A miniature pig model of pharmacological tolerance to long-term sedation with the intravenous benzodiazepines; midazolam and remimazolam

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

Two Cases of Inadequate Response to Remimazolam

We report the inadequate efficacy of remimazolam in two patients undergoing long-term benzodiazepine analog therapy. Remimazolam is a recently developed ultrashort-acting benzodiazepine. It is primarily used as an anesthetic in surgical procedures, as it has minimal effect on cardiac function and antagonists are available. It is expected to become more widely used in the future. On the other hand, similar to other benzodiazepines, benzodiazepine tolerance can also pose a challenge with remimazolam. Herein, we report two cases who were taking long-term oral benzodiazepine analogs. One patient did not fall asleep despite a sufficient dose of remimazolam and required a change to propofol. The other patient required a high dose of remimazolam to fall asleep; however, multiple signs of arousal were noted intraoperatively. Our findings suggest that remimazolam may not be an ideal anesthetic in long-term benzodiazepine analog users. Comprehensive assessment of preoperative medications and careful monitoring of intraoperative sedation levels are necessary. Furthermore, it may be advisable to consider the use of alternative agents such as propofol.

Remimazolam: An Updated Review of a New Sedative and Anaesthetic

Remimazolam (CNS7056) is a novel benzodiazepine for intravenous sedation; it has an ultra-short duration of action and was recently approved for use in procedural sedation and general anaesthesia. It acts on γ-aminobutyric acid type A receptors and is rapidly converted into an inactive metabolite by tissue esterase enzymes. Remimazolam has been successfully used in endoscopic inspection or surgery and general anaesthesia induction and maintenance with fast and predictable onset and recovery times, high procedure success rates, and minor respiratory and hemodynamic fluctuations and without serious drug-related adverse reactions. If needed, the effects of remimazolam can be reversed by flumazenil, which allows prompt termination of sedation. Although remimazolam has great potential for sedation in patients admitted to intensive care units, future studies are needed to evaluate its efficacy and safety in patients requiring sedation for a long period, and numerous studies are warranted to explore the optimal dose in different application scenarios. The review aimed to provide an introduction to the process of remimazolam synthesis and its current clinical uses and future clinical developments.

Miniature Companion Pig Sedation and Anesthesia

With their increase in popularity in North America as pets, miniature companion pigs are in need of veterinary professionals familiar with sedation and anesthesia for the species. This article provides a review of the agents used for sedation, premedication, induction, and maintenance of anesthesia for miniature companion pigs. This review also covers species-specific anatomic and physiologic factors of miniature companion pigs with respect to administration of anesthetics, endotracheal intubation, anesthetic maintenance, and common complications so that the reader can make an informed anesthetic plan for the species.

Remimazolam reduces sepsis-associated acute liver injury by activation of peripheral benzodiazepine receptors and p38 inhibition of macrophages

BACKGROUND

Remimazolam is a novel ester-type benzodiazepine with ultrafast onset of sedation effect and fast recovery of consciousness. It has potential advantages in the sedation of sepsis-associated acute liver injury (SALI) patients. However, the effect and mechanism of remimazo lam on inflammation in the liver have not yet been elucidated. This study investigated the anti-inflammatory effects and mechanisms of remimazolam on SALI both in vivo and in vitro.

METHODS

Lipopolysaccharide (LPS) plus galactosamine treated rat model and LPS-challenged RAW264.7 cells model were constructed to simulate SALI. Next, the models were used to explore the efficacy of remimazolam treatment on SALI. Benzodiazepine receptor inhibitor, PK11195, was also employed. Hepatic injury was assessed by quantifying levels of transaminases, examining liver pathology, and calculating the number of inflammatory cells in the liver. Inflammatory response was evaluated by determining levels of pro-inflammatory cytokines and chemokines in blood, as well as p38 phosphorylation (p-p38) in the liver.

RESULTS

SALIrat models showed significant liver damage as manifested by increased levels of transaminases, proinflammatory cytokines, chemokines, and p-38. Remimazolam treatment reduced the liver injury and pathological changes, suppressed pro-inflammatory reactions, and elevated p-p38. The protective effect of remimazolam on liver injury was significantly blocked by PK11195. In LPS-stimulated RAW264.7 cells, it was found that treatment with remimazolam reduced the inflammatory response in LPS-treated cells in a time-dependent manner and decreased the level of p-p38. These results suggest that PK11195 can block remimazolam-induced inhibition of proinflammatory cytokine release and p-38 phosphorylation.

CONCLUSIONS

This study shows that remimazolam can attenuate inflammatory response in SALI, which may be associated with activation of peripheral benzodiazepine receptors and inhibition of p38 phosphorylation in macrophages.

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.

Remimazolam Tolerance in Long-term Benzodiazepine Users: A Case Report of 2 Cases

A 60-year-old woman with a 5-year history of anxiolytic use, a diazepam-equivalent daily dose of 15 mg, was scheduled for esophageal stent removal. She was given remimazolam (0.5 mg/kg) but remained fully alert. She only lost consciousness with propofol (40 mg). A 61-year-old man with a 1-year history of anxiolytic use, diazepam-equivalent daily dose of 20 mg, was scheduled for hand tumor resection. He was given remimazolam (0.3 mg/kg) but remained fully alert. He only lost consciousness after desflurane inhalation. In a patient with a history of long-term benzodiazepine use, anesthetic or sedative agents aside from remimazolam should be considered.

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

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