Prospectives of Solid Self-microemulsifying Systems in Novel Drug Delivery

More than 60% of the new chemical entities are lipophilic in nature. Low aqueous solubility and low oral bioavailability is the major concern for these drugs for successful formulations into oral dosage form. Self-microemulsifying drug delivery system (SMEDDS) has gained much attention. SMEDDS are isotropic mixtures of oil, surfactant and co-surfactant that rapidly disperse in gastrointestinal fluid yielding micro/nano-emulsion containing solubilized drug which is absorbed by lymphatic pathway thereby bypassing hepatic first pass effect. Liquid SMEDDS formulations have some drawbacks out of which stability is major issue. Therefore liquid SMEDDS now has been converted into solid - SMEDDS by various techniques such as spray drying, spray cooling, super critical fluid technology, using adsorption carriers. Adsorption using solid carriers (Neusilin, Fujicalin, and dextran) is the successful inexpensive technique at initial research level whereas other requires expensive instrumentation. Current review focuses on biopharmaceutical aspects, characterization of SMEDDS and excipients used in the formulation, techniques used for conversion of liquid SMEDDS to solid SMEDDS (including examples of various research reports where these techniques are used). Various adsorbent carriers (alongwith their different features) which have been reported in research papers have been detailed. It thoroughly covers patent literature on SMEDDS and research carried on solid SMEDDS as well which is the most imperative part of the review.