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:

2. 5g of ointment that are formed was be taken and put into the weighing boat and it is labeled. The texture, clarity and colour that were formed was observed and recorded.
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.

Date : 6 MAY 2014

Title of experiment:
The effects of differences characteristic of active ingredient in formulation of suppository.

Objectives:
1) To study the effects of difference amount of polyethylene glycol used in the formulation of suppository.
2) To describe and elaborate the texture, clarity and colour of suppository  formed.

Introduction
Suppositories are solid, bullet-shaped preparations designed for easy insertion into the anus (back passage). The suppository dissolves at body temperature and gradually spreads over the lining of the lower bowel (rectum), where it is absorbed into the bloodstream.

Suppositories are used either to provide a local action in the rectum, or as an alternative to oral forms of medicine (example when someone is continuously feeling sick or is unable to take anything by mouth). The medicine is easily absorbed from the rectum as there is a rich supply of blood vessels in this area.

In this experiment we want to know how the difference of base composition used will influence the suppository’s action on releasing its active ingredient/s.

Procedure
1. Saturated stock solution of paracetamol was prepared( 10 g in 5 ml of distilled water).
2. 10 g Paracetamol suppository was prepared using following formula:

3. Suppository was formed by using suppository-mould to get its shape. The shape, texture and colour of suppository that are formed was observed and described.
4. One suppository was incorporated into the beaker that containing 10 ml of distilled water (37 degree Celsius) and the time taken for it to melt was recorded.
5. One suppository was incorporated into the dialysis bag. After that, the bag was incorporated 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 paracetamol from suppository was determined by using uv-visible spectrometer. Make sure distilled water is stirred using glass rod before taking the sample.

Result

                                                               result procedure no 3

result for procedure no 6

Discussion
1. compare the physical shape of suppositories that are formed in this experiment and give the comment.

In this experiment, all the suppositories formulated have the shape of a torpedo or torpedo-shaped due to all suppositories was made using moulds of similar torpedo shape. The quantities of PEG 1000 and PEG 6000 are different for each group. This leads to formation of suppositories with different physical characteristics.
In terms of texture, greasiness of the suppositories increases with increasing of amount of PEG 1000. This explains the decrease of degree of greasiness from suppository I to IV, as amount of PEG 1000 decreases from suppository I to IV. On the other hand hardness can be associated with amount of PEG 6000 in the suppositories. Note that increasing amount of PEG 6000 and decreasing amount of PEG 1000 in the suppositories in turn increases the hardness of the suppositories. This is due to hardness of PEGs increases with its molecular weight. It can be simply said that increasing the quantity of PEG 6000 in the formulation will yield suppositories with less greasiness and more hardness. However a suppository which is too hard and not greasy may cause pain during administration, thus this issue should be taken into consideration when formulating suppositories.

About the color of the suppositories, all of them are generally white. This is due to paracetamol used as the ingredient in the suppositories is white in color. However, the degree of transparency of the color in question differs between the suppositories. From suppositories I to IV transparency of the white color increase due to decreasing amount of PEG 1000 available. Note that amount of paracetamol in all suppositories are the same which is 1 mL.

2. plot a graph of time taken for suppository to melt against amount of PEG 6000 in a formulation. 

        Two types of PEG has been used in this experiment which are PEG 1000 and PEG 6000.  A graph of mean time versus amount of PEG 6000 has been plotted. Initially, the graph increasing gradually and then it were decreased. Polyethylene glycol (PEG) which having average molecular weight of greater than 1000 are wax-like, white solids with the hardness increasing with an increase in the molecular weight. Combination between PEG 1000 and PEG 6000 in this experiment is to achieve a suppository base of the desired consistency and characteristics.

