Etomidate
Amidate
Imidazole IV induction agent
GABA-A potentiation. Highly hemodynamically stable due to minimal SVR/contractility effects.
Indications
- •GA induction in hemodynamically unstable patients
- •RSI in shock
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Induction | 0.2–0.3 mg/kg IV | 0.2–0.3 mg/kg IV |
Pharmacokinetics
Onset 30–60 sec. Duration 5–10 min. Hepatic ester hydrolysis.
Hemodynamic effects
Minimal effect — drug of choice for cardiac compromise, hypovolemia, acute trauma.
Respiratory effects
Less apnea than propofol. CO₂ response preserved at induction doses.
Side effects
- !Adrenocortical suppression (11β-hydroxylase) for 6–24 h after a single dose — relevant in septic patients
- !Myoclonus during induction (50%) — pretreat with opioid or low-dose midaz
- !Injection pain in propylene glycol formulation
- !PONV ~30%
Contraindications
- ×Septic shock with adrenal insufficiency (relative — controversial)
Clinical pearls
- ★Single-dose adrenal suppression mortality signal in sepsis is small but real; consider hydrocortisone supplement.
- ★No analgesia — co-administer opioid.
Other drugs in Induction Agents
- Propofol
Potentiates GABA-A chloride conductance. Direct CNS depression with no analgesia.
- Ketamine
Non-competitive NMDA receptor antagonist. Also effects on opioid, monoaminergic, muscarinic receptors. Produces dissociative anesthesia with analgesia.
- Thiopental
Enhances GABA-A chloride currents (↑ channel-open duration) → rapid loss of consciousness. Classic barbiturate induction agent.
- Methohexital
GABA-A potentiation. Shorter-acting than thiopental; lowers seizure threshold (useful for ECT).
- Remimazolam
GABA-A benzodiazepine agonist with an ester linkage → rapid hydrolysis by tissue esterases (like remifentanil among opioids) → fast recovery, organ-independent.
Browse all classes: /reference/drugs
Suggested reading
- •Stoelting & Hines, Pharmacology & Physiology in Anesthetic Practice, 6e
- •Miller's Anesthesia, 9e
- •FDA package insert
