Glycerides lipid formulations

More importantly, lipid peroxidation can be controlled or minimized by design of formulation. While saturated lipids (e.g., MCTs) will themselves not be susceptible to peroxidation, they may contain sufLcient unsaturated impuritiesto be problematic. Similarly, monounsaturated lipids (e.g., oleic acid glycerides) are much less susceptible to peroxidation. The relative rates of peroxidation of oleic, linoleic, and linolenic acids are 6 64 100, respectively (Swern, 1995). Monounsaturated lipids may, however, may contain polyunsaturated impurities, which will catalyze the oxidation ofthe monounsaturated components (Swern, 1995). Surfactants, particularly those based on PEG, may contain peroxides that can promote lipid peroxidation thus, particular attention should be paid to the purity and source of all formulation components. 

As mentioned, hydrolysis is the other important mechanism by which some lipids (glycerides and phosphoglycerides) degrade and can lead to a reduction in pH due to liberation of free fatty acids this was discussed in Chapter 10 (Part I Parenteral Application). This phenomenon is less important for oral formulations when compared to parenteral products, since the former generally have low amounts of water in the formulation. Hydrolysis could occur on storage if water is absorbed from or through the gelatin shell. 

Typical solid lipids used are glycerides and/or fatty acids, and may constitute 30% of the formulation. These are from the same family of lipids found in parenteral nutrition emulsions, such as Intralipid, which have been successfully administered intravenously for several decades. Typical excipients are Dynasan 112, composed of short chain fatty acids, Compritol, lecithin, used as an emulsifier, and surfactants such as polysorbate 80, polaxamer 188, PVP, bile salts such as sodium glycocholate, and Span 85. Water can be replaced with oils or PEG 600 to yield dispersions which can be filled into soft gelatin capsules. 

There are many different polyglycolyzed glycerides and they are generally used to formulate water-insoluble drugs in lipid based formulations such as self-emulsifying drug delivery systems (SEDDS) in order to improve oral... 

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