       When the PEG 6000 is absence, the mean time is 36.49 minutes, while the mean time amount of PEG 6000 3g is 42.78 minutes. When the amount of PEG 6000 is 6g, the mean time is 39.68 minutes and when amount of PEG 6000 is 9g, the mean time is 37.16 minutes. The mean time for suppository to melt is decreasing when the amount of PEG 6000 is increasing. However, there is an inaccuracy of result. This may be due to some errors when experiment is carried out. For example, the water temperature has not reach 37ᴼC when the suppository is put in the water bath. Melting point of PEG is generally above body temperature. The high melting point also means that the bases do not melt in the body but dissolve and disperse the medication slowly, providing a sustained effect.


3. Plot the graph of UV absorption versus time. Give explanation. 

                                           Graph of UV absorption at 520nm versus Time ( group 8)

       In this experiment, the suppository is put into a dialysis bag and immersed in a 37oC water bath. The release of paracetamol from the suppository into the water is determined by the UV absorption. The paracetamol in the water sample that released from the dialysis bag will absorb ultraviolet radiation of 520nm. Thus, the intensity of UV absorption is directly proportional to the concentration of paracetamol present in the water sample. This meant that the UV absorption reading should be increased when the time is increased as the more paracetamol is released from the dialysis bag.

       The graph above shows the UV absorption at 520nm for suppository 3 which contain 0g of PEG 1000 and 9g of Peg 6000. We can observe that the graph is up  and down as time is increase. Theoretically, the graph should show a sigmoidal shape. This is due to the suppository will dissolve slowly and the drugs are released from the dialysis bag. So that, the concentration of drugs in the water is increases as the time increased until all the drugs are released and the concentration of drug inside the dialysis bag is equal to the concentration of drug in the distilled water (isotonic). Once the equilibrium is reached, there is no movement of drug and the graph will become constant.

       At time 0, the solution surrounding the dialysis bag is tested for the UV absorption. Theoretically, there should be no value for UV absorption as the diffusion has not occurred yet as there is no paracetamol in the solution. This error mybe due to delayed taking the sample which little bit paracetamol has been released from dialysis bag.

        From the graph obtained, the graph are keep on increasing of UV absorption with time except at the time of 10 minutes and 35 minutes there shows a drop of the value and cause different from the theoretical. This is due to error while hamdling the experiment.For example, the solution is not stirred well before taking solution to investigate and this will affect the result obtained. This may also due to the accidentally pouring of the distilled water in the beaker and this can cause the changed in the concentration of the drug. Other than that is, due to bubble present. This will affect the UV absorption.

4. plot a graph of UV absorption against time for formulation suppository that have different composition. give comment.

The higher the absorption of UV, the higher the amount of drug in the solution based on the equation where based on the Beer-Lambert law

A = εbc

ε=molar absorptivity of the compound or molecule in solution (M-1cm-1)
b= path length of the cuvette or sample holder (usually 1 cm)
c = concentration of the solution (M)

        As the suppository dissolve in the dialysis bag over time, the drug is released from the suppository and the concentration of the drug in the solution increases, leading to the increase of absorption of UV over time as stated in the Beer-Lambert law at the graph. However again due to errors in conducting the experiment, there is significant fluctuation observed on suppository I and II.
        Theoretically, the highest absorption UV should be suppository I, followed by II, III and IV.  However, due to error in experiment techniques such as parallax error, handling the equipments such as cuvette, pipette, the UV spectrometer etc, the result is different from the theory, where Suppository I has the highest absorption of UV at 520nm, followed by IV, III and II.

        Suppository IV has the highest amount of PEG 6000, followed by III, II and I. PEG 6000 is a high molecular weight with long chain length. The higher the amount of high molecular weight PEG, the higher the melting point and the firmer the suppository would be.  High concentration of high molecular weight PEG will also lengthen the dissolution time of the suppository,  which reduces the drug release. This will lower the concentration of drug in the solution and causes lower absorbance of UV.

5. What are the functions of each of the ingredient used in the suppository formulation? How the different amount of PEG1000 and PEG6000 used can interfere with the physical characteristic and the rate release of the suppository preparation.

