Numerous drug delivery systems for conveyance of drugs into the body (via different routes) are continuously being explored in order to treat and combat the ever increasing disease rates (Raffa et al., 2018). In the treatment regime, most commonly used route of drug delivery has been  oral route as it has many perks including highest patient compliance, cost effectiveness, minimum requirements for sterility, comfort of self- administration, a cascade  of options to construct dosage forms and luxury of self –administration by the patient (Goldberg et al., 2003).  For achieving optimized drug levels in the  circulation for the drug to show  therapeutic activity, firstly it has to pass through  biological membrane and be transported in the blood supply to be bioavailable (Behrens et al., 2002). However few challenges are faced in the oral administration of the drug. The main problematic areas are of drug dissolution, solubility of the chemical moities and the drug permeability (Alany, 2017). Approximately, 40% of the modern day drug molecules show poor aqueous solubility that provides major hindrance in the efficient oral delivery (Lipinski, 2002). Drug solubilization in the gastrointestinal cavity is the rate-limiting step for absorption of such drugs. Since majority of the recently developed drugs exhibit lipophilic character, hence they show limited dissolution in the gastric fluids that leads to limited absorption and low permeability of drugs through the gastric mucosal membrane.

 To overcome all these problems different strategies can be adopted such salt formulation, micro-ionization, inclusion in cyclo-dextrin, entrapment in micro/nanoparticles, loading in solid dispersion, solubility in lipid-based systems, mixed micelles, use of silica based mesoporous materials have been employed to enhance drug solubility (Vemula et al., 2010).

Modification of the conventional drug delivery systems of the existing drug entities into a new dosage forms can significantly enhance the efficacy of the drug. A few drugs have an ideal concentration spectrum that provides the maximum therapeutic effect while drug concentrations beyond the range of this spectrum can prove to be sub-therapeutic or toxic for the body (Hamada et al., 2012). The exceptionally moderate advancement in the treatment regimen calls for a dire need to implement a multidisciplinary research approach for the conveyance of optimal drug therapy (Orive et al., 2004). Conventional dosage forms involve the formulation of the drug into an appropriate form such as a compressed pill for the oral administration or an alternative for intravenous delivery. These dosage forms are known to have some serious limitations in terms of higher dosage requirement, below average drug efficacy, poor bioavailability, toxicity and side effects (Wilczewska et al., 2012).

Novel drug delivery systems (NDDS) are being developed to overcome hindrances encountered by conventional modes of drug delivery systems to enable health experts to provide optimal treatments (Barbe et al., 2004).

 NDDS have a number of advantages such as enhanced drug efficacy, targeted delivery, low toxicity, improved patience compliance, controlled or sustained delivery of the drug, increased drug stability, ease of drug solubilization and a maximum number of treatment options. Newly introduced systems include phyto-somes, lipo-somes, nano-particles, dendrimers, liquid crystals, etho-somes, micro-spheres, pro-niosomes, nio-somes, hydrogels and self- emulsifying drug delivery systems (Yue et al., 2010). Lipid- based systems are preferable over other systems as the drug is kept in the solubilized state until complete absorption thus conquering the hindrance of slow dissolution rates of the drug (Porter et al., 2007).  Among the lipid based systems, SEDDS is the most promising as it not only improves the drug solubilization but also enhances the drug particle diffusion across the gastrointestinal tract, membrane permeability and lymphatic absorption due to  presence of surfactants, mediums and oils (Pouton et al., 2010).  

Self-emulsifying drug delivery systems can be defined as isotropic systems of natural or synthetic oils, solid or liquid surfactants, or one or more hydrophilic co-solvents or surfactants (Tang et al., 2008). The first step in the preparation of SEDDS is agitation and then dilution in aqueous media such as in gastrointestinal fluids that render the system to form oil in water emulsion. The principle involved here is speculated to be the combined action of specificpharmaceutical excipients with low free energy. The droplets that are formed on the formation of emulsion are responsible for the increased surface area, rapid release of drug in the dissolved form or mixed micelle and transportation of drug through the unstirred water layer to the GI membrane for absorption (Gursoy et al., 2004). Another advantage of SEDDS is that the lipid SEDDS increase the lymphatic drug transport by facilitating the lipoprotein formation and increasing intestinal lymphatic liquid flux which enhances overall drug uptake and hence increases bioavailability of drug.