K.S. Salunkhe

The oral delivery of lipophilic drugs has a major challenge because of low aqueous solubility of such drugs. Self-microemulsifying drug delivery systems (SMEDDS) have ability to increase solubility and bioavailability of poorly soluble drugs. Self-micro emulsifying drug delivery systems are isotropic mixtures of oil, surfactant, co-surfactant of co-solvents can be used for the design of formulations in order to improve the oral absorption of highly lipophilic drugs. Self micro-emulsifying drug delivery system can be orally administered in hard or soft gelatin capsule and form fine stable emulsion (oil-in-water emulsion) aqueous dilution owing to the gentle agitation of gastrointestinal fluid. Efficiency of oral absorption of the drug from the SMEDDS depends on formulation elated parameters such as concentration of surfactant, co-surfactant, ratio of oil and surfactant, charge and droplet size. Thus, there are few drug products of the pharmaceutical market formulated as SMEDDS confirming the difficulty of formulating hydrophobic drug compounds in to such formulations. The fact that almost 40% of the new drugs are hydrophobic in nature which are studies with SMEDDS will continue and more drug compounds formulated as SMEDDS will reach pharmaceutical market.

Self nanoemulsifying drug delivery (SNEDDS) is used for drugs which exhibit low water solubility. Dissolution is the rate limiting factor for these drugs. SNEDDS are capable of improving the bioavailability substantially of such drugs. They are formulated by utilizing an oil phase, surfactant and a co-surfactant. This formulation forms nano emulsion (O/W type) on contact with aqueous body fluids i.e gastric juices when administered orally. Solid SNEDDS (s-SNEDDS) can also be formulated in the form of tablet which shows greater advantages. With recent and potential future developments, this technology will continue to enable novel applications in drug delivery and overcome limitations associated with the delivery of poorly water soluble drugs, mainly those belonging to BCS class-II and class-IV.