A phase IIb study comparing the safety and efficacy of remimazolam and midazolam in patients undergoing colonoscopy.

BACKGROUND AND AIMS: Remimazolam is an ultra-short-acting benzodiazepine currently being developed for procedural sedation and for induction and maintenance of anesthesia. This trial was the fourth study for procedural sedation. The aim was to compare the safety and efficacy profile of remimazolam and to refine suitable doses for subsequent phase III studies in this indication. METHODS: This was a randomized, double-blind, parallel group, active controlled clinical trial with 162 male and female patients, aged 18 to 70, scheduled to undergo a routine colonoscopy. Patients were randomized to receive 1 of 3 remimazolam doses or midazolam for sedation. Supplemental oxygen and 100 µg of fentanyl was given before procedures were started, and the colonoscopy commenced as soon as suitable sedation had been achieved (Modified Observer's Assessment of Alertness/Sedation score ≤3). Top-up doses of the study drug and/or fentanyl were allowed to maintain suitable sedation and/or analgesia. Response was defined as sufficient sedation, no rescue sedative, and no ventilation required. RESULTS: This study showed that a single dose of remimazolam or midazolam, followed by top-up doses to maintain suitable sedation, provided adequate sedation with a high success rate (>92%) for the remimazolam groups, compared with 75% for the midazolam group (P = .007). There was no requirement for mechanical ventilation in any group, and procedure failures were all due to use of rescue sedative. CONCLUSIONS: The high success rates and good safety profile of remimazolam observed in this study warrants further investigation and confirmation in phase III trials. ( CLINICAL TRIAL REGISTRATION NUMBER: NCT01145222.).

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.

A phase Ib, dose-finding study of multiple doses of remimazolam (CNS 7056) in volunteers undergoing colonoscopy.

BACKGROUND: We performed the first multiple dose study of remimazolam designed to assess both the feasibility of maintaining suitable sedation during colonoscopy and reversing the sedative effects of remimazolam with flumazenil. METHODS: Healthy volunteers received fentanyl followed by remimazolam for sedation during colonoscopy. Three dose groups of 15 volunteers each received remimazolam in increasing initial doses, plus top-up doses to maintain sedation for a 30-minute period. In a separate double-blind crossover part of the trial, 6 volunteers were sedated with a single high dose of remimazolam, followed by flumazenil or placebo to reverse the sedation. RESULTS: Successful sedation that was adequate for colonoscopy was achieved in >70% of subjects. After the procedure, subjects rapidly recovered to fully alert, with a median of <10 minutes overall. Failures were due to the inability to sedate or adverse events, with 1 subject failing due to hypotension (arterial blood pressure 80/40) and low SpO2 (<90%). There were no serious adverse events reported, and no events that were unexpected with the combination of a benzodiazepine and fentanyl. The study also showed that sedation was rapidly reversible (1.0 minutes flumazenil vs 10.5 minutes placebo) without resedation. CONCLUSIONS: Remimazolam has the attributes of a sedative drug, with success rates comparable with recent studies of other drugs. Remimazolam provided adequate sedation in 33 of 44 subjects undergoing colonoscopy, and its sedative effects were easily reversed with flumazenil.

A placebo- and midazolam-controlled phase I single ascending-dose study evaluating the safety, pharmacokinetics, and pharmacodynamics of remimazolam (CNS 7056): Part II. Population pharmacokinetic and pharmacodynamic modeling and simulation.

