Pharmacotherapeutic group: Psycholeptics, hypnotics and sedatives, ATC code: N05CD14.
Mechanism of action
Remimazolam is an ultra-short acting benzodiazepine sedative/hypnotic. The effects of remimazolam on the CNS are dependent on the dose administered intravenously and presence or absence of other medicinal products. Remimazolam binds to benzodiazepine sites of gamma amino butyric acid type A [GABAA] receptors with high affinity, while its carboxylic acid metabolite (CNS7054) has approximately 300 times lower affinity for these receptors. Remimazolam does not show clear selectivity between subtypes of the GABAA receptor.
Pharmacodynamic effects
The primary pharmacodynamic effect of remimazolam is sedation and hypnosis.
Sedation is observed starting at single bolus doses of 0.05 to 0.075 mg/kg in healthy young adults, with an onset of 1 to 2 min following dosing. Induction of mild to moderate sedation is associated with plasma levels of around 0.2 μg/mL. Loss of consciousness is seen at doses of 0.1 mg/kg (elderly) or 0.2 mg/kg (healthy young adults) and associated with plasma concentrations of around 0.65 μg/mL. During maintenance of anaesthesia plasma concentrations of remimazolam are normally in the range of 1 µg/mL when remifentanil was co-administered. Time to fully alert was 10 min for 0.075 mg/kg of remimazolam.
Remimazolam can cause anterograde amnesia after administration, which prevents patients from remembering events occurring during the procedure.
Clinical efficacy and safety
The efficacy of remimazolam was based on two pivotal studies CNS7056-022 and ONO-2745-05 in adult patients (aged 20 to 91 years) with ASA-PS I-IV who were undergoing mixed elective surgeries. The database for remimazolam additionally comprised additional propofol-controlled clinical trials in cardiac surgeries (CNS7056-010 and CNS7056-011).
ONO-2745-05: This was a phase IIb/III multicenter, randomized, parallel-group trial of remimazolam compared with propofol in surgical patients rated as ASA class I or II undergoing general anaesthesia conducted in Japan. Remimazolam was administered at a dose of 6 (n=158) or 12 mg/kg/h (n=156) by continuous intravenous infusion until loss of consciousness. After loss of consciousness, continuous intravenous infusion at a dose of 1 mg/kg/h was started, after which the infusion rate was adjusted as appropriate (maximum allowed dose, 2 mg/kg/h) based on monitoring of the general condition of individual subjects until the end of the surgery.
CNS7056-022: This was a European, confirmatory trial to establish non-inferior efficacy and superior haemodynamic stability of remimazolam compared with propofol for induction and maintenance of general anaesthesia during elective surgery in patients rated as ASA class III or IV. Patients were randomly assigned to the remimazolam (n=270) or the propofol arm (n=95). Remimazolam was administered at a dose of 6 mg/min for 3 min, followed by 2.5 mg/min for 7 min and 1.5 mg/min for an additional 10 min. Thereafter general anaesthesia was maintained with an infusion rate of 1 mg/min with adjustments between 0.7-2.5 mg/min based on monitoring of the general condition of individual subjects until the end of surgery.
The primary endpoints in the pivotal clinical trials, were defined as :
• Percentage of general anaesthesia maintenance time with Narcotrend index (NCI) ≤60 (CNS7056-022)
• Functional capability as a general anaesthetic as assessed by a composite of 3 variables: “intraoperative awakening or recall”, “requirement of rescue sedation with other sedatives” and “body movement.” (ONO-2745-05).
The primary endpoint was reached in both clinical trials (see table 3). All doses of remimazolam were non-inferior to propofol.
Table 3: Primary endpoints from pivotal clinical trials
| | CNS7056-022 | ONO-2745-05 |
| | RMZ61 | PROP | RMZ62 | RMZ123 | PROP |
| Capability as a general anaesthetic | - | - | 100% | 100% | 100% |
| Mean time Narcotrend index ≤ 60 | 95% | 99% | - | - | - |
Induction dose 6 mg/min (1), 6 mg/kg/h (2) or 12 mg/kg/h (3); RMZ; remimazolam, PROP: propofol
In CNS7056-022, haemodynamic stability, assessed as absolute or relative hypotension and vasopressor use, was a key secondary endpoint. This was assessed during the period before start of surgery and is summarised in table 4. Remimazolam treated patients had fewer events of mean arterial pressure (MAP) of 1 min below 65 mmHg and fewer vasopressor dosing events.
