TITLE: Assessment
on the Effects of Different Compositions of Ingredients on the Characteristics
of a Suspension Formulation
INTRODUCTION
A pharmaceutical suspension is a dispersion
formulation in which insoluble solid particles are dispersed in a liquid
medium. A well-formulated suspension must remain sufficiently homogeneous for
at least the period between shaking the container and removing the required
dose. Besides, the suspension must be easy to pour out from the container, has
a uniform solid particle size as well as possesses attractive taste and free
from gritty texture. The sediment produced on storage must be easily redispersed
after shaking, forming a homogeneous suspension.
In general, suspension comprises of an active
ingredient (solid phase) in a liquid medium, a wetting agent, flavouring agent,
colouring agents and preservatives. The function of a wetting agent such as Tragacanth
is to reduce the interfacial tension between the solid particles and the
liquid. Suspension is classified into a coarse suspension where the diameter of
the particles is more than 1 µm, or a colloidal suspension where the particle
size is less than 1 µm. In pharmaceutics, suspension formulation is used to
improve the stability of the active ingredient, taste, and bioavailability of
the product.
OBJECTIVE
To study the
effects of using different amounts of tragacanth on a formulation of suspension
APPARATUS
Weighing
balance
1 set of 1
ml pipette and pipette bulb
Weighing
boat 1 centrifuge
tube (15 ml)
Mortar and pestle 100 ml beaker
150 ml plastic bottle Centrifugator
50 ml measuring cylinder Viscometer
200 ml
measuring cylinder
MATERIALS
Chalk
Syrup BP
Tragacanth Double-strength Chloroform Water
Concentrated Peppermint Water Distilled Water
PROCEDURE
11. A suspension
of Paediatric Chalk Mixture (150ml) is prepared using the formulation
below:
2. 5ml of the suspension formed is poured into
the weighing boat and labelled. State and
compare the texture, clearness and colour of the suspension formed.
3. 50ml of suspension formed is poured into a
50ml measuring cylinder and the height of the solid phase sediment in the
cylinder is measured at intervals of 0, 5, 10, 15, 20, 25, 30, 40, 50 and 60
minutes.
4. Te
remaining suspension (95ml) is poured into a 100ml beaker and viscosity of the
suspension is determined using a viscometer.
5. 10ml of
suspension is poured into a centrifuge tube and the height of the solid phase
formed after centrifugation (1000rpm, 5 minutes, and 25°C) is determined.
RESULTS AND DISCUSSION
1. Compare
the physical appearance of the suspension formed and give your comment.
The color of all
suspensions I, II, III, and IV is white. The Chalk Mixture I contain no
Tragacanth powder and the amount of Tragacanth powder is increasing with Chalk
Mixture II (0.1g), III (0.3g), and IV (0.5g). Tragacanth powder is a suspending
agent. Suspension without Tragacanth powder will separate into two layers with
clear boundary. One layer is the clear liquid phase and another one is the
solid phase. Besides acting as a suspending agent, Tragacanth also act as thickening
agents. They increase the viscosity of suspension, which is necessary to
prevent sedimentation of the suspended particles. By using Tragacanth powder,
suspension is formed where the Chalk is suspended in the liquid and the suspension
becomes not clear and viscous. By using larger amount of Tragacanth powder, the
suspension formed becomes more viscous and cloudy. Besides, the time for
particles to precipitate is longer. This is because as more Tragacanth powder
is used, more Chalk will be suspended and the rate of precipitation will become
slower.
2. Plot a graph height of suspension versus time. Give
comments.
Our suspension mixture contains no Tragacanth, hence
the time taken for the solid to settle down at the bottom of measuring cylinder
is short. Tragacanth is a wetting agent which improves solid solubility in
water by reducing surface tension between solid particles and water.
The
change from 9 mm to 8 mm at 45 minutes is due to the filling of solid particles
between gaps leave by water particles. The deposition of solid at the bottom is
called caking. Fast caking is not a quality of a good suspension.
3. Plotted graph of height of sedimentation
against time for different amount of tragacanth.
For
Tragacanth powder, sedimentation generally does not occur at the beginning due
to the presence of Tragacanth powder as a suspending agent. However, the
sedimentation starts and the height of sediment increases with time. This is
due to the inter–particular attractive forces are stronger than the repulsive
forces of the Tragacanth powder on the chalk particles. Therefore, the
sedimentation formed increases with time until a maximum sedimentation level.
