monitoring (median 12.70 vs. 8.60 min, p < 0.001) were slightly longer. The incidence of Adverse Events in the remimazolam group and the propofol group (74.8% vs. 77.4%, p = 0.59) was not statistically significant, and none of them had Serious Adverse Events. The incidence of hypotension (13.5% vs. 29.7%, p < 0.001), hypotension requiring treatment (1.9% vs. 7.7%, p = 0.017), and injection pain (0.6% vs. 16.8%, p < 0.001) were significantly lower in the remimazolam group than in the propofol group.

Conclusion: Moderate sedation with 0.2 mg/kg remimazolam besylate is effective and safe during bronchoscopy. The incidence of hypotension and injection pain was less than with propofol, but the time to loss of consciousness and recovery were slightly longer.

Clinical Trial Registration:clinicaltrials.gov, ChiCTR2000039753

Profile of Remimazolam in Anesthesiology: A Narrative Review of Clinical Research Progress

Remimazolam is a novel short-acting γ-aminobutyric acid (GABA) receptor agonist with typical characteristics of benzodiazepine sedative drugs, nonorgan-dependent metabolism, long-term infusion without accumulation, and no injection pain. It is quite different from the other current sedative drugs and has broad prospects for application. It has been established that the metabolites of remimazolam are inactive, and the interactions with other drugs are weak with slight cardiopulmonary suppressive effects, showing good effectiveness and safety. During the 2-year period that it has been on the market, remimazolam has been used in multiple clinical scenarios, such as the induction and maintenance of general anesthesia and sedation in outpatient minor procedures or examinations. However, it's use has also prompted widespread concern around the world. Therefore, given its short- and rapid-acting, controllable characteristics remimazolam deserves in-depth study in order for it to be used in fast-track surgery, comfort diagnosis and treatment. Notably, such agents might be of great significance, especially in elderly individuals, patients with critical diseases or patients with liver and kidney insufficiency. The current study reviews recent clinical studies (2015-2022) on remimazolam and summarizes the characteristics of its applications. Specifically, the use of remimazolam in some specific populations are described. This study attempts to provide scientific support for the clinical application of this novel sedative drug in the field of anesthesia.

Equilibration rate constant, ke0, to determine effect-site concentration for the Masui remimazolam population pharmacokinetic model in general anesthesia patients

Effect-site concentration is widely used to determine drug dosage in anesthesia practice. To obtain effect-site concentration, a pharmacokinetic model with a corresponding equilibration rate constant between plasma and effect-site, k_e0, is necessary. Remimazolam, a novel short-acting benzodiazepine, has been approved as anesthetic/sedative. Recently, a remimazolam pharmacokinetic model has been published using a large dataset including wide range of subject characteristics (416 males and 246 females, age 18-93 years, total body weight 34-149 kg, height 133-204 cm, body mass index 14-61 kg m^-2, ASA physical status: I-IV, and Asian, White, American African, and 2 other races). This Masui model can be applicable to various patients, but a pharmacodynamic model including k_e0 was not developed simultaneously. A previous article has indicated that the time to peak effect of drug after its bolus should be used to determine k_e0 for a pharmacokinetic model without simultaneous development of corresponding pharmacodynamic model. The k_e0 value can be calculated using numerical analysis but not algebraic solution. We provide the detail method of the numerical analysis and a tool to have k_e0 value easily for the Masui remimazolam PK model. Additionally, we provide a multiple regression model to have k_e0 value for the PK model.

Effect-site concentration of remimazolam at loss and recovery of responsiveness during general anesthesia: a simulation study

Background

The objective of this study was to investigate the effect-site concentration (Ce) of remimazolam at loss of response (LOR) and recovery of response (ROR) in patients underwent general anesthesia using simulation. In addition, the relationships between patient’s factors and simulated Ce at LOR and ROR were examined.

