Etomidate is a potent, ultra-short-acting, non-barbiturate intravenous hypnotic agent used for the induction of general anesthesia. It is chemically unrelated to other intravenous anesthetics. It is characterized by rapid onset, short duration of action, minimal cardiovascular depression, and minimal histamine release, making it particularly valuable in hemodynamically unstable patients, the elderly, and those with significant cardiac disease. Its primary drawback is the suppression of adrenal steroidogenesis, which can be clinically significant with prolonged infusion.
Adult: Induction: 0.2 to 0.6 mg/kg (typically 0.3 mg/kg) IV over 30-60 seconds. Average dose: 20 mg for a 70 kg adult.
Note: For IV use only. Must be diluted or administered into a large vein (e.g., antecubital) to minimize pain and thrombophlebitis. Administer as a slow IV injection over 30-60 seconds. Pre-treatment with lidocaine or an opioid (e.g., fentanyl) can reduce injection pain and myoclonus. Always have resuscitation equipment and personnel trained in airway management present.
Etomidate acts as a positive allosteric modulator of the gamma-aminobutyric acid type A (GABA-A) receptor, the primary inhibitory neurotransmitter receptor in the central nervous system. It enhances GABA-mediated chloride ion influx into neurons, leading to hyperpolarization of the postsynaptic membrane and inhibition of neuronal firing, resulting in hypnosis and loss of consciousness.
Pregnancy: Category C: Animal studies show adverse effects. Should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Not recommended for obstetric procedures due to neonatal adrenal suppression.
Driving: Patients must be warned that etomidate causes sedation and amnesia. They must not drive or operate machinery for at least 24 hours after administration.
| Fentanyl, other opioids | Enhanced respiratory depression and CNS depression. | Major |
| Benzodiazepines (Midazolam, Diazepam) | Synergistic sedative and hypnotic effect. Reduced etomidate dose may be required. | Major |
| Propofol, Thiopentone | Additive CNS and cardiovascular depressant effects. | Moderate |
| Succinylcholine | Etomidate may prolong the duration of neuromuscular blockade. | Moderate |
| CYP3A4 Inducers (e.g., Rifampicin, Carbamazepine) | May increase metabolism of etomidate, potentially reducing its effect. | Moderate |
| CYP3A4 Inhibitors (e.g., Ketoconazole, Erythromycin) | May decrease metabolism of etomidate, potentially prolonging its effect. | Moderate |
Same composition (Etomidate (2mg/ml)), different brands: