FACULTY OF
PHRMACY
TECHNOLOGY PHARMACEUTICAL II
NFNF 2263
LABORATORY
REPORT
PRACTICAL 3: OINMENT
GROUP B4
LECTURER'S NAME :
DR. HALIZA BINTI KATAS
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
of different effects of ingredients towards the ointment formulation.
Objective:
To
study the effect of ointment composition towards the physical properties of the
ointment and the rate of drugs release from the ointment formulation.
Introduction:
Ointments
are preparations that are used as an external application. Ointment has a
greasy base and this would differentiate it with cream preparations. The base
is usually anhydrous and immiscible with skin secretions. A medicament would
usually be incorporated in the ointment. Sometimes, it can also contain a
mixture of medicaments that is dissolved or dispersed in the base.
Traditionally
the base in an ointment would consist of a mixture of waxes, fats, and oils.
Waxes are usually solid and hard at room temperature. Fats on the other hand would
be semi solid and soft at room
temperature whilst oils would be liquid at room temperature. Wax would render
the ointment to be more smooth and light in its consistency. By altering the
proportions of oil, fat and wax in the ointment may vary the consistency. For
example, if we were to add extra wax, then the ointments would be stiffer
whereas if we were to add more oil, the ointment would be less viscous.
Depending on the storage condition or the climatic condition, this proportion
may vary.
Apparatus: Ingredients:
Weighing
instrument Emulsifying wax
Weighing
boat White soft paraffin
100ml
beaker Liquid paraffin
Heater Acetylsalicylic acid
1 set of cream and
spatula Distilled
water
Mortar and pestle
Dialysis bag (10cm)
Thread
Glass rod
Water-bath
1 set of pipette (5
ml) and pipette-bulb
1 plastic kuvet
Spectrophotometer
UV/Vis
Procedure:
1. 50g
of Emulsifying Ointment was prepared for the following formulation:
Emulsifying
Ointment
|
Ingredients
(g)
|
Total
(g)
|
||
Emulsifying
wax
|
White
soft paraffin
|
Liquid
paraffin
|
||
I
|
21
|
25
|
4
|
50
|
II
|
17
|
25
|
8
|
50
|
III
|
13
|
25
|
12
|
50
|
IV
|
9
|
25
|
16
|
50
|
2.
5 g of cream was taken and put into the weighing boat and was labeled. The
texture, clarity and the color of the cream was described and compared.
3.
1.5 g of Acetylsalicylic acid powder was incorporated into 30 g of cream which
was prepared by levigation technique.
4.
Acetylsalicylic acid was filled into the dialysis bag and the two side of the
bag was tied.
5.
The bag was put into a beaker (200ml) filled with distilled water (100ml) which
was heated to 37°C.
6. Every 5 minutes, one
aliquot sample (3 – 4 ml) was pipette and the release of Acetylsalicylic acid
from the cream base was determined by using spectrometer UV-visible. The
distilled water was stirred with glass rod before the sample was taken
Results
and Discussions:
- Compare the physical appearance of ointment that are formed and discuss.
Top : from left: Group 1, Group 2
Bottom: from left : Group 4, Group 3
A stable ointment is
one that retained its homogeneity throughout its shelf life period. In this
experiment, Group 1 ointment contained 21 g of emulsifying wax and 4 g of
liquid paraffin, Group 2 ointment contained 17 g emulsifying wax and 8 g of
liquid paraffin, Group 3 ointment contained 13 g of emulsifying wax and 12 g of
liquid paraffin whereas, Group 4 ointment contained 9 g of emulsifying wax and
16 g of liquid paraffin. All the four groups are using the same amount of white
soft paraffin which is 25 g. The emulsifying wax varying in quantity for the
four groups, in which higher amount of it may increase the hardness of the
ointment. On the other hand, increased in the amount of liquid paraffin will
contribute to the oily, smooth texture when we touch. However, an ointment that
is too soft is messy to use while if the ointment is very stiff, it is
difficult to extrude and apply.
Based on the picture
above and carefully observation by applying touch testing, Group 1 ointment is to
be found forming a little bit harder texture of ointment when compared to Group
2, 3 and 4. While, Group 4 founded to form an ointment with characteristics of
soft and at the same time an oily texture. In term of spreadibility, ointment
from group 4 is the one that is easily to spread followed by group 3, group 2
and group 1 which is poorly spread. Whereas, for grittiness, group that their
ingredient contained higher amount of emulsifying wax tend to have higher
tendency of obtaining a gritty ointment, which is group 1. For greasiness, group 4 that used higher
amount of liquid paraffin result in a greasy ointment.
