Comparison of recovery profiles between total intravenous anaesthesia with propofol or remimazolam reversed with flumazenil in patients undergoing breast surgery: A randomised controlled trial

BACKGROUND

Remimazolam, a short acting benzodiazepine, is being used for general anaesthesia. The results of studies comparing recovery after propofol with that of remimazolam are inconsistent. Given that flumazenil reverses the sedative effects of remimazolam, we hypothesised that it would speed up recovery from remimazolam general anaesthesia.

OBJECTIVES

The aim of this trial was to compare the speed of recovery from general anaesthesia between propofol and remimazolam reversed with flumazenil in patients undergoing minimally invasive breast surgery.

DESIGN

Randomised, single-centre, double-blind controlled trial.

SETTING

A tertiary teaching hospital in South Korea from August 2022 to December 2022.

PATIENTS

Adult patients (≥19 years of age) about to undergo general anaesthesia for scheduled breast cancer surgery.

INTERVENTIONS

Patients were randomly allocated to either the propofol or the remimazolam/flumazenil group. The emergence process was monitored by only one anaesthesiologist.

MAIN OUTCOME MEASURES

The primary outcome was the time to eye opening to command during recovery from the general anaesthesia. Time to removal of the supraglottic airway (SGA) time to discharge, and the Riker sedation agitation scale (SAS) score (1 to 4) during emergence were compared as secondary outcomes.

RESULTS

The remimazolam group had a significantly shorter mean time to eye opening than the propofol group [127 ± 51 vs. 314 ± 140 s; mean difference 187 s (95% confidence interval (CI), 133 to 241 s; P  < 0.001]. The remimazolam group also had shorter times to SGA removal [169 ± 51 vs. 366 ± 149 s; mean difference 198 s (95% CI, 140 to 255 s); P  < 0.001] and time to discharge from the operating room [243 ± 55 vs. 449 ± 159 s; mean difference 206 s (95% CI, 145 to 267 s); P  < 0.001]. The SAS scores during emergence also differed significantly, with 1 patient in the propofol group and 25 in the remimazolam group attaining scores of 4 ( P  < 0.001).

CONCLUSION

Administration of remimazolam with flumazenil may be a promising option for patients undergoing breast cancer surgery, providing faster recovery and better SAS scores than propofol during emergence from general anaesthesia.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT05435911).

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Effects of Remimazolam Anesthesia with Two Induction Doses on Hemodynamics and Recovery Profile in Older Patients: Comparison with Propofol Anesthesia

Remimazolam has advantages such as hemodynamic stability and rapid onset. We investigated the effects of induction doses on hemodynamics and recovery profiles for remimazolam compared to propofol in older patients. Sixty-nine patients aged >65 years were randomly assigned to either the propofol anesthesia group (P group) or the remimazolam anesthesia group with an induction dose of 6 mg/kg/h (R6 group) or 12 mg/kg/h (R12 group), followed by 1 mg/kg/h. P group was anesthetized with 4 µg/mL of propofol effect-site concentration (Ce) with target-control infusion, followed by 2.5-3 µg/mL of Ce. The primary outcome was the difference between the baseline mean arterial pressure (MAP) and the lowest MAP during anesthesia (ΔMAP). ΔMAP was comparable between the P, R6, and R12 groups (43.8 ± 13.8 mmHg, 39.2 ± 14.3 mmHg, and 39.2 ± 13.5 mmHg, p = 0.443). However, the frequencies of vasoactive drug use were 54.5%, 17.4%, and 30.4% (p = 0.029), and the median doses of ephedrine 3 (0-6) mg, 0 (0-0) mg, and 0 (0-0) mg (p = 0.034), which were significantly different. This study showed remimazolam anesthesia with an induction dose of 6 mg/kg/h, rather than 12 mg/kg/h, could reduce the requirement for vasoactive drugs compared to propofol anesthesia.

Effective concentration of remifentanil for successful i-gel insertion during remimazolam induction

BACKGROUND

Remifentanil can be used as adjuvants during remimazolam induction without neuromuscular blockade. We evaluated the 95% effective concentration (EC) of remifentanil effect-site concentration (Ce) for the successful insertion of an i-gel using the biased-coin up-and-down method in adult patients during remimazolam induction.

METHODS

Forty 19-65 year-old patients scheduled to undergo surgery using i-gel were enrolled. Anesthesia was induced using remimazolam infusion (12 mg/kg/h). Simultaneously, remifentanil was infused at a predetermined Ce. After 5 min of anesthesia induction, the i-gel was inserted. The 95% EC (EC95) of remifentanil in each patient was determined using a biased-coin up-and-down method based on a successful insertion in a preceding patient. The step size of remifentanil Ce was 0.4 ng/ml. If the insertion failed, remifentanil Ce was increased in the next patient. Following successful insertions, the corresponding concentration decreased in subsequent patients with a probability of 1/19 or was maintained with a probability of 18/19. The time from remimazolam infusion initiation to a bispectral index (BIS) < 60 (time to BIS60) and hemodynamic variables were measured and recorded.

RESULTS

The EC95 (95% CI) of Ce was 2.07 (1.94, 2.87) ng/ml. The overall time to BIS60 was 154.0 ± 39.9 s. No patient experienced significant hypotension or bradycardia during remimazolam induction.

CONCLUSIONS

The EC95 of remifentanil Ce was 2.07 (1.94, 2.87) ng/ml for successful i-gel insertion during remimazolam induction at 12 mg/kg/h without hemodynamic instability in adult patients. Future studies should measure remifentanil Ce in elderly patients or using remimazolam at various infusion doses.

