Antidote
Lipid emulsion 20% (Intralipid)
Also called Intralipid
Indications
- Local anesthetic systemic toxicity with seizures, dysrhythmia or arrest, with airway care and ACLS (off-label; ASRA 2020)
- Refractory toxicity from other lipophilic drugs such as bupropion or TCAs, as a last resort (off-label)
- Calories and essential fatty acids in parenteral nutrition
Mechanism of action
Infused lipid forms an intravascular lipid phase that pulls lipid-soluble drugs such as bupivacaine out of plasma water, lowering free drug at the heart and brain (the sink), then carries it to muscle and liver (the shuttle). It also raises contractility and vascular tone within minutes and activates prosurvival kinases such as Akt, a postconditioning effect. The older metabolic theory, that fatty acids refuel a heart whose mitochondrial fatty-acid uptake bupivacaine blocks, has weaker support (Fettiplace 2018).
Pharmacology
- Cardiovascular: BP and contractility recover within minutes in animal models and case reports
- CNS: may shorten local anesthetic seizures; benzodiazepines stay first-line
- Metabolic: 2 kcal/mL; triglycerides climb steeply after rescue doses
- Respiratory: large or fast doses can cause hypoxemia and ARDS
Pharmacokinetics
| Onset | Minutes; the bolus may be repeated once or twice (ASRA) |
|---|---|
| Duration | Short, so toxicity can recur: observe 4–6 h after cardiovascular signs, 2 h after CNS-only signs |
| Half-life | Triglycerides about 15–40 min after a bolus in healthy adults |
| Distribution | Stays in plasma as chylomicron-sized droplets |
| Metabolism | Endothelial lipoprotein lipase splits triglycerides into free fatty acids and glycerol; the liver clears remnants |
| Clearance | Saturable; triglycerides rise more with lipid disorders, obesity or diabetes (label) |
| Elimination | Fatty acids are oxidized to CO₂ and water or stored |
Chemistry
- Intralipid 20%: 20 g soybean oil, 1.2 g egg yolk phospholipids and 2.25 g glycerin per 100 mL, pH 6–8.9
- Fatty acids mostly linoleic (44–62%), then oleic, palmitic and α-linolenic
- Droplets averaging under 500 nm; about 350 mOsm/kg, so peripheral IV is fine
- Never freeze; discard if separated; 1.2-micron filter and DEHP-free tubing; hang alone no more than 12 h
- Propofol, a 10% emulsion of a cardiodepressant, is not a substitute (ASRA)
Adverse effects and cautions
In the one-pagers
- Toxidromes and AntidotesCardiotoxic drugs: TCAs, β-blockers, CCBs, digoxin, LAST: Hypertonic sodium bicarbonate works through the sodium load and the alkalemia: AHA 2023 class 1 for TCAs, 2a for other sodium channel blockers (diphenhydramine, flecainide, lamotrigine, venlafaxine). Bolus until the QRS narrows, within AHA's ceilings (pH 7.50–7.55, sodium 150–155). Treat seizures with benzodiazepines, not phenytoin, and nev
- ACLS Algorithms in BriefSpecial circumstances and ECPR: Local anesthetic toxicity: Lipid emulsion 20%; smaller epinephrine doses: 1.5 mL/kg bolus; epinephrine ≤1 mcg/kg (ASRA 2020)
- Aortic Dissection and Hypertensive EmergencyIV antihypertensives: Clevidipine: 1–2 mg/h, double every 90 s (max 32): Lipid emulsion: egg and soy allergy
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Sources
- FDA label: Intralipid 20% (2025)
- ASRA LAST checklist (2020)
- Fettiplace and Weinberg 2018 (mechanisms)
- Grunbaum 2016 (lab interference)
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow your local protocols and medical direction.