Emulsion forming drug delivery system for lipophilic drugs

In the recent years, there is a growing interest in the lipid-based formulations for delivery of lipophilic drugs. Due to their potential as therapeutic agents, preferably these lipid soluble drugs are incorporated into inert lipid carriers such as oils, surfactant dispersions, emulsions, liposomes etc. Among them, emulsion forming drug delivery systems appear to be a unique and industrially feasible approach to overcome the problem of low oral bioavailability associated with the BCS class II drugs. Self-emulsifying formulations are ideally isotropic mixtures of oils, surfactants and co-solvents that emulsify to form fine oil in water emulsions when introduced in aqueous media. Fine oil droplets would pass rapidly from stomach and promote wide distribution of drug throughout the GI tract, thereby overcome the slow dissolution step typically observed with solid dosage forms. Recent advances in drug carrier technologies have promulgated the development of novel drug carriers such as control release self-emulsifying pellets, microspheres, tablets, capsules etc. that have boosted the use of "self-emulsification" in drug delivery. This article reviews the different types of formulations and excipients used in emulsion forming drug delivery system to enhance the bioavailability of lipophilic drugs.