Methods

The medical records of 81 patients who underwent elective surgery under general anesthesia using remimazolam with simulation of Ce between August 4, 2021 and October 12, 2021, were retrospectively reviewed. Remimazolam was administered as an induction dose of 6 or 12 mg/kg/h until the patient became unresponsive, followed by 0.3–2 mg/kg/h to maintain BIS values below 60. Simultaneously, simulations of manual infusion mode were performed using Asan Pump software and the Ce of remimazolam was simulated using the Schüttler model. Whenever infusion rate of remimazolam was manually changed, the simulated Ce was confirmed almost simultaneously. LOR and ROR, defined as unresponsive and eye-opening to verbal commands, respectively, were recorded in the Asan Pump program.

Results

The median (1Q, 3Q) simulated Ce at LOR and ROR were 0.7 (0.5, 0.9) and 0.3 (0.2, 0.4) μg/ml, respectively. LOR was achieved in 1.9 min after remimazolam infusion with cumulative doses of 0.3 mg/kg. There was a significant relationship between age and simulated Ce at ROR (Ce at ROR = –0.0043 × age + 0.57, r = 0.30, P = 0.014).

Conclusions

For optimal dosage adjustment, simulating Ce while administering remimazolam with a weight-based dose during anesthesia is helpful. Elderly patients may recover from anesthesia at lower Ce of remimazolam.

What's New in Intravenous Anaesthesia? New Hypnotics, New Models and New Applications

New anaesthetic drugs and new methods to administer anaesthetic drugs are continually becoming available, and the development of new PK-PD models furthers the possibilities of using arget controlled infusion (TCI) for anaesthesia. Additionally, new applications of existing anaesthetic drugs are being investigated. This review describes the current situation of anaesthetic drug development and methods of administration, and what can be expected in the near future.

A population pharmacokinetic model of remimazolam for general anesthesia and consideration of remimazolam dose in clinical practice

BACKGROUND

Remimazolam besylate is a novel short-acting benzodiazepine. An appropriate pharmacokinetic model of remimazolam is desirable in anesthesia practice. The aim of the study was to develop a pharmacokinetic model using plasma samples from patients anesthetized with remimazolam. Influence of patient characteristics, context-sensitive decrement-times, and dose regimens were also examined.

METHODS

Data were obtained from four trials on patients, and seven trials on healthy volunteers. The characteristics of 416 male and 246 female subjects were as follows: age, 18-93 years; body weight, 34-149 kg; and American Society of Anesthesiologists physical status (ASA-PS), I-IV. 2231 arterial and 3200 venous samples were used for the final model. The equilibration rate constant between arterial plasma and effect-site was estimated using the concept of time to peak effect. The final model was used to generate context-sensitive decrement times and dose regimens for general anesthesia.

RESULTS

A three-compartment model plus virtual venous compartment with allometric scaling of adjusted body weight (ABW), age, sex, and ASA-PS as covariates were selected as the final model. Elimination clearance was lower in males, and in subjects with higher ABW and ASA-PS scores. Approximately 10% or 20% higher dose rate was necessary in females than in males or ASA-PS I/II than III/IV patient. The context-sensitive half-time for effect-site concentration in a 55-year-old, 70-kg, 170-cm male or female ASA-PS I/II patient after > 6-h infusion was 16.7 or 15.9 min.

CONCLUSION

Remimazolam pharmacokinetic model for general anesthesia was successfully developed. ABW, ASA-PS, and sex has a considerable impact on the remimazolam concentration.

Remimazolam tosilate compared with propofol for gastrointestinal endoscopy in elderly patients: a prospective, randomized and controlled study

Background

Remimazolam tosilate (HR7056, RT), a novel ultrashort-acting benzodiazepine, can be used for procedural sedation and general anaesthesia. However, few studies have focused on the sedative effect of RT during gastrointestinal endoscopy in elderly patients. The purpose of this study is to compare the sedative effect of RT and propofol for gastrointestinal endoscopy in elderly patients.

