Lipid Based Parenteral Drug Delivery System

Lipid-based drug delivery systems in the form of triglyceride emulsions, micellar systems and liposomes have been used for parenteral administration for the last few decades. Large number of new chemical entities (NCE) presents formulation and bioavailability problems because of the dose and poor solubility in solvent and co-solvent systems. In addition, high drug concentrations can lead to irritation and pain at the site of injection. There is an increasing interest to expand the range of targetable lipid based systems to solubilize a wide variety of drugs, to improve stability, ease of processing and manufacture in a sterile form. New class of parenteral lipid based drug delivery system includes Tocol emulsions, solid lipid nanoparticles and nanosuspensions, sterically stabilized phospholipid micelles, lipid microbubbles and lipoprotein drug carriers. This review article covers the challenges faced by the formulation scientist at each stage of product development of lipid based drug delivery system. INTRODUCTION : In the past, surfactant systems as well as phospholipids emulsified triglyceride emulsions have been used as drug carriers for parenteral nutrition. Since many drugs are hydrophobic, they are sufficiently soluble in vegetable oils to enable the formulations like drug-loaded emulsions e.g. the intravenous anaesthetic Propofol. Lipid based drug delivery system are described under following titles like tocol emulsions, solid lipid nanoparticles and nanosuspensions, sterically stabilized phospholipid micelles, lipid microbubbles and lipoprotein drug carriers respectively. Tocols: Tocols represent a family of tocopherols, tocotrienols, and their derivatives. They are fundamentally derived from the simplest tocopherol, 6-hydroxy-2-methyl-2-phytylchroman, which is also referred as ‘‘tocol’’. The most common tocol is D-αtocopherol, also known as vitamin E. Tocols can be an excellent solvents for water insoluble drugs and are compatible with other cosolvents, oils and surfactants, ‘‘solubility in vitamin E’’ parameter (SVE) to predict solubility of a drug in vitamin E. SVE can be defined as the solubility in chloroform divided by the solubility in methanol, expressed in mg/ml. An SVE of greater than 10, preferably greater than 100, would indicate solubility in vitamin E. Many tocol emulsions have been developed like Paclitaxel emulsion, an antineoplastic drug .