The objective of this experiment is to study and evaluate the effects of different content materials on the physical characteristics of the formed suspension.
Introduction
Suspension formulation is a type of dispersed system
where the solid molecules do not dissolved homogenously in the liquid phase. A
good suspension must stay in the state of homogenous after being shaken, be
easy to pour out from the container and having a uniform solid particle size, and
also attractive taste and texture. Precipitation formed from the storage must
be easily dispersed again after shaken and the dispersion formed must be
homogenous. Normally, suspension composed of active ingredient (solid phase)
dispersed in the liquid carrier,
wetting agent, flavoring agent and coloring agent. Wetting agent (ex:
Tragacanth) is used to reduce the surface tension between solid particle and
liquid. Suspension is 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. In pharmaceutics, suspension is used to improve the stability,
the taste and the bioavailability of the active ingredient.
Paediatric Chalk Mixture is a type of antacid
preparation use to treat diarrhoea. The materials that made up this suspension
are such as chalk, tragacanth, concentrated cinnamon water, syrup BP, double
strength chloroform water and distilled water. It is a suspension formulation
thus patients must shake the bottle before using this preparation.
Weighing balance 1
1ml pipette and pipette bulb
1 weighing boat 1
15 ml centrifuge tube
1 set of mortar and pestle 1
100ml beaker
1 150ml plastic bottle Centrifugator
1 50ml measuring cylinder Viscometer
1 200ml measuring cylinder
Materials
Chalk
Syrup BP
Tragacanth Double-strength
chloroform water
Concentrated peppermint water
Distilled water
Procedures and
1.
A formulation of Paediatric Chalk
Mixture suspension (150 mL) is prepared by using this formula:
Table
1
Paediatric Chalk Mixture
|
Group
|
Tragacanth (g)
|
1
|
5
|
0.0
|
2
|
6
|
0.1
|
3
|
7
|
0.3
|
4
|
8
|
0.5
|
Group / Comparison
|
Texture
|
Clarity
|
Colour
|
5
|
More dilute
|
Clear
|
Cloudy
|
6
|
Dilute
|
Not clear
|
Milky, chalky
|
7
|
Concentrated
|
Opaque
|
White
|
8
|
More concentrated
|
Highly opaque
|
White
|
3. 50ml suspension was poured into
a 50ml measuring cylinder and the height of sediment formed in the cylinder is
measured at interval of 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60
minutes.
Time (min)
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
Height (mm)
|
0
|
18
|
15
|
12
|
11
|
10
|
10
|
9
|
9
|
9
|
9
|
9
|
9
|
4. The
rest of the suspension (95 ml) was poured into 100 ml beaker and the viscosity
of the suspension was measured by the viscometer.
When the Tragacanth
used is 0.0g
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
0
|
0
|
2
|
2
|
2
|
3.5
|
Average + SD
|
1.583 ± 1.3571
|
|||||
When the Tragacanth
used is 0.1g
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
2
|
2
|
2
|
3
|
2
|
3
|
Average + SD
|
2.333 ± 0.5164
|
|||||
When the Tragacanth
used is 0.3g
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
2.5
|
1.5
|
2
|
2.5
|
3
|
3.5
|
Average + SD
|
2.5 ± 0.7071
|
|||||
When the Tragacanth
used is 0.5g
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
0
|
10
|
5.5
|
3
|
3
|
3
|
Average + SD
|
4.083 ± 3.3825
|
|||||
Weight of Tragacanth (g)
|
0.0
|
0.1
|
0.3
|
0.5
|
Viscosity(x ± SD)
|
1.583±1.3571
|
2.333±0.5164
|
2.5±0.7071
|
4.083±3.3825
|
5. 10ml
of the suspension was poured into a centrifuge tube.Then,the height of sediment
is determined after centrifugation.(1000rpm, 5 minutes, 25°c)
Discussion
1. Compare the physical appearance of
the suspensions that formed.
The texture
of the solution become more concentrated which directly proportional to the
amount of tragacanth that had been added. When amount of the tragacanth is
zero, the clarity of the solution is very clear due to absence of suspending
agent and the chalk will sediment drastically in high sedimentation rate
compare to the other solutions which the clarity is decrease with the
increasing amount of tragacanth. The higher amount tragacanth cause the
suspension look highly opaque due to low sedimentation rate of suspensoid.
