Midazolam
Versed
Short-acting benzodiazepine
GABA-A potentiation at benzodiazepine receptor.
Indications
- •Premedication (anxiolysis, amnesia)
- •Procedural sedation
- •Status epilepticus
- •ICU sedation
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Premed adult IV | 1–2 mg IV | — |
| Premed peds PO | — | 0.5–1 mg/kg PO (max 20 mg); 0.5 mg/kg starting, escalate to 1 mg/kg in resistant pre-school children |
| Premed peds IV | — | 0.05–0.1 mg/kg IV (max 2 mg per dose, titrate to effect) |
| Premed peds intranasal | — | 0.2–0.3 mg/kg IN (use 5 mg/mL concentration to minimize volume) |
| Status epilepticus | 5–10 mg IV/IM/buccal/intranasal | 0.15 mg/kg IV (max 5 mg); 0.2 mg/kg IM/IN/buccal |
| ICU infusion | 0.02–0.1 mg/kg/hr | 0.05–0.2 mg/kg/hr |
Pharmacokinetics
Onset 1–3 min IV. Duration 30–60 min. Hepatic CYP3A4 (interactions with macrolides, azoles).
Hemodynamic effects
Mild ↓BP at induction doses; minimal otherwise.
Respiratory effects
Synergistic respiratory depression with opioids.
Side effects
- !Paradoxical agitation (peds, elderly)
- !Prolonged sedation in elderly + hepatic dysfunction
- !Tolerance with chronic use
Contraindications
- ×Acute angle-closure glaucoma (relative)
- ×Severe respiratory depression without monitoring
Reversal / antidote
Flumazenil 0.2 mg IV q1 min (max 1 mg) — caution in benzo-dependent (seizure risk).
Clinical pearls
- ★PO peds dose tastes bitter — consider mixed in cherry syrup.
- ★Avoid in elderly when alternatives exist; one of strongest delirium triggers.
- ★Intranasal midaz works for combative pediatric induction.
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Other drugs in Benzodiazepines & Reversal
- Flumazenil
Competitively binds benzodiazepine site on GABA-A receptor → displaces benzo agonists → reverses sedation, respiratory depression, amnesia.
- Lorazepam
Allosteric positive modulator at GABA-A receptors → ↑frequency of Cl⁻ channel opening → membrane hyperpolarization. Hypnotic, anxiolytic, anticonvulsant, anterograde amnesia. Glucuronidated only — no CYP metabolism — useful in liver disease.
- Diazepam
Allosteric positive modulator at GABA-A. Hypnotic, anxiolytic, anticonvulsant, skeletal-muscle relaxant. Produces highly lipid-soluble + active metabolites (desmethyldiazepam, oxazepam, temazepam) → very long total duration in elderly + chronic dosing.
Browse all classes: /reference/drugs