Computer- aided formulation development - Computer-Aided Applications in Pharmaceutical Technology - page 18

2.1 Introduction

This chapter introduces the concept of formulation development assisted
by computer applications. Due to their complex composition, preparation
and stability issues of emulsions were selected to showcase various
computer-aided tools in pharmaceutical formulation development.
Successful development of an emulsion formulation is dependent on both
formulation ingredients and processing parameters, which is especially
signifi cant for more complex formulation types, such as self-emulsifying
systems or double emulsions. The examples provided illustrate techniques
used to defi ne a design space, select the appropriate formulation
ingredient, and optimize the formulation composition as well as process
parameters, according to the quality-by-design (QbD) concept.
Importantly, methods that allow simultaneous optimization of multiple
factors are also presented. The following chapters will provide a deeper
insight into selected in silico methods.

2.2 Application of computer-aided
techniques in development of
pharmaceutical emulsions

Emulsions are disperse systems made of two immiscible liquids. One
liquid is dispersed into the other, in the presence of surface active agents,
such as emulsifi er(s). The two immiscible liquids are usually oil and
water, and the main types of simple emulsions are oil-in-water (o/w) or
water-in-oil (w/o). In the pharmacy, emulsions have a great potential as
vehicles for active ingredients for different routes of administration
(topical, parenteral, oral). However, emulsions are thermodynamically
unstable systems, and different phenomena during storage could occur,
including gravitational separation (creaming/sedimentation), fl occulation,
coalescence, Ostwald ripening, and phase inversion.
Stability and properties of emulsions are infl uenced by different factors.
Formulation and process optimization techniques would be useful for
fi nding the ideal emulsion formulation. The main parameters relating to
the stability, effectiveness, and safety of the pharmaceutical emulsion
should be optimized simultaneously.
More intense application of different in silico techniques in process
and formulation optimization started at the end of the last century
(Gašperlin et al., 1998, 2000; Prinderre et al., 1998; Simovic et al., 1999).

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