Efficacy and safety of remimazolam tosylate for sedation during upper gastrointestinal endoscopy: study protocol for a multicenter randomized controlled trial

BACKGROUND

Gastrointestinal endoscopy has been associated with difficult experiences and can leave patients with an unpleasant impression. Propofol and midazolam are the most commonly used intravenous anesthetics for sedation during gastrointestinal endoscopy. However, cardiac and pulmonary adverse events are the primary concerns associated with the use of these sedatives. Remimazolam tosylate is an ultra-short-acting benzodiazepine drug with a mild inhibitory effect on the respiratory and circulatory systems. These properties qualify remimazolam tosylate to be used as a replacement for propofol or midazolam as a sedative during gastrointestinal endoscopy. This study aims to describe the efficacy and safety of remimazolam tosylate as a sedative for upper gastrointestinal endoscopy.

METHODS

A multicenter, randomized, single-blind, parallel-controlled, noninferiority clinical study will be conducted to evaluate the efficacy and safety of remimazolam tosylate as a sedative during upper gastrointestinal endoscopy. Participants (n = 1800) will be randomized to receive remimazolam tosylate at 0.15 mg/kg (experimental group 1), remimazolam tosylate at 0.2 mg/kg (experimental group 2), or propofol at 1.5 mg/kg (control group). Procedure success will be assessed and defined as the completion of upper gastrointestinal endoscopy without the administration of a rescue sedative agent or more than two top-up doses of the trial drug in any 5-min period after initial administration. Sedation quality will be evaluated using the Modified Observer's Assessment of Alertness/Sedation score. Adverse events will be recorded to evaluate safety.

DISCUSSION

This study will determine the optimal dosage of remimazolam tosylate during upper gastrointestinal endoscopy and will describe its efficacy and safety. These findings may contribute to a more comfortable and safer experience for patients compared with that when the conventional sedative propofol is used.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04727034. Registered on February 18, 2021.

Novel anesthetics in pediatric practice: is it time?

PURPOSE OF REVIEW

Steadily mounting evidence of anesthesia-induced developmental neurotoxicity has been a challenge in pediatric anesthesiology. Considering that presently used anesthetics have, in different animal models, been shown to cause lasting behavioral impairments when administered at the peak of brain development, the nagging question, 'Is it time for the development of a new anesthetic' must be pondered.

RECENT FINDINGS

The emerging 'soft analogs' of intravenous anesthetics aim to overcome the shortcomings of currently available clinical drugs. Remimazolam, a novel ester-analog of midazolam, is a well tolerated intravenous drug with beneficial pharmacological properties. Two novel etomidate analogs currently in development are causing less adrenocortical suppression while maintaining equally favorable hemodynamic stability and rapid metabolism. Quaternary lidocaine derivatives are explored as more potent and longer lasting alternatives to currently available local anesthetics. Xenon, a noble gas with anesthetic properties, is being considered as an anesthetic-sparing adjuvant in pediatric population. Finally, alphaxalone is being reevaluated in a new drug formulation because of its favorable pharmacological properties.

SUMMARY

Although a number of exciting anesthetic drugs are under development, there is currently no clear evidence to suggest their lack of neurotoxic properties in young brain. Well designed preclinical studies are needed to evaluate their neurotoxic potential.

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.

Induction and maintenance of procedural sedation in adults: focus on remimazolam injection

Introduction: Procedural sedation (PS) is a humane way to help patients get through painful medical procedures by the administration of sedative drugs combined with analgesics. However, each of the currently used medications has certain shortcomings, urging the search for a new drug. Remimazolam, a novel benzodiazepine, is an ultra-short-acting hypnotic agent invented out of the 'soft drug' development.Areas covered: This presented review provides an overview of the drugs used in clinical practice for the induction and maintenance of procedural sedation in adults, focusing on the newly investigated benzodiazepine remimazolam. Literature search was conducted using the MEDLINE and ClinicalTrial.gov databases from January 2007 to December 2020.Expert opinion: Based on the reported clinical trials so far, remimazolam has demonstrated its effectiveness and safety with promising properties including rapid onset, short duration of action, predictable and consistent recovery profile, metabolism almost unaffected by liver or renal function, with non or minimal cardiorespiratory depression, and availability with a reversal drug. With marketing approval received recently, remimazolam is expected to have a place in the practice for procedural sedation in the near future if its efficacy and safety are further confirmed by more clinical trials and post-market analyses.

JM-1232(-) and propofol, a new combination of hypnotics with short-acting and non-cumulative preferable properties

Drug interactions are significant in anesthesiology because drug combinations can potentially possess novel properties. The pharmacological advantages of a new combination of the benzodiazepine receptor agonist JM-1232(-) and propofol were investigated in mice. Male adult mice were administered JM-1232(-) or propofol or combinations of the two drugs intravenously. Loss of the righting reflex was evaluated as achieving hypnosis, and the time until recovery of the reflex was measured as hypnosis time. After determining the ED50, doses double and triple the ED50 of propofol were injected with JM-1232(-) to compare hypnosis time. The injections were repeated four times, and the hypnosis times were compared. Flumazenil was administered separately immediately after the last dose was injected. The ED50 values ([95% confidence interval]) for hypnosis were 3.76 [3.36-4.10] for JM-1232(-) and 9.88 [8.03-11.58] mg kg-1 for propofol. Co-administration of 0.5 and 1 mg kg-1 JM-1232(-) reduced the ED50 values of propofol to 1.76 [1.21-2.51] and 1.00 [0.46-1.86] mg kg-1, respectively. The drug combination for hypnosis produced a supra-additive interaction. Hypnosis time was significantly shorter in the groups given the mixtures compared to each hypnotic administered alone. After repeated injections, hypnosis time with the mixtures showed smaller prolongation than that with the hypnotic alone. Flumazenil completely restored the recovery time after anesthesia. The combination of JM-1232(-) and propofol showed a supra-additive interaction, and the reduced hypnotic dose contributed to a faster recovery even after multiple injections.

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

BACKGROUND

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

METHODS

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

RESULTS

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

ETHICS AND DISSEMINATION

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

PROTOCOL REGISTRATION NUMBER

CRD42020170745.