      Paracetamol is a NSAID, having only anti-pyretic activity and analgesic effect, but no anti-inflammatory activity like other NSAIDs. Paracetamol has very low water-solubility. Thus, it should be homogenously dispersed in a water-soluble suppository base. It should not be dissolved in the base because this can reduce the release rate of Paracetamol.
      PEG 1000 and PEG 6000 are the examples of water-soluble suppository base used. The base acts as a carrier for the drug. It is designed to dissolve or disperse within the rectal mucosa, so that the drug homogenously dispersed within can be delivered into the plasma via diffusion through the plasma membrane. Then, the drug will exert its effect either locally or systemically.
       In the perspective of physical characteristics, a high molecular weight PEG can increase hardness, but decrease the stickiness and the hygroscopicity of the suppositories in the order from I to IV. This is because there is more abundant hydrogen bondings in the PEG used.
       The higher the amount of the high molecular weight PEG (eg PEG 6000), the slower will be the drug release rate from the suppository. Similarly, PEG 1000 can cause drug release rate to be faster. This can be proven by the decrease in the average UV absorbance from suppository I to suppository IV, when the amount of PEG 6000 increases. This is because suppository IV which consist of polyethylene glycol 6000 only form more hydrogen bonds within itself thus release the drug at the slowest rate.

      A combination of both PEG 1000 and PEG 6000 is beneficial, both to the physical characteristics and the drug release rate. A softer, less brittle preparation can be produced, where the drug is dispersed and liberated at a moderate rate. This is very important in ensuring that a certain amount of drug is constantly absorbed, and avoiding leakage of drug from the rectum which can be a waste.

Conclusion
As a conclusion, all the suppositories formulated have the torpedo-shaped.In terms of texture, greasiness of the suppositories increases with increasing of amount of PEG 1000. Increasing amount of PEG 6000 and decreasing amount of PEG 1000 in the suppositories in turn increases the hardness of the suppositories. About the color of the suppositories, all of them are generally white.
The release of paracetamol from the suppository into the water is determined by the UV absorption. Thus, the intensity of UV absorption is directly proportional to the concentration of paracetamol present in the water sample means that the UV absorption reading should be increased when the time is increased as the more paracetamol is released from the dialysis bag.
Theoretically, the highest absorption UV should be suppository I, followed by II, III and IV.However in this experiment, the result that we get is Suppository I has the highest absorption of UV at 520nm, followed by IV, III and II.

references
1.  Ashok Katdare, Mahesh Chaubal, Excipient Development for Pharmaceutical, Biotechnology, and Drug Delivery Systems, Informa Healthcare Inc (2006), New York

Retrieved from “http://books.google.com.my/books?id=_QVIS81xti8C&pg=PA211&lpg=PA211&dq=high+molecular+weight+of+PEG+on+suppository&source=bl&ots=JacNUi9BeM&sig=KhJJ9TUMqdH-YVyYyLfCiyES8Ek&hl=en&sa=X&ei=DThuU7a0CoKTrgfjnYDYBQ&redir_esc=y#v=onepage&q=high%20molecular%20weight%20of%20PEG%20on%20suppository&f=false”

2. Suppositories, U.S. Pharmacopoiea, Retrieved from http://www.pharmacopeia.cn/v29240/usp29nf24s0_c1151s68.html

3. Samantha_lewis1222, Exam 5, Anti Nauseant PEG suppositories, Quizlet, Retrieved from “http://quizlet.com/21295765/exam-5-anti-nauseant-peg-suppositories-flash-cards/”

Date : 26th MARCH 2014

Title of experiment:
The effects of differences characteristic of active ingredient in formulation of suspension.

Objectives:
1) To study the effects of difference amount of tragacanth used in the formulation of suspension.
2) To describe and elaborate the texture, clarity and colour of suspension formed.
3) To determine the viscosity and the ratio of height’s precipitate formed using different amount of tragacanth.


