TITLE:
The use of wetting
agent in suspension
OBJECTIVE:
To determine the effect
of different amount of tragacanth on the sedimentation rates of
suspensions.
INTRODUCTION:
Suspensions are
heterogenous systems consisting of at least two phases which are the continuous
or external phase and
dispersed or internal phase. Common pharmaceutical products that are
suspensions are ear
drops, enemas, inhalations, lotions and mixtures for oral use.
Suspensions possess
certain advantages as dosage forms which are the insoluble drugs may be
more palatable or
stable, the suspended insoluble powders are easy to swallow and absorption
will be quicker than
solid dosage forms. However, suspensions also possess some disadvantages
which are the
preparation requires shaking before use, the accuracy of dose is likely to be
less
than with equivalent
solution and storage conditions can affect disperse system.
Diffusible suspensions
are suspensions containing light powders which are insoluble or only very
slightly soluble in the
vehicle but which on shaking disperse evenly throughout the vehicle for
long enough to allow an
accurate dose to be poured. Indiffusible suspensions are suspensions
containing heavy
powders which are insoluble in the vehicle and which on shaking do not
disperse evenly
throughout the vehicle long enough to allow an accurate dose to be poured. In
the preparation of
indiffusible suspensions, the main difference when compared to diffusible
suspensions is that the
vehicle must be thickened to slow down the rate at which the powder
settles. This is
achieved by the addition of a suspending agent. The most common suspending
agent used is
Tragacanth BP.
MATERIALS AND METHODOLOGY:
APPARATUS:
1 x 1 mL graduated
pipette 1 x 100 mL
beaker
1 x pipette bulb
Parafilm
1 x weighing boat 1 x
Weighing balance
1 x set of mortar and
pestle 1 x
Viscometer
1 x 50 mL graduated
cylinder
1 x 200 mL graduated
cylinder
MATERIALS:
Chalk
Distilled water
Double strength
chloroform water Syrup BP
Tragacanth Concentrated
peppermint water(or any flavouring agent)
METHODOLOGY:
1. A suspension of Pediatric Chalk Mixture (150 mL)
was prepared according to the following
formula :
Ingredient
|
Suspension
|
||
A
|
B
|
D
|
|
Chalk
(g)
|
3
|
3
|
3
|
Tragacanth
(g)
|
0.0
|
0.1
|
0.5
|
Concentrated
peppermint water (mL)
|
0.6
|
0.6
|
0.6
|
Syrup
BP (mL)
|
15
|
15
|
15
|
Double
Strength Chloroform water (mL)
|
75
|
75
|
75
|
Distilled
water q.s. (mL)
|
150
|
150
|
150
|
2. 5mL of the suspension was poured into a weighing
boat and each formulation was labelled.
The
texture, clarity and colour of each suspension was compared.
3. The sedimentation rate of each suspension was
determined. The suspension was shaked
vigorously
making sure all of the particles are uniformly suspended, and the time was
noted.
The
boundary between the sediment and the supernatant was observed and the time it
takes for
the
boundary to pass each 10mL graduation until the volume of sediment has reached
80mL
was
recorded.
4. The grated cylinder was set down on the lab bench
and the lab timer was started at this point.
5. For suspensions A to D, the sedimentation volume
of the suspensions was recorded at t= 0, 2,
5, 10, 15,
and 30 min.
6. The
obtained data was recorded in the following table:
Suspension
|
Sedimentation
volume at pre-determined time (min)
|
Distinct
boundary (yes/no)
|
|||||
0
|
2
|
5
|
10
|
15
|
30
|
||
A
|
|||||||
B
|
|||||||
D
|
|||||||
7. The sedimentation volume ratio was calculated
using the following formula:
Sedimentation
volume ratio = Hu/Ho
Hu: ultimate height of the sediment, i.e., the
height of the sediment at a particular time
Ho: initial height of the total suspension
8. The ease
of re-dispersibility of each formulation was examined after the last
measurement. To
do this:
i. The Parafilm was snugged on the mouth of the
graduated cylinder, and re-enforce the seal with
your
gloved hand.
ii. The number of inversions it takes to completely
re-disperse the drug was counted.
iii. The observations were recorded.
