AMIDATE
Clinical safety rating
cautionComprehensive clinical and safety monograph for AMIDATE (AMIDATE).
AMIDATE (etomidate) is a nonbarbiturate hypnotic agent that acts as a positive allosteric modulator of the GABA-A receptor at the beta-2/3 subunit, enhancing the inhibitory effects of GABA and producing rapid sedation and anesthesia.
| Metabolism | Primarily hepatic via hydrolysis by esterases to inactive metabolites (carboxylic acid and ethanol); also undergoes glucuronidation. |
| Excretion | Renal: <5% unchanged; Hepatic metabolism to carboxylic acid metabolite (inactive); Metabolite renally eliminated; Fecal: negligible. |
| Half-life | Terminal elimination half-life: 2.5–4 hours (adults); 1–2 hours (children); Prolonged in hepatic impairment or with continuous infusion. |
| Protein binding | 97–98% bound; Primary binding to albumin; Reduced binding in neonates and hepatic/renal disease. |
| Volume of Distribution | Vd: 2.5–4.5 L/kg; Large Vd indicates extensive tissue distribution (highly lipophilic). |
| Bioavailability | IV: 100%; IM: >90%; Rectal: ~50% (variable). |
| Onset of Action | IV: 15–30 seconds (loss of consciousness); IM: 2.5–5 minutes (induction); Rectal: 5–10 minutes (sedation). |
| Duration of Action | IV: 3–5 minutes (single dose for induction); IM: 10–20 minutes; Rectal: 20–30 minutes; Prolonged with multiple doses or continuous infusion due to accumulation. |
| Molecular Weight | 340.42 |
0.2-0.6 mg/kg IV bolus for induction of anesthesia.
| Dosage form | INJECTABLE |
| Renal impairment | No adjustment required; pharmacokinetics unchanged in renal impairment. |
| Liver impairment | No specific guidelines; use with caution in severe hepatic impairment due to potential for decreased clearance. |
| Pediatric use | 3-5 mg/kg IV bolus for induction in children; lower doses may be sufficient. |
| Geriatric use | Reduce dose to 0.15-0.3 mg/kg IV bolus due to increased sensitivity and decreased clearance. |
| 1st trimester | Avoid due to potential teratogenicity; limited human data. |
| 2nd trimester | Use only if clearly needed; no well-documented fetal risk but limited data. |
| 3rd trimester | May cause neonatal respiratory depression if used near term; use with caution. |
Clinical note
Comprehensive clinical and safety monograph for AMIDATE (AMIDATE).
| Placental transfer | Rapidly crosses the placenta; achieves equilibrium between maternal and fetal circulation within minutes. |
| Breastfeeding | Excreted into breast milk in small amounts; unlikely to cause adverse effects in infant with short-term use. Monitor infant for sedation and respiratory depression if maternal use is prolonged or high dose. |
| Lactation Rating | L3 |
| Teratogenic Risk | Pregnancy Category D. First trimester: Associated with congenital anomalies (e.g., neural tube defects, cardiovascular malformations) based on human data. Second/third trimesters: May cause fetal CNS depression, hypotonia, and respiratory depression with chronic use. Avoid in pregnancy unless benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal vital signs (heart rate, blood pressure, oxygen saturation), fetal heart rate, and uterine activity. Assess for signs of CNS depression or respiratory distress in newborn. Long-term use requires periodic fetal growth ultrasound and non-stress tests. |
| Fertility Effects | May impair fertility in males via decreased sperm motility and count; effects reversible upon discontinuation. Impact on female fertility not well established. Use with caution in patients planning conception. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to etomidate or any componentAcute porphyria (variegate or intermittent)Adrenal cortical insufficiency (relative risk of adrenal suppression)
| Precautions | Suppresses adrenal steroidogenesis via reversible inhibition of 11-beta-hydroxylase (cortisol and aldosterone synthesis) – risk of adrenal insufficiency, especially with prolonged infusion or multiple doses, May cause myoclonus (involuntary muscle movements) during induction, Can produce hypotension less frequently than other induction agents, but still possible, Use caution in patients with adrenal suppression, sepsis, or hepatic impairment, May cause pain on injection (use large vein or consider pretreatment) |
| Food/Dietary | None known. However, because etomidate is administered intravenously in a fasting state prior to procedures, food intake is restricted per standard pre-procedural fasting guidelines (typically NPO for 6-8 hours). |
| Clinical Pearls | Amidate (etomidate) is an ultra-short acting non-barbiturate hypnotic used for induction of anesthesia and for procedural sedation. Key pearls: (1) Single dose causes adrenal suppression via 11β-hydroxylase inhibition; avoid continuous infusion or repeated doses. (2) Preferred for hemodynamically unstable patients due to minimal cardiovascular depression. (3) High incidence of myoclonus and pain on injection; pretreat with opioid or benzodiazepine to reduce myoclonus. (4) Contraindicated in porphyria. (5) Rapid onset (30-60 sec) and short duration (3-5 min) limit use to induction only. |
| Patient Advice | This medication is given only by a healthcare professional in a hospital or clinic setting. · You may experience involuntary muscle movements (myoclonus) or pain at the injection site. · Tell your doctor if you have adrenal gland problems, porphyria, or if you are pregnant or breastfeeding. · The effects are short-lived; you will be monitored closely during and after administration. · Do not drive or operate machinery for at least 24 hours after receiving this medication. |
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