Intravenous Fat Emulsion
**Intravenous Fat Emulsion (IFE/ILE)** is a sterile, non-pyrogenic fat emulsion prepared for intravenous administration. Historically utilized primarily as a **parenteral calorie and essential fatty acid source**, it has emerged as a critical **rescue antidote** in veterinary toxicology. It is highly effective for treating life-threatening toxicities caused by highly lipophilic (fat-soluble) drugs when traditional therapies fail. **Key Clinical Applications:** * **Toxicology Rescue:** Local anesthetics (bupivacaine, lidocaine), macrocyclic lactones (ivermectin, moxidectin), calcium channel blockers (amlodipine), beta-blockers, and certain antidepressants/antipsychotics. * **Parenteral Nutrition (PN):** Provides dense calories (approx. 2 kCal/mL for 20% solutions). *Note: Its use in critically ill patients for nutrition is controversial due to potential immunosuppression and infection risks.* > **Clinical Pearl:** Always use the 20% emulsion for toxicology rescue, as the 10% emulsion provides too much fluid volume and the 30% is not formulated for direct IV administration without compounding.
Mechanism: **Toxicologic Mechanism (Antidote):** * **"Lipid Sink" Theory:** IFE creates an expanded intravascular lipid phase. Highly lipophilic toxins partition out of target tissues (e.g., myocardium, CNS) and into this "lipid sink" within the plasma, reducing the free (active) drug concentration at receptor sites. * **Metabolic/Cardiac Enhancement:** Provides a direct energy substrate (free fatty acids) to the myocardium, overcoming mitochondrial lipid metabolism blockade (e.g., by bupivacaine) and increasing intracellular calcium to improve cardiac contractility. **Nutritional Mechanism:** * Provides a dense source of calories and essential fatty acids (linoleic, linolenic acids) necessary for cellular integrity and metabolism.
Dosing by species
- Parenteral Nutrition (PN) · 25-60% of calories administered. Traditionally not recommended at > 2 g/kg/day for TPN therapy. · IV · CRI · As needed · Consult a veterinary nutritionist.
- Rescue agent for fat-soluble drug/toxin intoxication · IFE 20% via a sterile, peripheral IV catheter as a 1.5 mL/kg bolus over 1-3 minutes, then 0.25-0.5 mL/kg/min for 30-60 min. The bolus could be repeated in case of cardiac arrest. If symptomatic after traditional dosing, consider additional doses of 1.5 mL/kg IV over 30 min q4-6h for 24-36 hours until clinical signs resolve, or maintaining a CRI of 0.5 mL/kg/hour until clinical signs resolve. · IV · Bolus followed by CRI · Until clinical signs resolve · Extrapolated from general veterinary/human guidelines.
- Parenteral Nutrition (PN) · 25-60% of calories administered. Traditionally not recommended at > 2 g/kg/day for TPN therapy. · IV · CRI · As needed · Consult a veterinary nutritionist. Keep PPN solutions below 600 mOsm/L.
- Rescue agent for fat-soluble drug/toxin intoxication · IFE 20% via a sterile, peripheral IV catheter as a 1.5 mL/kg bolus over 1-3 minutes, then 0.25-0.5 mL/kg/min for 30-60 min. The bolus could be repeated in case of cardiac arrest. If symptomatic after traditional dosing, consider additional doses of 1.5 mL/kg IV over 30 min q4-6h for 24-36 hours until clinical signs resolve, or maintaining a CRI of 0.5 mL/kg/hour until clinical signs resolve. · IV · Bolus followed by CRI · Until clinical signs resolve · Do not exceed 8 mL/kg/day generally, though this has been exceeded in acute toxicosis without ill effect.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Severe egg yolk allergies
- Abnormal fat metabolism
- Premature and low-birth weight infants (human black box warning)
- Blood coagulation disorders
- Pulmonary disease
- Renal impairment
- Severe liver damage
- Patients at high risk for fat emboli
Adverse effects
- Sepsis or thrombophlebitis (secondary to IV catheterization)
- Fat overload syndrome (hyperlipidemia, hepatomegaly, icterus, splenomegaly, fat embolism, thrombocytopenia, hemolysis, prolonged clotting times)
- Pulmonary toxicity (temporary)
- GI effects
- Somnolence
- Headache
- Flushing
- Pancreatitis
- Hypercoagulability
- Hypersensitivity
Drug interactions
- Lipid Soluble Drugs · IFE may act as a 'lipid sink', reducing the free circulating levels and clinical efficacy of concurrently administered lipophilic medications.
Monitoring
- Serum/plasma drug levels (for toxicology tracking)
- Blood glucose
- Serum triglycerides and gross lipemia
- PCV and Total Protein
- IV catheter site status (phlebitis/sepsis)
- Hydration status and vital signs (temp, HR, RR)
- Serum electrolytes (including phosphorus)
- Renal and liver function tests
- CBC
- Coagulation times (if using heparin)
Overdose
In the event of inadvertent overdose or severe fat overload, **stop the infusion** until the lipid has cleared from the plasma. Clearance can be evaluated visually (inspecting hematocrit tubes for lipemia) or via laboratory methods (triglyceride concentrations, nephelometry). If severe hyperlipidemia occurs during toxicity treatment, **heparin therapy (75-250 Units/kg SQ q6h)** may be considered to increase lipid clearance via lipoprotein lipase activation. However, weigh risks carefully, as heparin may alter the antidote mechanism. Monitor PTT; if PTT exceeds 2-2.5X normal, lower heparin dose (75 Units/kg SQ q6-8h) or discontinue.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.