Jyothishmathi College of Pharmacy, Rangareddy, Hyderabad, India
A B S T R A C T
The oral delivery of hydrophobic drugs represents a major challenge because of the low aqueous solubility. Self micro emulsifying drug delivery systems (SMEDDSs) have gained exposure for their ability to increase bioavailability and solubility of poorly soluble drugs. SMEDDS are isotropic mixtures of oils, surfactants/solvents and co-solvents/co-surfactants can be used for the design of formulations in order to improve the oral absorption of highly hydrophobic drug compounds. SMEDDS can be orally administered in soft or hard gelatin capsules and form fine relatively stable oil-in-water (o/w) emulsions upon aqueous dilution owing to the gastro intestinal motility of the gastrointestinal fluids. The efficiency of oral absorption of the drug compound from the SMEDDS depends on many formulation related parameters, like surfactant concentration, oil/surfactant ratio, polarity of the emulsion, droplet size and charge, all of which in together grouped to determine the self-emulsification ability. Thus, only very specific pharmaceutical excipient combinations will lead to efficient self-micro emulsifying systems. Although many studies have been carried out, there are few drug products on the pharmaceutical market formulated as SMEDDS confirming the difficulty of formulating lipophilic drug compounds into such formulations. Significant improvement in the oral bioavailability of these drug compounds has been explained for each case. The fact that almost 40% of the new drug compounds are lipophilic in nature states that studies with SMEDDS will continue, and more drug compounds formulated as SMEDDS will reach the pharmaceutical market in the future.
Keywords: Self-micro emulsifying drug delivery systems (SMEDDSs), Lipophillic / hydrophobic compound, Aqueous solubility, Droplet Size, Oral Bioavailability.