9. 95mL of suspensions was poured into a 100mL
beaker and the viscosity of the suspension was
determined
using a viscometer at 12 000 rpm for 2 min.
10. The data
was recorded in the following table:
Suspension
|
A
|
B
|
D
|
Viscosity
(cP)
|
|||
Mean
|
|||
SD
|
11. Each suspension was poured into a plastic
bottle. After storing all the suspensions for a
period of
5 days, the ease of redispersion in each system and which system is most
acceptable
were
determined.
RESULT:
2.
Texture
|
clarity
|
colour
|
|
A
|
Very dilute
|
Clear when still
|
Very light milky white
|
B
|
concentrated
|
Cloudy when still
|
Light milky white
|
D
|
Very concentrated
|
Opaque when still
|
Milky white
|
3.
Suspension
|
Pass each 10
mL graduation (min)
|
|
90
|
80
|
|
A
|
0.69
|
0.88
|
B
|
4.53
|
5.37
|
D
|
>15
|
>15
|
6.
Suspension
|
Sedimentation volume at pre-determined time(min)
|
Distinct boundary (yes/no)
|
|||||
0
|
2
|
5
|
10
|
15
|
20
|
||
A
|
100mL
|
88mL
|
80mL
|
76mL
|
73mL
|
70mL
|
Yes
|
B
|
100mL
|
100mL
|
77mL
|
73mL
|
68mL
|
62mL
|
No
|
D
|
100mL
|
100mL
|
100mL
|
100mL
|
100mL
|
100mL
|
No
|
7. Sedimentation volume ratio:
Sedimentation volume ratio:Hu/Ho
Hu: ultimate height of the sediment
Ho: initial height of total suspension
Suspension
|
Sedimentation
volume ratio (Hu/Ho) at pre-determined time(min)
|
|||||
0
|
2
|
5
|
10
|
15
|
30
|
|
A
|
1
|
88:100
|
80:100
|
76:100
|
73:100
|
70:100
|
B
|
1
|
1
|
77:100
|
73:100
|
68:100
|
62:100
|
D
|
1
|
1
|
1
|
1
|
1
|
1
|
8.
Suspension
|
No of inversions
it takes to completely re-disperse the drug
|
A
|
1
|
B
|
2
|
D
|
3
|
10.
Suspension
|
A
|
B
|
D
|
||||||
Viscosity(cP)
|
5.76
|
5.58
|
5.58
|
6.69
|
6.54
|
6.21
|
7.87
|
7.55
|
7.42
|
Mean
|
5.67
|
6.48
|
7.61
|
||||||
SD
|
0.58
|
0.20
|
0.29
|
||||||
Standard deviation
formula :
Mean formula:
11.
Suspension
|
Ease of re-dispersion after storing all the
suspensions for a period of 4
|
A
|
Easy
|
B
|
Less easy
|
D
|
Difficult
|
DISCUSSION:
1. Compare and discuss physical appearances of all
the suspensions produce
Texture
|
clarity
|
Colour
|
|
A
|
Very dilute
|
Clear when still
|
Very light milky white
|
B
|
concentrated
|
Cloudy when still
|
Light milky white
|
D
|
Very concentrated
|
Opaque when still
|
Milky white
|
2. Plot Hu /
Ho vs. time for each of the suspensions (Table 1). Discuss the findings.
Sedimentation
volume ratio:Hu/Ho
Hu: ultimate height of the sediment
Ho: initial height of total suspension
Suspension
|
Sedimentation volume ratio (Hu/Ho)
at pre-determined time(min)
|
|||||
0
|
2
|
5
|
10
|
15
|
30
|
|
A
|
1
|
88:100
|
80:100
|
76:100
|
73:100
|
70:100
|
B
|
1
|
1
|
77:100
|
73:100
|
68:100
|
62:100
|
D
|
1
|
1
|
1
|
1
|
1
|
1
|
The graph above shows a
relationship between Hu/Ho versus time. As the time increases, the
sedimentation volume ratio decreases. Each
product contains different amount of tragacanth. In
this experiment,
tragacanth is been used as manipulative data. Suspension A contains 0.0g
tragacanth while
Suspension B contains 0.1g tragacanth and Suspension D contains 0.3g
tragacanth. The higher
the amount of tragacanth in a suspension, the slower the sedimentation
rate.