Introduction
A suspension is a two phased system in which a finely divided solid is dispersed in a continuous phase of solid, liquid, or gas. The undissolved solid exists in equilibrium with a saturated solution of the solid in the continuous phase. A pharmaceutical suspension is a coarse dispersion in which insoluble solid particles are dispersed in a liquid medium. Normally, they are visible under a microscope, and some can be seen with the naked eye. Particles in a suspension precipitate if the suspension is allowed to stand undisturbed. Generally, suspension comprised of active ingredient/s, wetting agent, flavouring, colouring as well as preservatives. The function of wetting agent such as tragacanth that we are used in this experiment is to reduce the surface tension between liquid and solid particles.

Apparatus
1 weighing boat, 1 set mortar and pestle, 1 plastic bottle 150 ml, 1 measuring cylinder 50 ml, 1 measuring cylinder 200 ml, 1 set pipette 1ml, 1 beaker 100 ml, viscometer tool, homogenization tool

Material
Chalk, tragacanth, concentrated peppermint water, syrup BP, double-strength chloroform water, distilled water.

Procedure
1) A formulation of Pediatric Chalk Mixture suspension (150ml)  were prepared by using this formula:

2) 5 ml of suspension that are formed was poured into the weighing boat and the texture, clarity and colour of the suspension that is formed was examined.

3) 50 ml of suspension that are formed was poured into 50 ml measuring cylinder, and the height of precipitate formed in the measuring cylinder was measured at every 5 minutes ( 0 minute to 60 minutes).

4) The remaining volume of the suspension that are formed( 95 ml) was poured into the 100 ml beaker and the viscosity of the suspension  was determined by using viscometer tool.

5) 10 ml of suspension that are formed was poured into the homogenize  tube and the height of solid phase formed in the tube after homogenization was determined ( 1000 rpm, 5 minutes,25 ° C)

result

Discussion

Compare the physical appearance of the suspensions that formed.

The texture of the solution become more concentrated which directly proportional to the amount of tragacanth that had been added. The clarity of the solution is clear when amount tragavanth is zero. This is due to the absence of suspending agent and the chalk sendiment in high sendimentation. Compare to others, their clarity is decrease as the amount of tragacanth increase. The higher amount tragacanth cause the suspension look highly opaque due to low sedimentation rate of suspensoid as well as the colour of suspension, it  become white when higher amount of suspending agent is present in the solution. The use of suspending agents causing disperse element become suspense in long duration and homogenous white colour can be directly observed.

Plot a graph of height of sediment vs. time. Give explanation.

The graph above is the formation of sediment for formulation I. Sediment starts once the time started to count.when time is increase, the height of the sendimentation decrease. This is because the sediment arrange themselves to each other cause forming a more compact sendiment.Sedimentation occurs due to the gravitational forces in which comparatively large drug particles will be sedimented. The height of the sediment becomes constant when all the chalk particles are sedimented.

plot a graph of height sediment against difference amount of tragacanth used

        For suspension 1 which is the one that without tragacanth, there is a sharp increase in the height of sedimentation from 0 to 100 mm from 0 to 5 minutes. After 5th minutes, the height of sedimentation had been decreased gradually until it reached the height where equilibrium is reached. The sharp increase in the height of sedimentation is due to the particles that tend to regroup and flocculate. Therefore, the dispersed phase settles to the bottom quickly. For suspension 2 (with 0.1g of tragacanth), there is an increase of height from time to time. For suspension 3, which contain 0.3g of tragacanth, the height of the sediment increases. This is due to the presence of greater amount of tragacanth in the suspension which makes suspension 3 becomes more stable than suspension 2. The greater the amount of suspending agent used, the longer the time taken for the sediment to form since the suspension is more stable. For suspension 4, which contains 0.5g tragacanth, the height of the sediment increases dramatically. The height of the sediment is then remains constant from 20 to 60 minutes. With a high amount of tragacanth, the particles remain suspend in the suspension which counteract the gravity force, thus there is no caking of suspension. It is readily to be redispersed and it can be considered as a stable suspension. Tragacanth acts as suspending agent that increases the viscosity of the suspension. The lesser the tragacanth content, the faster the insoluble particles settle at the bottom of measuring cylinder.


