Phospholipid-stabilized emulsions compounds

Phospholipid-stabilized intravenous emulsions have been widely used for parenteral nutrition and have also been introduced as drug carrier systems, especially for lipophilic compounds. The aim of the authors in the next papers we review here (50,51) was to consider in detail various mediods, c.g., PCS. nuclear magnetic resonance (NMR). transmission electron micnoscopiy (TEM). and small-angle x-ray diffraction studies (SAXS), to determine parameters related to the internal structure of the particle in a model intravenous emulsion stabilized by phospholipids. An emulsion with an extremely high fat load and a classical emulsifier was chosen. PCS measurements were used to derive a particle size distnbu-tion and this was then us ) to calculate the total oil droplet surface area. The result indicated that there should be an excess of surfactants of 150%. Such an excess was not confirmed by either NMR or SAXS measurements and the dis-... 

Food formulations are complex colloidal systems that may contain water and oil, fat substances, protein aggregates, salts, and soluble carbohydrates, and starch granules or gels. Emulsifiers present a special challenge as regards their safety and the stability of emulsions. Compounds used include mono- and digylcerides, sorbitan fatty acid esters, polyoxyethylene sorbitan esters, and phospholipids. The trend is to use most natural additives as possible, such as proteins and phospholipids (30). 

Propofol is properly named 2,6-diisoproplylphenol. Because there are 12 carbon atoms, this compound is not very soluble in water, and it is much more soluble in hydrophobic solvents. Therefore propofol is formulated as an emulsion2 of the 2,6-diisoproplylphenol suspended in a mixture of soybean oil and water. An egg-based phospholipid (e.g., lecithin) is added to stabilize the emulsion. By the way, you can buy flavored water-soybean oil-lecithin mixtures, but you call it mayonnaise. 

Fluorinated surfactants (or fluorosurfactants, i.e., surfactants with hydrophobic tails comprising a fluorocarbon moiety) provide an alternative means of achieving extremely stable PFC emulsions, as they can provide very low PFC/water interfacial tensions [cr , another factor in Eq. (2)]. d s yet, this option has not been developed, in part because of the added cost involved in the evaluation for approval of a novel active excipient. A further means of effectively increasing the stability of EYP-based PFC emulsion consists of supplementing standard phospholipids with mixed fluorocarbon-hydrocarbon diblock compounds, such as 14 or 15. Such diblocks, which have fluorophilic-lipophilic amphiphilic properties, are expected to improve the adhesion of the phospholipid film onto the PFC droplet. 

Compounds such as (12.227a) can be used in emulsion polymerisation of polystyrene [65]. Di-acetylenic phospholipids such as (12.227b) will form hollow open-ended cylindrical tubes 0.5 mm diameter and up to 300 mm long. Subsequent polymerisation to increase stability can be effected with UV radiation [66,67]. 

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