LECTURER'S NAME: PROF DR HALIZA KATAS
PROCEDURE:
0.1g Tragacanth
0.3g Tragacanth
TITLE:
Assessment of the Effects of Different Compositions
of Ingredients Used on the Characteristics of a Suspension Formulation
AIM:
To study the effects of using different amounts of tragacanth on a
suspension formulation
INTRODUCTION:
Suspensions
possess certain advantages over other dosage forms. Some drugs are insoluble in
all acceptable media and must, therefore, be administered as a tablet, capsule,
or as a suspension. Because of their liquid character, suspensions represent an
ideal dosage form for patients who have difficulty swallowing tablets or
capsules. This factor is of particular importance in administration of drugs to
children. Suspensions of insoluble drugs may also be used externally, often as
protective agents. Suspensions also possess some disadvantages relative to
other dosage forms. The primary disadvantage is their physical instability;
i.e., that they tend to settle over time leading to a lack of uniformity of
dose. This can, however, be minimized by careful formulation and by shaking the
suspension before each dose is delivered. An additional disadvantage is that
the texture of suspensions may be unpleasant to patients and should be
carefully considered during formulation. A suspension formulation is a type of
disperse system where the insoluble solid particles are dispersed homogenously
in the liquid phase. A good suspension must be in a homogenous form after
shaking, easily poured from the container, has a uniform solid particle size
and possess better feel and taste. Sediment that is formed upon storage has to
be easily redispersed after shaking, forming homogenous suspension. Suspension
can be 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 pharmaceutical practice, suspension is used to improve the
stability of the active ingredient, taste, and bioavailability.
APPARATUS:
Weighing balance
|
Viscometer
|
Weighing boat
|
1
centrifugation tube 15ml
|
Mortar and pestle
|
pipette (1ml) and bulb-pipette
|
Plastic bottle 150ml
|
Measuring
cylinder 200ml
|
Centrifugation equipment
|
Measuring cylinder 50ml
|
100ml beaker
|
MATERIALS:
Chalk
|
Double-strength Chloroform Water
|
Tragacanth
|
Concentrated
Peppermint Water
|
Syrup BP
|
Distilled water
|
PROCEDURE:
1.
A suspension of
Paediatric Chalk Mixture (150ml) is prepared using the formulation
below:
Chalk 3g
Tragacanth
Refer to table 1
Concentrated Peppermint
Water
0.6mL
Syrup
BP 15mL
Double Strength
Chloroform
Water
75mL
Distilled Water,
q.s. 150mL
|
Table
1
Paediatric
Chalk Mixture
|
Group
|
Tragacanth
(g)
|
I
|
1,
5, 9
|
0.0
|
II
|
2,
6, 10
|
0.1
|
III
|
3,
7, 11
|
0.3
|
IV
|
4,
8, 12
|
0.5
|
2. Some
of the suspension formed (5ml) 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 the 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. The
remaining suspension (95ml) is poured into a 100ml beaker and viscosity of the
suspension formed is determined using a viscometer.
5. 10ml
of suspension is poured into a centrifugation tube and the height of the solid
phase formed after centrifugation (1000rpm, 5 minutes, and 25°C) is determined.
RESULTS:
1. Height of suspension formed in the cylinder in
0,5,10,15,20,25,30,35,40,45,50,55 and 60 min
Time/min
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
Height/mm
|
11.9
|
11.9
|
11.8
|
11.7
|
11.7
|
11.4
|
11.2
|
11.1
|
10.8
|
10.7
|
10.6
|
10.6
|
10.4
|
2.
Viscosity of
suspension formed
0.0g Tragacanth
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (Cp)
|
1.9
|
1.8
|
2.0
|
3.0
|
3.4
|
4.2
|
Average + SD
|
2.72±0.9766
|
|||||
0.1g Tragacanth
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (Cp)
|
1.5
|
1.3
|
1.6
|
1.2
|
1.6
|
1.2
|
Average + SD
|
1.4±0.1835
|
|||||
0.3g Tragacanth
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (Cp)
|
3.4
|
3.7
|
3.8
|
3.9
|
4.0
|
3.8
|
Average + SD
|
3.767±0.2066
|
|||||
0.5g Tragacanth
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (Cp)
|
2.3
|
3.4
|
2.7
|
3.2
|
2.8
|
3.5
|
Average + SD
|
2.98±0.4622
|
|||||
3.
Height of
suspension after undergo centrifudge (1000rpm,5 minute, 25 ˚C )
0.0g Tragacanth
Height (mm)
|
|
Before centrifuge
|
24
|
After centrifuge
|
6
|
Height ratio before
and after centrifuged
|
4:1
|
0.1g Tragacanth
Height (mm)
|
|
Before centrifuge
|
0
|
After centrifuge
|
10
|
Height ratio before
and after centrifuged
|
0:10
|
0.3g Tragacanth
Height (mm)
|
|
Before centrifuge
|
7.9
|
After centrifuge
|
1.4
|
Height ratio before
and after centrifuged
|
7.9 : 1.4
|
DISCUSSION
1.