Volatiles or TIVA: Which is the standard of care for pediatric airway procedures? A pro-con discussion

Anesthesia for pediatric airway procedures constitutes a true art form that requires training and experience. Communication between anesthetist and surgeon to establish procedure goals is essential in determining the most appropriate anesthetic management. But does the mode of anesthesia have an impact? Traditionally, inhalational anesthesia was the most common anesthesia technique used during airway surgery. Introduction of agents used for total intravenous anesthesia (TIVA) such as propofol, short-acting opioids, midazolam, and dexmedetomidine has driven change in practice. Ongoing debates abound as to the advantages and disadvantages of volatile-based anesthesia versus TIVA. This pro-con discussion examines both volatiles and TIVA, from the perspective of effectiveness, safety, cost, and environmental impact, in an endeavor to justify which technique is the best specifically for pediatric airway procedures.

Society of Anesthesia and Sleep Medicine Guideline on Intraoperative Management of Adult Patients With Obstructive Sleep Apnea

The purpose of the Society of Anesthesia and Sleep Medicine Guideline on Intraoperative Management of Adult Patients With Obstructive Sleep Apnea (OSA) is to present recommendations based on current scientific evidence. This guideline seeks to address questions regarding the intraoperative care of patients with OSA, including airway management, anesthetic drug and agent effects, and choice of anesthesia type. Given the paucity of high-quality studies with regard to study design and execution in this perioperative field, recommendations were to a large part developed by subject-matter experts through consensus processes, taking into account the current scientific knowledge base and quality of evidence. This guideline may not be suitable for all clinical settings and patients and is not intended to define standards of care or absolute requirements for patient care; thus, assessment of appropriateness should be made on an individualized basis. Adherence to this guideline cannot guarantee successful outcomes, but recommendations should rather aid health care professionals and institutions to formulate plans and develop protocols for the improvement of the perioperative care of patients with OSA, considering patient-related factors, interventions, and resource availability. Given the groundwork of a comprehensive systematic literature review, these recommendations reflect the current state of knowledge and its interpretation by a group of experts at the time of publication. While periodic reevaluations of literature are needed, novel scientific evidence between updates should be taken into account. Deviations in practice from the guideline may be justifiable and should not be interpreted as a basis for claims of negligence.

Metabolism of remimazolam in primary human hepatocytes during continuous long-term infusion in a 3-D bioreactor system

Background

Remimazolam is an ultra-short acting benzodiazepine under development for procedural sedation and general anesthesia. It is hydrolyzed by CES1 to an inactive metabolite (CNS7054).

Purpose

In this study, the effect of continuous remimazolam exposure on its metabolism and on CES1 expression was investigated in a dynamic 3-D bioreactor culture model inoculated with primary human hepatocytes.

Methods

Remimazolam was continuously infused into bioreactors for 5 days at a final concentration of 3,000 ng/ml (6.8 µM). In parallel, 2-D cultures were run with cells from the same donors, but with discontinuous exposure to remimazolam.

Results

Daily measurement of clinical chemistry parameters (glucose, lactate, urea, ammonia, and liver enzymes) in culture supernatants indicated no noxious effect of remimazolam on hepatocyte integrity as compared to untreated controls. Concentrations of remimazolam reached steady-state values of around 250 ng/ml within 8 hours in 3-D bioreactors whereas in 2-D cultures remimazolam concentrations declined to almost zero within the same time frame. Levels of CNS7054 showed an inverse time-course reaching average values of 1,350 ng/ml in perfused 3-D bioreactors resp. 2,800 ng/ml in static 2-D cultures. Analysis of mRNA expression levels of CES1 indicated no changes in gene expression over the culture period.

Conclusion

The results indicated a stable metabolism of remimazolam during 5 days of continuous exposure to clinically relevant concentrations of the drug. Moreover, there was no evidence for a harmful effect of remimazolam exposure on the integrity and metabolic activity of in vitro cultivated primary human hepatocytes.

A new method for determining levels of sedation in dogs: A pilot study with propofol and a novel neuroactive steroid anesthetic

BACKGROUND

Different levels of consciousness are required in order to perform different medical procedures. Sedation scales established to objectively define various levels of sedation in humans have not been thoroughly characterized in non-human species. Postural changes in rats or dogs are useful as gross measures of sedation but are inadequate for quantitative assessment since graded levels of sedation are difficult to delineate and obscured by movement abnormalities.

NEW METHOD

A new canine sedation scoring (CSS) method was developed based on the modified observer's assessment of alertness and sedation score (MOAA/S) used in humans. The method employed a combination of physical, auditory and somatosensory stimuli of increasing intensity. Cardiovascular, respiratory, and a neurophysiological measure of sedation (bispectral index: BIS) data were recorded. Validation studies were performed following intravenous loading and constant rate infusion of propofol or a novel synthetic neuroactive steroid (SGE-746).

RESULTS

Four levels of consciousness were identified: 1) Awake, 2) Moderate Sedation (MS), 3) Deep Sedation (DS) and 4) General Anesthesia (GA). Cardiorespiratory measurements obtained after bolus administration of propofol and SGE-746 and at the end of each CRI remained within normal limits. Canine sedation scores correlated with BIS for SGE-746. SGE-746 exhibited a more gradual exposure-response relationship than propofol. Larger increases in the plasma concentration from awake values were required to achieve different levels of sedation with SGE-746 compared to propofol.

COMPARISON WITH EXISTING METHODS

No other canine sedation scoring methods are widely accepted.

CONCLUSION

A CSS method, based on the human MOAA/S scale defined four levels of consciousness in dogs and provided better resolution of sedation depth than BIS alone.

A Phase 1, Single-center, Double-blind, Placebo-controlled Study in Healthy Subjects to Assess the Safety, Tolerability, Clinical Effects, and Pharmacokinetics–Pharmacodynamics of Intravenous Cyclopropyl-methoxycarbonylmetomidate (ABP-700) after a Single Ascending Bolus Dose

Background

Cyclopropyl-methoxycarbonylmetomidate (ABP-700) is a new “soft” etomidate analog. The primary objectives of this first-in-human study were to describe the safety and efficacy of ABP-700 and to determine its maximum tolerated dose. Secondary objectives were to characterize the pharmacokinetics of ABP-700 and its primary metabolite (cyclopropyl-methoxycarbonyl acid), to assess the clinical effects of ABP-700, and to investigate the dose–response and pharmacokinetic/pharmacodynamic relationships.