Table 4: Secondary endpoints in phase 3 clinical trial CNS7056-022
| Endpoint | Remimazolam | Propofol |
| N = 270 | N = 95 |
| MAP < 65 mmHg | | |
| MAP <65 mmHg within start of IMP to 15 minutes after first skin incision over 1 minute, number of events | | |
| Mean ± Standard deviation | 6.62 ± 6.604 | 8.55 ± 8.944 |
| CI 95% | (5.83 to 7.41) | (6.75 to 10.4) |
| Median (minimum, maximum) | 5 (2, 10) | 6 (3, 11) |
| Difference of least square means between treatments (95% CI) | 1.9292 (0.2209 – 3.6375) |
| Norepinephrine Use | | |
| Norepinephrine boluses or infusion or continuous infusion over 2 minutes, number of events | | |
| Mean ± Standard deviation | 14.06 ± 13.540 | 19.86 ± 14.560 |
| CI 95% | (12.4 to 15.7) | (16.9 to 22.8) |
| Median (minimum, maximum) | 12 (0, 63) | 21 (0, 66) |
| Difference of least square means between treatments (95% CI) | 5.8009 (2.5610 – 9.0409) |
| MAP < 65 mmHg AND/OR Norepinephrine use | | |
| Number of events | | |
| Mean ± Standard deviation | 20.68 ± 16.444 | 28.41 ± 17.468 |
| CI 95% | (18.7 to 22.6) | (24.9 to 31.9) |
| Median (minimum, maximum) | 21 (0, 68) | 30 (0, 75) |
| Difference of least square means between treatments (95% CI) | 7.7301 (3.8090 – 11.651) |
| IMP = investigational medicinal product; MAP = mean arterial pressure |
The onset and recovery profile of remimazolam was characterised by time-to-event secondary endpoints assessed in the pivotal clinical trials. In each trial, time to recovery endpoints were slightly longer in the remimazolam groups than in the propofol group (table 5).
Table 5: Induction and recovery endpoints in phase 3 clinical trials
| Median time | CNS 7056-022 | ONO-2745-05 |
| | RMZ1 | PROP4 | RMZ62 | RMZ123 | PROP |
| Induction endpoints | | | | | |
| - Time to loss of consciousness Patients (n) 95% CI Q1; Q3 Min; Max | 2.5 min 268 2.5 – 2.8 min 2.0; 3.3 min NA | 3 min 95 3.0 – 3.2 min 2.5; 3.7 min NA | 100.5 s 150 NA NA 24; 165 s | 87.5 s 150 NA NA 30; 170 s | 80 s 75 NA NA 17; 280 s |
| Recovery endpoints Time from stop of IMP§ administration to | | | | | |
| - Extubation Patients (n) 95% CI Q1; Q3 Min; Max | 12 min 263 11 – 13 min 8; 18 min NA | 11 min 95 10 – 12 min 8; 15 min NA | 15.5 min 150 NA NA 3; 104 min | 18 min 150 NA NA 2; 58 min | 12 min 75 NA NA 3; 42 min |
| - Awakening# Patients (n) 95% CI Q1; Q3 Min; Max | 15 min 257 13 – 17 min 9; 26 min NA | 12 min 95 10 – 13 min 8; 16 min NA | 12 min 150 NA NA 1; 87 min | 12 min 150 NA NA 0; 50 min | 10 min 75 NA NA 0; 24 min |
| - Orientation## Patients (n) 95% CI Q1; Q3 Min; Max | 54 min 262 47 – 61 min 31; 88 min NA | 30 min 95 27 – 33 min 22; 48 min NA | 21 min 149 NA NA 3; 106 min | 21 min 149 NA NA 2; 125 min | 14 min 75 NA NA 4; 86 min |
| - Modified Aldrete score ≥9 Patients (n) 95% CI Q1; Q3 …Min; Max | 53 min 260 44 – 58 min 30; 98 min NA | 37 min 94 28 – 45 min 21; 88 min NA | NA | NA | NA |
| - Discharge from operation room Patients (n) 95% CI Q1; Q3 Min; Max | NA | NA | 25 min 150 NA NA 4; 144 min | 25 min 150 NA NA 5; 125 min | 16 min 75 NA NA 5; 87 min |
Induction doses remimazolam (1) 6 mg/min, (2) 6 mg/kg/h or (3) 12 mg/kg/h, (4) propofol dose equipotent to remimazolam
# ONO-2745-05: eye opening; CNS7056-022: response to verbal command ((MOAA/S≥4)
## ONO-2745-05: stating date of birth; CNS7056-022: orientation to place, time, situation and person
§ Investigational medicinal product
Clinical Safety
The incidence of treatment-emergent adverse events in the propofol-controlled trials was 90.7% in the low induction dose remimazolam groups, 83.7% in the high induction dose remimazolam groups and 92.5% in the propofol groups. Particularly the incidence of haemodynamic adverse events was lower for the remimazolam dose groups as compared to the propofol groups (table 6).
Table 6: Number of patients with haemodynamic instability adverse events in propofol-controlled clinical trials
| Total number of patients | remimazolam N=671 | propofol N=226 |
| Number of patients with events |
| Hypotension n (n/N%) [95%CI] | 344 (51.3%) [47.5-55.0] | 150 (66.4%) [59.0-72.2] |
| Bradycardia n (n/N%) [95%CI] | 96 (14.3%) [11.9-17.2] | 50 (22.1%) [17.2-28.0] |
Paediatric population
The European Medicines Agency has deferred the obligation to submit the results of studies with Byfavo in one or more subsets of the paediatric population in the condition of general anaesthesia (see section 4.2 for information on paediatric use).