Tragacanth has been
used in pharmaceutical product as binding agents. Binding agents are
used to impart cohesiveness to the granules and gives it a sufficient strength.
This is to prevent
them from crumbling. It
is also to impart plasticity and thus increase the interparticulate bonding
strength within the
tablet.
3. Briefly explain the principle of analysis using
viscometer. Plot the viscosity vs tragacanth
Content
(Table 2). Discuss the findings.
Viscometers
measure the viscosity and flow properties of fluids . Viscosity arises from the
internal
friction of a fluid and is defined as a liquid’s resistance to flow or shear
stress.
Suspension
|
A
|
B
|
D
|
Amount of tragacanth (g)
|
0.0
|
0.1
|
0.5
|
Viscosity (cP)
|
5.67
|
6.48
|
7.61
|
From the experiment, the result obtained show that
the larger the amount of tragacanth, the more viscous the suspension is. The
amount of suspending agent used in any given formulation depends on the volume
of vehicle being thickened. It does not vary with the amount of powder in the
preparation. A suspending agent is intended to increase the viscosity of the
vehicle and therefore slow down the sedimentation rates.
4. After storing the suspensions for a period of 4
days, determine the ease of re-dispersion of
each.
Suspension
|
Ease of re-dispersion after storing all the
suspensions for a period of 4
|
A
|
Easy
|
B
|
Less easy
|
D
|
Difficult
|
5. Based on all the observations, which product
would be considered to be most acceptable?
Explain.
Suspension D because it has the highest
amount of tragacanth (0.5g) which acts as a
suspending agent compared to SuspensionA (0
g) and B (0.1g). The stability and physical
properties of suspension will be affected
by using different amount of Tragacanth. It slower
the rate of dispersion and make the vehicle
become more viscous. Ideal suspension must
possess characteristics such as it should
be readily re-dispersed just by gentle shaking, it settle
slowly and the suspension should pour readily and evenly from its
container. That is why
Suspension D is the
most acceptable because it possess the characteristics. The easy
redispersion of sedimented particles in a
suspension is vital for the uniformity of dose. The
viscosity of suspension also should be
maintained at the optimum range so that it will not
cause difficulty in administration and
pouring. Thus, when amount of tragacanth powder
increase,
sedimentation rate will occur more slowly and thus sediment height will be
lower.
6. Briefly explain the function of each excipients
used in the suspension formulation. Explain the
influence
of tragacanth on the physical characteristics and stability of a suspension.
Chalk is
the active ingredient in this formulation of suspension. The function of chalk
is as
absorbent
that absorb excessive fluid in watery faeces and make it more solid. Syrup BP
function
as a sweetening and also as a flavoring agent, Double strength Chloroform Water
is
used as
preservative. As suspension contains moisture , it is susceptible to microbial
growth ,
thus
preservatives need to be added. Water used as a vehicle and bulking agent to
add volume
up to 150
ml. Concentrated peppermint water is used as flavoring agent that gives the
preparation
a nice scent. Tragacanth act as a thickening agent in the suspension. It
increases
the
viscosity of a solution . It also increases the stability of the preparation ,
where the
suspended
particles take a longer time to settle at the bottom as the amount of the
tragacanth
increase
and easily redispersed when the suspension is agigated. Different amount of
tragacanth
use in the suspension causes the suspension to have different texture,
appearance
and
colour. The more Tragacanth uses , the
more viscous the suspension as Tragacanth is a
thickening
agent. Higher amount of Tragacanth uses also appears to be more cloudy as it is
better
dispersed. And the colour of suspension lso look more stable , as the suspended
solid
take a
longer time to sediment at the bottom when the tragacanth used in increasing
amount.
CONCLUSION:
The effect of different amount of tragacanth on the
sedimentation rates of suspensions was
determined.
REFERENCE:
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