Methods

Sixty subjects were divided into 10 cohorts and received an increasing, single bolus of either ABP-700 or placebo. Safety was assessed by clinical laboratory evaluations, infusion-site reactions, continuous monitoring of vital signs, physical examination, adverse event monitoring, and adrenocorticotropic hormone stimulation testing. Clinical effects were assessed with modified observer’s assessment of alertness/sedation and Bispectral Index monitoring. Pharmacokinetic parameters were calculated.

Results

Stopping criteria were met at 1.00 mg/kg dose. No serious adverse events were reported. Adverse events were dose-dependent and comprised involuntary muscle movement, tachycardia, and ventilatory effects. Adrenocorticotropic hormone stimulation evoked a physiologic cortisol response in all subjects, no different from placebo. Pharmacokinetics were dose-proportional. A three-compartment pharmacokinetic model described the data well. A rapid onset of anesthesia/sedation after bolus administration and also a rapid recovery were observed. A quantitative concentration–effect relationship was described for the modified observer’s assessment of alertness/sedation and Bispectral Index.

Conclusions

This first-in-human study of ABP-700 shows that ABP-700 was safe and well tolerated after single-bolus injections up to 1.00 mg/kg. Bolus doses of 0.25 and 0.35 mg/kg were found to provide the most beneficial clinical effect versus side-effect profile.

New Hypnotic Drug Development and Pharmacologic Considerations for Clinical Anesthesia

Since the public demonstration of ether as a novel, viable anesthetic for surgery in 1846, the field of anesthesia has continually sought the ideal anesthetic-rapid onset, potent sedation-hypnosis with a high therapeutic ratio of toxic dose to minimally effective dose, predictable clearance to inactive metabolites, and minimal side effects. This article aims to review current progress of novel induction agent development and provide an update on the most promising drugs poised to enter clinical practice. In addition, the authors describe trends in novel agent development, implications for health care costs, and implications for perioperative care.

Novel propofol derivatives and implications for anesthesia practice

Propofol (2,6-diisopropylphenol) is the most commonly used intravenous agent for induction of anesthesia. It is also used for maintenance of anesthesia and sedation in both Intensive Care Units and outpatient procedural settings. Its success in the clinical setting has been a result of its rapid onset, short duration of action, and minimal side effects despite disadvantages associated with its oil emulsion formulation. Early attempts to alter the standard emulsion or to develop new formulations with cyclodextrins and micelles to resolve issues with pain upon injection, the need for antimicrobial agents, and possible hyperlipidemia have mostly failed. With these challenges in the foreground, attention has now shifted to the use of more prodrugs and exogenous alternatives, the success of which is yet to be determined. These new agents must offer significant clinical advantages over the well-entrenched, generic propofol oil emulsion to justify higher costs and to be well received in the increasingly cost-conscious healthcare marketplace.

The role of etomidate as an anaesthetic induction agent for critically ill patients

Etomidate is an anaesthetic induction agent which may be favoured in critically ill patients because of its cardiovascular stability. However, etomidate causes adrenocortical suppression which may be particularly harmful in these patients. This article reviews current evidence and debates the use of etomidate in critical illness.

Comparative evaluation of propofol in nanoemulsion with solutol and soy lecithin for general anesthesia

INTRODUCTION

The vehicle for propofol in 1 and 2% solutions is soybean oil emulsion 10%, which may cause pain on injection, instability of the solution and bacterial contamination. Formulations have been proposed aiming to change the vehicle and reduce these adverse reactions.

OBJECTIVES

To compare the incidence of pain caused by the injection of propofol, with a hypothesis of reduction associated with nanoemulsion and the occurrence of local and systemic adverse effects with both formulations.

METHOD

After approval by the CEP, patients undergoing gynecological procedures were included in this prospective study: control (n=25) and nanoemulsion (n=25) groups. Heart rate, noninvasive blood pressure and peripheral oxygen saturation were monitored. Demographics and physical condition were analyzed; surgical time and total volume used of propofol; local or systemic adverse effects; changes in variables monitored. A value of p<0.05 was considered significant.

RESULTS

There was no difference between groups regarding demographic data, surgical times, total volume of propofol used, arm withdrawal, pain during injection and variables monitored. There was a statistically significant difference in pain intensity at the time of induction of anesthesia, with less pain intensity in the nanoemulsion group.

CONCLUSIONS

Both lipid and nanoemulsion formulations of propofol elicited pain on intravenous injection; however, the nanoemulsion solution elicited a less intense pain. Lipid and nanoemulsion propofol formulations showed neither hemodynamic changes nor adverse effects of clinical relevance.

Adult and pediatric anesthesia/sedation for gastrointestinal procedures outside of the operating room

PURPOSE OF REVIEW

This review presents current trends of safe and efficient anesthesia and sedation for adults and children for gastrointestinal procedures outside of the operating room with a special focus on total intravenous anesthesia (TIVA), target-controlled infusion (TCI), intravenous or topical lidocaine, and the use of the video laryngoscope.

RECENT FINDINGS

The concepts of a well tolerated and adequate anesthesia or sedation for gastrointestinal procedures outside of the operating room have to meet the needs of the adult and pediatric patients and the special requests of the gastroenterologists. Anesthesia and sedation of adults for gastrointestinal procedures with TIVA or TCI and spontaneous breathing is well established. Many institutions perform anesthesia for pediatric patients undergoing gastrointestinal procedures with an inhalational agent, especially in young children and for short procedures. Unlike adults, in young children the airways frequently must be secured with a tracheal tube or laryngeal mask. Respiration may be spontaneous, assisted, or controlled. TIVA and TCI are increasingly chosen for older children and longer procedures. A local anesthetic administered intravenously or topically to the upper airways and the use of the video laryngoscope can facilitate the insertion of the endoscope.

