Title
Assessment on the Impact of Different Ingredients on the Characteristics of an Ointment Formulations
Date
31st March 2015
Objective
- To investigate the effects produced in response to the use of different amount of tragacanth in the suspension formulations.
Introduction
A
suspension formulation is a type of disperse system which disperses the solid
phase in the liquid phase. It is normally used in suspending the liquid-insoluble
active ingredients to maintain the efficiency of the active ingredients. So,
the active ingredient can distribute well in the liquid vehicle and performs a
good bioavailability. A
good suspension must stay in homogenous state after being shaken and be easy to
be poured out from the container. It also can improve its attractive taste and
texture.
Suspension
can be classified as coarse suspension where the particle diameter is more than
1 µm, or colloidal suspension where the particle size is less than 1 µm. The normal
size of the solid particles recommended must be larger than 1 micrometer.
A normal suspension is
composed of active ingredient (solid phase) dispersed in the liquid carrier, suspending
agent, flavoring agent and coloring agent. The suspending agent plays an
important role in suspension formulation as it helps in reducing the surface
tension between solid particle and liquid. So, the solid particles can
distribute well in liquid carrier. The example of the suspending agent is
tragacanth.
Apparatus & Materials
Chloroform
Distilled water
Methanol
Developing chamber
TLC plate
Filter paper
Chloramphenicol eye drops
Chloramphenicol powder
Acetone
Mefenamic acid in Ponstan capsules
Iodine
Procedures
1) Formulations of Pediatric Chalk Mixture (150ml)
was prepared by the following formulation.
Chalk
|
3g
|
Tragacanth
|
Referred
to table 1
|
Concentrated Cinnamon Water
|
0.6ml
|
Syrup BP
|
15ml
|
Double Strength Chloroform Water
|
75ml
|
Distilled Water, q.s.
|
150ml
|
Table 1
Pediatric Chalk Mixture
|
Group
|
Tragacanth(g)
|
I
|
1,5
|
0.0
|
II
|
2,6
|
0.1
|
III
|
3,7
|
0.3
|
IV
|
4,8
|
0.5
|
2) 5ml of suspension was poured into the weighing
boat and labeled. Texture, clarity and color of the suspension formed was
described and compared.
3) 50ml of suspension was poured into 50ml
measureable cylinder. Height of the solid phase precipitated in the cylinder
was measured at the interval of 0,5,10,15,20,25,30,35,40,50,60 minutes.
4) The rest of suspension (95ml) was poured into
100ml beaker and the viscosity of the suspension was measured by a viscometer.
5) 10ml of suspension was poured into
centrifugation tube and the height of the solid phase was measured after the
centrifugation(1000rpm, 5 minutes, and 25oC)
Results
Viscosity
0.0g Tragacanth
Readings
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity
(cP)
|
0.50
|
0.50
|
0.70
|
0.50
|
0.00
|
0.50
|
Average ±
SD
|
0.45 ±
0.21
|
|||||
0.1g Tragacanth
Readings
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity
(cP)
|
1.00
|
0.50
|
0.50
|
0.50
|
0.50
|
0.50
|
Average ±
SD
|
0.58 ± 0.19
|
|||||
0.3g Tragacanth
Readings
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity
(cP)
|
2.00
|
1.50
|
1.50
|
1.50
|
1.50
|
1.50
|
Average ±
SD
|
1.58 ±
0.19
|
|||||
0.5g Tragacanth
Readings
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity
(cP)
|
2.00
|
4.50
|
4.00
|
4.50
|
4.00
|
4.00
|
Average ±
SD
|
3.83 ±
0.85
|
|||||
Questions
1. Compare the
physical features of the suspensions formed and give comments.
0.0g of tragacanth has a more diluted suspension with clear clarity and
it is colourless. 0.1g of tragacanth has
a diluted texture with no clear clarity and it has milky colour. 0.3g of tragacanth has a concentrated
suspension texture with opaque clarity and white colour. 0.5g of tragacanth has a more concentrated
suspension with more opaque clarity and it is white colour.
Suspension is a mixture of small particles being dispersed throughout a
liquid. If a suspension is left for a
long period of time, the probability of
the particles to sediment at the bottom of the container is high. The characteristic of a good suspension is
the particles are easily dispersed upon shaking and it takes a longer time
before sediment. Tragacanth is a natural
gum that is being used in pharmaceutical as emulsifier, thickener, stabilizer
and texturant additive.
