Phospholipids

Synonyms: Coatsome; glycerol phosphatides; Lipoid; phosphatides; phosphatidic acid; phosphatidylcholine; phosphatidylethanolamine; phosphatidylglycerol; phosphatidylinositol; phosphatidylserine; phosphoglycerides; PhosphoLipid; purified egg yolk PC; sphingomyelin.

Description: Phospholipids occur as white powders. They are sometimes supplied as clear, nearly colorless chloroform or methylene chloride solutions. Phosphatidylglycerols, phosphatidic acids, and phosphatidylserines are available as sodium or ammonium salts. Phospholipids can be purified from natural sources, such as eggs or soybeans, or can be chemically synthesized. Lecithins are partially purified mixtures of naturally occurring phospholipids.

Chemical Name: 

Anionic surfactant; biodegradable material; cationic surfactant; dispersing agent; emulsifying agent; emulsion stabilizer; membraneforming agent; nonionic surfactant; solubilizing agent; suspending agent; wetting agent.

• Phospholipids are amphiphilic molecules and are the major component of most cell membranes.

• They are able to selfassociate and form a variety of structures, including micelles and liposomes

• Numerous pharmaceutical formulations use phospholipids to form various types of liposomes, including unilamellar (one bilayer membrane surrounding an aqueous chamber), multilamellar (two or more concentric membranes, each surrounding an aqueous chamber), and multivesicular (numerous aqueous chambers joined in a honeycomb-like arrangement) liposomes.

• Modified phospholipids have been used to enhance the properties of the resulting liposomes.

• The covalent attachment of polyethylene glycol (PEG) to the phospholipid, or PEGylation, provides steric hindrance to the surface of the liposomes, resulting in decreased uptake by the reticuloendothelial system (RES), also known as the mononuclear phagocyte system, and a prolonged circulation half-life following intravenous administration; the so-called ‘stealth liposomes.’

• Conjugation with antibodies produces immunoliposomes, which are able to target specific cell types and deliver a payload of encapsulated drug.

• Phospholipids can be anionic, cationic, or neutral in charge. Because of their amphiphilic nature, phospholipids will associate at hydrophobic/hydrophilic interfaces.

• The charged lipids can be used to provide electrostatic repulsion and physical stability to suspended particles.

• Thus, they have been used to physically stabilize emulsions and suspensions.

• Phospholipids have also been used in formulations administered as lung surfactants, in intravenous fat emulsions, and in oral solutions (e.g. Rapamune).

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Generally, phospholipids have little or no acute toxicity (i.e. they are well tolerated even when administered at doses in the g/kg range). The clearance of most phospholipids occurs by wellknown metabolic pathways.(

Observe normal precautions appropriate to the circumstances and quantity of the material handled. Eye protection and gloves are recommended.

Lecithin