SUMMARY

Both anesthesiologists and nonanesthesiologists have to achieve a consensus and develop quality-improvement strategies to provide safe and efficient anesthesia and sedation for gastrointestinal procedures outside of the operating room for pediatric and adult patients. Techniques using TIVA, TCI, intravenous or topical application of lidocaine, and the video laryngoscope may improve and facilitate gastrointestinal procedures for the patients, the anesthesiologists, and the gastroenterologists.

Design, Synthesis, and Biological Evaluation of Novel CNS 7056 Derivatives as Sedatives in Rats and Rabbits

A new water-soluble benzodiazepine derivative, CNS 7056 (named as remimazolam), has been undergoing many reactions in recent years to provide an intravenous agent with a predictable fast-onset, short duration of action, and rapid recovery profile. Based on the structure of CNS 7056 with proven activity, seven new CNS 7056 derivatives were designed, and their sedative activities upon mouse, rats, and rabbits were examined. Sedative activities of EL-001˜007 were screened. The results indicated that the shorter the side chain at C3 position is, the higher the sedative activity is. EL-001 was chosen as the optimal compound for studies of ED50 , LD50 , latency to LRR and the duration of LRR, and its anesthetic activity was compared with that of CNS 7056 in rats and rabbits. Studies showed that EL-001 is a potent sedative in rodent and lagomorpha, with a short duration of action. Compared with CNS 7056, EL-001 has a shorter period of induction despite a slightly longer sedative duration and recovery time.

First Human Study of the Investigational Sedative and Anesthetic Drug AZD3043: A Dose-Escalation Trial to Assess the Safety, Pharmacokinetics, and Efficacy of a 30-Minute Infusion in Healthy Male Volunteers

BACKGROUND

AZD3043 is a positive allosteric modulator of the γ-aminobutyric acid type A receptor that is rapidly metabolized to an inactive metabolite by esterases present in blood and liver. Preclinical results suggest that AZD3043 has the potential as a short-acting IV sedative/anesthetic drug with rapid and predictable recovery characteristics and a favorable safety and tolerability profile.

METHODS

Our primary objective in this phase 1, single-center, open-label study was to evaluate the safety and tolerability of AZD3043 after IV infusion and to estimate the maximal tolerated dose. Secondary objectives included the evaluation of AZD3043 pharmacokinetics, pharmacodynamics, and efficacy. Sequential ascending-dose cohorts of 5 or 6 healthy male volunteers aged 18 to 45 years received a single 30-minute IV infusion of AZD3043. Assessments included adverse events, vital signs, blood gases, laboratory values, clinical signs of sedation/anesthesia, and bispectral index.

RESULTS

Fifty-three subjects received AZD3043 in infusion rate cohorts of 1, 3, 6, 12, 18, 27, 36, 54, and 81 mg/kg/h. There were no discontinuations, and dose escalation was stopped on reaching the predefined exposure limit. Adverse events occurring in >1 subject were headache (n = 4), erythema (n = 3), chest discomfort (n = 2), nausea (n = 2), and dyspnea (n = 2). The frequency and character of adverse events appeared unrelated to dose. There were no spontaneous reports of pain on injection and no clinically relevant changes in respiratory rate or arterial blood pressure. However, heart rate increased dose-dependently at infusion rates >18 mg/kg/h. Occurrence of sedation/anesthesia corresponded with dose; the lowest applied infusion rate to induce anesthesia according to clinical signs of sedation/anesthesia at predefined time points was 12 mg/kg/h (1 of 6 subjects anesthetized), and all subjects in the 3 highest dose groups were anesthetized. The onset of anesthesia ranged from 4 minutes in the highest infusion rate group to 29 minutes in the 12-mg/kg/h infusion rate group. Return of response to oral command occurred at 3 minutes after the end of infusion in the single subject who was anesthetized in the 12-mg/kg/h group and median 25 minutes in the 81-mg/kg/h group. Involuntary movements ranging from minor twitches to extensive movements were accompanied by increased muscle tone.

CONCLUSIONS

AZD3043 was well tolerated in this first human study and seems to exhibit rapid onset and recovery, indicating potential use as a short-acting drug for anesthesia and sedation.

A Phase IIa, randomized, double-blind study of remimazolam (CNS 7056) versus midazolam for sedation in upper gastrointestinal endoscopy

BACKGROUND

This exploratory study was the first study of remimazolam in patients to assess the safety and efficacy of different single doses for procedural sedation.

METHODS

Patients scheduled to undergo a diagnostic upper gastrointestinal endoscopy were randomized to receive 1 of 3 doses of remimazolam or midazolam (25 per group) in a double-blind manner. After a single dose of study drug to achieve sedation, patients underwent gastroscopy. We assessed the success of the procedure, sedation levels, recovery from sedation, and safety.

RESULTS

A single dose of remimazolam resulted in a successful procedure in 32%, 56%, and 64% of patients in the low (0.10), middle (0.15), and high (0.20 mg/kg) dose groups compared with 44% of patients in the midazolam (0.075 mg/kg) dose group. The onset of sedation was 1.5 to 2.5 minutes in the remimazolam dose groups compared with 5 minutes for midazolam. Because this was a single administration study, sedation could be maintained for as long as necessary to complete the procedure, using rescue midazolam or propofol. Recovery from sedation was rapid for all treatment groups but was influenced by the choice of rescue medication. There were no obvious differences in the safety profiles of remimazolam and midazolam.

CONCLUSIONS

This exploratory dose-finding study showed that a single administration of remimazolam (0.10-0.20 mg/kg) was capable of inducing rapid sedation with a quick recovery profile in patients undergoing a diagnostic upper gastrointestinal endoscopy. The safety profile was favorable and appeared to be similar to that of midazolam, warranting further development of this short-acting compound.

