FACULTY OF
PHRMACY
TECHNOLOGY PHARMACEUTICAL II
NFNF 2263
LABORATORY
REPORT
PRACTICAL 2: SUSPENSION
GROUP B4
LECTURER'S NAME :
DR. NG SHIOW FERN
GROUP MEMBERS:
1. LEE
LI SHAN A136251
2. YIP
LEE ANN A136282
3. MUHAMMAD
SHAHIR BIN ABU BAKAR A136436
4. AINAA
ZURIANI BINTI ABDUL AZIZ A136650
5. NOOR
FARAHIN BINTI ARIFFIN A136602
Title:
Evaluation on the effect of different composition of
tragacanth on the characteristics
of a suspension.
Objective:
To study the effect on the texture, clarity and the
colour of the suspension, the rate of
sedimentation and viscosity of the suspensions of
based on different compositions of
tragacanth used.
Introduction:
Suspension can be divided into
oral, topical, parenteral and ophthalmic. It is a formulation whereby the
insoluble solid is being suspended in a liquid by the aid of suspending agent.
The dispersed phase of a suspension is the solid while the continuous phase is
the liquid. Some drugs are typically stable in the form of suspension rather
than in solution. One of the function of suspension is to mask the bad taste of
some drug. A good suspension should be physically and chemically stable,
resistant to microbial contamination, homogenously dispersed when shaken ,
easily poured and is consist of uniform dispersed size particles. Besides,
suspension should be able to redisperse when the solid particles settled. These
properties are being examined in this experiment.
Wetting agents which is also known as surfactants have to be added because the drugs are not readily suspended in the liquid medium which is the aqueous phase. The examples of suspension are tragacanth which is used in this experiment and sodium lauryl sulphate. The role of surfactant is to reduce the interfacial surface tension between the drug particles and the suspension vehicles. Other excipients added to a suspension include preservatives to prevent microbial growth, colouring agent, syrup to improve the taste and many more. The advantages of suspension are that it improves the stability of the active ingredient, palatability and bioavailability of the formulation.
The physical appearance of the suspension is being studied by observation while the viscosity and rate of sedimentation is being studied using the viscometer and centrifuge.
Apparatus:
Weighing boat, mortar and pestle, 50mL measuring
cylinder, 200mL measuring
cylinder, centrifuge tube, 100mL beaker, pipette,
100mL beaker, Coulter Counter,
Viscometer, Centrifugation machine
Material:
Chalk,
tragacanth, concentrated peppermint water, syrup BP, double strength
chloroform water, and distilled water.
Procedure:
1. Prepare a suspension formulation of Paediatric
Chalk Mixture by using the following formula:
Chalk 3g
Tragacanth refer to
the table below
Concentrated peppermint water 0.6mL
Syrup BP 15mL
Double strength chloform water 75mL
Distilled water, q.s. 150mL
Paediatric 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
|
1. 5 mL of the suspension is poured into a weighing boat and the texture,
clarity and colour of the suspension formed are observed.
2. 50 mL of the suspension is poured into a 50mL measuring cylinder and the
height of the solid phase that is sedimentated at intervals of 5 minutes for 1
hour is measured.
3. The remaining suspension (95mL) is poured into a 100mL beaker and the
viscosity is determined by using the viscometer.
4. 10mL of the suspension is poured into a centrifuge
tube and the height of the solid phase is measured after centrifuging at
1000rpm for 5 minutes at 25°C.
