Self-emulsifying drug delivery systems (SEDDS) possess unparalleled potential in improving oral bioavailability of poorly water-soluble drugs. Following their oral administration, these systems rapidly disperse in gastrointestinal fluids, yielding micro- or nanoemulsions containing the solubilized drug. Owing to its miniscule globule size, the micro/nanoemulsifed drug can easily be absorbed through lymphatic pathways, bypassing the hepatic first-pass effect. We present an exhaustive and updated account of numerous literature reports and patents on diverse types of self-emulsifying drug formulations, with emphasis on their formulation, characterization, and systematic optimization strategies. Recent advancements in various methodologies employed to characterize their globule size and shape, ability to encapsulate the drug, gastrointestinal and thermodynamic stability, rheological characteristics, and so forth, are discussed comprehensively to guide the formula-tor in preparing an effective and robust SEDDS formulation. Also, this exhaustive review offers an explicit discussion on vital applications of the SEDDS in bioavailability enhancement of various drugs, outlining an overview on myriad in vitro, in situ, and ex vivo techniques to assess the absorption and/ or permeation potential of drugs incorporated in the SEDDS in animal and cell line models, and the subsequent absorption pathways followed by them. In short, the current article furnishes an updated compilation of wide-ranging information on all the requisite vistas of the self-emulsifying formulations, thus paving the way for accelerated progress into the SEDDS application in pharmaceutical research.

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Nimesulide, a non-steroidal anti-inflammatory drug, was incorporated into multilamellar liposomes to improve its performance on topical administration. The drug was loaded onto liposomes employing thin film hydration technique. Various process and formulation variables were investigated to obtain the liposomal products of desired quality. Liposomes were monitored for percent drug entrapment, after separating the unentrapped drug by mini column centrifugation, for vesicular properties (such as size distribution profile, morphological attributes and agglomeration tendency), drug diffused through synthetic semipermeable membrane, and drug leakage. Systematic optimization studies were carried out using 3(2) factorial design to select the optimized liposomal composition with reference to percent drug entrapment, drug diffusion and leakage. The optimized batch of liposomes was subjected to drug permeation and drug retention studies employing rat skin and human cadaver skin. In comparison to methanolic solution of pure nimesulide, liposomal formulations were found to retain higher amounts of nimesulide in the skin. Anti-inflammatory studies, using carragenan-induced rat paw edema model, indicated significantly better performance of liposomally entrapped nimesulide in comparison to the marketed gel formulation and the Carbopol gel containing nimesulide.

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One of the biggest challenges confronting the contemporary drug delivery science today is to improve on the oral bioavailability of a vast number of drugs exhibiting poor and inconsistent gastrointestinal absorption. Self-emulsifying drug delivery systems (SEDDS) have been proved as highly useful technological innovations to surmount such bioavailability hiccups by virtue of their diminutive globule size, higher solubilization tendency for hydro-phobic drugs, robust formulation advantages, and easier scalability in the industrial milieu. Besides, these systems are also known to inhibit the P-glycoprotein (P-gp) efflux, reduce metabolism by gut Cytochrome P-450 enzymes, and circumnavigate the hepatic first-pass effect, facilitating absorption of drugs via intestinal lymphatic pathways. In the last two decades, the phenomenal success of SEDDS as a potential tool for oral delivery of drugs has extrapolated their applications to non-oral delivery also. Various innovative approaches and patented techniques have been reported on formulation of diverse oral and non-oral self-emulsifying (SE) systems not only of various synthetic and semisynthetic drugs, but also of several phytopharmaceuticals, nutraceuticals, and biological macromolecules. Of late, an escalating number of reports have been pouring in on special types of SE systems, mostly nanosized, employing functional excipients such as polar lipids, phospholipids, cellulosic polymer, diblock polymers, etc. This review paper provides an updated bird's-eye view account on the publications and patents of such novel SE approaches for use in both oral and non-oral therapeutics. Providing a relatively pithy overview, this paper thus endeavors to act as a repertoire of knowledge and know-how to guide the product development scientist in formulating variegated SE systems.