Time to Loss of Consciousness With Remimazolam Versus Propofol for Anesthetic Induction in Laparoscopic Cholecystectomy (REMIPROP-LOC)

Time to Loss of Consciousness With Remimazolam Versus Propofol During Anesthetic Induction for Laparoscopic Cholecystectomy: A Single-Center Randomized Controlled Trial

The goal of this clinical trial is to compare two medicines used to induce general anesthesia in adults undergoing elective laparoscopic cholecystectomy. The study aims to determine whether remimazolam leads to a different time to loss of consciousness than propofol.

The main question it aims to answer is: Does remimazolam change the time to loss of consciousness compared with propofol during anesthesia induction?

Researchers will compare remimazolam with propofol to evaluate the time required for participants to lose consciousness. The study will also compare blood pressure, heart rate, and other safety outcomes during anesthesia induction.

Participants will:

• Be randomly assigned to receive either remimazolam or propofol for anesthesia induction.
• Receive standard monitoring and anesthesia care throughout surgery.
• Have their time to loss of consciousness, vital signs, and any adverse events recorded during the induction period.

Study Overview

• Status: Not yet recruiting
• Conditions: Cholelithiasis; Intravenous Anesthesia
• Intervention / Treatment: Drug: Remimazolam; Drug: Propofol

Detailed Description

General anesthesia can be induced with several intravenous hypnotic agents. Propofol remains a standard choice due to its rapid onset and predictable clinical effect; however, it is frequently associated with dose-dependent cardiovascular depression. Remimazolam, an ultra-short-acting benzodiazepine, represents an alternative with a distinct metabolic pathway via tissue esterases, potentially offering greater hemodynamic stability. Nonetheless, current literature comparing induction kinetics between these two pharmacological strategies exhibits high heterogeneity, often driven by variations in drug delivery methods and mixed surgical profiles.

To improve the internal validity of these clinical comparisons, this protocol restricts the evaluation to a single, specific surgical model. Narrowing the clinical environment to a uniform surgical procedure eliminates major confounding variables-such as widely divergent operational durations, patient positioning dynamics, unexpected blood loss, and varying baseline nociceptive stimuli-which typically complicate broader, multi-procedural anesthesia trials.

Furthermore, because the physical characteristics of the study medications preclude complete investigator masking during drug administration, specific operational safeguards are built into the clinical workflow. Anesthesia delivery during the induction phase relies entirely on pre-specified, automated delivery algorithms (comparing a fixed-rate continuous infusion against a pharmacokinetic target-controlled model) rather than subjective, clinician-guided titration. Utilizing fixed algorithmic delivery protocols prevents clinical preferences from influencing drug administration, thereby controlling for potential execution bias.

Following the induction phase, physiological tracking and depth-of-anesthesia monitoring are managed through objective, automated indices to ensure that post-induction adjustments remain standardized across both evaluation groups. This structured approach ensures that the resulting clinical observations reflect the distinct pharmacological and pharmacokinetic profiles of the selected hypnotic strategies rather than confounding clinical management choices.

• Study Type: Interventional
• Enrollment (Estimated): 66
• Phase: Phase 4

Contacts and Locations

• Study Contact: Name: Gabriel M Figueiredo Mascarenhas, MD; Phone Number: +5571987894554; Email: gabrielfigueiredomascarenhas@gmail.com

Study Locations

• Brazil
  • Sergipe
    • Aracaju, Sergipe, Brazil
      • Hospital Univeritário da Universidade Federal de Sergipe
      • Contact: Grace D Anne Azevedo Doria, BPharm, MSc, PhD; Phone Number: +55 (79) 2105-1782; Email: setgpi.huse@hubrasil.gov.br

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients aged 18 years or older.
• American Society of Anesthesiologists (ASA) physical status I or II.
• Scheduled to undergo elective laparoscopic cholecystectomy under Total Intravenous Anesthesia (TIVA).