Macroscopic and macromolecular specificity of alkylphenol anesthetics for neuronal substrates

We used a photoactive general anesthetic called meta-azi-propofol (AziPm) to test the selectivity and specificity of alkylphenol anesthetic binding in mammalian brain. Photolabeling of rat brain sections with [³H]AziPm revealed widespread but heterogeneous ligand distribution, with [³H]AziPm preferentially binding to synapse-dense areas compared to areas composed largely of cell bodies or myelin. With [³H]AziPm and propofol, we determined that alkylphenol general anesthetics bind selectively and specifically to multiple synaptic protein targets. In contrast, the alkylphenol anesthetics do not bind to specific sites on abundant phospholipids or cholesterol, although [³H]AziPm shows selectivity for photolabeling phosphatidylethanolamines. Together, our experiments suggest that alkylphenol anesthetic substrates are widespread in number and distribution, similar to those of volatile general anesthetics, and that multi-target mechanisms likely underlie their pharmacology.

Phenyl acetate derivatives, fluorine-substituted on the phenyl group, as rapid recovery hypnotic agents with reflex depression

We report the synthesis of novel, potentially hypnotic fluorine-substituted phenyl acetate derivatives. We describe the structure-activity relationship that led us to the promising derivative: ethyl 2-(4-(2-(diethylamino)-2-oxoethoxy)-5-ethoxy-2-fluorophenyl) acetate (55). The unique pharmacological features of compound 55 are its relatively high affinity for the GABAA receptor, together with a unique affinity for the NMDA receptor, different to propanidid and AZD3043. In animal models, compound 55 showed stronger hypnotic potency and longer duration of LORR than propanidid and AZD3043, but also maintained a rapid recovery time to walking and behavioral recovery. In particular, compound 55 displayed reflex depression during infusion.

Synergistic antinociceptive interactions between fospropofol and alfentanil in mice

BACKGROUND

Combination therapy, which provides the opportunity to achieve optimal analgesia with reduced side effects at lower drug doses, is a valid approach for the treatment of pain. The analgesic interaction between fospropofol and alfentanil has not been investigated till date. We sought to determine the nature of the interaction between fospropofol and alfentanil in mice models of the formalin test, hot-plate test and the tail-flick test.

METHODS

The effects of fospropofol, alfentanil and their combinations were examined in the formalin-induced paw inflammatory hyperalgesia, the hot-plate test and the tail-flick test in mice. In the three models, dose-response curves were established and their respective ED50 (50% effective dose) values were determined separately for each agent. Fixed-ratio combinations of fospropofol and alfentanil were tested for their combined antinociceptive effects, and the type of interaction was determined by the isobolographic analysis.

RESULTS

Fospropofol, alfentanil and their combination produced a dose-dependent decrease in the number of flinches during phase 1 of the formalin test. In the hot-plate test and in the tail-flick test, fospropofol, alfentanil and their combination significantly and dose dependently prolonged the latency of withdrawal. In the three models, isobolographic analysis revealed a significant synergistic interaction between fospropofol and alfentanil. The ED50 value for the drug combination was significantly lower than the theoretical additive value (p<0.05).

CONCLUSIONS

The results demonstrate that fospropofol and alfentanil provide synergistic antinociceptive interactions in the formalin, hot-plate, and tail-flick tests. The observed synergistic interaction between fospropofol and alfentanil are indicative of the effectiveness of the combination treatment in pain management and should be explored further in patients undergoing minor surgical procedures.

Total intravenous anesthesia will supercede inhalational anesthesia in pediatric anesthetic practice

Inhalational anesthesia has dominated the practice of pediatric anesthesia. However, as the introduction of agents such as propofol, short-acting opioids, midazolam, and dexmedetomidine a monumental change has occurred. With increasing use, the overwhelming advantages of total intravenous anesthesia (TIVA) have emerged and driven change in practice. These advantages, outlined in this review, will justify why TIVA will supercede inhalational anesthesia in future pediatric anesthetic practice.

An improved design of water-soluble propofol prodrugs characterized by rapid onset of action

BACKGROUND

Phosphate ester prodrugs of propofol (fospropofol, HX0969W) were designed to avoid the unsatisfactory water solubility of the parent drug. However, in previous clinical trials, there were reported prodrug side effects such as paresthesia and pruritus. The accumulation of a phosphate ester component was found to be the main culprit. To exclude this potential risk, we designed 2 amino acid propofol prodrugs (HX0969-Gly-F3, HX0969-Ala-HCl) based on the lead compound (HX0969) by introducing the amino acid group into the structures of the propofol prodrugs. We hypothesized that the improved propofol prodrugs could not only eliminate those adverse effects but also retain their rapid action and good water solubility.

METHODS

The lead compound HX0969 was synthesized by the sodium borohydride-iodine system. HX0969W, HX0969-Gly-F3, and HX0969-Ala-HCl were synthesized from HX0969. The solubility of fospropofol, HX0969W, HX0969-Gly-F3, and HX0969-Ala-HCl in normal saline was tested. The bioconversions from those prodrugs to propofol in different physiological media (rat plasma, rhesus monkey plasma, and rat hepatic microsomes) were determined in vitro. An in vivo test in the rats was performed to measure the 50% effective dose (ED50) of the 4 propofol prodrugs. Their action onset time and duration time were also measured after their equipotent doses were given.

RESULTS

(1) The water solubility of fospropofol, HX0969W, HX0969-Gly-F3, and HX0969-Ala-HCl was 461.46 ± 26.40 mg/mL, 189.45 ± 5.02 mg/mL, 49.88 ± 0.58 mg/mL, and 245.99 ± 4.83 mg/mL, respectively; (2) The hydrolysis tests in both the rat plasma and the rhesus monkey plasma revealed that the 2 amino acid prodrugs released propofol to a greater extent at a more rapid rate than the 2 phosphate prodrugs during the testing period of 5 hours. All 4 prodrugs released propofol rapidly in the presence of rat hepatic enzymes; (3) Compared with the previous prodrugs (fospropofol, HX0969W), the 2 novel compounds (HX0969-Gly-F3, HX0969-Ala-HCl) had a much shorter onset time when a much lower dose was given.