Methods

A total of 82 patients aged ≥65 years with an American Society of Anaesthesiologists (ASA) grade I-II and a body mass index (BMI) of 18.0 to 30.0 kg/m² who were scheduled for gastrointestinal endoscopy from Jan 2021 to Aug 2021 were selected and randomly divided into a RT group and a propofol group. Alfentanil 5 μg/kg was used for analgesia in both groups. The RT group was given remimazolam tosilate 0.15 mg/kg with supplemental doses of 0.05 mg/kg as need, while the propofol group was given propofol 1.5 mg/kg with supplemental doses of 0.5 mg/kg. The supplemental doses were determined by the modified observational alertness/sedation assessment (MOAA/S) score and the patients’ body movements. Sedative effects, such as the time to loss of consciousness (LOC) (MOAA/S score ≤ 1), successful sedation in one dose, number of supplemental doses after successful induction, and recovery time, were evaluated. Sedation-related side effects, such as injection pain, haemodynamic events and respiratory depression, were also noted. Postoperative nausea and vomiting (PONV), visual analogue scale (VAS) scores at rest, remedial analgesics, and dizziness or headache were recorded. In addition, patients’ satisfaction and physician’s satisfaction of the procedure were compared between the two groups.

Results

Data from 77 patients were analysed. The success rate of sedation in both groups was 100%. The time to LOC (MOAA/S score ≤ 1) in the RT group was longer than that in the propofol group (20.7 ± 6.1s vs. 13.2 ± 5.2s, P < 0.001). There were fewer patients in the RT group reporting injection pain than that in the propofol group (0/39 vs. 5/38, P = 0.025). Haemodynamic events and respiratory depression in the RT group were less frequent than those in the propofol group ((6/39 vs. 17/38, P = 0.005), (2/39 vs. 9/38, P = 0.026), respectively). The number of supplemental doses after successful induction in the RT group was greater than that in the propofol group (4/9/11/13/1/1 vs. 8/4/18/6/2/0 requiring 0, 1, 2, 3, 4 or 5 supplemental doses, P = 0.014). The characteristics of the patients enrolled, postoperative parameters of the patients, and patients’ and physician’s satisfaction of the procedure were comparable in the two groups.

Conclusions

Compared with propofol, RT can be safely and effectively used for gastrointestinal endoscopy sedation in elderly patients, and the incidence of sedation-related adverse reactions, especially haemodynamic events and respiratory depression, is lower. When RT is used, the number of supplemental doses after successful induction may increase slightly.

Trial registration

Chictr.org.cn ChiCTR2000040498. Retrospectively registered (date of registration: December 1, 2020).

Review of remimazolam and sedatives in the intensive care unit

Remimazolam is a novel intravenous ultra-short acting benzodiazepine that has the potential of being a safe and effective new sedative for use in intensive care unit (ICU) settings. Because remimazolam metabolizes rapidly by being hydrolyzed to an inactive metabolite (CNS 7054) through non-specific tissue esterase activity, specific dosing adjustment for older adults and for patients with renal or hepatic impairment patients (except for those with severe hepatic impairment) is not required. In addition, research has shown that remimazolam may be reversed by administration of flumazenil, as its half time was sufficiently short compared to flumazenil. It shows a lower incidence of cardiorespiratory depression, less injection pain, and no fatal complications such as propofol infusion syndrome and malignant hyperthermia of inhalational anesthetics. Future studies to study the suitability of remimazolam for managing the sedation of ICU patients who need sedation for a long time over several days is required.

Remimazolam - current knowledge on a new benzodiazepine intravenous anesthetic agent

Intravenous anesthetic agents such as midazolam, propofol, and ketamine are routinely used to provide anesthesia and sedation. They have been shown to effectively induce and maintain amnesia, sedation, and hypnosis in various patient groups and clinical settings. However, all anesthetic agents have the potential to cause unwanted side effects such as hemodynamic instability, respiratory depression, or slow recovery due to prolonged post-procedural sedation. Remimazolam, a recently approved benzodiazepine for general anesthesia and procedural sedation in Korea, has been successfully used for these purposes. To date, inconclusive knowledge has been obtained regarding the use of remimazolam in different patient populations and under various surgical conditions. With respect to the specific pharmacokinetic and pharmacodynamic characteristics of remimazolam, the use of remimazolam is expected to increase providing safe general anesthesia and sedation. This review aims to provide an overview of the basic and clinical pharmacology of remimazolam and to compare it with midazolam and propofol.