There are differences
of colour when we observed carefully through the ointments formed by the four
groups. Group that used high amount of liquid paraffin resulted in a light
white colour of ointment. From the experiment, it is to be found that group 4
ointment tend to possess a light colour of ointment followed by group 3, group
2 and group 1, in which the colour of their ointment tend to intense, forming a
purely white ointment.
2. Plot graph of UV absorption against time and give
explanation.
Time (minutes)
|
UV Absorption
|
||||||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
|
UV Absorption at 300 nm
|
0.025
|
0.069
|
0.080
|
0.103
|
0.153
|
0.163
|
0.187
|
0.272
|
0.278
|
0.334
|
0.326
|
0.403
|
0.489
|
The UV spectrometer
measures the releasing of acetylsalicylic acid from the ointment in the
dialysis bag to the distilled water. The release of the drugs from the ointment
involved the diffusion mechanism. The water is set to 37 0C to mimic
the temperature of human body as ointment will be applied to human skin.
Meanwhile, the dialysis bag represents the skin membrane.
The graph above shows
the relationship between the UV absorption against time for acetylsalicylic
acid ointment. Based on the graph, it shows the gradual increasing in the
absorption of UV. The UV absorption of the ointments increases when the time
increases, which means that the longer the time, the higher the amount of drugs
passing through the membrane or the higher the bioavailability is.
Theoretically, the acceleration of UV absorption at the first 5 minutes is
caused by greater hypertonicity of the content in dialysis bag compared to the
surrounding distilled water.
As the experiment
proceeds, the content in the dialysis bag becomes closer to isotonicity to the
distilled water as some of the acetylsalicylic acid has been moved to the
distilled water. This will result in the reduced gradient of the graph when
time passes by. If the experiment is continued beyond 60 minutes, it may
result in a straight line graph as the concentration of acetylsalicylic acid in
the distilled water equals to the concentration of acetylsalicylic acid at the
dialysis bag.
In this experiment,
some of the precaution steps must be taken during conducting the experiment.
The rope should tie both end of the dialysis bag tightly to prevent leakage of
the ointment. We must also stir the distilled water before sample is taken out
for measurements to ensure uniform distribution of the released active ingredient.
Besides, the smooth surface of the cuvette should not face the source of UV
light and the smooth surface should be cleaned before it is placed into the
device.
3. Result for emulsifying ointment I, II, III and
IV.
Time (min)
|
Average of the UV
absorption at 300nm (x ± SD)
|
||||||
0
|
5
|
10
|
15
|
20
|
25
|
||
Emulsifying Ointment
|
I
|
0.2500±
0.2500
|
0.2650±
0.2550
|
0.2780±
0.2600
|
0.2875±
0.2585
|
0.2975±
0.2575
|
0.3065±
0.2575
|
II
|
0.2455±
0.2175
|
0.2830±
0.2120
|
0.2915±
0.1905
|
0.3305±
0.1635
|
0.3375±
0.1465
|
0.3780±
0.1270
|
|
III
|
0.0930±
0.0630
|
0.0225±
0.0015
|
0.0375±
0.0095
|
0.0415±
0.0195
|
0.0600±
0.0235
|
0.0480±
0.0190
|
|
IV
|
0.0185±
0.0065
|
0.0410±
0.0280
|
0.4065±
0.3935
|
0.0650±
0.0380
|
0.0950±
0.0580
|
0.0980±
0.0650
|
|
Time (min)
|
Average of the UV
absorption at 300nm (x ± SD)
|
|||||||
30
|
35
|
40
|
45
|
50
|
55
|
60
|
||
Emulsifying Ointment
|
I
|
0.3130±
0.2590
|
0.3255±
0.2575
|
0.3375±
0.2625
|
0.3550±
0.2570
|
0.3755±
0.2665
|
0.3895±
0.2615
|
0.3960±
0.256
|
II
|
0.3830±
0.1430
|
0.4115±
0.1015
|
0.4305±
0.0875
|
0.4130±
0.1600
|
0.3885±
0.1325
|
0.4210±
0.1340
|
0.4445±
0.0975
|
|
III
|
0.0690±
0.0530
|
0.0575±
0.0415
|
0.0780±
0.0520
|
0.0810±
0.0580
|
0.0645±
0.0375
|
0.0995±
0.0665
|
0.0595±
0.0105
|
|
IV
|
0.1275±0.0595
|
0.1700±0.1020
|
0.1935±0.0845
|
0.2385±0.0955
|
0.2310±0.0950
|
0.2910±0.1120
|
0.3560±0.1330
|
|
Based on the graph
plotted, it can be seen that emulsifying ointment IV has the highest UV
absorption. This means that the amount of acetylsalicylic acid present in the
solution is the highest. This may be caused by the amount of emulsifying wax
used in this ointment as it is the smallest percentage which is 9g compared to
other ointments. Amount of emulsifying wax used in ointment will affect the
distribution of hydrophilic and hydrophobic phase. Acetylsalicylic acid is a
hydrophilic drug. So, when the dialysis bag is immersed in the water, water
diffuses into the dialysis bag via osmosis. This causes the acetylsalicylic
acid to dissolve in the presence of water. Due to the immiscibility of water
and hydrocarbon base, the dissolved acetylsalicylic acid will diffuse out of
the dialysis bag into the water medium. This causes the UV absorption measured
to be the greatest. From the line graph of emulsifying ointment IV, there is a
sudden increase in the UV absorption value at 10 minute. This may be caused by
experiment procedure error.
