Emulsions are manufactured by a high shear-mixing process, such as homogenization.
Manufacturing
process
Emulsions
are manufactured by a high shear-mixing process, such as homogenization. The
two phases of the emulsion are assembled separately, by dissolving and mixing
of the ingredients to form appropriate solutions. Then, phases are combined by
slow addition of the dispersed phase into the continuous phase with continuous
mixing. An optimum amount of mixing shear and time are determined based on the
rate of change of the size distri-bution of the dispersed phase with mixing.
The resulting emulsion can then be packaged and/or dispensed.
The
sequence of addition of formulation ingredients to the emulsion can be critical
for the stability of the emulsion. For example, if an o/w emul-sion is desired
and the system contains two surfactants with different HLB values, the
surfactant with the higher HLB value should be added first.
In
addition, volatile ingredients, such as flavors, and thermosensitive
ingredients should be added last, after the emulsion has been formed, to
minimize loss during processing. The API may be predissolved in one of the
phases or added last depending on drug’s solubility, stability, and
par-titioning properties.
Self-emulsifying
and self-microemulsifying drug delivery systems are manufactured as nonaqueous
preconcentrates by simple mixing to dis-solve all ingredients. The resulting
formulations can then be packaged in single or multidose containers for
distribution. In cases where the SEDDS or the SMEDDS is to be administered as a
unit dose without dilution prior to administration, the dosage form can be
packaged in a soft gelatin capsule.
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