COMPUTER AIDED DRUG
DEVELOPMENT
ASSIGNMENT ON
ROLE OF COMPUTERS IN THE DEVELOPMENT OF
EMULSION
PROFESSOR M.PHARM(PHARMACEUTICS)
PES COLLEGE OF PHARMACY PES COLLEGE OF PHARMACY
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DISCUSS IN DETAIL THE ROLE OF COMPUTERS IN THE
DEVELOPMENT OF EMULSION.
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 emulsifier(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), flocculation,coalescence, Ostwald ripening, and
phase inversion.
Stability and properties of emulsions are influenced by different factors.
Formulation and process optimization techniques would be useful for
finding 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 has started.
FORMULATION:-
The following components are used in emulsions:
1) Oil:- Generally a fatty acid ester / a medium or long chain saturated
,partially unsaturated hydrocarbons are used in the formulation.
2) Water:- water is the second phase used for the preparation of emulsion
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3) Emulsifying Agent:- emulsifying agent is the third substance or agent in
the emulsion which produce a film at the interface between two
immiscible liquids and stabilize the system . these are also called as
emulsifiers or emulgents.
STEPS INVOLVED IN THE DEVELOPMENT OF
EMULSIONS
1) Screening of oils and emulsifying agents
2) Finding the optimized process conditions
3) Formulation optimization
4) Preparation of emulsions
5) Characterization of emulsions
6) Evaluation
1) SCREENING OF OILS AND EMULSIFYING AGENTS FOR
EMULSIONS:-
Surfactants can also be used as emulsifying agent. To find out the
appropriate oil phase and surfactant the solubility of the drug is checked
in various oils along with the surfactants.
The excess amount of the drug is added to oil or surfactant and then the
resulting mixture was shaken reciprocally at 37 0C for 72 hrs followed by
centrifugation for 12 min at 12000 rpm . the supernatant is filtered
through a membrane filter and the drug concentration in the filtrate is
determined using various analytical techniques.
The oil and the surfactant showing the higher solubility was used in the
preparation of emulsion.
The screening oil and emulsifying agents can also be done by using
various optimization techniques like Factorial design :- Fractional
Factorial Design , Plackett Burman Design and D-optimal design
and the desired oil and emulsifying agent can be obtained. The results
can evaluated using Design Expert Software.
2) TO FIND OUT OPTIMISED PROCESS CONDITIONS:-
For the preparation of a stable emulsion it is almost necessary to have
accurate process condition.
The main three process conditions which are considered during the
preparation of emulsions are as follows:-
a) Mixing rate
b) Homogenisation
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c) Mixing time
It has been found that the mixing time and the mixing rate are the most
critical process conditions to be considered during the preparation of
emulsions.
The optimised process conditions can also be found out by using Factorial
Design
3) FORMULATION OPTIMIZATION:-
Optimization of the emulsions is done by using D-optimal experimental
design (mixture design). The results can be evaluated using Expert Design
software.
Eg:- effect of three preservatives benzoic acid , sorbic acid and benzyl
alcohol and be studied using about methods on emulsions.
These optimization my mixture design can be done by using various
softwares like Design Expert , CHEMIX School, JMP etc.
As the simultaneous study of effect different factors on emulsions is
difficult , due to complicated nonlinear correlation , Artificial Neuron
Network (ANN) technique can solve this formulation problem.
4) PREPARATION OF EMULSIONS :-
There are different methods for the preparation of emulsions
a) Phase inversion method
b) Dry gum method
c) Wet gum method
d) Membrane emulsification method
General method of preparation of emulsion is:-
Generally O/W emulsion is prepared by dividing the oily phase completely into
minute globules surrounding each globule with an envelope of emulsifying agent
and finally suspending the globules in the aqueous phase .
Conversely the W/O emulsion is prepared by dividing aqueous phase into small
globules which are surrounded by the film of emulsifying agent and finally
suspended in oily phase.
5) CHARACTERIZATION OF EMULSIONS:
• The globule size of the emulsions was observed usion transmission
electron microscopy.
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• The viscosity is measured by using Brookfield viscometer or by suing
digital viscometer set at particular rpm.
• Electric conductivity is measured using conductivity meter. Based on
electrical conductivity the phase system of emulsion is determined.
• The pH of the emulsion was determines using digital pH meter.
• Appropriate HLB value was also determined .
• The refractive index was measured using thermostated Abbe refractometer.
6) EVALUATION:-
The evaluation of the emulsion is done as follows.
a) Droplet size analysis
It is measured using microscopic method ,electronic counting method
b) Refractive index and % transmittance:-
RI was measured using Abbe’s refractometer and the % transmittance was
measured using UV spectrophotometer.
c) Drug Content:-
The % drug content was estimated by dissolving the emulsion in suitable
solvent and analyzing using UV spectrophotometer .
d) In vitro Dissolution studies:-
It is carried out to assess the drug release. It is carried out using dissolution
apparatus.
Hence the application of computers in the development of the emulsions plays a
vital role and their role is significant in the formulation development.
They are not only used for primary screening but also used for optimization pof
process condition and also formulation .
The specific characteristics of the emulsion like its stability demands the usage
of the computer aided methods which will decrease the time and also the number
of experiments to get stable emulsion .
And also to decrease the formulation failure and thus giving the potential
application of computers in the development of emulsions.
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