Date : 12 May 2014
Title of experiment:
The effects of differences characteristic of active ingredient in formulation of ointment.
Objectives:
1) To study the effects of difference amount of emulsifying wax, white soft paraffin and liquid paraffin used in the formulation of ointment.
2) To describe and elaborate the texture, clarity and colour of ointment that was formed.
Introduction
Ointments are preparations for external use, intended for application to the skin. Typically, they have an oily or greasy consistency and can appear “stiff” as they are applied to the skin. Ointments contain drug that may act on the skin or be absorbed through the skin for systemic action.
Procedure
1. 50 g Emulsifying ointment was prepared by using following formula:
3. 1.5 g Acetylsalicylic acid powder was incorporated into 30 g of ointment by using levigation technique.
4. 5 g of ointment that containing Acetylsalicylic acid was incorporated into the dialysis bag.
5. The bag was introduced into the beaker that containing 50 ml of distilled water that already heated into 37 degree Celsius.
6. 3-4 ml of sample was pipette at every 5 minutes and the liberation of Acetylsalicylic acid from its ointment base was determined by using uv-visible spectrometer.
result
result for procedure no 2
discussion
1. compare the physical shape of ointment that are formed in this experiment and give comment.
In this experiment, Group 5 ointment contained 21 g of emulsifying wax and 4 g of liquid paraffin, Group 6 ointment contained 17 g emulsifying wax and 8 g of liquid paraffin, Group 7 ointment contained 13 g of emulsifying wax and 12 g of liquid paraffin whereas, Group 8 ointment contained 9 g of emulsifying wax and 16 g of liquid paraffin. All the four groups use the same amount of white soft paraffin which is 25 g. The amount of emulsifying wax will determine the hardness of the ointment while the amount of liquid paraffin will contribute to the texture of the ointment whether it has oily and smooth texture.
All the ointment that is formulated is white in colour and turbid. The degree of the turbidity of the ointment depends on the amount of emulsifying wax added to the formulation. As the amount of the emulsifying wax increased in the formulation it will be easier for the ointment to spread upon application. Other than that, the greasiness of the formulation also increases as the amount of emulsifying wax increases in the formulation. The quantity emulsifying wax in the formulation will also cause the variation ofhardness of the ointment. The lower the quantity of emulsifying wax, the softer the ointment produced.
Based on the results obtained, group 5 produces an ointment that is hard, greasy and difficult to spread compared to other groups. This is because the amount of emulsifying wax used is highest. While group 8 uses small amount of emulsifying wax produces an ointment that is less hardness, greasy and easily spread The hardness of the ointment causes the drug to be difficult to diffuse out into the water.. As the hardness is low, it will not give many effects on the diffusion of the drug. Ointments which been produced by group 6 and 7 shows almost similar physical characteristic in terms of hardness, spreadibility and greasiness to the groups 5 and 8 respectively.
In term of spreadibility, ointment from group 8 is the one that is easily to spread followed by group 7, group 6 and group 5 which is poorly spread. In term of greasiness, group 8 that used higher amount of liquid paraffin result in a greasy ointment. All of the four groups show white color of ointment, but there is slightly different in the color intensity. Group 8 shows light color of ointment with less intensity of white color which is slightly yellowish white as this ointment contains high amount of liquid paraffin. This is because the intensity of white color increases when the amount of liquid paraffin decrease. In term of transparency, all groups produce turbid ointments.
2. plot a graph of UV absorption against time. give comment.
The graph is based on type IV ointment. From the graph, UV absorption increases as the time become longer. The experiment set up mimic the release of drug from the ointment to the blood stream through skin. The distilled water represents blood plasma whereas the dialysis bag represents the membrane phospholipids bilayer. The UV absorption value represents the amount of acetylsalicylic acid that was released from the ointment to distilled water through diffusion across the dialysis bag. The temperature of water bath was set at 37 degree Celsius. Theoretically, the release of drug should be high at the beginning and then become constant when the amount of acetylsalicyclic acid release reaches its maximum value. However in this experiment, the release of drug increases at the beginning become constant as time proceeds but it continue to release drug after that. The latter part of the graph is contrast with the theory. This may due to impurities which was introduced and causes the UV absorption value to increase.
3. plot a graph of UV absorption against time for formulation ointment that have different composition. compare and give comment.
In the formulation, emulsifying wax and liquid paraffin are modified to investigate the permeation of acetylsalicylic acid from the ointment. The ratio of emulsifying wax and liquid paraffin in all four formulations are different. Emulsifying wax is water miscible base, while liquid paraffin is hydrocarbon base. Emulsifying wax helps in dispersing the hydrophilic acetylsalicylic acid, while liquid paraffin assists in diffusion of acetylsalicylic acid out of the ointment, through the dialysis bag into the distilled water. With a high proportion of emulsifying wax and low proportion of liquid paraffin, formulation I is the hardest among the four formulations and should has the slowest release rate. Acetylsalicylic acid is hydrophilic, therefore it disperses well in the ointment with high percentage emulsifying wax.
