OBJECTIVES
1) To know the effects of different
ointment formulation on the physical characteristic of the ointment.
2) To determine the effects of different
ointment formulation on the rate of release of drug from the formulation.
INTRODUCTION
Ointment formulation is a semisolid
medicinal preparation usually having a base of fatty or greasy material. It is
homogeneous, viscous and thick oil (oil 80% - water 20%) with a high viscosity.
Ointments are used
topically for several purposes, e.g., as protectants, antiseptics, emollients,
antipruritics, kerotolytics, and astringents. The vehicle or base of an
ointment is of prime importance if the finished product is expected to function
as any one of the above categories. In the case of a protective ointment, it
serves to protect the skin against moisture, air, sun rays and other external
factors. It is necessary that the ointment neither penetrates the human skin
barriers nor facilitates the absorption of substances through this barrier. An
antiseptic ointment is used to destroy or inhibit the growth of bacteria.
Frequently bacterial infections are deeply seated; a base which has the
capacity to either penetrate or dissolve and release the medication effectively
is therefore desired. Ointments used for their emollient effect should be easy
to apply, be non-greasy and effectively penetrate the skin.
Ointments can be prepared either by
mechanical trituration or by fusion methods. Irrespective of the method
employed for the preparation, ointments should be smooth and free from granular
or gritty particles. For trituration, in this finely subdivided insoluble
medicaments are evenly distributed by grinding with a small amount of the base
followed by dilution with gradually increasing amounts of the base. The
ingredients are melted together in descending order of their melting points and
stirred to ensure homogeneity in fusion.
Ointment bases,
as described, may by used for their physical effects or as vehicles for
medicated ointments. Each ointment base type has different physical
characteristics and therapeutic uses based upon the nature of its components.
The different formulation of ointment will affect the texture and physical
characteristics of ointment and the rate of the drug release from the
formulation to target site. Properties which affect choice of an ointment base
include stability, penetrability, solvent property, irritant effects and ease
of application and removal.
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
Ingredients:
Emulsifying wax
White soft paraffin
Liquid paraffin
Acetylsalicylic acid
Distilled water
Procedure:
- 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
|
- 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.
- 1.5 g of Acetylsalicylic acid powder
was incorporated into 30 g of cream which was prepared by levigation
technique.
- Acetylsalicylic acid was filled into
the dialysis bag and the two side of the bag was tied.
- The bag was put into a beaker (200ml)
filled with distilled water (100ml) which was heated to 37°C.
- 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
:
3.
TIME(MIN)
|
AVERAGE
OF UV ABSORPTION AT 300 NM (x ± SD)
|
||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
|||
Emulsifying oinment
|
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
|
0.225 ± 0.0015
|
0.2285 ± 0.0065
|
0.267 ± 0.027
|
0.321 ± 0.01
|
||
TIME
(MIN)
|
UV
absorption
|
||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
|||
UV
absorption at 310nm
|
0.073
|
0.120
|
0.140
|
0.180
|
0.243
|
0.263
|
0.286
|
||
Discussion:
1. Comparison of the
physical appearance of the each ointment.
Group
|
Texture
|
Clarity
|
Colour
|
||
Spreadibility
|
Greasiness
|
Hardness
|
|||
5
|
+
|
Least greasy
|
++++
|
Turbid
|
Chalky white
|
6
|
++
|
Relatively greasy
|
+++
|
Turbid
|
Chalky white
|
7
|
+++
|
Greasy
|
++
|
Turbid
|
Slightly light white
|
8
|
++++
|
Most greasy
|
+
|
Turbid
|
Light white
|
2. Plot UV absorption
graph against time. Give explanation.
From this experiment, distilled water
filled in the beaker represents the blood circulation in the body. Since
distilled water is hypotonic so acetylsalicylic acid inside the dialysis bag
can diffuse out from it. Hence, acetylsalicylic acid will diffuse out to the
hypotonic solution against concentration gradient. As a result, the content of acetylsalicylic
acid in the distilled water increases. Dialysis bag acted as phospholipid
bilayer and this experiment is conducted in 37ºC because the temperature is setted
up as human body temperature. The UV absorption value obtained from the
spectrophotometer represents the amount of acetylsalicylic acid released from
the ointment in the dialysis bag into the distilled water in the beaker.