Exclusion Criteria:

• Patients younger than 18 years or older than 50 years
• American Society of Anesthesiologists (ASA) physical status III to V
• Body Mass Index (BMI) < 17.5 kg/m² or > 30 kg/m²
• Hemodynamically unstable patients
• Altered or impaired renal or hepatic function
• Neuromuscular disorders
• History of alcohol or drug dependence
• History of allergy or hypersensitivity to any of the anesthetic medications utilized in the protocol

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Remimazolam; Patients will receive intravenous remimazolam for both the induction and maintenance of general anesthesia. Anesthesia induction will be initiated via continuous intravenous infusion at a fixed rate of 6 mg/kg/h until loss of consciousness is achieved. Following induction, anesthesia maintenance will be transitioned to a continuous intravenous infusion of remimazolam at a baseline rate of 1 mg/kg/h, which will be titrated dynamically to maintain objective depth-of-anesthesia monitoring using a bispectral index (BIS) target value between 40 and 60 until the end of the surgical procedure.	Drug: Remimazolam; Lyophilized powder reconstituted for intravenous injection. Administered via an electronic infusion pump at a fixed continuous induction rate of 6 mg/kg/h until clinical benchmarks are achieved. Maintenance is sustained at a baseline continuous infusion rate of 1 mg/kg/h. To ensure a strictly standardized anesthetic baseline, all patients receive a uniform, weight-based co-administration of intravenous fentanyl and a neuromuscular blocking agent at induction, followed by a continuous intraoperative analgesic infusion of remifentanil via target-controlled infusion (TCI) guided by the Minto model (effect-site targeting). Maintenance remimazolam doses are precisely titrated based on real-time bispectral index (BIS) values to target a depth of anesthesia between 40 and 60.
Active Comparator: Propofol; Patients will receive intravenous propofol for both the induction and maintenance of general anesthesia. Anesthesia induction will be performed using a target-controlled infusion (TCI) model with a fixed target concentration of 4 mcg/mL until loss of consciousness is achieved. Following induction, anesthesia maintenance will be continued via propofol infusion, titrated dynamically to maintain objective depth-of-anesthesia monitoring using a bispectral index (BIS) target value between 40 and 60 until the end of the surgical procedure.	Drug: Propofol; Intravenous 1% lipid emulsion formulation of propofol. Administered via an automated target-controlled infusion (TCI) system programmed with the Marsh pharmacokinetic model. Induction is initiated at a fixed effect-site target concentration of 4 mcg/mL. To ensure a strictly standardized anesthetic baseline, all patients receive a uniform, weight-based co-administration of intravenous fentanyl and a neuromuscular blocking agent at induction, followed by a continuous intraoperative analgesic infusion of remifentanil via target-controlled infusion (TCI) guided by the Minto model (effect-site targeting). Maintenance propofol infusion rates are dynamically adjusted to maintain an objective bispectral index (BIS) within the 40-60 range.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to Loss of Consciousness (TLOC)	The duration, measured in seconds, from the exact initiation of the intravenous hypnotic agent infusion (either remimazolam or propofol) until the participant achieves clinical loss of consciousness. Loss of consciousness is strictly defined as the co-occurrence of two clinical criteria: the complete loss of response to a standardized verbal command (calling the patient's name aloud) and the absence of the eyelash/palpebral reflex (córneo-palpebral reflex), assessed continuously during the anesthesia induction phase.	From the initiation of the hypnotic agent infusion until the achievement of loss of consciousness (estimated time frame of up to 5 minutes during the anesthesia induction phase).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of Anesthesia-Induced Hypotension	Percentage of participants experiencing at least one episode of hypotension. Hypotension is operationally defined as a decrease in blood pressure of more than 20% from the participant's documented baseline value, or a mean arterial pressure (MAP) lower than 65 mmHg.	From the exact initiation of anesthetic induction until the completion of the surgical procedure (estimated up to 2 hours).
Incidence of Perioperative Adverse Events	Proportion of participants experiencing specific anesthesia-related adverse events, including bradycardia (heart rate < 50bpm), episodes of apnea within the Post-Anesthesia Care Unit (PACU), or any clinical event requiring unplanned therapeutic interventions.	From the initiation of anesthetic induction until 1 hour after arrival at the Post-Anesthesia Care Unit (PACU)
Incidence of Early Postoperative Delirium	Percentage of participants with delirium at discharge from the Post-Anesthesia Care Unit (PACU), assessed using the 4AT (4 A's Test), a validated rapid screening tool for delirium.	Within 1 hour after arrival at the Post-Anesthesia Care Unit (PACU).
Bispectral Index (BIS) Values at Key Anesthetic Milestones	Objective tracking of depth of anesthesia using bispectral index (BIS) values (measured on a scale from 0 to 100, where 100 indicates fully awake and 0 indicates flat-line EEG). Continuous values will be extracted and compared at specific clinical time points: at the initiation of induction, during laryngoscopy, and periodically throughout the intraoperative period.	From initiation of anesthetic induction through the intraoperative period (estimated up to 2 hours).
Time to Tracheal Extubation	The duration, measured in minutes, from the exact clinical cessation of the maintenance hypnotic delivery (propofol or remimazolam) and the remifentanil infusion until the safe and successful removal of the endotracheal tube.	From the cessation of anesthetic maintenance until tracheal extubation (estimated up to 20 minutes).
Incidence of Postoperative Pain Requiring Opioid Rescue	Percentage of participants experiencing acute postoperative pain that necessitates the administration of supplemental opioid rescue analgesia as part of their recovery management.	Within 1 hour after arrival at the Post-Anesthesia Care Unit (PACU).
Incidence of Postoperative Nausea and Vomiting (PONV)	Percentage of participants experiencing episodes of nausea, vomiting, or retching during the immediate recovery phase.	Within 1 hour after arrival at the Post-Anesthesia Care Unit (PACU).

