Tittle: Effects of different component to the formulation of ointments
Objectives:
1) To
determine whether the difference in ointment component will affect their
physical characteristic.
2) To
determine the rate of drug release from ointment.
Introduction:
An ointment is
a homogeneous, viscous, semi-solid preparation, most commonly a greasy, thick
oil (oil 80% - water 20%) with a high viscosity, that is intended for external
application to the skin or mucous membranes. They are used as emollients or
for the application of active ingredients to the skin for protective,
therapeutic, or prophylactic purposes and where a degree of occlusion is
desired.
Ointments are used topically on a variety of body
surfaces. These include the skin and
the mucous membranes of the eye (an eye
ointment), vulva, anus,
and nose. An ointment may or may not be medicated.
Ointments are usually very moisturizing, and good
for dry skin. They have a low risk of sensitization due to having few
ingredients beyond the base oil or fat, and low irritation risk. There is
typically little variability between brands of generics and name brand drugs.
They are often disliked by patients due to greasiness. Therefore it need to be
attractive and easy to apply on skin for patient compliance and also need to be
in good rate of drug release.
Chemical and apparatus:
a) Apparatus
Weighting scale, weighting boat, 500 ml beaker,
heater, slap & spatula set, mortar & pestle set, dialysis bag, thread,
glass rod, water-bath, 5ml pipette & pipette-bulb, Spectrometer UV-visible,
b) Chemicals
Emulsifying wax, White soft paraffin, liquid
paraffin, Acetylsalicylis Acid, distilled water.
Procedure:
1. The
Emulsifying Ointment (50 g) is prepared by using this formula
3. 1.5
g of Acetylic acid had been incorporated with the 30g of ointment with
levigation technique.
4. The
acetylic acid ointment is filled in the dialysis bag and tied at both edge.
5. The
base was put in the 500ml beaker that contain distilled water that been heated
to
37 0C.
6. The
aliquot sample is pipette out about 3-4 ml in every 5 minute intervals and the
release of Acetylic acid is determined from the ointment base by using
Spectrometer UV-visible. The distiied water need to be stir first with glass
rod before take the sample.
RESULT
1. Compare the physical texture of the
ointment formed and give explanation.
The hardness of the ointment
decreases from ointment I to ointment IV because the content of emulsifying wax
is decreased from ointment I to IV. In ointment IV with emulsifying wax of only
9g, is not enough to produce “interlocking wax” structure, thus ointment IV is
very soft and clear while ointment I with 21g of emulsifying wax is very hard
and opaque. Emulsifying wax prevents the coalescence of
globules of the dispersed phase and increases the viscosity of the ointments.
Thus, high proportion of emulsifying wax in the ointment will decrease the
spread ability of the ointments causes it difficult to be applied onto the
skin.
The greasiness of the ointments
increases as liquid paraffin amount is increases. Liquid paraffin’s function is
to soften the ointment. This will aid in the ointment penetration through the skin
but give greasy feeling on skin and difficult to remove by washing with water.
This graph
is fluctuated but on the whole there shows an increase of UV absorption against
time. The UV spectrometer measure the releasing of acetylsalicylic acid from
the ointment in the dialysis bag immersed in the 100 ml 37˚C distilled
water.
The great increase in the UV absorption value at the first 5 minutes is due to
the great concentration difference between content in dialysis tube and the
distilled water. The content of in the dialysis bag is hypertonic to the
distilled water. So, large amount of ointment with acetylsalicylic acid
diffuses to the distilled water with high concentration gradient different. The
amount of ointment diffuse is proportional to the acetylsalicylic acid. The
high value of UV absorption may due to the presence of residual at both end of
the dialysis bag, left during the insertion of ointment into the dialysis bag.
So when the dialysis bag is immersed in the distilled water, the residual will
dissolve in the water.
This makes
there are content of acetylsalicylic acid that are not from the diffusion
through the dialysis bag. After the residual at both end of dialysis bag has
dissolved, the acetylsalicylic acid diffused out only through the pore of
dialysis bag, so the reading after 5 minutes shows regular increase. A sudden
large increase in the UV absorption does not occur after 5 minutes as the
concentration gradient across the dialysis bag decrease, the amount of
acetylsalicylic acid in the distilled water increases with time. The gradual
increase in the UV absorption indicates the gradual release of acetylsalicylic
acid from the dialysis bag. The concentration of content in distilled
water gradually increased until equal the concentration of the content in
dialysis bag. This will result in the reduced increase in the UV absorption
when times pass by.
Due to time constriction, the results of this experiment are not complete.
However, we can predict the pattern of the graph as it will increase gradually
until a constant is achieved. 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. The content in dialysis bag is
isotonic to the distilled water content concentration.
Some of the precautions steps can be taken during conducting the experiment are
to avoid over stirring the distilled water as this might break the dialysis bag
and result a large amount release of the ointment from it. Besides, the
residual that retained at both end of the dialysis bag should be removed before
immersing the dialysis bag in the distilled water to ensure accuracy of the
result. The rope should tie both end of the dialysis bag tightly to prevent
leakage of the ointment. The cuette should be cleaned for the fingerprint
around the surface of it so that the measurement is correct. The distilled
water in the beaker should cover the whole dialysis bag to ensure consistent
diffusion.
4. What are the functions of each material used
in this preparation of ointment? How does the different emulsifying wax and liquid
paraffin components affect the physical appearance of the ointment formed and
the release rate of the drug from the ointment?
Emulsifying wax is an
emulsifying agent that is used to make the oil droplets in ointment becomes
soluble and mixable with water in order to allow the formation of the ointment.
It also allows the ointment to have self-emulsifying property. Liquid paraffin
and soft paraffin are the hydrophobic bases of the ointment. Liquid paraffin
softens the ointment formed and reduces the viscosity of the ointment in the
presence of emulsifying wax. It increases the spreadibility and decreases the
hardness of the ointment. White soft
paraffin enhances the penetration of acetylsalicylic acid through skin
surface as well as the absorption through the membrane into circulation.
From the experiment, different proportions of
materials are used to produce 50g of emulsifying ointment. High concentration
of emulsifying wax hardened the ointment while a high concentration of liquid
paraffin produces a watery, greasy, and soft ointment due to the reduced
viscosity of ointment. Therefore, higher concentration of emulsifying wax and
lower concentration of liquid paraffin produce harder and less greasy ointment
compared to lower concentration of emulsifying wax and higher concentration of
liquid paraffin in an ointment formulation.
CONCLUSION
From the experiment, we can conclude
that the rate of drug released from the ointment is reduced with increased
concentration of emulsifying wax in the formulation of Ointment.
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