Based on the graph above, the greater the
time taken the greater UV absorption of ointment. This is because the released
of acetylsalicylic acid of ointment from the dialysis bag in the beaker
increases as time increases. This shows that the absorption of the formulation
is increases in a longer period of time and decreases as the ingredients in the
formulation is getting lesser. This means that amount of acetylsalicylic acid
in the distilled water increases with time. The gradient of the graph
represents the rate of drug (acetylsalicylic acid) release to the blood
circulation (distilled water). When the UV absorption value increases, the
acetylsalicylic acid release from the dialysis bag into the surrounding
solution also increases.
3.
TIME(MIN)
|
AVERAGE
OF UV ABSORPTION AT 300 NM (x ± SD)
|
||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
|||
Emulsifying ointment
|
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
|
0.225 ± 0.0015
|
0.2285 ± 0.0065
|
0.267 ± 0.027
|
0.321 ± 0.01
|
||
Based on the graph above, the average UV
absorption for each formulation increases with time as the concentration of
acetylsalicylic acid in the beaker is increases. In every interval of 5
minutes, 3ml of content in the beaker were taken rendering a progressive
decrease in amount of solution in the beaker. The active ingredient in the
ointment was being released into the solution in the beaker from time to time.
Thus, the concentration of the active ingredient- acetylsalicylic acid
increases progressively which is indicated by an increase in the average UV
absorption.
The standard deviation for formulation is
quite normal. The deviation are might due to some errors occurred throughout
the experiment. The series 3 shows a more consistent value compared to other
series while the value of standard deviation for series 2 and 4 is still
acceptable.
Drug diffusion of emulsifying ointment is
affected by the formulation of emulsifying wax and liquid paraffin.
Theoretically, drug diffusion of emulsifying ointment 4 is the most followed by
emulsifying ointment 2, 3 and the drug diffusion of emulsifying ointment 1 is
the least. The more the emulsifying wax, the more the drug will be diffuse out.
This is shown in the graph above.
4.
What is the function of each ingredient that is used in the ointment? How the
different composition of the emulsifying wax and liquid paraffin affects the
physical properties of the ointment and the release rate of a drug from it?
Emulsifying wax acts as an emulsifying
agent that decreases the interfacial surface tension so that the drug particles
can be distributed uniformly in the ointment and to prevent any sedimentation
from occurring.
White soft paraffin is an ointment base
which is used as an emollient and moisturizer. To increases the greasiness of
the ointment so that it can penetrate through the skin hydrophobic lipid
bilayer more easily. In this experiment, to aid the diffusion of
acetylsalicylic acid from the dialysis bag.
Liquid paraffin acts as the base too. It
softens the ointment formed. It also decreases the ointment viscosity and acts
as emollient.
When the proportion of the emulsifying wax
decreases and liquid paraffin increases, the spreadibility and greasiness of
the ointment increase while the hardness decreases and thus the drugs can be released
from the formulation and penetrate through the skin lipid bilayer more readily.
Therefore, the rate of release of drug increases. However, this is different
from results of formulation IV which may be due to the experiment errors such
as the distilled water is not stirred before sampling. So, ideally, the
formulation IV should have the highest rate of release.
Conclusion
From the compounding, our ointment is
spreadable, relatively greasy, hard, turbid and chalky white in colour. From
the graph of UV absorption against time, it is shown that the absorption of the
formulation is increases with time and then decreases as the contents of
ointment is getting lesser. We can conclude that the larger amount of the
emulsifying agent, the faster the diffusion of ointment.
Reference
i. Ointments: Preparation and Evaluation
of Drug Release. UNC. http://pharmlabs.unc.edu/labs/ointments/prep.htm
Retrieved on: 19/5/2014
Retrieved on: 19/5/2014
ii. Allen. 9th
edition. Ansels’s Pharmaceutical Dosage
Form and Drug Delivery System. Chapter10. Wolter Kluwer
iii. UV absorption spectrometry. http://teaching.shu.ac.uk/hwb/chemistry/tutorials/molspec/uvvisab1.htm
Retrived on: 20/5/2014
Retrived on: 20/5/2014
iv. Visible and Ultraviolet
Spectroscopy. http://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/spectrpy/uv-vis/spectrum.htm
Retrived on: 20/5/2014
Retrived on: 20/5/2014