Factors affecting prolonged time to extubation in patients given remimazolam

Purpose

To analyze the cause of prolonged recovery from general anesthesia with remimazolam.

Methods

We studied 65 patients under general anesthesia with remimazolam. According to time to extubation, patients were divided into short period (SP) (n = 34, < 15 min) and long period (LP) (n = 31, ≥ 15 min) groups. Variables affecting time to extubation such as age, sex, height, body weight, body mass index (BMI), plasma albumin concentration, ASA class, duration of surgery, and total duration of general anesthesia, and total dose of remimazolam were compared between SP and LP groups. At the end of remimazolam infusion and upon extubation, predictive remimazolam concentrations were calculated using pharmacokinetic/pharmacodynamic three compartment modeling.

Results

LP group showed significantly higher BMI, older age, and lower plasma albumin concentration compared with those of SP group. Logistic regression analysis showed that the probability of time to extubation of ≥ 15 min was higher in patients with BMI greater than 22.0 kg/m² (AUC 0.668, 95% CI 0.533‒0.803), ages older than 79.0 years (AUC 0.662, 95% CI 0.526‒0.798), and plasma albumin concentrations lower than 3.60 g/dl (AUC 0.720, 95% CI 0.593‒0.847). LP group showed significantly lower predicted remimazolam concentration than SP group upon extubation despite no difference in concentration between both groups at the end of infusion. Pharmacological analysis estimates that LP group is more sensitive to remimazolam than SP group through amplified responses.

Conclusions

Lower remimazolam doses should be considered for the overweight patients, elderly, and those with lower plasma albumin concentration.

Pharmacodynamic analysis of intravenous bolus remimazolam for loss of consciousness in patients undergoing general anaesthesia: a randomised, prospective, double-blind study

BACKGROUND

Remimazolam is a new rapid offset benzodiazepine used for procedural sedation and general anaesthesia. This study evaluated the efficacy and safety of i.v. bolus remimazolam during induction of anaesthesia.

METHODS

A total of 120 patients undergoing general anaesthesia were randomly allocated into six dose groups (n=20) of i.v. bolus remimazolam (0.02-0.27 mg kg^-1). Loss of consciousness, respiratory depression, patient state index (PSI), and haemodynamic variables were evaluated during anaesthetic induction. Parametric time-to-event models were used to identify the 50% effective dose (ED50)/95% effective dose (ED95) associated with loss of consciousness and respiratory depression. Non-linear mixed-effect models analysed the PSI and haemodynamic changes after i.v. bolus remimazolam.

RESULTS

Loss of consciousness and respiratory depression onset showed steep dose-responses with ED50/ED95 of 0.11/0.19 and 0.14/0.27 mg kg^-1 and Hill coefficients of 5.3 and 4.6, respectively. Older age was significantly associated with lower ED50/ED95 for both endpoints. ED50/ED95 and the Hill coefficient of PSI decline were 0.12/0.68 mg kg^-1 and 1.7, respectively. We propose optimal doses of 0.25-0.33, 0.19-0.25, and 0.14-0.19 mg kg^-1 in patients aged <40, 60-80, and >80 yr, respectively, based on the ED95 estimates for the corresponding age groups. The maximum percentage reduction of MAP was 27.8% and the ED50/ED95 were 0.14/2.60 mg kg^-1. The effect of remimazolam on heart rate was insignificant.

CONCLUSIONS

The ED50/ED95s of i.v. bolus remimazolam were successfully estimated from the time to loss of consciousness and respiratory depression. No serious adverse events occurred within the range of tested doses.

CLINICAL TRIAL REGISTRATION

NCT04901871.

Quality of Recovery After General Anesthesia with Remimazolam in Patients' Undergoing Urologic Surgery: A Randomized Controlled Trial Comparing Remimazolam with Propofol

Background

Remimazolam is a new medication with sedative and hypnotic effects. It has been demonstrated non-inferior to propofol in general anesthesia with regard to efficacy and safety. However, whether general anesthesia with remimazolam is better than propofol in terms of patients' recovery quality remains unknown.