CONCLUSIONS

Application of the amino acid group to the propofol prodrug can make the prodrug have good water solubility and a more rapid onset of action. In rat plasma, the 2 improved amino acid prodrugs (HX0969-Ala-HCl, HX0969-Gly-F3) had a more rapid rate of propofol release than the 2 phosphate ester prodrugs (fospropofol, HX0969W). The in vivo tests showed that HX0969-Ala-HCl and HX0969-Gly-F3 given IV could have a more rapid onset of action in a smaller dose than fospropofol and HX0969W. This novel design can enhance the efficiency of prodrugs converting to propofol.

Synthesis and evaluation of fluorine-substituted phenyl acetate derivatives as ultra-short recovery sedative/hypnotic agents

Background

Soft drugs are molecules that are purposefully designed to be rapidly metabolized (metabolically labile). In anesthesia, the soft drug is useful because it enables precise titration to effect and rapid recovery, which might allow swift and clear-headed recovery of consciousness and early home readiness. Propofol may cause delayed awakening after prolonged infusion. Propanidid and AZD3043 have a different metabolic pathway compared to propofol, resulting in a short-acting clinical profile. Fluorine imparts a variety of properties to certain medicines, including an enhanced absorption rate and improved drug transport across the blood-brain barrier. We hypothesized that the introduction of fluorine to the frame structure of propanidid and AZD3043 would further accelerate the swift and clear-headed recovery of consciousness. To test this hypothesis, we developed a series of fluorine-containing phenyl acetate derivatives.

Methodology/Principal Findings

Fluorine-containing phenyl acetate derivatives were synthesized, and their hypnotic potencies and durations of LORR following bolus or infusion administration were determined in mice, rats and rabbits. The metabolic half-lives in the blood of various species were determined chromatographically. In vitro radioligand binding and γ-aminobutyric acid_A (GABA_A) receptor electrophysiology studies were performed. Among the 12 synthesized fluorine-containing phenyl acetate derivatives, compound 5j induced comparable duration of LORR with AZD3043, but more rapid recovery than AZD3043, propanidid and propofol. The time of compound 5j to return to walk and behavioral recovery are approximately reduced by more than 50% compared to AZD3043 in mice and rats and rabbits. The HD₅₀ of compound 5j decreased with increasing animal size.

Conclusions/Significance

The rapid recovery might make compound 5j suitable for precise titration and allow swift and clear-headed recovery of consciousness and early home readiness.

Comparison of procedural sequence in same-day consecutive bidirectional endoscopy using moderate sedation: a prospective randomized study

BACKGROUND

A sequential bidirectional endoscopy is commonly performed. However, the optimal sequence of procedures for same-day bidirectional endoscopy using moderate sedation has not been established.

GOALS

The aim of this study was to characterize the optimal sequence of endoscopies for sequential bidirectional endoscopy.

STUDY

This was a single-center, prospective, randomized study. A total of 163 patients aged 18 to 80 years, who were referred for bidirectional endoscopy for any indication, were randomized to start with upper or lower endoscopy. Initially, all patients received intravenously 50 mg of meperidine and 2.5 mg of midazolam. Patient's discomfort and satisfaction, as expressed by the amount of analgesia added to sustain conscious sedation, and the postprocedure satisfaction reported by the patients were set as primary outcomes.

RESULTS

There was no significant difference in the total dose of midazolam added, patient's pain assessment and satisfaction from the anesthesia and the procedure, duration of endoscopies, or the time to cecal intubation between the esophagogastroduodenoscopy first and colonoscopy first groups. The rate of diagnosis of significant pathologies and the rate of procedures performed during the examinations were similar in both the study groups. Evaluation of patient's postprocedural recovery did not reveal significant differences. There was no significant variance between the performing physicians regarding anesthetic dosing, duration of examination, pain scoring, and the related patient's pain postprocedural assessment.

CONCLUSIONS

There were no significant differences in the patient's discomfort and satisfaction, regardless of the procedural sequence.

Seeking structural specificity: direct modulation of pentameric ligand-gated ion channels by alcohols and general anesthetics

Alcohols and other anesthetic agents dramatically alter neurologic function in a wide range of organisms, yet their molecular sites of action remain poorly characterized. Pentameric ligand-gated ion channels, long implicated in important direct effects of alcohol and anesthetic binding, have recently been illuminated in renewed detail thanks to the determination of atomic-resolution structures of several family members from lower organisms. These structures provide valuable models for understanding and developing anesthetic agents and for allosteric modulation in general. This review surveys progress in this field from function to structure and back again, outlining early evidence for relevant modulation of pentameric ligand-gated ion channels and the development of early structural models for ion channel function and modulation. We highlight insights and challenges provided by recent crystal structures and resulting simulations, as well as opportunities for translation of these newly detailed models back to behavior and therapy.

Modifying methoxycarbonyl etomidate inter-ester spacer optimizes in vitro metabolic stability and in vivo hypnotic potency and duration of action

BACKGROUND

Methoxycarbonyl etomidate is the prototypical very rapidly metabolized etomidate analog. Initial studies suggest that it may be too short acting for many clinical uses. We hypothesized that its duration of action could be lengthened and clinical utility broadened by incorporating specific aliphatic groups into the molecule to sterically protect its ester moiety from esterase-catalyzed hydrolysis. To test this hypothesis, we developed a series of methoxycarbonyl etomidate analogs (spacer-linked etomidate esters) containing various aliphatic-protecting groups and spacer lengths.

METHODS

Spacer-linked etomidate esters were synthesized and their hypnotic potencies and durations of action following bolus administration were measured in rats using a loss-of-righting reflexes assay. Octanol:water partition coefficients and metabolic half-lives in pooled rat blood were determined chromatographically.

RESULTS

All spacer-linked etomidate esters produced hypnosis rapidly and in a dose-dependent manner. ED50s for loss of righting reflexes ranged from 0.69 ± 0.04 mg/kg for cyclopropyl-methoxycarbonyl metomidate to 11.1 ± 0.8 mg/kg for methoxycarbonyl metomidate. The slope of a plot of the duration of loss of righting reflexes versus the logarithm of the dose ranged 12-fold among spacer-linked etomidate esters, implying widely varying brain clearance rates. The in vitro metabolic half-lives of these compounds in rat blood varied by more than two orders of magnitude and were diastereometrically selective.