The amount of Tragacanth powder are0.0g,
0.1g, 0.3g, and 0.5g. Based on theory, the more the amount of Tragacanth powder
present, the lower the sediment formed and the time needed for sedimentation to
occur is longer. This is due to the sediment formed in the suspension
containing higher amount of Tragacanth powder is more stable and less
flocculation occur. They need more time for sedimentation to occur
compared to suspension containing less amount of Tragacanth powder. Therefore,
the amount of Tragacanth powder in the formulation will influence the height of
sediment formed and the time for sedimentation of suspension to occur.
But based on the result we observed,
there is increase in volume of sedimentation when the amount of tragacanth is
0.0g, and also decrease in sedimentation when the amount of tragacanth is 0.1g.
there are also about a costatnt height of sedimentation that occur for 0.3g and
0.5g of tragacanth powders. This is maybe due to some errors occur during
experiment. We having a problem during observed and measured the height of
sediment. This is because it is quite difficult for us to observe the
sedimentation height. So, maybe there is error during observation and reading
the height of sediment.
4.
Explain briefly the mechanism of
viscometer analysis. Plot a graph of viscosity of
the suspension versus the amount of Tragacanth (g).
Give explanation.
The viscosity of suspension is measured by using the
viscometer. In this experiment, spindle with greater diameter is needed to
measure the suspension with lower viscosity and smaller diameter spindle is
used to measure a more viscous suspension.
Viscosity is measured by detecting the drag caused by relative motion of
the fluid and a surface with the suspension flow in only one direction.
From
the experiment, the result obtained shows that the greater the content of the
tragacanth, the more viscous the suspension is. However, there showed lower
viscosity of suspension with 0.5g tragacanth in the graph. When the content of
tragacanth is 0.00g, the cP value is 3.03, measure by using a bigger diameter
of spindle. Follow by 4.33 for tragacanth content 0.1g. For the suspension with
0.3g of tragacanth, the mean value of viscosity is 6.58. For the suspension
with 0.5g of tragacanth, the viscosity value is 4.90.
Theoretically,
the viscosity of suspension will increase with the increasing amount of
tragacanth. It is because tragacanth is a suspending agent, addition of
tragacanth will form a more stable suspension with a low sedimentation rate.
Hence, in this experiment, some errors had occurred and affect the accuracy
ofresult. This may be due to the human error in operating the viscometer. So,
the standard deviation value is high as some of the individual reading deviate much
from the mean value. A few precaution steps can be considered to improve the
accuracy of results. For instant, suspension should be stirred properly before
every subsequent measurement is taken. Avoid human error in using the
viscometer and use the correct diameter spindle. Make sure the spindle does not
touch the base of beaker holding the suspension.
6. Plot a
graph of height of ratio of sediment as a result of centrifugation vs. weight
of Tragacanth. Give explanation.
Mean
0.0: (0.176+0.133)/2 = 0.1545
0.1: (0.813+0.750)/2 = 0.7815
0.3: (0.244+0.244)/2 = 0.2440
0.5: (0.256+0.176)/2 = 0.2160
From the graph shown, it can
be seen that in the beginning of
the graph, the suspension without
adding tragacanth has the lowest height ratio. This is because there is no
tragancanth added at the beginning of the experiment. When 0.1g of tragacanth
is added, the height ratio of the solid phase formed increases sharply. When
0.3g and 0.5g of tragacanth are being added respectively, the height ratio
decreases. The results obtained are not so accurate as there might be errors
presence throughout the experiment.
Theoretically, the more the tragacanth used, the larger the height ratio
will be obtained. As tragacanth
is a suspending agent, thus it can be seen that it thickens the suspension and after centrifuging, more solid phase has shown showing that it has stabilised with the chalk and thickening it. Thus, as more
tragacanth use, the more the solid phase can be
found.
7. What is the function of each ingredients used in this
suspension formulation? How does different amount of Tragacanth used can
influence the physical characteristics and the stability of certain suspension?
As the amount of Tragacanth
used increased, the suspension will become more viscous and stable against
coagulation. Tragacanth may increase the viscosity of the aqueous vehicle and
thus slow the rate of sedimentation of the particles but they will also form
adsorbed layers around the particle so that the approach of their surfaces and
aggregation to the coagulated state is hindered. Therefore, there will be less
flocculation and once the sedimentation occurs; the suspension becomes more
difficult to redisperse.
CONCLUSION
The different
amount of Tragacanth powder will affect the rate of sedimentation, the height
of sediment formed and viscosity of suspension formulation.
REFERENCE
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