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:
Weighing
instrument
Weighing
boat
100ml
beaker
Heater
1 set of cream and
spatula
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
MATERIALS:
Emulsifying
wax
White soft
paraffin
Liquid
paraffin
Acetylsalicylic
acid
Distilled water
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.
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.
RESULT AND
CALCULATION:
Time (min)
|
|||||||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
|
UV Absorption on 310 nm
|
0.030
|
0.068
|
0.070
|
0.095
|
0.112
|
0.128
|
0.157
|
-
|
-
|
-
|
-
|
-
|
-
|
*(-) means
no reading were taken since experiment stopped after 30 minutes
Time(min)
|
Average of UV absorption at 300 nm ( x ± SD)
|
||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
|||
I
|
0.0225 ±
0.0075
|
0.062 ± 0.006
|
0.066 ± 0.01
|
0.0945 ±
0.0005
|
0.1105 ±
0.0015
|
0.159 ± 0.031
|
0.139 ± 0.018
|
||
II
|
0.049 ± 0.024
|
0.285 ± 0.165
|
0.316 ± 0.176
|
0.3535 ±
0.1735
|
0.398 ± 0.155
|
0.422 ± 0.159
|
0.451 ± 0.165
|
||
III
|
0.037 ± 0.002
|
0.041 ± 0.001
|
0.0795 ±
0.0335
|
0.078 ± 0.023
|
0.11 ± 0.052
|
0.127 ± 0.065
|
0.1545 ±
0.0845
|
||
IV
|
0.0815 ±
0.0185
|
0.152 ± 0.031
|
0.218 ± 0.006
|
0.2225 ±
0.0015
|
0.2285 ±
0.0065
|
0.267 ± 0.027
|
0.321 ± 0.01
|
||
DISCUSSION
1. Compare
the physical appearance of the ointment formed and give your explanation.
Ointment
1 (21 g EW, 25 g WSP, 4 g LP) :
It
has low spreadibility. It also has high greasiness compared to other ointment.
The hardness is the most suitable compared to other ointment. The colour
produce is white.
Ointment
2 (17 g EW, 25 g WSP, 8 g LP) :
Spreadibility
is low. More greasiness compared to ointment III and IV and less greasiness
compared to ointment I. It has the most suitable hardness compared to ointment
III and IV but less compared to ointment I. white colour also has been produced
as same to others.
Ointment
3 (13 g EW, 25 g WSP, 12 g LP) :
It
has high spreadibility. It also has high greasiness compared to ointment IV and
less greasiness compared to ointment I and II. The hardness is the most
suitable compared to ointment IV and less hardness compared to ointment I and
II. The colour produce is also white.
Ointment
4 (9 g EW, 25 g WSP, 16 g LP) :
Spreadibility
is very high. Less greasiness compared to others ointment. The hardness is the
lower compared to others ointment. White colour also has been produced as same
to others.
EW
: Emulsifying Wax, WSP : White Soft Paraffin, LP : Liquid Paraffin
2. Plot graph of UV absorption against time. Discuss.
This graph measures the release of
acetylsalicylic acid from the ointment in the dialysis bag immersed in the
100ml 37C distilled water. Generally, UV
absorption increase with time. Initially, at the first 5 minutes, the UV
absorption value surge up follow by gradual increasing of the UV absorption
value until 30 minutes. This due to the hypertonicity of dialysis content to
distilled water is at maximum now. As time increase further, the increasing
pattern of UV absorption becomes smaller and almost constant. This is due to
more acetylsalicylic acid diffuse out of dialysis bag, making the concentration
of this solute between inside and outside dialysis bag reach to equilibrium
(isotonic). If experiment continued to 60 minutes, UV absorption may increase further
with smaller increasing pattern.
The present UV absorption value at 0 minute
explains the present of acetylsalicylic acid in the distilled water. It might
due to residue of ointment which sticks on outside of dialysis bag during
insertion of the ointment into the dialysis bag’s hole.
3. Plot a graph of UV
absorption against time for different composition of emulsifying ointment.
Compare and discuss your result.
Emulsifying
wax is used to keep water and oil together. Liquid paraffin is used to reduce
the viscosity of base so that it can be easily expelled out from container. In
this experiment, the ratio of emulsifying wax and liquid paraffin are different
for every group. This is to investigate the permeation of acetylsalicylic acid
from the ointment which small amount of acetylsalicylic acid permeate the
dialysis bag with the high content of emulsifying wax. Thus, the value of UV
absorption will become smaller.
According
to the theory, UV absorption of the formulation must increase with time because
more amount of acetylsalicylic acid diffuse out of the dialysis bag when
exposed longer in the water bath. Hence, more UV is absorbed by acetysalicyclic
acid. As we can see in tthe graph, most of the formulation have increasing
pattern which means the UV absorption increase as longer time remain in the
water bath. The graph that shows most UV absorption is formulation from group
IV followed by group II, III and I. The graph match with the theory as group I
formulation with the highest content of emulsifying wax have lowest UV
absorption, followed by group II,III and IV. Group IV have the lowest content
of emulsifying wax, thus have highest UV absorption.
4.
Discuss the functions of the materials in the ointment. How does the different
composition of the emulsifying wax and liquid paraffin components affect the
physical appearance of the ointments formed and the releasing rate of the drug
from the ointments?
One of the materials used is the
emulsifying ingredients. The emulsifying wax is an emulsifying agent that is
used to prepare oil in water emulsion that makes the oily form becomes soluble
in water and miscible with water. It allows the ointment to have self-emulsifying
property. It also acts as a surfactant that reduces the surface tension and
hence increases acetylsalicylic acid released from the formulation. A high
concentration of emulsifying wax results in a hard ointment. Big and coarse
crystals can be formed by a high percentage of emulsifying wax and a low
content of liquid paraffin.
The white soft paraffin oil is also
known as white petroleum jelly. This is not an active ingredient but it acts as
a moisturizer by providing a thin layer of oil on the skin surface to prevent
water to evaporate from the skin surface. It is a very greasy moisturizer and
thus used as a base that enhances the absorption of acetylsalicylic acid
through the membrane into the circulation.
Besides, the liquid paraffin acts to
soften and reduce the viscosity of the ointment due to the addition of
emulsifying wax. It also acts as an emollient. It increases the spreading
ability of the acetylsalicylic acid and also decreases the hardness of the
ointment. A high composition of liquid paraffin reduces the amount of the
emulsifying wax needed in the formulation. A high proportion of liquid paraffin
used in the formulation produces a watery, greasy and soft ointment which
subsequently decreases the rate of drug released from the ointments.
The acetylsalicylic acid used in the
formulation acts as active ingredient. It is a salicylate drug which often used
as an analgesic to relieve minor aches and pains. Besides, it also acts as an
antipyretic to reduce fever, and as an anti-inflammatory drug. Distilled water
is the solution in which its impurities are removed by the process of
distillation. It allows the measurement of the UV absorption to be taken. It
increases the accuracy of the reading of the UV absorption taken.
The
composition of ointment will affect its physical property and the drug’s
release rate from the ointment.
REFERRENCES:
1.
Pharmaceutics:
the science of dosage form design,
Aulton, M.E.2002
2.
http://www.teachsoap.com/emulsifywax.html
4.
www.buzzle.com/articles/liquid-paraffin-oil.html
5.
www.chemicalland21.com/lifescience/phar/ACETYLSALICYLIC%20ACID.htm
6.
www.pharmpedia.com/Emulsifying_agent