Result :
Result 1 :
Pediatric Chalk Mixture
|
Amount of Tragacanth (g)
|
Physical Appearances
|
I
 |
0.0
|
Texture: watery, easily disperse and sediment, less viscous
Clarity: less cloudy, 2 layers formed
Colour of suspension: less milky
|
II
 |
0.1
|
Texture : less viscous, easily sediment and redisperse
Clarity: opaque
Colour of suspension : milky white
|
III
 |
0.3
|
Texture: less viscous, easily redisperse
Clarity: opaque
Colour of suspension: milky white
|
IV
 |
0.5
|
Texture: viscous, difficult to sediment
Clarity: opaque
Colour of suspension: milky white
|
Result 2:
Time (min)
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
Height (mm)
|
120
|
120
|
118
|
117
|
117
|
117
|
117
|
117
|
116
|
116
|
115
|
115
|
115
|
Result 3:
SUSPENSION I
(0.0g Tragacanth):
Group 1
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
0.5
|
0.0
|
0.5
|
0.5
|
1.0
|
0.5
|
Average + SD
|
0.5 ± 0.289
|
|||||
SUSPENSION II
(0.1g Tragacanth):
Group 2
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
0.5
|
0.5
|
0.5
|
1.5
|
2.0
|
1.0
|
Average + SD
|
1.0 ± 0.577
|
|||||
SUSPENSION III
(0.3g Tragacanth):
Group 3
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
1.5
|
1.5
|
1.5
|
1.5
|
1.5
|
1.5
|
Average + SD
|
1.5 ± 0
|
|||||
SUSPENSION IV
(0.5g Tragacanth):
Group 4
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
20
|
20
|
10
|
10
|
0
|
10
|
Average + SD
|
11.67 ± 6.872
|
|||||
Amount of Tragacanth (g)
|
0.0
|
0.1
|
0.3
|
0.5
|
Viscosity (cP)
(x ± SD)
|
0.5 ± 0.289
|
1.0 ± 0.577
|
1.5 ± 0
|
11.67± 6.872
|
Formula
of standard deviation (SD):
Result 4:
Height (mm)
|
||||
Group 1
|
Group 2
|
Group 3
|
Group 4
|
|
Before centrifuge
|
80
|
80
|
80
|
80
|
After centrifuged
|
17
|
11
|
18
|
19
|
Height separation ratio
|
80/17
|
80/11
|
80/18
|
80/19
|
Amount of tragacanth (g)
|
0.0
|
0.1
|
0.3
|
0.5
|
Height separation ratio
|
80/17
|
80/11
|
80/18
|
80/19
|
Discussion:
1. Compare the
physical appearance of the suspension formed and give the analysis.
In this experiment, Tragacanth powder is used as the
suspending and wetting agent that will decrease interfacial tension between solid
particle and liquid from continuous phase. The suspending agent works by
increasing the viscosity of the liquid vehicle, and thereby slowing down
settling in accordance with Stokes Law. Thus, it reduces the sedimentation rate
of particles in suspension. This will lead to even distribution and allow the
pharmaceutical product to be withdrawn from the container to be consumed by the
consumer.
On prolonged standing suspensions tend to cake as some crystals knit together at point of contact at the bottom of the container. Therefore, a second important function for suspending agents is to facilitate redistribution of a suspension on shaking.
As the amount of Tragacanth added to the formulation is increased, the more viscous the suspensions will be. Besides, the formulation will be more opaque and cloudy. This is because the suspension stays disperse in the medium for a longer time compared to the formulation without Tragacanth. The opacity and the cloudiness indicates that the disperse particles is totally dispersed in the medium.
2. Plot the
graph of height of sedimentation versus time. Give explanation.
Graph of Height of Sedimentation
(mm) against Time (min)
The graph above shows the relationship between the heights of
sedimentation (mm) against time (min). Based on the graph, as the time taken
increases, the height of sedimentation decreases. The suspension was white in
colour. Some light are used to observe the sedimentation clearly to avoid from
making error. For the last 15 minutes, the height of sedimentation of
suspension has become no change which is it maintain at 115 mm. This is because
all of the Tragacanth that is contain in the suspension was already
sedimented.
