Computer- aided formulation development - Computer-Aided Applications in Pharmaceutical Technology - page 22

A back propagation (BP) network was well trained by experimental data
pairs and then used as an interpolating function to estimate the stability
of emulsions of different formulations. It was found that multiple w/o/w
emulsions could be prepared by using mixtures of Span 80 and Tween 80
with different mass ratio as both lipophilic and hydrophilic emulsifi ers.
The stability is sensitive to the mixed HLB numbers and concentration of
the emulsifi ers. By feeding the ANN with 39 pairs of experimental data,
the ANN was well trained and could predict the infl uences of several
formulation variables on the immediate emulsions stability. The validation
test indicated that the immediate stability of the emulsions predicted by
the ANN was in good agreement with measured values. The ANN
therefore could be a powerful tool for rapid screening for emulsifi er
formulation.
Different optimization techniques, for example experimental design
using response surface modeling or ANN method, could be used to
determine the optimal cosmetic formulations, such as depilatory cream
or an o/w emulsion vehicle for a permanent hair dye (Moulai Mostefa
et al., 2006; Balfagon et al., 2010).

2.3 Application of computer-aided
techniques in development of
microemulsion drug carriers

Microemulsions are thermodynamically stable and optically isotropic
transparent colloidal systems consisting of water, oil, and surfactant.
Although they are clear, low viscous liquids, the different types of
microstructures are identifi ed (i.e. w/o, o/w, and bicontinuous), all
organized on the level below 100 nm. The microstructure of
microemulsions is determined by physicochemical properties and
concentrations of the constituents. Such unique systems, as well as their
water-free preconcentrates, so-called self-microemulsifying oil/surfactant
mixtures, are of increasing interest as potential drug delivery vehicles
with long-term stability, considerable capacity for drug solubilization,
and great potential for bioavailability enhancement (Fanun, 2009).
Development of such carriers requires a complex strategy balancing all
relevant aspects. In systems consisting of water, oil, and tenside(s), a
diverse range of colloidal systems and coarse dispersions may form (e.g.
emulsions, microemulsions, micelles, lyotropic liquid crystals), depending
on physicochemical properties and quantitative ratios of constituents and

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