Compare the
physical characteristics of the suspensions and give your comment.
Physical
characteristic
|
Paediatric Chalk
Mixture
|
|||
I
|
II
|
III
|
IV
|
|
Texture
-smoothness
-viscosity
-redispersibility
|
||||
+
|
++
|
+++
|
++++
|
|
+
|
++
|
+++
|
++++
|
|
++++
|
+++
|
++
|
+
|
|
Clarity
|
Cloudy
|
Cloudy
|
Cloudy
|
Cloudy
|
Colour
|
White
|
Milky white
|
Milky white
|
Milky white
|
Layer
|
2 layers
|
1 layer
|
1 layer
|
1
layer
|
Mixture I does not contain any Tragacanth in
their formulation. Thus, the suspension has a rough or less smooth and less
viscous texture. However, it is easy to redisperse when shaken. It forms 2
layers where one is clear and another one is white. Mixture II, III and IV
contain 0.01g, 0.03g and 0.05g of Tragacanth respectively. The increasing
weight of Tragacanth makes the texture become smoother and more viscous. The
three suspensions share the same characteristics like cloudy, milky white and
one layer.
2.
Plot a graph
of UV absorption against time. Explain.
Time/min
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
Height/mm
|
11.9
|
11.9
|
11.8
|
11.7
|
11.7
|
11.4
|
11.2
|
11.1
|
10.8
|
10.7
|
10.6
|
10.6
|
10.4
|
The graph above shows the
relationship between the heights of sedimentation with time. The suspension was
white in colour, we need to use some light to observe the sedimentation clearly
to avoid from making error. As observed on the graph, it is shows that the
longer time taken the lower the heights of sedimentation. The result shows
error as the correct observation should have increased heights of sedimentation
instead of decreasing heights of sedimentation. This may be due to reading error or the mistake in the procedure during the experiments.
3.
Plot the
graph of height of solid phase against time for different amount of tragacanth
in the suspension. Give your comment.
Time (minute)
|
Height of the
sediment (millimetre)
|
|||||||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
||
Amount of
tragacanth (g)
|
0
|
95
|
20
|
16.5
|
14.5
|
13.5
|
13
|
13
|
13
|
13
|
13
|
13
|
13
|
13
|
0.1
|
11.95
|
11.85
|
11.7
|
11.6
|
11.6
|
11.6
|
11.3
|
11.2
|
11.05
|
11
|
10.9
|
10.85
|
10.65
|
|
0.3
|
0
|
4.5
|
8
|
8
|
11
|
11.5
|
19
|
32
|
32
|
32
|
34.5
|
34.5
|
34.5
|
|
0.5
|
0
|
1.25
|
4.5
|
8.5
|
10
|
13
|
16.5
|
18
|
19.5
|
21
|
21
|
21
|
21
|
|
The graph above shows the
relationship of the height of sedimentation with time for four different
suspensions that contain different amounts of tragacanth. From the graph, it
shows that the more the tragacanth content, the more the sediment formed. The experiment
show incorrect results which may be due to experimental error.
By concept, the height of sediment
decreases as the weight of tragacanth increases. The more the tragacanth
content, the less the sediment formed. Suspension which contains more tragacanth
is more stable as the tragacanth is the suspending agent. It is added to reduce
sedimentation by structuring the continuous phase to produce a deflocculated
system. For formulation with optimum amount of tragacanth, the system is stable
and no slow flocculation occurs. A good suspension is a suspension that the
sedimentation process does not happen quickly when the suspension is shaken.
This is to allow that all the material in the suspension can disperse for a
longer time to increase the efficiency of suspension administration.
The curve of 0.0g and 0.1g
tragacanth illustrates decreasing formation of sediments. This observation is
incorrect as along the time, the amount of sedimentation should be increased.
This may be due to reading or experimental errors during the experiment.
However, in the curve 0.0g tragacanth, initial formation of sedimentation is
high. This can be explained due to the absence of tragacanth (suspending agent)
and in which the system becomes not stable and the particles tend to flocculate
and sediment easily.
4. Explain briefly the mechanism of viscometer analysis. Plot a graph of viscosity of the suspension versus the amount of tragacanth (g). Give explanation.
