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

Transcutaneous Electrical Acupoint Stimulation Combined with Moderate Sedation of Remimazolam Tosilate in Gastrointestinal Endoscopy: A Prospective, Randomized, Double-Blind, Placebo-Controlled Clinical Trial

INTRODUCTION

Further clinical validation is required to determine whether transcutaneous electrical acupoint stimulation (TEAS) can replace opioids and be used in combination with remimazolam for sedation during gastrointestinal endoscopy.

METHODS

A total of 108 outpatients who underwent diagnostic gastrointestinal endoscopy were randomly divided into three groups: fentanyl plus remimazolam group (group C), TEAS plus remimazolam group (group E), and placebo-TEAS plus remimazolam group (group P). The assessments of patient satisfaction, physician satisfaction, and pain scale score during the examination constituted the primary endpoints of the study. The secondary endpoints were the time of recovery, recovery of normal behavioral function and discharge, incidence of adverse reactions, and dose of remimazolam.

RESULTS

Compared with group C, group E had a greater median score for patient satisfaction at follow-up and a slightly lower median score for physician satisfaction. The pain score of group E was slightly greater than that of group C, but the difference was not significant. However, in group C, the incidence of hypoxemia, the rate of nausea and the severity of vertigo were greater, and the number of patients discharged and resuming normal behavioral function was greater than those in the other two groups. The dose of remimazolam in group C and group E was less than that in group P.

CONCLUSIONS

TEAS combined with moderate sedation of remimazolam can provide an ideal sedative effect, which preferably suppresses discomfort caused by gastrointestinal endoscopy and has fewer sedation-related complications.

TRIAL REGISTRATION

ID: NCT05485064; First registration (29/07/2022); Last registration (02/11/2022) (Clinical Trials.gov).

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

Remimazolam: A Retrospective Study of Initial Safety and Recovery Data in Diverse Procedural Sedation

PURPOSE

The new ultra-short-acting benzodiazepine, remimazolam, offers a pharmacokinetic and pharmacodynamic advantage over commonly used procedural sedation medication. This retrospective study explored the real-world utilization of remimazolam during procedural sedation to support the development of a nurse sedation protocol. The primary outcome was to identify associations between recovery time, adverse reactions, and dose-response in expanded patient populations.

METHODS

This study reviewed charts of 292 adult patients from 3 hospitals within one institution who received remimazolam during procedural sedation between June 1, 2021 and December 31, 2021. Data were analyzed using logistic and linear regression.

FINDINGS

The median time to alert in patients receiving remimazolam alone was 12 minutes (interquartile range 10, 17) and increased when additional sedation medications were utilized. Receiving additional sedative medication significantly increased the odds of hypoxia (OR 2.77, 95% CI 1.30-5.91, P = 0.008) after adjusting for body mass index (BMI), American Society of Anesthesiologists physical status (ASA-PS), and total remimazolam dose. There was a 25% increase in odds of experiencing hypoxia for every 5 kg/m2 increase in BMI (95% CI 1.01-1.54, P = 0.037).

IMPLICATIONS

Remimazolam presents as a promising option for nurse procedural sedation, offering minimal impact on hemodynamics and respirations, quick recovery, and no residual sedative effects.

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.

The safety and efficacy between remimazolam and propofol in intravenous anesthesia of endoscopy operation: a systematic review and meta-analysis

BACKGROUND

Propofol is the most widely used intravenous anesthetic in endoscopic surgery, but is associated with several adverse reactions. Public research has shown that remimazolam, a safe general anesthetic, is increasingly being used as a substitute for propofol in clinical operations. Our meta-analysis aimed to analyze whether the adverse reaction rate of remimazolam in endoscopic surgery is acceptable and whether the surgical success rate is not lower than that of propofol.

AIM

This meta-analysis examined the adverse events and efficacy of remimazolam vs. propofol during endoscopic surgery.

METHOD

MEDLINE, Embase, ClinicalTrials.gov, and Google Scholar were comprehensively searched. Seven studies comparing remimazolam and propofol were included in our meta-analysis. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and Cochrane manual were used to assess the quality of the results published in all included studies to ensure that our meta-analysis results are reliable and worthwhile.

RESULTS

Compared to propofol, the use of remimazolam reduced postoperative injection pain [relative risk (RR)=0.06, 95% confidence interval (CI): 0.03-0.12, P <0.00001], postoperative hypotension (RR=0.45, 95% CI: 0.28-0.73, P =0.001), and postoperative respiratory depression (RR=0.20, 95% CI: 0.08-0.47, P =0.0002); however, it also slightly reduced the success rate of the operation [risk difference (RD)=-0.02, 95% CI: -0.04 to -0.01, P =0.0007]. There were no significant differences in the occurrence of bradycardia symptoms after the operation (RD=-0.01, 95% CI: -0.03 to 0.01, P =0.35), recovery time after the operation [standardized mean difference (SMD)=0.68, 95% CI: -0.43 to 1.80, P =0.23] or discharge time (SMD=0.17, 95% CI: -0.58 to 0.23, P =0.41). We also performed a subgroup analysis of each corresponding outcome.

CONCLUSION

Our analysis showed that remimazolam may be a safer shock option than propofol for endoscopic surgery. However, further research is required to determine their utility.

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 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.

Sedation efficacy of different dose of remimazolam with sufentanil for nerve block in young and elderly patients: a randomized, controlled study

Purpose

Anxiety and pain commonly occur during nerve block, we aimed to investigate the sedation efficacy of different doses of remimazolam with sufentanil in young and elderly patients.

Methods

In this randomized trial, patients aged 18–85 years who underwent nerve block was enrolled. All patients received sufentanil 0.08 μg/kg for analgesia. Young patients (age < 65 years) were randomized into the control group (Group C, 0.9% saline), medium-dose remimazolam (Group M, 0.06 mg/kg) and high-dose remimazolam group (Group H, 0.08 mg/kg). Elderly patients (age ≥ 65 years) were randomized into the Group C, low-dose remimazolam group (Group L, 0.04 mg/kg) and Group M. Primary outcome was the success rate of procedure sedation. Respiratory depression and hypoxia were the interested safety outcomes.

Results

Ninety young and 114 elderly patients were enrolled, respectively. In comparison with Groups C and M, young patients in Group H had the highest success rate of procedure sedation (80.0 vs. 73.3 vs. 43.3%, P = 0.006). Elderly patients in Groups M and L had similar success rates of procedure sedation, which were significantly higher than that in Group C (78.9 vs. 78.9 vs. 50.0%, P = 0.007). In elderly patients, the incidence of respiratory depression and hypoxia tended to be higher in Group M than those in Groups L and C (both P < 0.001).

Conclusion

Remimazolam 0.08 mg/kg provided the best sedation efficacy in young patients while remimazolam 0.04 mg/kg with the trend of less respiratory adverse events was more optimal for elderly patients.

Trial registration

http://www.chictr.org.cn/showproj.aspx?proj=122016.

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.

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.

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.