Patients and Methods

Patients enrolled in this study were randomized to remimazolam or propofol group. In remimazolam group, general anesthesia was induced with remimazolam and sufentanil and maintained with remimazolam and remifentanil. In propofol group, general anesthesia was induced with propofol and sufentanil and maintained with propofol and remifentanil. Neuromuscular blocking agent cisatracurium was also injected during anesthesia. Sedation level was monitored by bispectral index (BIS). Our primary outcome was the quality of patients' postoperative recovery, using the Quality of Recovery-15 (QoR-15) scale. Secondary outcomes included SpO2, HR, MBP and frequency of application of vasoactive drugs during anesthesia, as well as incidences of adverse events in the post anesthesia care unit (PACU).

Results

The global scores of QoR-15 scale were lower in remimazolam group at postoperative day 1 and day 3 compared to propofol group, but differences between the two groups only had clinical significance at postoperative day 1. Among the five dimensions of QoR-15 scale, scores for physical comfort and emotional state were lower in remimazolam group than propofol group. MBP and HR were higher in remimazolam group than propofol group after anesthesia induction. SpO2 was similar in the two groups. The frequency of application of vasoactive drugs during anesthesia was higher in propofol group than remimazolam group. There was no statistical difference in the incidences of adverse events between the two groups.

Conclusion

General anesthesia with remimazolam can provide more stable hemodynamics but also cause temporary reduction in the quality of recovery in patients undergoing urologic surgery, compared to propofol.

Effect of remimazolam tosilate on early cognitive function in elderly patients undergoing upper gastrointestinal endoscopy

BACKGROUND AND AIM

Remimazolam tosilate (RT) is under evaluation as a sedative for endoscopic procedures. Herein, we aimed to evaluate safety including cognition recovery of RT administered in elderly patients undergoing upper gastrointestinal endoscopy and assess its safety dosage.

METHODS

Ninety-nine patients presenting for upper gastrointestinal endoscopy were randomized to receive 0.1 mg/kg RT (R1) or 0.2 mg/kg RT (R2), or propofol (P). Cognitive functions (memory, attention, and executive function) were measured via neuropsychological tests conducted before sedation and 5 min after recovery to full alertness. Adverse events were also assessed.

RESULTS

There were no statistical differences between postoperative and baseline results for R1 group and P group, whereas those for R2 group revealed worsened postoperative cognitive functions (immediate recall and short delay recall) than baseline (P < 0.05). Compared with P group, Scores demonstrated worse restoration of immediate recall in R1 group, immediate recall, short-delayed recall, and attention function in R2 group (P < 0.05). Patients in R2 group had a longer sedation time (12.09 vs 8.27 vs 8.21 min; P < 0.001) and recovery time (6.85 vs 3.82 vs 4.33 min; P < 0.001) than that in R1 group and P group. Moreover, the incidence of hypotension was 3.0% in R1 group, whereas it was 21.2% in R2 group and 48.5% in P group (P < 0.05).

CONCLUSION

The addition of 0.1 mg/kg RT as an adjunct to opiate sedation for upper gastrointestinal endoscopy not only achieves more stable perioperative hemodynamics but also achieves acceptable neuropsychiatric functions in elderly patients.

Remimazolam: pharmacological characteristics and clinical applications in anesthesiology

A novel ultra-short-acting benzodiazepine (BDZ), remimazolam (CNS 7056), has been designed by ‘soft drug’ development to achieve a better sedative profile than that of the current drugs. Notably, the esterase linkage in remimazolam permits rapid hydrolysis to inactivate metabolites by non-specific tissue esterase and induces a unique and favorable pharmacological profile, including rapid onset and offset of sedation and a predictable duration of action. Similar to other BDZs, its sedative effects can be reversed using flumazenil, a BDZ antagonist. The pharmacokinetics and pharmacodynamics of remimazolam are characterized by relatively high clearance, small steady-state volume of distribution, short elimination half-life, short context-sensitive half-life, and fast onset and recovery, indicating rapid elimination, minimal tissue accumulation, and good control. In addition, remimazolam possesses a superior safety profile, including low liability for cardiorespiratory depression and injection pain, making it a preferred hypnotic agent in various clinical settings. Early clinical investigations suggest that remimazolam is well tolerated and effective for procedural sedation and for induction and maintenance of general anesthesia. To date, however, the clinical use of remimazolam has been confined to a few volunteer studies and a limited number of clinical investigations. Therefore, further studies regarding its recovery issues or postoperative complications, characteristics of electroencephalogram changes, and cost-benefit analyses are required to facilitate its widespread use.