Colour of suspension become white when high amount of suspending agent present
in the solution. Suspending agents causing disperse element become suspense in
long duration and homogenous white colour can be directly observed.
2.
Plot a graph of height of sediment
vs. time. Give explanation.
Time (min)
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
Height (mm)
|
0
|
18
|
15
|
12
|
11
|
10
|
10
|
9
|
9
|
9
|
9
|
9
|
9
|
The graph above is the formation of sediment for
formulation I. Sediment starts once the time started to count.With increasing
the time, the height of the sediment decrease as time goes,the sediment arrange
themselves closer to each other thus forming a more compact
sediment.Sedimentation occurs due to the gravitational forces in which
comparatively large drug particles will be sedimented. The height of the
sediment becomes constant when all the chalk particles are sedimented.
3.
Plot a graph of height of sediment
vs. time for the formulation of suspension that contain varied amount of
Tragacanth. Give explanation.
Time
(minutes)
|
Height
of sediment (mm)
|
|||||||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
||
Amount
of Tragacanth powder (g)
|
0.0
|
0
|
18
|
15
|
12
|
11
|
10
|
10
|
9
|
9
|
9
|
9
|
9
|
9
|
0.1
|
0
|
3
|
3
|
4
|
5
|
5
|
5
|
5
|
5
|
5
|
5
|
5
|
5
|
|
0.2
|
0
|
2
|
4
|
6
|
7
|
8
|
8
|
9
|
9
|
10
|
10
|
10
|
10
|
|
0.3
|
0
|
1
|
3
|
7
|
11
|
15
|
18
|
20
|
20
|
21
|
21
|
21
|
21
|
|
For suspension without
tragacanth, the height of sedimentation increases sharply to 18mm within 5
mintues. However, it decreases gradually after 5 minutes. This is due to the
absence of tragacanth which is the suspending agent. The particles tend to
concentrate and flocculate, eventually the sediment aggregate and form a
compact cake at the bottom of cylinder. During the sedimentation, the smaller
particles tend to fill in the spaces available between larger particles. As the
time goes on, the spaces between particles are fully filled by the smaller
particles and no more spaces are available. This explains the height of
sediment remains the same after 35th minutes.
For suspension with
0.1g tragacanth added, the height of sediment increases slowly until it reach a
plateau of 5mm height at 20th minutes. This occurs because of the
tragacanth which is the suspending agent acts by increasing the viscosity of
dispersion medium. But this little amount is not enough to support the
dispersed phase for long period. Hence, sediment starts to form at 20th
minutes.
For suspension with
0.2g tragacanth added, the height of sediment increases gradually within 40
minutes. At 45th minutes, the sediment of 10mm height only starts to
form. This is due to the higher amount of suspending agent compared to the suspension
above. The greater the amount of suspending agent, the more stable the
suspension is.
For suspension with
0.3g tragacanth added, the height of sediment increases merely 1mm in 5 minutes
time. However, it increases greatly to 21mm at 45th minutes. The
dispersed phase actually remains suspended during this period. There is no
caking occurs due to the high amount of tragacanth powder.
4. Describe briefly the mechanism of
viscometer. Plot a graph of viscosity vs. weight of Tragacanth. Give
explanation.
Tragacanth used in the
formulations acts as the suspending agent which is used to reduce the surface tension and prevent clumping and
allows redispersion. Also, tragacanth acts as the thickening agent due to its
thixothropic property. Hence, it imparts the viscosity to the suspension.
Higher the content of tragacanth used, higher the viscosity of the suspension.
This can be shown in our result. Theoretically, the graph obtained should be
linear as the increasing of the viscosity versus the content of tragacanth
should be in proportional manner. However, non-linear graph is obtained. This
may be due to some errors happened in the experiment. For examples, there are
presence of foreign particulate matters in the suspension and the happening of
technique errors when measuring and reading the cP value.
Weight
of Tragacanth (g)
|
0.0
|
0.1
|
0.3
|
0.5
|
 Ratio
of height ( x ±SD) |
7.00±5.07
|
11.00±5.07
|
17.00±5.07
|
20.00±5.07
|
5. Plot a graph of height of ratio of
sediment as a result of centrifugation vs. weight of Tragacanth. Give
explanation.