From the experiment it shows that suspension that has little or no
content of tragacanth appear more dilute meanwhile suspension with higher
content of tragacanth appear more concentrated.
Diluted suspension indicated that most of tragacanth particles undergoes
sedimentation.
2. Plot a graph of height of sediment against time.
Give explanation.
Time (min)
|
Height of sedimentation
(mm)
|
|||||||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
||
Tragacanth (g)
|
0.0
|
0
|
18
|
18
|
12
|
17
|
11
|
11
|
10
|
10
|
10
|
10
|
9
|
9
|
The graph above has shown the
relationship between the height of sediment with time and the amount of
Tragacanth used. Pediatric Chalk Mixture is formulated with 0.0 g Tragacanth
which there is no Tragacanth added in the suspension. Tragacanth is a suspending
agent and works as a thickening agent for the suspension. Thus, it takes a
short period of time of sedimentation in the absence of Tragacanth than
suspension which contains Tragacanth. At t=0, no sedimentation is occured. At
the first five minutes, the suspension starts to sediment at the bottom of the
test tube at 18mm height. It continues to settle rapidly with time. The
sedimentation is complete at 60minutes.
3. Plot a graph of height of sendimentation against time for
the formulations of suspension with different contents of tragacanth.
Time (min)
|
Height of
sedimention (mm)
|
|||||||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
||
Tragacanth (g)
|
0.0
|
0
|
18
|
18
|
12
|
17
|
11
|
11
|
10
|
10
|
10
|
10
|
9
|
9
|
0.1
|
0
|
0
|
0
|
3
|
3
|
3
|
3
|
3
|
4
|
4
|
4
|
4
|
4
|
|
0.3
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
13
|
13
|
13
|
16
|
17
|
17
|
|
0.5
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
The graph above showed that the relationship between the
height of sedimentation with time for four different amounts of tragacanth
which are 0.0 g, 0.1 g, 0.3 g, and 0.5 g. Theoretically, height of
sendimentation will decrease when the amounts of tragacanth increases. This is
because, tragacanth is the suspending agent, which make the suspension more
stable and slowly to sendiment.
For the suspension I that contains 0.0g of tragacanth, at 0
min, the height of sedimentation is 0 mm and the height dramatically increases
after 5 min due to absent of suspending agent. Particles in the suspension
tends to flocculate and therefore will settle to the bottom faster. As the time
passing, the height decrease gradually due to particles filled up the spaces
between the porous structure of sendiment and become more compact. Gradually, the sendiment will forms cake at
the bottom of the measuring cylinder. At the end of sendimentation, the pore
are fully filled with the particles, and therefore left no space for the
particle, so the height will remain constant.
For the suspension II that contains 0.1g of tragacanth the
height of sedimentation for the first 10 min is 0mm, after 10min the height
increase slowly until 40min the height become constant. The slowly increase of
height is because, the amounts of tragacanth is smaller, is not enough to
suspend the particle in the suspension.
For the suspension III that contains 0.3g of tragacanth, the
suspension will sediment in the 40min of experiment. It takes longer time to
sendiment because contains sufficient amount of suspending agent, to make the
suspension stable.
For the suspension IV that contains 0.5g of tragacanth, the
suspension will sediment longer than three suspension above, this is because,
it contains higher amounts of tragacanth that hold the suspension to make it stable.
Thus there is no caking of suspension.
4. Explain briefly the mechanism of viscometer analysis. Plot a graph of viscosity versus weight of Tragacanth(g). Give comments.
The rotational viscometer works by rotating its motorized cylindrical rotor which being inserted into the sample. The rotation speed must be constant. During this experiment, the sample is placed in a beaker. Then, a suitable metal spindle is rotated in the sample at fixed rpm and the torque is measured. Based on the internal resistance to a rotation provided by the shear stress of the sample, the absolute viscosity of it can be determined. The unit of viscosity is centipose (cP), equivalent to mPa.s in SI unit.
Amount of
Tragacanth (g)
|
0.0
|
0.1
|
0.3
|
0.5
|
Viscosity
(Cp) (Ave ± SD)
|
0.45 ±
0.21
|
0.58 ±
0.19
|
1.58 ±
0.19
|
3.83 ± 0.85
|
Tragacanth often used in pharmaceuticals as emulsifier, stabilising agent or thickening agent to help increase the stability of certain formulation. From the graph above, it shows the increase in the viscosity of the formulation in the increase of the amount of tragacanth used in the formulation. Thus, it can be conclude that tragacanth does imparts viscosity to the solution. It is responsible to prevent a formulation from severe sedimentation or caking. However, the viscosity is just sufficient for the formulation to be stable as too high viscosity can cause difficulties of pouring prior to administration as well as affecting drug absorption.