Neurological sedative indicators during general anesthesia with remimazolam

BACKGROUND

The bispectral index (BIS) value during general anesthesia with the newly developed anesthetic remimazolam is reported to be relatively high; however, the reason for this and the appropriate indicator for assessing the sedation level during remimazolam anesthesia have not been determined. In this study, the level of sedation during general anesthesia with remimazolam was evaluated using several different indicators.

METHODS

Thirty patients who underwent breast surgery under general anesthesia with remimazolam were included. BIS®, Sedline® and the pupil resting diameters were measured simultaneously. The intraoperative dose of remimazolam was adjusted to obtain a BIS in the range of 40-60; if a BIS < 60 could not be achieved, the intraoperative dose was increased up to the maximal dose of 2 mg/kg/h.

RESULTS

The mean intraoperative BIS and patient state index (PSI) in all patients was 50.6 ± 9.1 and 43.0 ± 11.8, respectively. Five patients showed a mean intraoperative BIS > 60 and eight patients showed mean intraoperative PSI > 50. The mean intraoperative spectral edge frequency (SEF) of BIS® or Sedline® was 15.3 ± 2.5 Hz or 10.6 ± 3.0 Hz, each. The mean intraoperative resting pupil diameter was 1.7 ± 0.2 mm. There were no patients with awareness during anesthesia.

CONCLUSIONS

Processed electroencephalograms (BIS and PSI), and SEF of BIS® were relatively high during anesthesia with remimazolam, but SEF of Sedline® or pupillary diameter could be a supportive indicator to confirm sedation level during remimazolam anesthesia.

Efficacy of Pre-Treatment with Remimazolam on Prevention of Propofol-Induced Injection Pain in Patients Undergoing Abortion or Curettage: A Prospective, Double-Blinded, Randomized and Placebo-Controlled Clinical Trial

Background

Propofol-induced injection pain (PIP) is a well-known problem in general anesthesia. We hypothesized that pre-treatment with remimazolam prevents PIP in patients undergoing abortion or curettage.

Materials and Methods

In this prospective, single-center, double-blinded, randomized, placebo-controlled clinical trial, adult patients aged 18 to 60 undergoing abortion or curettage were randomly assigned to three groups. Group Lido received system lidocaine (a bolus of 0.5 mg kg⁻¹, iv). Group Remi received remimazolam (a bolus of 0.1 mg kg⁻¹, iv). Group NS received identical volumes of 0.9% normal saline. Sixty seconds after the injection of lidocaine, remimazolam or saline, patients were injected with propofol at a rate of 12 mL/min until the loss of consciousness. The primary outcome was the incidence of PIP at the time of induction using 4-point scale. Secondary outcomes included propofol-induced injection pain, vital signs, the characteristics of anesthesia and surgery, and adverse events.

Results

The incidence of patients with PIP was higher in group NS than that in group Lido and group Remi (75.7, 44.3, and 42.9%, respectively, p < 0.001). The percentages of patients with moderate PIP were higher in group NS than that in group Lido and group Remi (20.0, 2.9, and 1.4%, respectively, p < 0.001). Moreover, the consumption of propofol and the incidence of adverse event (hypoxemia and chin lifting) in group Remi were lower than that in group NS and Lido, and less patients got physical movement and cough in group Remi. The recovery time in group NS was longer than that in group Lido and Remi.

Conclusion

Our findings indicate that pre-treatment with remimazolam reduced the incidence and intensity of PIP in abortion or curettage patients, equivalent to that of lidocaine without severe adverse effects.

Trial Registration

Chinese Clinical Trial Registry (identifier: ChiCTR2100041805).

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.

