Original Articles
Ashish Kumar and Arun Nanda
Abstract
Oral delivery of lipophilic drugs having low aqueous solubility presents a major challenge in pharmaceutical product development because these drugs have limited solubility in gastrointestinal fluids and hence have poor absorption and bioavailability. Various pharmaceutical techniques involving chemical modification (e.g. pro-drug, salt formation etc.) or formulation modification (e.g. size reduction, solid dispersion, lipid based drug delivery systems etc.) are available for solubility enhancement of poorly aqueous soluble drugs. The formulation approach is better option than chemical modification approach which may lead to the change in chemical structure which in turn may influence pharmacological activity of drug. Out of various formulation approaches Lipid based drug delivery systems have taken much attention due to their excellent ability to improve the solubility and bioavailability of poorly water soluble drugs and higher degree of biocompatibility. Lipid based drug delivery systems may include emulsions (self emulsifying drug delivery systems), vesicular systems (Liposomes, Neosomes) and particulate system (solid lipid particle). Self emulsifying drug delivery systems are isotropic mixture of natural or synthetic oils, surfactants and/or one or more hydrophilic co-surfactants which upon mild agitation followed by dilution in aqueous media, such as GI fluids, can form fine oil−in−water (o/w) emulsions or microemulsions. Self emulsifying drug delivery systems are gaining popularity in pharmaceutical research and development because of many advantages like reduction in intra-subject and inter-subject variability and food effect, capability to deliver peptides that are prone to enzymatic hydrolysis in GIT, suitable for formulating both liquid and solid dosage form and ease of manufacture and scale-up.