Anaes · Anaesthetic adjuncts

Benzodiazepines in anaesthesia

Also known as Midazolam · Diazepam · Lorazepam · Remimazolam · Flumazenil (antagonist) · GABA-A positive allosteric modulator

Benzodiazepines are the versatile perioperative drug class — the premedicant, the procedural sedative, the anxiolytic, the anticonvulsant, the co-induction agent, and the alcohol-withdrawal treatment — unified by a single molecular mechanism: positive allosteric modulation of the GABA-A receptor. The framework rests on four exam-critical ideas: the benzodiazepine binds at the interface between the alpha and gamma subunits and, unlike the barbiturate, increases the FREQUENCY (not the duration) of chloride channel opening, and cannot open the channel directly — a ceiling effect that makes benzodiazepines safer in overdose than barbiturates; the four agents differ in onset, duration and metabolism — midazolam (rapid, short, with an active metabolite), diazepam (slow, long, multiple active metabolites), lorazepam (slow, long, no active metabolite, the drug of status epilepticus), and remimazolam (ultra-short, ester-hydrolysed, organ-independent clearance with a constant context-sensitive half-time); the class produces dose-dependent respiratory depression that is powerfully synergistic with the opioid, only mild cardiovascular depression, and a signature anterograde amnesia; and flumazenil, the competitive antagonist, reverses the effect but has a shorter half-life than most benzodiazepines, so resedation is the danger and the patient must be monitored for 2 to 4 hours after reversal. Built on the remimazolam-versus-midazolam endoscopy trial (Akram 2026), the remimazolam dental-sedation study (Grossi 2026), the flumazenil benzodiazepine-toxicity review (Segev 2026), the emergence-delirium prediction work (Wang 2026), the intranasal midazolam premedication study (Nacar 2026), the remimazolam ICU-delirium report (Hong 2026), the remimazolam-propofol adjunct trial (Kazokas 2026), and the remimazolam tracheal-stent sedation case (Amagasa 2026).