From
the result above, we can see that when the weight of the tragacanth increase,
the ratio of the height of sediment will increase as well. In the experiment ,
we have found that the height of sediment have decrease with the weight of the
tragacanth. When the weight of tragacanth increase, the height of the sediment
will decrease. The formation of the sediment is due to the instability of the
suspension, the suspension that contain more tragacanth will be more stable and
less sediment will be formed after centrifugation while the suspension with
less tragacanth will be less stable and more sediment will be formed after the
centrifugation. Tragacanth is a suspending agent that can increase the
viscosity of the solvent and thus the solvent can hold the suspended particles
from settle down for a longer time and thus it is more stable.
6.
What
are the functions each of the materials that have been used in suspension’s
formulation? How different concentration of tragacanths can affect the physical
characteristics and stability of the suspension’s formulation.
Chalk (active
ingredient) as adsorbent which not mix well with watery elements. The
major function of this active ingredient is to treat diarrhea.
Tragacanth (thickening agent) viscous
in nature, it provides thixotrophy to the solution. They increase in viscosity of the solution, which is
necessary to prevent sedimentation of the suspended particles as per Stoke’s’s
law. Besides acting as a suspending agent, they also impart viscosity to the
solution. It is a better thickening agent than acacia. A good suspension should have well developed
thixotropy. At rest the solution is sufficient viscous to prevent sedimentation
and thus aggregation or caking of the particles. When agitation is applied the
viscosity is reduced and provide good flow characteristic from the mouth of
bottle.The physical stability of suspension was mainly dependent on the type of
suspending agent rather than the physical characteristics of the drug.
Concentrated cinnamon water (flavouring
agents) added to increase patient acceptance.
The four basic taste sensations are salty, sweet,
bitter and sour. It has been proposed that certain flavours should be used to
mask these specific taste sensations.
Syrup BP (flavouring agents) employed as a base for medicinal
purposes consists of a concentrated or saturated solution of refined sugar in
distilled water which is thick, viscous liquid
consisting primarily of a solution of sugar in water,
containing a large amount of dissolved sugars but showing little tendency to
deposit crystals. The viscosity arises from the multiple hydrogen
bonds between the dissolved sugar, which has many hydroxyl
(OH) groups, and the water. Technically and scientifically, the term syrup is also
employed to denote viscous, generally residual, liquids, containing substances
other than sugars in solution.
Double
strength chloroform water (preservative) is included in
pharmaceutical dosage form to control the microbial bio burden of the
formulation. Ideally, preservatives should possess a broad spectrum of
antimicrobial activity encompassing Gram-positive and Gram-negative bacteria
and fungi, be chemically and physically stable over the shelf-life of the
product ,have low toxicity, should not be adsorbed on to the container, should
be compatible with other formulation additives and its efficacy should not be
decreased by pH.The naturally occurring suspending
agents such as tragacanth, acacia, xanthan gum are susceptible to microbial
contamination. If suspension is not preserved properly then the increase in
microbial activity may cause stability problem such as loss in suspending
activity of suspending agents, loss of colour, flavour and odour, change in
elegance etc. Antimicrobial activity is potentiated at lower pH.
Distilled water (vehicle) which is as vehicle
to carry all the active ingredients in the pharmaceutical suspensions into
patient’s bodies. The principle of using water in healing and renewing the body has been well
known from early history. Distilled water
is the purest water that can assist in healing process. Higher concentration of
tragacanth cause more opaque, more viscous and more difficult to sediment. For
stability, higher concentrations of tragacanth lead to more stable suspensions.
But too high viscosity is not good in suspension formulation as when it
sediment, it not easily to re-disperse even after we put effort in shaking the
suspension, and then finally cause imbalance and inaccurate dosing. This will
lessen the therapeutic effect of the drug preparation itself.
Conclusion:
Conclusion:
As a conclusion, the assessment here showed that the different composition in the formulation will affect the physical property of the suspension.
References:
Do u all think that 60 minutes are enough for all the insoluble solutes to sediment?
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