Plot a graph of viscosity against amount of tragacanth 

       Based on the graph, at first the viscosity of the suspension firstly dropped when as the amount of tragacanth increased from 0.0g to 0.3g. The viscosity of suspension will increase when the amount of tragacanth is 0.5g. As the amount of tragacanth increase, the viscosity of the suspension will also increase. Tragacanth act as a common gelling agent and a is a high molecular weight polymer. It will be hydrated when water is added to it due to the presence of galacturonic acid. The attraction of R-COO group with water causes long and short distance order, leading to overall thickening effect. This effect will increase when more tragacanth is added as the more tragacanth molecule will interact with water, leading to increase in thickness of the suspension. The graph is different from stated in the fact could be due to error occurred while handling the equipment or materials during the experiment.

      A viscometer contains a spindle which will turn in a suspension fluid at a known speed. The viscometer will measures the torque required to turn a spindle in a suspension fluid at a known speed. The torque required to turn the spindle is quantified as the shear stress acting across the surface area of the spindle. The fixed speed of the viscometer would be the shear rate. The higher the shear stress the higher the viscosity of the suspension. The viscometer is measured in the unit of centipoise (cP)


Plot a graph of height ratio of the precipitation caused by centrifuge against content of tragacanth. Give comment. 

       From the graph, overall it show that when the content of tragacanth increases, the height ratio increase. This is  similar to the theory. This is because when content of tragacanth which act as suspending agent increases, the suspension is suspended better, thus the sedimentation volume will increase which cause the height ratio to be higher. In contrast, in suspension with low concentration of tragacanth, the solid is not suspend well, thus they tend to sediment in closely manner and producer a lower sedimentation volume.

       However, during the experiment, when 0.5 g of tragacanth was used, the height ratio decreases. This may due to errors that were made during the experiment. First, before the sample was being placed into the centrifuge, less than 10ml of the sample was taken. This cause the mixing to  be uneven which may cause inaccurate result. Besides, when height ratio is measured, the results were taken approximately as the sediment is cloudy and white in colour. The measurement may be varied between different subjects

What is the function for each ingredients used in the suspension preparation? How does the different amount of tragacanth usage affects the physical property and stability of a suspension formulation?
     In the formulation, the chalk act as an active ingredient. Tragacanth act as suspending agent and also act as thickening agents. Concentrated cinnamon water act as flavoring agent for the suspension. Double strength chloroform water act as simple preservative in oral dosage form. Distilled water act as solvent.
The higher the amount of tragacanth, the more viscous the suspension. They increase the viscosity of the solution to reduce the sedimentation rate of the suspended particles as per Stoke’s law. Tragacanth is an large size polyelectrolyte. They will adsorb onto the surface of particle, and hinder the particles to be close to each causing aggregation of particles via steric stabilization mechanism as well as charge repulsion from the galacturonic acid residue of the tragacanth molecule. Too much tragacanth would cause the suspension to be too thick which will hardened the suspension to be poured out from the container.

Conclusion
The texture of the solution become more concentrated which directly proportional to the amount of tragacanth that had been added. The clarity is decrease as the amount of tragacanth increase.

As the amount of tragacanth increase, the viscosity of the suspension will also increase. When the content of tragacanth increases, the height ratio of sediment will also increase.

