Novel Lipid Carriers for Oral Delivery of Lipophilic Drugs

Most of the new chemical entities discovered today are highly lipophilic in nature and show poor solubility and membrane permeability resulting in poor oral bioavailability. The need for an effective carrier system led to the development of novel lipid based carriers for enhancing the solubility and bioavailability of such drugs Lipids are fatty acids and their derivatives, and substances related biosynthetically or functionally to these compounds. Lipids employed in drug delivery are chemically classified asTriglycerides, Mono/di Glycerides, Propylene glycol esters, fatty acids and phospholipids. These excipients enhance the drug solubility and bioavailability by eitherin vivo solubilisation, prolongation of gastric residence time, promotion of intestinal lymphatic transport, affecting membrane permeability, reduced metabolism and efflux activity or combination of these mechanisms. Microemulsion and nanoemulsions, self emulsifying drug delivery system, solid lipid nanoparticles and nanostructured lipid carriers and liposomes are some of the most widely used novel lipid based carriers. Due to their advantages over traditional lipid based systems and ease of scale up and production has led to commercialisation of some of these formulations. These systems have high potential in replacing the traditional lipid based systems in delivery of poorly soluble drugs.