CONCLUSIONS

We created 13 new analogs of methoxycarbonyl etomidate and identified two that have significantly higher potency and potentially address the too-brief duration of action for methoxycarbonyl etomidate. This work may provide a blueprint for optimizing the pharmacological properties of other soft drugs.

Efficacy comparison of the novel water-soluble propofol prodrug HX0969w and fospropofol in mice and rats

BACKGROUND

HX0969w is a novel water-soluble prodrug designed to release propofol and gamma-hydroxybutyrate (GHB) and has a sedative-hypnotic effect. This study was performed to compare the efficacy of HX0969w with fospropofol in mice and rats.

METHODS

We performed hydrolysis studies in the plasma from mice and rats. The half-maximal effective doses (ED50) and half-maximal lethal doses (LD50) of fospropofol and HX0969w were determined. A pharmacodynamics comparison of these two compounds was also performed. Time to loss of righting reflex, time to return of righting reflex, recovery time, and adverse effects were recorded.

RESULTS

The hydrolysis studies demonstrated that HX0969w released propofol as expected. HX0969w ED50 values in mice and rats were 133.03 and 53.79 mg kg(-1), respectively, and LD50 values were 607.11 and 283.79 mg kg(-1), respectively. The calculated therapeutic index (TI), safety index (SI), and certain safety factor (CSF) of HX0969w were 4.56, 3.33, and 2.92 for mice, and 5.28, 3.94, and 3.49 for rats, respectively. The pharmacodynamic comparison studies suggest that HX0969w has a longer onset time and shorter duration than fospropofol.

CONCLUSIONS

Similar to fospropofol, HX0969w is an effective, water-soluble prodrug that is capable of inducing a sedative-hypnotic effect in mice and rats. Unlike fospropofol, HX0969w releases GHB instead of formaldehyde. Further studies regarding the efficacy and safety of HX0969w are necessary.

Critical parameters in drug delivery by intravenous infusion

INTRODUCTION

Intravenous infusion is commonly used to deliver medications and fluids to patients. The duration of an infusion is short (hours) in the operating room where intravenous agents are infused to anesthetize patients and to manage circulation. Critically ill patients often receive infusions for days. Infusion technology has become increasingly sophisticated and complex. The technical advances broaden the clinical application of intravenous infusion methodology and provide safety features.

AREAS COVERED

This article provides an historical overview of intravenous infusion and discusses components of infusion systems. A section describes configuration of components to meet clinical needs. The article describes physical properties of infusion systems, emphasizing how critical parameters of resistance to flow, infusion pump performance and interactions between fluid flows and the dead volume influence medication and fluid delivery. The authors emphasize the use of infusions in the intensive care and operating room environments, although the general principles apply to other clinical settings.

EXPERT OPINION

Intravenous infusion systems contribute significantly to clinical care, but in a deceptively simple way. Several critical parameters combine to influence the performance of an infusion system, with a number of pitfalls potentially confounding utility of the technology. Safe and effective clinical application of intravenous infusion technology depends on an appreciation of this complexity which impacts the performance of infusion systems.

Anesthetic drug development: Novel drugs and new approaches

The ideal sedative–hypnotic drug would be a rapidly titratable intravenous agent with a high therapeutic index and minimal side effects. The current efforts to develop such agents are primarily focused on modifying the structures of existing drugs to improve their pharmacodynamic and pharmacokinetic properties. Drugs currently under development using this rational design approach include analogues of midazolam, propofol, and etomidate, such as remimazolam, PF0713, and cyclopropyl methoxycarbonyl-etomidate (MOC-etomidate), respectively. An alternative approach involves the rapid screening of large libraries of molecules for activity in structural or phenotypic assays that approximate anesthetic and target receptor interactions. Such high-throughput screening offers the potential for identifying completely novel classes of drugs. Anesthetic drug development is experiencing a resurgence of interest because there are new demands on our clinical practice that can be met, at least in part, with better agents. The goal of this review is to provide the reader with a glimpse of the novel anesthetic drugs and new developmental approaches that lie on the horizon.

A comparative study of non-lipid nanoemulsion of propofol with solutol and propofol emulsion with lecithin

BACKGROUND AND OBJECTIVES

Some formulations have been proposed to reduce the adverse reactions due to the lipid emulsion containing soybean oil used as propofol carrier. This study for endoscopy sedation was aimed at evaluating and comparing the safety, effectiveness and adverse effects of the use of propofol nanoemulsion compared to propofol currently commercialized.

METHOD

In this prospective study, 150 patients were submitted to upper digestive endoscopy. These patients were allocated into two groups: the control group (CONT Group; n=75) and the nanoemulsion group (NE Group; n=75). HR, SBP, DBP, SpO(2) and BIS (which is considered to be appropriate between 65 and 75 during procedure) were monitored. Gender, age, weight, height, BMI, ASA physical status, times and doses were analyzed, as well as adverse effects (phlogistic signs and pain on injection, apnea, nausea/vomiting) and alterations in monitoring variables. A p-value < 0.05 was considered significant.

RESULTS

The groups had similar results concerning anthropometric data and physical status. None of the patients developed apnea or presented phlogistic signs in the injection site. The incidence of pain on injection in the CONT Group was 82.7% and 53.3% in the NE Group (p<0.001), and the incidence of nausea and vomiting was 10.7% in the CONT Group and 2.7% in the NE Group (p>0.05). The times, induction doses and the SBP and DBP values at the end of examination and at the moment of discharge from the PACU were lower in the NE Group (p<0.05).

CONCLUSIONS

Lipid propofol and propofol nanoemulsion were equivalent concerning effectiveness, safety and adverse effects in the doses used. There was a lower incidence of pain on injection in the nanoemulsion formulation.