Collaborators and Investigators

• Sponsor: Universidade Federal de Sergipe
• Collaborators: Cristália Produtos Químicos Farmacêuticos Ltda.
• Investigators: Principal Investigator: Fabrício A Dias Antunes, MD, MSc, PhD, Universidade Federal de Sergipe

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): June 1, 2027
• Study Completion (Estimated): June 1, 2027

Study Registration Dates

• First Submitted: July 8, 2026
• First Submitted That Met QC Criteria: July 15, 2026
• First Posted (Actual): July 21, 2026

Study Record Updates

• Last Update Posted (Actual): July 21, 2026
• Last Update Submitted That Met QC Criteria: July 15, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Propofol; General Anesthesia; Remimazolam; Intravenous Anesthesia
• Additional Relevant MeSH Terms: Digestive System Diseases; Biliary Tract Diseases; Cholelithiasis; Organic Chemicals; Hydrocarbons; Hydrocarbons, Cyclic; Hydrocarbons, Aromatic; Phenols; Benzene Derivatives; Propofol; remimazolam
• Other Study ID Numbers: 97389426.1.0000.5546

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Individual participant data (IPD) underlying the published results will be shared upon reasonable request after publication of the main findings. All shared data will be fully de-identified to protect participant privacy. Access will be granted to qualified researchers whose proposed use is methodologically sound and ethically appropriate. Data will be provided through a controlled process and only for research purposes aligned with the objectives of the study.
• IPD Sharing Time Frame: IPD and supporting documents will be available beginning 12 months after publication of the primary results and will remain available for at least 5 years thereafter.
• IPD Sharing Access Criteria: Access to de-identified IPD and supporting documents will be granted upon reasonable request to qualified researchers. Requests must include a methodologically sound proposal and a commitment to use the data only for research purposes aligned with ethical and scientific standards. Data will be shared through a controlled process after approval by the study team.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No