HYPNOMIDATE

Indications

• Induction of general anesthesia
• Procedures requiring rapid onset and recovery from anesthesia

Dosage

Children: Refer to the BNF for Children for specific dosing instructions.

Adults: 150–300 micrograms/kg (maximum per dose 60 mg), to be administered over 30–60 seconds. For elderly patients, 150–200 micrograms/kg (maximum per dose 60 mg) is recommended.

Mechanism of action

Etomidate binds at a distinct binding site associated with a Cl- ionopore at the GABA_A receptor, increasing the duration of time for which the Cl- ionopore is open. This prolongs the post-synaptic inhibitory effect of GABA in the thalamus, leading to its anesthetic effects.

Pharmacodynamics

Etomidate acts as a hypnotic agent that depresses central nervous system function via the GABAergic system, particularly affecting the reticular-activating system. It produces anesthesia without analgesic effects, inducing unconsciousness within approximately one circulation time. Recovery from etomidate is rapid due to extensive redistribution and quick metabolism, resulting in minimal residual sedation.

Pharmacokinetics

Etomidate has a rapid onset of action due to its high lipid solubility, which facilitates quick distribution into the central nervous system. Following administration, it undergoes rapid redistribution and is primarily metabolized by the liver, with a short elimination half-life. The drug's effects are generally brief, making it suitable for short procedures. The pharmacokinetic profile allows for quick recovery, with little residual effects.

Contra-indications

• Acute porphyrias
• Adrenal insufficiency
• Acute circulatory failure (shock)
• Hypovolaemia
• Sepsis

Adverse effects

• Apnoea
• Hypotension
• Nausea
• Respiratory disorders
• Movement disorders
• Skin reactions
• Vascular pain
• Vomiting
• Arrhythmias
• Cough
• Hiccups
• Hypersalivation
• Muscle rigidity
• Neuromuscular dysfunction
• Nystagmus

Interactions

• Angiotensin-converting enzyme (ACE) inhibitors
• Angiotensin-II receptor antagonists
• Other sedatives and analgesics may increase the risk of severe hypotension

Precautions

• Careful monitoring of fluids and electrolytes is required
• Should only be administered by experienced personnel
• Use with caution in patients with underlying adrenal insufficiency

Pregnancy

Etomidate should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Consult local guidelines and consider alternatives when possible.

Breast-feeding

It is not known whether etomidate is excreted in human milk. Caution should be exercised when administering to a nursing mother.

Storage

Store at room temperature, protected from light. Do not freeze. Keep out of reach of children.

Formulations

• Hypnomidate 2 mg per 1 ml solution for injection ampoules
• Etomidate-Lipuro 2 mg per 1 ml emulsion for injection ampoules

Mechanism of action

Etomidate binds at a distinct binding site associated with a Cl^- ionopore at the GABA_A receptor, increasing the duration of time for which the Cl^- ionopore is open. The post-synaptic inhibitory effect of GABA in the thalamus is, therefore, prolonged.

Pharmacodynamics

Etomidate is a non-barbiturate hypnotic that acts at the level of the reticular-activating system to produce anesthesia. Etomidate is an imidazole compound that appears to depress CNS function via GABA. Duration of action is intermediate between thiopental and methohexital, and recovery from a single dose is rapid with little residual depression. Like the barbiturates and propofol, etomidate is does not induce analgesia. Etomidate induces unconsciousness within one circulation time. Recovery is rapid as a result of extensive redistribution and rapid metabolism.