On the other hand,
ointment I have the slowest rate of drug released which accounts for its lowest
UV absorption in this experiment. This is because of the high amount of
emulsifying wax which is 21g. This will cause the emulsifying ointment to
become hard and the hydrophilic drug is dispersed into the ointment by the
emulsifying effect. The hardness of the ointment causes the drug to be
difficult to diffuse out into the water.
Emulsifying ointment
II is the second lowest UV absorption value while emulsifying ointment III has
the second highest UV absorption value. This result can be said accurate as the
emulsifying wax used for emulsifying ointment II and III are 17g and 13g
respectively. The UV absorption value of emulsifying ointment III is higher
than ointment II. Therefore, the UV absorption value of emulsifying ointment
III is definitely higher than emulsifying ointment II, which is shown in the
graph. Proper ratio of the two bases will enable optimum and constant release
of drug into the environment. This is because the emulsifying wax will
distribute the drug into hydrocarbon bases evenly. When water diffuse in,
emulsifying wax will emulsify water with ointment bases evenly where the drug
can dissolves in water. Therefore, constant rate of release of drug can be
achieved.
The results obtained
from the experiment may not accurate due to some errors occurring during the
experiment. Firstly, there may not exactly 1.5g of acetylsalicylic acid present
in the ointment formulation because some is lost when grinding in mortar and
pestle. There is also some loss of the ointment during the transfer of ointment
into the dialysis bag. Some ointment may stick outside of the bag which causes
an inaccurate result. There are several precaution steps that must be taken
when using the UV spectrophotometer. Firstly, don't touch the optical surface
of cuvettes with fingers to avoid erratic reading. Then, do not overfill or
under fill the cuvette, the cuvette should be three-fourth full. Besides,
preserve the instrument from dust particles. Moreover, never wash the cuvettes
with chromic acid. Wash the cuvette with the distilled water and then with
methanol before storage.
4. What is the function of each material that used
in the preparation of ointment? How do the different contents of Emulsifying
Wax and Liquid Paraffin affect the physical characteristics of ointment and
also the rate of drug release from the ointment?
White soft paraffin and
liquid paraffin are hydrocarbon bases of the ointment. They are made up of long
chain alkane hydrocarbon. They are immiscible with water, thus low water
absorbing capacity. White soft paraffin is used as emollient and a heavy
moisturizer. It also enhances the penetration of drugs through the skin
surface. Liquid paraffin is used to reduce viscosity of the base, softens the
ointment formed, so that it can be spread and applied easily. Emulsifying wax
(a mixture of cetostearyl alcohol and SLS) is an anionic emulsifying agent that
makes the ointment become water-miscible which allows it to be readily washed
from the skin. It allows the ointment to have self-emulsifying property. It is
incompatible with cationic therapeutic agent, as the structure of the base
would be modified.
As the ointment contains
high amount of emulsifying wax and low amount of liquid paraffin, a hard
ointment with the presence of big and coarse crystals is formed. On the other
hand, a watery, greasy, and soft ointment is formed if it contains low amount
of emulsifying wax and high amount of liquid paraffin. A high amount of
emulsifying wax decreases the rate of the drug release. This is because the
hard ointment prepared from high amount of emulsifying wax will decrease the
drug diffusion from ointment by holding the active ingredient (acetylsalicylic
acid) tightly and thus retard the drug released. A high amount of liquid
paraffin increases the rate of drug release from the ointment. However, an
optimum ratio of the phases is needed to produce an ointment with good physical
property and also the drug releasing rate.
Conclusion:
Physical
properties of the ointment and the rate of release of drug from the formulation
can be influence by different composition of the ointment. Thus, the components
of the formulation must be in suitable proportion to produce a drug which has
desired therapeutic effect.
References:
1. Aulton, M.E. 2002.
Pharmaceutics: The science of dosage form design. Edinburgh: Churchill
Livingstone
2. Florence,A.T. &
Attwood, D. 1998. Physico-chemical principles of pharmacy. 3rd Ed. New York:
Macmillan.
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