Fat Emulsions (Monograph)

Drug class: Caloric Agents
VA class: TN300
CAS number: 8001-23-8

Medically reviewed by Drugs.com on Dec 23, 2024. Written by ASHP.

Introduction

Fat emulsions are caloric agents that contain soybean oil or a combination of soybean and safflower oils as a source of fatty acids for parenteral nutrition.

Uses for Fat Emulsions

Fat emulsions are used as a source of calories and essential fatty acids for patients requiring parenteral nutrition of extended duration (usually longer than 5 days). Fat emulsions are also used as a source of essential fatty acids for patients with an essential fatty acid deficiency (EFAD). The essential fatty acids contained in fat emulsions can prevent or correct the biochemical abnormalities of EFAD and the clinical manifestations of EFAD syndrome, including eczematous, desquamative dermatitis usually occurring in skin folds; poor hair growth or loss of hair; decreased intraocular pressure; impaired wound healing; hepatic dysfunction; anemia; thrombocytopenia; and, in infants, growth retardation.

Fat emulsions generally are used in combination with amino acid and dextrose injections during parenteral nutrition. Dosage, route of administration (peripheral or central IV), and concomitant infusion of protein and other nonprotein calories depend on various factors including nutritional and metabolic status of the patient, anticipated duration of parenteral nutritional support, and tolerance of the veins.

For further information on chemistry and stability, pharmacology, uses, cautions, and dosage and administration of fat emulsions, and specialized references on nutritional support, the manufacturers’ labeling should be consulted.

Pharmacology

Fat emulsions are metabolized and used as a source of calories, resulting in increased heat production and oxygen consumption and decreased respiratory quotient. Following IV infusion of fat emulsions, the fat particles are removed from the systemic circulation in a manner generally believed to be similar to the enzymatic clearance of chylomicrons produced endogenously after enteral fat intake. Following IV infusion of fat emulsions, a transient increase in plasma triglyceride concentrations occurs. The triglycerides are hydrolyzed to free fatty acids and glycerol by lipoprotein lipase. The resulting free fatty acids may enter tissues where they undergo oxidation or resynthesis into triglycerides for storage. Free fatty acids also may circulate bound to albumin in plasma and subsequently may undergo hepatic oxidation or conversion to very low-density lipoproteins (VLDL) that reenter the systemic circulation.

Egg phosphatides present in fat emulsions contain the saturated and unsaturated fatty acid residues present in neutral fats. Phosphatides are the hydrophobic components of membranes that provide electrically insulated membrane layers and are involved in the formation of membrane structures. Phosphatides also contain the choline or ethanolamine ester of phosphoric acid. Choline inhibits fat deposition in the liver.

Glycerin present in fat emulsions is metabolized to carbon dioxide and glycogen or is used in the synthesis of body fats.

Chemistry

Fat emulsions are oil-in-water emulsions containing soybean oil or a combination of soybean and safflower oils as a source of fatty acids in water for injection. These emulsions contain emulsified fat particles of approximately 0.33–0.5 µm in diameter, similar to that of naturally occurring chylomicrons. The oils consist of a mixture of neutral triglycerides of principally unsaturated fatty acids. The principal component fatty acids of the commercially available fat emulsions are linoleic, oleic, palmitic, linolenic, and stearic acids. The commercially available fat emulsions contain egg phosphatides as an emulsifying agent and glycerin to adjust tonicity.

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