Safety and efficacy of remimazolam compared with propofol in induction of general anesthesia

BACKGROUND

Remimazolam is a new ultra-short acting benzodiazepine anesthetic which has predictable sedative duration and rapid recovery in gastrointestinal endoscopy. Propofol is a commonly used intravenous anesthetic in clinical work which also has rapid action, short action time and rapid recovery. To date, there have been relatively few articles comparing the two for general anesthesia induction. So we conducted a randomized trial to evaluate whether remimazolam is superior to propofol during anesthesia induction in terms of the efficacy and safety.

METHODS

One hundred and eighty nine ASA I or II patients scheduled for elective surgery were divided into four groups: remimazolam 0.2mg/kg (group R1), 0.3mg/kg(group R2), 0.4mg/kg(group R3), and propofol group(group P). All patients were anesthetized with single shot of experimental drugs during induction period. Efficacy was measured by completing the induction of anesthesia without rescue sedation and safety was defined as no severe adverse events.

RESULTS

Success induction rates in remimazolam groups were 89%(group R1), 94%(group R2) and 100%(group R3) while success induction rate in group P was 100%. Hypotension rates during induction were lower in R1 group (13%) and R2 group (24%) compared with group P (44%). Hypotension rate in R3 group (34%) was similar to propofol (44%). Injection site pain in group P was 27% while no pain was observed in remimazolam groups.

CONCLUSIONS

Remimazolam is a safe and effective sedative drug during induction with less adverse effects for general anesthesia in ASA I or II patients.

Current status of perioperative hypnotics, role of benzodiazepines, and the case for remimazolam: a narrative review

Anaesthesiologists and non-anaesthesiologist sedationists have a limited set of available i.v. hypnotics, further reduced by the withdrawal of thiopental in the USA and its near disappearance in Europe. Meanwhile, demand for sedation increases and new clinical groups are using what traditionally are anaesthesiologists' drugs. Improved understanding of the determinants of perioperative morbidity and mortality has spotlighted hypotension as a potent cause of patient harm, and practice must be adjusted to respect this. High-dose propofol sedation may be harmful, and a critical reappraisal of drug choices and doses is needed. The development of remimazolam, initially for procedural sedation, allows reconsideration of benzodiazepines as the hypnotic component of a general anaesthetic even if their characterisation as i.v. anaesthetics is questionable. Early data suggest that a combination of remimazolam and remifentanil can induce and maintain anaesthesia. Further work is needed to define use cases for this technique and to determine the impact on patient outcomes.

A population pharmacodynamic Markov mixed-effects model for determining remimazolam-induced sedation when co-administered with fentanyl in procedural sedation

The clinical effects of remimazolam (an investigational, ultra‐short acting benzodiazepine being studied in procedural sedation) were measured using the Modified Observer’s Assessment of Awareness/Sedation Scale (MOAA/S). The objective of this analysis was to develop a population pharmacokinetic/pharmacodynamic model to describe remimazolam‐induced sedation with fentanyl over time in procedural sedation. MOAA/S from 10 clinical phase I–III trials were pooled for analysis, where data were collected after administration of placebo or remimazolam with or without concomitant fentanyl. A Markov model described transition states for 35,356 MOAA/S‐time observations from 1071 subjects. Effect‐compartment models of remimazolam and fentanyl linked plasma concentrations to the Markov model, and drug effects were described using a synergistic maximum effect (E_max) model. Simulations were performed to identify the optimal remimazolam‐fentanyl combination doses in procedural sedation. Fentanyl showed synergistic effects with remimazolam in sedation. Increasing age was related to longer recovery from sedation. Patients with body mass index greater than 25 kg/m² had ~30% higher rates of distribution from plasma to the effect site (keo), indicating a slightly faster onset of sedation. Simulations showed that remimazolam 5 mg was more appropriate than 4 or 6 mg when administered with fentanyl 50 μg. The model and simulations support that a combination of remimazolam 5 mg with fentanyl 50 μg is an appropriate dosing regimen and the dose of remimazolam does not need to be changed in elderly patients, but some elderly patients may have a longer duration of sedation.