3. Plot the graph of the height of sedimentation against
time for the suspensions with different composition of tragacanth. Give your
explaination.
|
Time (min)
|
Average height of sedimentation (mm)
|
|||||||||||||
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
||
|
Tragacanth (g)
|
0.0
|
56.50
|
12.00
|
9.00
|
7.75
|
6.75
|
6.00
|
6.00
|
6.00
|
5.50
|
5.50
|
5.50
|
5.50
|
5.50
|
|
0.1
|
44.00
|
42.50
|
43.50
|
43.00
|
42.25
|
41.75
|
41.50
|
41.00
|
41.25
|
41.25
|
41.25
|
41.50
|
41.50
|
|
|
0.3
|
120.50
|
120.00
|
119.00
|
118.00
|
118.00
|
118.00
|
117.00
|
117.00
|
117.00
|
116.50
|
116.50
|
116.50
|
116.50
|
|
|
0.5
|
120.00
|
119.00
|
118.00
|
117.50
|
117.00
|
117.00
|
117.00
|
117.00
|
116.50
|
116.50
|
116.00
|
115.50
|
115.50
|
|
The graph above shows the relationship
of the height of sedimentation with time for four different suspensions that
contain different amounts of tragacanth which are 0.0g, 0.1 g, 0.3g and 0.5g.
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.
However from the graph, it shows that
the more the tragacanth content, the more the sediment formed. This may be due
to the experimental error. In the suspension which is containing 0.0g of
tragacanth, the absence of tragacanth results in quick sedimentation of solid
particles and hence a flocculated system is produced. For the suspension which
is containing 0.5 g amount of tragacanth, the sedimentation gradually formed
with a increase of height.
4. Briefly
explain on mechanism analysis of viscometer. Plot a graft of viscosity against
the amont of tragacanth. Explain.
All
fluids have an internal friction between molecules, and this measures how well
it flows. Due to the internal friction, energy is required to move the liquid
and viscosity is the measure of the resistance to flow. A viscometer measures
the torque required to rotate a spindle in a fluid. The spindle is driven by a
synchronous motor through a calibrated spring and the deflection of the spring
is displayed by the viscometer. By changing speeds and spindles, a variety of
viscosity ranges can be measured. For a given viscosity, the viscous drag, or
resistance to flow (indicated by the degree to which the spring winds up), is
proportional to the spindle's speed of rotation and is related to the spindle's
size and shape. The drag increases with an increase of spindle's size and/or
rotational speed. For a given spindle geometry and speed, an increase in
viscosity will be indicated by an increase in the deflection of the spring. The
minimum range is obtained by using the largest spindle at the highest level;
the maximum range by using the smallest spindle at the slowest speed.
Based on
the graph, viscosity of suspension is directly proportional to the amount of
Tragacanth used. Tragacanth is a suspending agent. Tragacanth performs two
functions. Besides acting as a suspending agent it also imparts viscosity to
the solution. Tragacanth forms a film around particle and decrease
interparticle attraction. It also acts as thickening agent to increase the
viscosity of the solution, which is necessary to prevent sedimentation of the
suspended particles as per Stoke’s’s law.
A good
suspension should have thixotropic properties. At rest the solution is
sufficient viscous to prevent sedimentation and thus aggregation or caking of
the particles. The viscosity is decreased when agitation is applied and thus
provide good flow characteristic from the mouth of bottle. Tragacanth solution
is viscous in nature, it provides thixotrophy to the solution. Thus, the
viscosity of suspension increases as the amount of Tragacanth used increases.The
selection of amount of suspending agent is dependent on the presence of other
suspending agent, presence or absence of other ingredients which have an
ability to act as a suspending agent or which contributes viscosity to the
medium. The concentration of Tragacanth used as suspending agent is around
1-5%.
From the graph, there is a sudden increase in viscosity when 0.5g
of Tragacanth is used. This may due to some errors occurred during the
experiment. This may include technical errors which are related to the
operation of viscometer, such as touching of the sensor at the base of the
container and use of the wrong spindle. Precaution steps should be taken to
minimize the error occurred during experiment. For example,the spindle should
be washed after each measure to remove the liquid left on the sensor because
the residual of the previous liquid may affect the reading of viscometer.
5. Plot
a graph of height of sedimentation formed after centrifuge against the
composition of tragacanth(g). Give your explanations.