BACKGROUND: A new benzodiazepine, remimazolam, which is rapidly metabolized by tissue esterases to an inactive metabolite, has been developed to permit a fast onset, a short, predictable duration of sedative action, and a more rapid recovery profile than currently available drugs. We report on modeling of the data and simulations of dosage regimens for future study. METHODS: A phase I, single-center, double-blind, placebo and active controlled, randomized, single-dose escalation study was conducted. Fifty-four healthy subjects in 9 groups received a single 1-minute IV infusion of remimazolam (0.01-0.3 mg/kg). There were 18 control subjects taking midazolam and 9 placebos. Population pharmacokinetic and pharmacodynamic modeling of the data was undertaken and the parameters obtained were used for Monte-Carlo simulations of alternative dosing regimens. RESULTS: A 4-compartment mammillary pharmacokinetic model of midazolam and a physiologically based recirculation model of remimazolam were fitted to the observed plasma levels. The recirculation model of remimazolam explained the observed high venous, compared with arterial, concentrations at later time points. The 2 models were used to simulate the arterial concentrations required for the pharmacodynamic models of sedation (Bispectral Index and Modified Observer's Assessment of Alertness/Sedation [MOAA/S]) and gave population mean pharmacodynamic parameters as follows: Bispectral Index-IC(50): 0.26, 0.07 µg/mL; γ: 1.6, 8.6; k(e0): 0.14, 0.053 min(-1); I(MAX): 39, 19, and MOAA/S-IC(50): 0.4, 0.08 µg/mL; γ: 1.4, 3.4; k(e0): 0.25, 0.050 min(-1) for remimazolam and midazolam, respectively. Simulations to obtain >70% of the population with MOAA/S scores of 2 to 4 were developed. This criterion was achieved (95% confidence intervals: 67%-74%) with a 6-mg initial loading dose of remimazolam followed by 3-mg maintenance doses at >2-minute intervals. Recovery to a MOAA/S score of 5 is predicted to be within 16 minutes for 89% (95% confidence intervals: 87%-91%) of the treated population after this loading/maintenance dose regimen. CONCLUSIONS: Population pharmacokinetic and pharmacodynamic models developed for remimazolam and midazolam fitted the observed data well. Simulations based on these models show that remimazolam delivers extremely rapid sedation, with maximal effect being reached within 3 minutes of the start of treatment. This property will enable maintenance doses to be given more accurately than with slower-acting drugs. No covariate effects considered to be clinically relevant were observed, suggesting that dosing by body weight may offer no advantage over fixed doses in terms of consistency of exposure to remimazolam within the weight range studied (65-90 kg).

A placebo- and midazolam-controlled phase I single ascending-dose study evaluating the safety, pharmacokinetics, and pharmacodynamics of remimazolam (CNS 7056): Part I. Safety, efficacy, and basic pharmacokinetics.

BACKGROUND: A new benzodiazepine, remimazolam, metabolized by tissue esterases to an inactive compound, CNS 7054, has been developed to permit a fast onset, a short and more predictable duration of sedative action, and a more rapid recovery profile than with currently available benzodiazepines. We report on the safety and efficacy of the first human study. METHODS: A phase I, single-center, double-blind, placebo- and active-controlled, randomized, single-dose escalation study was conducted. Up to 10 cohorts of healthy subjects were scheduled to receive a single 1-minute IV infusion of remimazolam, midazolam, or placebo. In the 10 possible cohorts, remimazolam doses were from 0.01 to 0.35 mg/kg. In cohorts 1 to 3, 6 subjects received remimazolam and 1 placebo. From cohort 4 onward, an additional 3 subjects in each cohort received midazolam (0.075 mg/kg). Safety, pharmacokinetics, and pharmacodynamics were measured. A stop criterion of loss of consciousness for >5 minutes in >50% of subjects was predefined. RESULTS: The stop criterion was reached in cohort 9 (0.30 mg/kg remimazolam) so that 81 subjects were enrolled. Remimazolam was well tolerated in all dose cohorts, and no serious adverse events (AEs) were reported. Three AEs of mild (Spo(2) 85%-88%) hemoglobin desaturation (2 in the remimazolam groups and 1 in the midazolam group) resolved spontaneously, and 1 AE of moderate hemoglobin desaturation (Spo(2) 75%) resolved with a chin lift in the highest remimazolam dose group. No supplemental oxygen or manual ventilation was required. Vital signs remained stable throughout, although there was an increase in heart rate 2 minutes postdose for both remimazolam and midazolam. There were no reports of hypo- or hypertension. The pharmacokinetic behavior of remimazolam was linear and its systemic clearance approximately 3 times that of midazolam. Clearance was essentially independent of body weight. A rapid onset and dose-dependent sedation was observed after administration of remimazolam at 0.05 mg/kg and higher. Remimazolam (0.075 to 0.20 mg/kg) induced peak sedation levels similar to or higher than those achieved with midazolam (0.075 mg/kg). Median recovery times after approximately equieffective doses of remimazolam (0.10 and 0.15 mg/kg) and midazolam (0.075 mg/kg) were 10 and 40 minutes, respectively. CONCLUSIONS: Remimazolam provided sedation with rapid onset and offset, and was well tolerated. There was no supplemental oxygen or ventilation required. On the basis of these data, further studies on the potential utility of remimazolam for sedation/anesthesia are warranted.