Droplet Size. This is a crucial factor in self-emulsification
performance because it determines the rate and extent of
drug release as well as the stability of the emulsion (10, 18).
Photon correlation spectroscopy, microscopic techniques or
a Coulter Nanosizer are mainly used for the determination
of the emulsion droplet size (10, 19, 20). The reduction of
the droplet size to values below 50 μm leads to the formation
of SMEDDSs, which are stable, isotropic and clear o/w
dispersions (6).
Zeta potential measurement. This is used to identify the charge
of the droplets. In conventional SEDDSs, the charge on an
oil droplet is negative due to presence of free fatty acids
(17).
Determination of emulsification time. Self-emulsification time,
dispersibility, appearance and flowability was observed and
scored according to techniques described in H. Shen et al.
(21) used for the grading of formulations.
Application
SEDDS formulation is composed of lipids, surfactants, and
cosolvents. The system has the ability to form an oil-in-water
emulsion when dispersed by an aqueous phase under gentle
agitation. SEDDSs present drugs in a small droplet size and
well-proportioned distribution, and increase the dissolution
and permeability. Furthermore, because drugs can be
loaded in the inner phase and delivered by lymphatic bypass
share, SEDDSs protect drugs against hydrolysis by enzymes
in the GI tract and reduce the presystemic clearance in the
GI mucosa and hepatic first-pass metabolism. Table I shows
the SEDDSs prepared for oral delivery of lipophilic drugs
in recent years.
Conclusion
Self-emulsifying drug delivery systems are a promising approach
for the formulation of drug compounds with poor
aqueous solubility. The oral delivery of hydrophobic drugs
can be made possible by SEDDSs, which have been shown
to substantially improve oral bioavailability. With future
development of this technology, SEDDSs will continue to
enable novel applications in drug delivery and solve problems
associated with the delivery of poorly soluble drugs.
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