Potential strategy for assessing QT/QTc interval for drugs that produce rapid changes in heart rate: Electrocardiographic assessment of the effects of intravenous remimazolam on cardiac repolarization

AIMS: Remimazolam is a new, ultra‐short‐acting benzodiazepine developed for intravenous (IV) use during procedural sedation and in general anaesthesia. Two trials were conducted to characterize its effects on cardiac repolarization. METHODS: A thorough QT/QTc (TQT) study assessed electrocardiography effects of therapeutic and supratherapeutic doses of remimazolam and midazolam. To investigate whether RR‐QT hysteresis effects due to rapid heart rate changes might have confounded the QTc assessments in the TQT trial, a second trial used continuous IV remimazolam infusion to achieve stable heart rates during periods of stable remimazolam plasma concentration. RESULTS: During the TQT, both compounds produced a 10–20‐beats/min increase in heart rate within 30 seconds, persisting for 5–10 minutes. Within 30 seconds, the upper bound of the 2‐sided 90% confidence interval for the placebo‐corrected change from baseline for QTcI (ΔΔQTcI) exceeded 10 ms for both doses of remimazolam (ΔΔQTcI 7.2 [3.2, 11.2] ms for the 10 mg dose and 10.4 [6.5, 14.3] ms for the 20 mg dose) as well as for the 7.5‐mg dose of midazolam (8.2 [4.4, 12.1] ms). At 2 minutes after IV bolus, the upper bound of the 2‐sided 90% confidence interval for ΔΔQTcI exceeded 10 ms only for the remimazolam 20‐mg dose (6.3 [2.3, 10.2] ms). During the second study, during periods of stable heart rate, remimazolam had no clinically significant effect on QTc (peak ΔΔQTcI 3.4 [−1.1, 7.6] ms). CONCLUSION: Remimazolam does not prolong cardiac repolarization (QTc). The methods reported here may allow assessment of the QTc effects of other drugs given by IV bolus.