Liposomes lecithin applications

In recent years, pharmaceutical patents accounted for almost 25% of the nonfood patent activity. Pharmaceutical applications, particularly those involving liposomes, should require increasing quantities of refined lecithins. An increased demand for lecithin as a dietary supplement is also anticipated, as the result of dietary reference intakes being established for choline. Besides being a multifunctional food ingredient, lecithin has the benefit of being a widely recognized health food. 

Liposomes in which lecithin is included as a component of the bilayer have been used to encapsulate drug substances their potential as novel delivery systems has been investigated. This application generally requires purified lecithins combined in specific proportions. 

For medical or pharmaceutical applications, attention must be paid to the problems that can be caused by the possible toxicity of the surfactant remaining in the final product. Antonietti et al. [89] proposed the use of natural, nontoxic, and nondenaturing surfactants based on mixtures of lecithin and sodium chlolate for the formation of globular microemulsions. Pure lecithin is known to form bilayers or liposomes. The role of sodium cholate is to increase the curvature and flexibility of the interfacial layer, allowing the formation of small droplets. The final microlatex particles have a size ranging from 22 to 40 nm, depending on surfactant composition and concentration. The ability to functionalize the surface of these particles was demonstrated by the incorporation of protein molecules. 

In another excellent study (42). double labeling was carried out. H-Phos-phatidylcholine and C-iretinoin were intercalated in soybean lecithin liposomes and applied on female hairless rat in vivo and on human fdtin in vitro. After 6 and 12 h of in vivo application the distribution of the labels was determined in SC. epidermis, and dermis. These studies revealed that the ratio of the labels in... 

Like cells, only much smaller, spherical objects called liposomes are enclosed by a phospholipid bilayer that separates a watery interior from an external (also watery) environment. Liposomes occur naturally but can also be prepared from lecithin as a phosphatidylcholine source. Following their chance discovery in 1961, liposomes originally received attention as models for membrane structure. Subsequently, their use as novel vehicles for drug delivery was demonstrated and has led to important applications in medicine. 

Another important class of surfactants in cosmetics is the phospholipids (e.g., lecithin obtained from egg yolk or soybean), which are used as emulsifiers as well as for the formation of liposomes and vesicles. Liposomes are multi-lamellar bUayers of phospholipids that on sonication produce singular bilayers or vesicles. They are ideal systems for cosmetic applications. They offer a convenient method for solubilizing water insoluble active substances in the hydrocarbon core of the bilayer. They will always form a lamellar liquid crystalline structure on the skin and, therefore, they do not disrupt the structure of the stratum comeum. Phospholipid liposomes may be used as an indicator for studying skin irritation by surfactants. 

Lecithin is also used for the preparation of liposomes and vesicles which are ideal for drug delivery. This is due to their high degree of biocompatability, in particular for intravenous application. Liposomes can solubilize lipid soluble drugs in the hydrocarbon core of the bilayers, whereas water-soluble drugs can be solubilized in the aqueous film between the bilayers. 

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