OINTMENTS

Title:   Effect Assessment of Different Ingredients on the Characteristics of an Ointment

Objectives:    

To study the effects of different ointment composition on the physical characteristics of ointment formed and the rate of drug released from it

Introduction:

Ointment formulation is a semisolid dosage form that is suitable for external application on skin. It is oily preparations that contain one or more active ingredients that is soluble or spread homogenously. A good ointment must have an appealing texture, easy to use on skin characteristic as well as releasing it active ingredient from it.

Generally, ointment composed of active ingredient either powder or liquid that is incorporated into the oily semisolid. In Pharmaceutics, ointment preparation is used to act as local treatment at application site, increasing the moisture of the skin (emollient effect).

Materials:

Emulsifying wax                                                         Acetylsalicylic acid

White soft paraffin                                                     Distilled water

Liquid paraffin

Apparatus:

Weighing balance                                                        Needles

Weighing boat                                                 Glass rod

100ml beaker                                                               Water Bath

Heater                                                                         Pipette

Glass slab & spatula                                                    Plastic Cuvette

Mortar & pestle                                                           UV spectrophotometer

Dialysis bag (10cm)  

Procedure:

1.      Emulsifying ointment (50g) is prepared using the formula below:

  

2.       5g of ointment formed is taken out and put into the weighing boat and it is then labelled. The texture, clarity, colour of ointment, spreadibility, greasiness, and hardness of the ointment is explained and compared

3.      1.5g Acetylsalicylic acid powder is incorporated into the 15g ointment prepared by using levigation technique. If necessary, the acetylsalicylic acid is first mashed into fine powders by using mortar and pestle.

4.      The acetylsalicylic acid ointment is put into dialysis beg and both end of the bag were tied up neatly.

5.      The bag consisting acetylsalicylic acid ointment is put into 250ml beaker containing 50ml distilled water that has been heated to 37ºC.

6.      At time interval of 5 minutes, 3-4ml aliquot sample is pipette and the release of acetylsalicylic acid from the ointment base is determined by using UV spectrophotometer. Ensure that the distilled water is mixed by using glass rod before taking out the sample.

Results:

Discussion:

1.                  Discuss and compare the physical characteristics of the ointment.

For the texture of emulsifying ointment I, it is poorly spread, greasy and it’s hardness was hardest. The transparency is clear and the colour is white. The texture of emulsifying ointment II, it is poorly spread, greasy and hard. The transparency is slightly transparent and the colour is white. For the emulsifying ointment III, the texture are easily spread, greasy and less hardness. While for the transparency and colour are turbid and white respectively. For the emulsifying ointment IV, the texture are easily spread, greasy and less hard. The transparency is turbid and the colour is white.

The emulsifying ointment I and II are poorly spread because the amount of liquid paraffin is low compared to emulsifying ointment III and IV. This is because the liquid paraffin help to increase the spread ability of the ointment. The greasiness of all the emulsifying ointment is greasy because of the white soft paraffin. The emulsifying ointment I is the hardest ointment compared to others. This is because the amount of emulsifying wax in the emulsifying ointment I is the highest than the others. The emulsifying ointment I and II is transparent while the emulsifying ointment III and IV is turbid while the colour of all emulsifying ointment is white.

2.   Plot the graph of UV absorption at 300 nm against time (min). Discuss.

Based on the graph above, the result shown the increasing value of the UV absorption against time. It indicates that the amount of the acetylsalicylic acid particles is increased as the time increase. The ointment where contained acetylsalicylic acid is immersed in the water, throughout this experiment, the acetylsalicylic acid particles are released into the water via dialysis bag. Over the time, the amount of the acetylsalicylic acid released in the water increased. The UV light is used for determine the amount of particle in the solution and it gives the value. The values are increase, so, it shows the acetylsalicyclic acid is there and increased as the time increase. This also indicated the ointment preparation is good as the content can be released into the solution.

3. Plot the graph of UV absorption against time for ointment formulation that have different composition. Compare and discuss the results.

Based on this experiment, we are needed to prepare four different formulation of ointments with different amount of emulsifying wax and liquid paraffin. This is needed to investigate the permeation of acetylsalicyclic acid from the ointment. Generally, the UV absorption of all the formulations must increases with time. This states that the longer the ointment stay in the water bath, the more acetylsalicylic acid will be diffuse out of the beg, so more UV will be absorbed. Besides, the highest concentration of acetylsalicyclic acid should be produced in the formulation with the highest proportion of liquid paraffin and lowest proportion of emulsifying wax.

From the graph plotted above, we can see that formulation 2 has the highest concentration of acetylsalicyclic acid compare to the others and formulation 3 has the lowest amount of acetylsalicyclic acid in the distilled water. Theoretically, when the amount of liquid paraffin increases and the amount of emulsifying wax decreases, the drug can diffuse better to the surrounding of distilled water. Due to the some erorors done during the experiment, the results that we got are slightly different from the theoretical point of view. From the graph, we can also see that the amount of UV absorbed are sometimes decreases by the times goes by which is supposedly to be increases with time. This happened due to the errors done during the experiment.

There are some errors that have been done during the experiment which may affect the results of the experiment. Firstly, the amount of ointment in the dialysis beg may be differ in each group due to the difficulty to fill in the ointments into the beg. When we filled the ointments into the dialysis beg, the ointments may contaminate the outer membrane of the beg. This is due to the incorrect technique of filling the ointments into the dialysis beg. Besides, the techniques used in preparing the formulation of ointments may be differ in each group, so the consistency of the product formed is not guaranteed.

4. What is the function of each ingredient used in the preparation of this ointment? how the use of emulsifying wax content and different liquid paraffin affect the physical characteristics of an ointment formulation and release rate of a drug from it?

Emulsifying Wax contains Cetostearyl Alcohol and either Sodium Lauryl Sulphateor  sodium salts of similar sulphated higher primary aliphatic alcohols.Function of emulsifying wax is to emulsify the ointments. It helps to combine the oil and water in mixture by creating an emulsion between the oil and water.Besides that, it also can function as surfactant which reduces the surface tension thus increase the release of acetylsalicylic acid.

When the concentration of the emulsifying wax is high, it will give result in formation of hard ointment. High percentage of emulsifying wax plus low percentage of liquid paraffin will makes the formation of big and coarse crystals. High concentration of emulsifying wax has a slower drug release compared with the low concentration of emulsifying wax.

White soft paraffin is also known as white petroleum jelly. This is not an active ingredient as such, but works as a moisturiser by providing a layer of oil on the surface of the skin to prevent water evaporating from the skin surface. It is a very greasy moisturiser.

Liquid paraffin is used to reduce the viscosity of the base, increases the spreading ability of the acetylsalicylic acid and decreases the hardness of the ointment. The acetylsalicylic acid used in the formulation acts as active ingredient. It often used as an analgesic and antipyretic agent and as anti- inflammatory drug. In ointment preparation, is used as a topical aid in the removal of excessive keratin in hyperkeratotic skin disorders. It works as an exfoliant, promoting the sloughing away of dead skin cells.

Conclusion:

The emulsifying ointment that have high amount of emulsifying ointment will be the hardest and low amount of liquid paraffin is poorly spread. Other than that the the amount of the acetylsalicylic acid particles is increased as the time increase.

References:

1.      Aulton, M.E. 2002. Pharmaceutics: The science of dosage form design. Edinburgh: Churchill Livingstone

2.      Banker, G.S. & Rhodes, C.T. 1990. Modern pharmaceutics. 2^nd Ed. New York: Marcel Dekker.

    Appendices :

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