For this
part of experiment, we are using centrifuges to investigate the effect of
different amount of tragacanth on the height separation produced from the
suspension after undergoes centrifugation at 1000 rotation per minute for 5
minutes within 25ºC. Based on centrifugation theory, centrifuge helps to
separate suspended material from the mediums they are mixed with. This is done
by spinning closed containers of the mixture very quickly around a fixed
central point. Depending on the rotational speed and distance from the axis of
rotation, centrifugal forces as the driving force, forces the denser material
in the suspension against the walls of the container, effectively separating it
from the solution. Particles of higher density or larger size typically travel
at a faster rate and at some point will be separated from particles less dense
or smaller. This can be explained by Stokes equation.
From the equation above, we can see that the rate of
particle sedimentation is proportional to the particle size, difference in
density between the particle and the medium and the rate may become zero when
the particle density is the same as the medium density. However, the sedimentation rate will decrease
as the medium viscosity increases, whereas increases as the gravitational force
increases. In this experiment, different amount of tragacanth are used which
later give different reading on fraction obtained for centrifugal separation.
So, from the theory, the result would be decreased in the ratio separation as
the amount of tragacanth used increase. On the other hand, from the graph, we
could see that group 2 obtain an increase in the height separation from their
suspension. It could be due to an error that they might mislooked either during
conducting their experiment or error taking from the reading.
Tragacanth
acts as a suspending agent, in which it imparts viscosity to the solution,
besides forming film around particles and decrease interparticle attraction. It
also acts as thickening agent which is important in the increase of viscosity
of the solution that helps in preventing sedimentation of the suspended
particles. Therefore, when the amount of tragacanth used is increased, the
height separation ratio should decrease as tragacanth helps suspend the
particles in the suspension.
6. What is
the function of each material that has been used in preparation of this
suspension? How does the different amount of tragacanth used influence the
physical characteristics and stability of suspension formulation?
Chalk is the active ingredient. Functioning as the
suspending and thickening agent, tragacanth increase the viscosity of the
solution. Tragacanth is also used in order to prevent the sedimentation of the suspended
particles. Concentrated peppermint water act as a flavourant which is able to
mask the unpleasant taste of the drug. On top of that, both Syrup BP
Double-strength Chloroform Water act as the sweetening agent. Syrup BP also
acts as a cosolvent to increase the solubility of the ingredients and prevent
crystallisation. Distilled water is the vehicle for suspension.
The
stability and physical characteristics of suspension depends on the different
amount of tragacanth used in formulation. Tragacanth act as the suspending
agent and thickening agent in suspension formulation. With the increase in the
amount of tragacanth, the viscosity of
suspension will also increase. As such, when the viscosity increases, the terminal settling velocity decreases thus the dispersed phase settle
at a slower rate and they remain dispersed for longer time in suspension. Hence, the stability will also
increase. However, the viscosity will determine the easiness for the suspension
to be poured. Higher viscosity suspension will cause the suspension difficult
to be poured. Thus, the viscosity of suspension should be maintained in an
optimum range for perfect suspension's stability.
By
changing the pH of the suspension, the stability of suspension will also change as a result of steric repulsion force.
There is some relationship between pH and amount of tragacanth used. At lower
pH, the thickness of steric layer increase and will form loops and tail. This
shows the tragacanth changes the conformation on the surface and transforms
flocculated particles into deflocculated particles spontaneously.
The peptization is a result of the conformational
change of the gum tragacanth molecules on the surface, and the
flocculation-deflocculation process is reversible.
Conclusion:
The rate of sedimentation and the height of sediment
formed in the suspension depend on the amount of different Tragacanth powder
used to form the suspension. The higher the amount of Tragacanth powder, the
lower the height of sediment formed. This is due to the action of Tragacanth
powder that prevent the solution from forming sediment.
References:
1. Michael E.Aulton, Aulton’s
Pharmaceutics The Design And Manufacture of Medicines, third edition, 2007,
Churchill Livingstone Elsevier
2.
http://abacus.bates.edu/~ganderso/biology/resources/centrifugation.html
No comments:
Post a Comment