In short
Etomidate is a general anaesthetic used to induce anaesthesia by intravenous injection. It is being studied in one Phase 3 clinical trial to see whether the choice of anaesthetic affects how quickly patients with severe unipolar depression respond to electroconvulsive therapy (ECT). The trial is authorised in the EU Clinical Trials Information System and plans to enrol 174 participants.
Key points
- Etomidate is a general anaesthetic without analgesic activity, given by intravenous injection.
- It is being compared with propofol and methohexital as an anaesthetic for electroconvulsive therapy in severe unipolar depression.
- The single EU trial is Phase 3 and is currently authorised.
- The trial plans to enrol 174 participants.
- The main measure is time to first clinical response, defined as at least a 50% reduction on the MADRS depression scale.
- Etomidate is available as a 2 mg/mL solution for injection in ampoules.
What is etomidate?
Etomidate is a general anaesthetic without analgesic activity, meaning it causes loss of consciousness but does not relieve pain. It is a chemically synthesised small-molecule substance, identified chemically as (R)-(+)-ethyl-1-(1-phenylethyl)-1H-imidazole-5-carboxylate. In the United Kingdom, etomidate is listed as a valid prescribable product under the recommended International Non-proprietary Name (rINN), with the trade name Hypnomidate used for a 20 mg/10 mL solution for injection. It is classified under the Anatomical Therapeutic Chemical (ATC) code N01AX07, a group of general anaesthetics.
How does etomidate work?
Etomidate produces anaesthesia with a rapid onset of action, usually within one minute after intravenous injection. The duration of anaesthesia is dose dependent but relatively brief, typically three to five minutes when an average dose of 0.3 mg/kg is used. The most characteristic effect of etomidate on the respiratory system is a slight elevation in arterial carbon dioxide tension (PaCO2). Reduced cortisol plasma levels have been reported with induction doses of 0.3 mg/kg etomidate, persisting for approximately 6 to 8 hours and appearing unresponsive to ACTH administration. In patients with severe cardiovascular disease, intravenous administration of up to 0.6 mg/kg of etomidate has little or no effect on myocardial metabolism, cardiac output, peripheral circulation or pulmonary circulation.
Which conditions is it used or studied for?
- Induction of general anaesthesia — etomidate is used to start anaesthesia before surgery or other procedures.
- Severe unipolar depression treated with electroconvulsive therapy — the current Phase 3 trial is comparing etomidate with other anaesthetics during ECT sessions to see which one leads to a faster clinical response.
How is etomidate given?
Etomidate is given by intravenous injection as a sterile, clear, colourless solution. Each millilitre contains 2 mg of etomidate in propylene glycol 35% v/v, with a pH of 6.0 (range 4.0 to 7.0). In the United Kingdom, the product is available as 20 mg/10 mL solution for injection ampoules, with a pack size of 5 ampoules. In the ECT trial, etomidate is given intravenously, with the trial record listing a 500 mg amount.
What do the clinical trials show?
One Phase 3 clinical trial, authorised in the EU Clinical Trials Information System under the number 2025-524829-40-00, is investigating etomidate in patients with severe unipolar depression who are being treated with electroconvulsive therapy. The trial plans to enrol 174 participants. Etomidate is one of three anaesthetic agents being compared; the others are propofol and methohexital, while suxamethonium is used as a muscle relaxant.
The primary endpoint is the time to first clinical response, measured as the number of completed ECT sessions from treatment initiation to the first Montgomery-Åsberg Depression Rating Scale (MADRS) assessment showing a reduction of at least 50% from baseline. The study aims to determine whether the choice of anaesthetic agent influences the speed of clinical response to ECT during the treatment course.
A separate published study compared etomidate and propofol on intubating conditions and the onset time associated with cisatracurium administration, although the full results of that comparison are not summarised in the available source.
What side effects are known?
The available sources describe a few known effects of etomidate. A slight elevation in arterial carbon dioxide tension (PaCO2) is described as the most characteristic effect on the respiratory system. Reduced cortisol plasma levels have been reported with induction doses of 0.3 mg/kg, persisting for approximately 6 to 8 hours and appearing unresponsive to ACTH administration. The source does not group these effects into common and serious categories, so they are listed here as reported effects.