The precaution step in this test include ensuring the right choose of appropriate spindle of the viscometer according to the amount of Tragacanth being used. Although, the preparation steps of the suspension must in the correct way since the viscosity can be affected if wrong amount of substances being used.
6. Plot a graph of height of ratio of sediment as a result of centrifugation vs. amount of tragacanth. Give explanation.
According to the theory, the larger the amount of tragacanth powder added, the smaller the height ratio of the sediment. This is because the tragacanth powder is a type of suspending agent which suspends the solid particles in the liquid vechicle to form a stable suspension. It also increases the viscosity of the solution, which is necessary to prevent sedimentation of the suspended particles. A more stable suspension can be formed by adding larger amount of tragacanth powder into the suspension and less sediment will be formed.
Although the height ratio decreases when the amount of tragacanth added from the value of 0g to 0.1g, the result shows that the height ratio of sediment increases when 0.3g and 0.5 g tragacanth powder is added. This may be due to the parallel error occurred during the experiment. The amount of tragacanth added is not accurately measured and there is some leakage when transferring the suspension into the centrifuge tube. As the value is converted into millimetre unit, some of the group members use the wrong unit to measure the height of the sediment. This causes the wrong recording of the result and may also affect the final result of the experiment.
6. What is the function of each material used in the preparation of this suspension? How the usage of different value of tragacanth can influence the physical properties and stability of a suspension formulation?
According to the theory, the larger the amount of tragacanth powder added, the smaller the height ratio of the sediment. This is because the tragacanth powder is a type of suspending agent which suspends the solid particles in the liquid vechicle to form a stable suspension. It also increases the viscosity of the solution, which is necessary to prevent sedimentation of the suspended particles. A more stable suspension can be formed by adding larger amount of tragacanth powder into the suspension and less sediment will be formed.
Although the height ratio decreases when the amount of tragacanth added from the value of 0g to 0.1g, the result shows that the height ratio of sediment increases when 0.3g and 0.5 g tragacanth powder is added. This may be due to the parallel error occurred during the experiment. The amount of tragacanth added is not accurately measured and there is some leakage when transferring the suspension into the centrifuge tube. As the value is converted into millimetre unit, some of the group members use the wrong unit to measure the height of the sediment. This causes the wrong recording of the result and may also affect the final result of the experiment.
6. What is the function of each material used in the preparation of this suspension? How the usage of different value of tragacanth can influence the physical properties and stability of a suspension formulation?
The function of chalk is as an active ingredient. The
function of tragacanth is it acts as suspending and emulsifying agent. The function of concentrated cinnamon water
is as flavouring agent to mask the taste.
The function of syrup BP is as sweetening agent. The function of double
strength chloroform water is as preservative and sweetening agent. The function of distilled water is as
vehicle.
Different amount of tragacanth can influence the
physical properties and stability of the suspension formulation. According to the experiment carried out small
amount of tragacanth will give diluted suspension with clear clarity and
colourless solution meanwhile a greater amount of tragacanth will give more
concentrated suspension with opaque clarity as well as white colour
solution. Stability of suspension is
also affected with amount of tragacanth used.
Tragacanth is the suspending agent.
Thus, the higher the amount of tragacanth used , the higher the
viscosity of the suspension. This will
prevent the suspended particles to sediment and gives a higher stability of
suspension.
Conclusion
Tragacanth do influences the physical and chemical characteristics of suspensions. Formulation contains no tragacanth will be easily redispersed upon shaking but have very high sedimentation rate. In contrast, the formulation contains high amount of tragacanth will cause difficulties in pouring prior to administration. Thus, the amount of tragacanth to be used in a certain formulation must be calculated correctly to maintain the stability and produce a good suspension.
References
http://www.pformulate.com/labclass/suspendwhatis.cfm
http://www.pharmamirror.com/knowledge-base/pharmaceutical-dictionary/suspensions-definition/
http://www.pharmamirror.com/knowledge-base/pharmaceutical-dictionary/suspensions-definition/
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