Viscometer is a device that used to measure
and determines the viscosity of a sample fluid. A rotational viscometer is used
in this experiment. When immersed in a sample fluid, the rotational viscometer
senses torque (twisting force) required to rotate a spindle at constant speed
to calculate the viscosity of the fluid. The measured torque is proportional to
the dynamic viscosity. Different viscosity of sample fluid requires different
type of the spindle to have an accurate measurement on the viscosity. A more
viscous suspension should use a thinner spindle and vice versa. Typical
rotational viscometer consists of one cylinder rotating inside another
stationary cylinder. The sample fluid will occupy the gap in between the two
cylinders which will in turn resist rotation. The torque required to maintain
constant rotational rate while overcoming viscous resistance and it is
correlated with viscosity. Thus it can be said that the dynamic viscosity is
proportional to the measured torque. The continuous changes in magnetic field
cause the rotor magnet to spin. Thus, viscosity measurement is a direct
correlation between fluid friction and applied torque. This measured data is
then converted to a viscosity value and output to the users. The standard
rotational viscometer is common used for measuring the viscosity of
non-Newtonian fluids either in chemical or food industries.
Amount
of Tragacanth (g)
|
0.0
|
0.1
|
0.3
|
0.5
|
Viscosity
(cP)
(average±SD)
|
2.99±0.2650
|
1.93±0.5250
|
4.18±0.4000
|
2.95±0.0300
|
Tragacanth is a
suspending agent that is used to suspend the chalk powder in this experiment.
The viscosity of the suspension increasing with the increasing amount of
Tragacanth added. Thus, a more stable suspension can be formed. From the graph
plotted based on the result obtained from the experiment, it showed that the
viscosity of the suspension increases gradually with the increase amount of
Tragacanth added. Formulation III with
0.3g Tragacanth is the most viscous suspension in this experiment with an
average viscosity of 4.18cP. The least viscous suspension is Formulation II
which has 0.1g Tragacanth record an average viscosity of 1.93cP.
5.
Plot a graph
of height of ratio of sediment as a result of centrifugation vs. weight of
Tragacanth. Give explanation.
From the graph, the height ratio is increased as the volume of
tragacanth increased. However, this result is not correct due to experiment
error which might due to incorrect handling of the experiment procedure .The
actual result should be decreased of height ratio when the volume of tragacanth
increased. This is because tragacanth acts as a suspending agent and can ensure
stability of suspension.
Thus, more adding of tracaganth powder, slower the sedimentation rate
and separation of the suspension will be lesser. An ideal suspension is where
it has low viscosity after shear is applied and high viscosity when there is no
shear. A suspension has to be pour readily and evenly.
6.
What is the
function of each ingredient used in the suspension preparation? How does the
different amount of Tragacanth powder affect the physical characteristics and
stability of the suspension formulation?
The suspension has chalk, tragacanth,
peppermint oil, syrup, double strength chloroform water and distilled water.
Chalk is the active ingredient of the
suspension, tragacanth as suspending agent, peppermint oil as flavouring, syrup
as vehicle of drug; double strength chloroform water gives preservative
properties and distilled water as the vehicle.
Tragacanth is the suspending agent or
thickening agent which can ensure stability of suspension. In fact, suspension
consists of solid as dispersed phase and liquid as dispersed medium. Without
any suspending agent, solid will collide each other, form granules which then
sediment to form caking. This process is known as sedimentation which is
affected by diameter of particle, difference of density between dispersed phase
and continuous phase, gravity and viscosity of medium.
When we add tragacanth, it will adsorb
on solid surface, reduces surface tension and free energy. Initially,
suspension is thermodynamically unstable, solid particles tend to form granules
due to high surface tension. When tragacanth is added, reduced surface tension
will prevent these solid particles to collide each other. So, no larger
granules are formed. As diameter of solid particles is small, so the rate of
sedimentation is decreased (according to Stoke’s equation).
An ideal suspension has high viscosity
when there is no shear but low viscosity when we apply shear on it. Generally,
suspension has to be therapeutically active, physical and chemical stable and
has good appealing. Specifically, a good suspension can be poured readily and
evenly, uniform particle size range in the suspension and suitable viscosity.
Therefore, tragacanth or any other suspending agent must added to the
formulation to ensure stability of suspension.
CONCLUSION:
Tragacanth plays an important
role in suspension formulation. An increase amount of tragacanth show that the
formulation needs a longer time to suspend and the suspended material will
retain much longer in the formulations. Suspension with 0.1g tracaganth is only
slightly viscous, indicating that it can be redispersed readily upon shaking.
Different amount of Tragacanth powder will affect the rate of sedimentation,
the height of sediment formed and viscosity of suspension.
REFERENCES:
1. Ghosal & Srivastava,
2009. Fundamentals of Bio analytical Techniques And Instrumentation. PHI
Learning Pvt. Ltd.
2. John F. Marriott,
Pharmaceutical Compounding and Dispensing, 2006, Pharmaceutical Press Sdn Bhd
