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midazolam

Brand: Versed, Nayzilam, Seizalam

⚠ BBW ISMP High Alert Beers Criteria Prototype: diazepam
Drug Class: benzodiazepine
Drug Family: benzodiazepine
Subclass: short-acting benzodiazepine
Organ Systems: cns

Mechanism of Action

Positive allosteric modulator of GABA-A receptors with rapid onset; highly lipophilic water-soluble prodrug that becomes lipophilic at physiologic pH, allowing rapid BBB penetration.

GABA-A receptor (benzodiazepine binding site)

Indications

  • procedural sedation and anxiolysis
  • anesthesia induction/maintenance
  • ICU sedation
  • status epilepticus (IM, intranasal, buccal)
  • acute repetitive seizures

Contraindications

  • acute narrow-angle glaucoma
  • concurrent potent CYP3A4 inhibitors (protease inhibitors)
  • hypersensitivity to benzodiazepines

Adverse Effects

Common

  • respiratory depression
  • sedation
  • anterograde amnesia
  • hiccups
  • hypotension

Serious

  • respiratory arrest
  • cardiac arrest
  • paradoxical reactions
  • dependence (prolonged use)

Pharmacokinetics (ADME)

Absorption IV: 100%; IM: 90%; intranasal: ~55%
Distribution Highly lipophilic at physiologic pH; Vd 1–3.1 L/kg; crosses BBB rapidly
Metabolism CYP3A4 to active 1-hydroxy-midazolam (25–60% activity); then glucuronidation
Excretion Renal as glucuronides
Half-life 1.8–6.4 hours
Onset IV: 1–5 minutes; IM: 5–15 minutes; intranasal: 5–10 minutes
Peak 20–60 minutes
Duration 1–6 hours
Protein Binding 97%
Vd 1–3.1 L/kg

Drug Interactions

Drug / Agent Mechanism Severity
CYP3A4 inhibitors (ketoconazole, ritonavir) dramatically increase midazolam levels major
opioids additive respiratory depression major
flumazenil reverses sedation but has shorter half-life — resedation can occur moderate

Nursing Considerations

  1. Airway management equipment and flumazenil must be immediately available whenever midazolam is administered for procedural sedation
  2. Titrate IV doses slowly in small increments (0.5–1 mg); allow 2–3 minutes between doses to assess effect before administering more
  3. In ICU patients on prolonged infusions, tolerance and withdrawal can develop rapidly; plan for structured weaning protocol
  4. For intranasal administration in seizures (Nayzilam): 5 mg per nostril; second dose may be given after 10 minutes if seizure continues

Clinical Pearls

  • Midazolam is water-soluble at acidic pH (allowing IV formulation) but becomes lipophilic at physiologic pH — this biphasic property explains both its IV compatibility and rapid CNS penetration
  • Midazolam IM is the preferred route for prehospital status epilepticus treatment (RAMPART trial) — equal efficacy to IV lorazepam with faster administration time

Safety Profile

Pregnancy use-with-caution
Lactation avoid
Renal Adjustment Not required
Hepatic Adjustment Required
TDM Not required

Concordance Terms

Cross-referenced clinical concepts — click any term to see all content where it appears.

Acute Repetitive Seizures Anesthesia Induction/maintenance Benzodiazepine ICU Sedation Procedural Sedation And Anxiolysis Status Epilepticus (IM, Intranasal, Buccal)
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