In the experiment, dialysis tube had been use to determine the ability of the acetylsalicylic acid of ointment to pass through the membrane and enter into the water. The amount of the sample that passed through the dialysis tube is measured by using the ultraviolet spectrophotometry. Based on the results, we can see that UV absorption at 300 nm is increasing with time for each of the ointments. Increasing in UV absorption indicates that there is increasing in the numbers of particle of the ointment diffuse through the dialysis tube membrane.
Generally, the UV absorption of all the formulations increases with time. This implies that the longer the time of ointment remains in the water bath, the more the amount of acetylsalicylic acid diffuses out of the dialysis bag. Hence, more UV is absorbed by acetylsalicylic acid. From the graph plotted above, the steepest graph of emulsifying ointment is from group II, it show the highest UV absorption that is the highest amount of permeation of acetylsalicylic acid in the sample. This is followed by emulsifying ointment IV, I and III.
Ointment II has 17 g of the emulsifying wax and 8 g amount of liquid paraffin,the amount is well enough for the acetylsalicylic acid to penetrate the dialysis tube and has the highest average UV absorption. However, ointment IV has the least amount of the emulsifying wax and the highest amount of the liquid paraffin. Therefore, the acetylsalicylic is easier to penetrate the dialysis tube membrane and resulted with a bit higher average UV absorption.
Possibility error that may occur during this experiment is that there is small leakage at the dialysis bag, which cause the acetylsalicylic acid to diffuse through the dialysis bag into the distilled water at a higher rate with higher concentration. The error may also due to the threads tying the both ends of the bag are loosen. There are a few small fluctuations in the line graph. This may due to the aliquot sample is taken without stirring the distilled water. Ointment should be filled into the bag gently and carefully to prevent the leakage of the bag. Distilled water should be stirred before obtaining the sample, so that the acetylsalicylic acid diffuse out from the ointment dispersed evenly in the distilled water. Since the ointments are prepared by different groups using different techniques, the consistency of products is not guaranteed. Moreover, the outer membrane of dialysis bag may be contaminated with the emulsifying ointment during the filling of ointment into the bag.
4. What is the function of each ingredients used in the preparation of the this ointment? How does different amount of Emulsifying Wax and Paraffin liquid affect the physical characteristics of an ointment formulation as well as the rate of release of the drug?
The ingredients used are acetylsalicylic acid, emulsifying wax, white soft paraffin, liquid paraffin and acetylsalicylic acid
Acetylsalicylic acid act as active ingredient of the ointment which provide therapeutic effect for the ointment. It is a non steroidal anti-inflammatory drug (NSAID) which has antipyretic, anti-inflammatory effect. It also inhibits platelet aggregation.
Emulsifying wax is an anionic surfactant containing a hydrophilic tail and hydrophobic chain. It act as emulsifiers by adsorbing on surface of acetylsalicylic acid which is hydrophilic and decrease it’s interfacial tensions. This will help to distribute the drug evenly and prevent sedimentation of the drug in the hydrocarbon base ointment.
White soft paraffin which is also known as petroleum jelly act as hydrocarbon base of the ointment. It also acts as moisturizer and by providing a layer of oil on the surface of the skin to prevent water evaporating from the skin surface. It also contributes to the greasiness of the ointment.
Liquid paraffin is a white, odorless, tasteless mineral oil that acts as hydrocarbon base of the ointment. It helps to rehydrate the skin by retaining the moisture. It helps to reduce the viscosity of ointment. It provides the greasiness of the ointment.
Emulsifying wax has higher melting point and contributes to the hardness of the ointment formed; liquid paraffin has low melting point thus contributes to a softer ointment. The higher the ratio of emulsifying wax to liquid paraffin used, the harder is the ointment formed. While the higher the ratio of liquid paraffin to emulsifying wax the softer is the ointment, and the higher spread ability of the ointment. A softer ointment will also enables the drugs to be released from the formulation and penetrate the skin lipid bilayer more readily and increase the rate of drug release.
Conclusion
As a conclusion, the amount of emulsifying wax determine the hardness of the ointment while the amount of liquid paraffin determine whether ointment has oily and smooth texture.
Based on result,Group 5 produces an ointment that is hard, greasy and difficult to spread compared to other group.While group 8 produces an ointment that is less hardness, greasy and easily spread.Ointments which been produced by group 6 and 7 shows almost similar physical characteristic in terms of hardness, spreadibility and greasiness to the groups 5 and 8 respectively.
In term of spreadibility, ointment from group 8 is the one that is easily to spread followed by group 7, group 6 and group 5 which is poorly spread. In term of greasiness, group 8 produce greasy ointment. Group 8 shows light color of ointment with less intensity of white color which is slightly yellowish white. In term of transparency, all groups produce turbid ointments.
For the graph UV absorption against time, the graph is based on type IV ointment.In this experiment, the release of drug increases at the beginning become constant as time proceeds but it continue to release drug after that.
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