Reference

1. NPCS Board of Consultants & Engineers, Handbook on Textile Auxiliaries, Dyes and Dye Intermediates Technology, Asia Pacific Business Press, Delhi

2. John F. Mariott, Keith A Wilson, Christopher A Langley, Dawn Belcher, Pharmaceutical Compounding and Dispensing, Pharmaceutical Press (2006), London

3. Yokoyama, A., Srinivasan, K. R., Fogler, H. S. (1988/11)."Stabilization mechanism of colloidal suspensions by gum tragacanth: The influence of pH on stability." Journal of Colloid and Interface Science 126(1): 141-149. http://hdl.handle.net/2027.42/27076

4. A. Nussinovitch, Hydrocolloid Applications: Gum Technology in the Food and Other Industries, Blackie Academic and Professional (1997), London

Date of experiment
12 March 2014

Title
The effects of differences characteristic of active ingredient in formulation of emulsion

Introduction
        An emulsion is mixture of two liquids that would not normally mix. That is to say, a mixture of two immiscible liquids. By definition, an emulsion contains tiny particles of one liquid suspended in another. Chemically, they are colloids where both phases are liquids. They are typically milky in appearance and the suspended material may be colloidal in nature.
       A classic example of an emulsion is oil and water when mixed slowly under vigorous stirring. However, when the agitation is stopped, the two liquids separate and the emulsion breaks down.
          Stable emulsions can be formed from two immiscible liquids when an emulsifier is used. Such emulsions do not separate out after a change in conditions like temperature or over time.

Objectives
     1) Determine the effect of HLB surfactants on emulsion stability.
     2) Examine the effects of physical and stability of the emulsion formulation with the use of different agent.

Apparatus
8 test tubes, 1 measuring cylinder 50 ml, 2 set pasture pipette and droppers, weighing boat, 1 set mortar and pestle, light microscope, microscope slides, 1 set pipette 5 ml and bulb, 1 beaker 50 ml, viscometer apparatus, water bath, refrigerator, vortex mixture tool

Materials
Mineral oil, distilled water, span 20, tween 80, larutan sudan III, acacia, syrup, vanillin and alcohol

Procedure
     1) 8 test tubes were labeled and straight line were drawn 1 cm from the bottom of each of the test tubes.
     2) Then, 4 ml of oil (Table 1) and 4 ml of distilled water were added into each of the test tubes.

     3) Span 20 and Tween 80 (Table 2) were drops into the mixture of oil and water in each of the test tubes. The test tubes were closed and the mixture was mix using Vortex mixture tool for about 45 seconds. The times taken for the interface to achieve the 1 cm line were recorded. The HLB values for each sample were determined.

     4) 1g of the emulsion that is formed in each test tube was weight in the weighing boat and Sudan III (0.5%) solution were drops to the emulsion. Dispersion of color in the samples were described and compared. A little sample for each of the test tubes was spread on a microscope slide and observed under a light microscope. The shape and size of globular that are formed were drawn and compared.

    5)  By using the wet gum method, a formulation of Mineral Oil Emulsion were prepared using the formula below:

          Wet gum method
           a)      Acacia is added to the mortar and triturated with water until smooth gum is formed.

           b)      The oil is added to the mixture while triturating continuously until a smooth emulsion is obtained.

       6)  40 g of emulsion that are formed was added into a 50ml beaker and homogenizing process was done for 2 minutes using a homogenizing device.

       7)  2 g of emulsion that are formed was taken before and after the homogenizing process and put into the weighing boat and labeled. A few drops of Sudan III solution was added into the emulsion and smooths it. The texture, consistency, shape, degree of greasiness and dispersion color of samples was described and compared under light microscope.
                                                                           
     8) Viscosity of the emulsion (15 g in 50 ml beaker) that are formed after the homogenizing was determined by using the viscometer equipment that has been calibrated at all times by using the "Spindle" type LV-4. The samples are then exposed to a temperature of 45 ⁰C (water bath) for 30 minutes and then at a temperature of 4 ⁰C (refrigerator) for 30 minutes. Viscosity of the emulsion after exposure to temperature cycles completed was determined and emulsion reaches room temperature (10-15 minute).

     9) 5 g of emulsion that have been homogenized was added into a centrifuge tube and it is centrifuged (4500 rpm, 10 minute, 25 ⁰C).  The resulting high separation was measured and the ratio of the separation was determined.

Results

result for mineral oil

       to calculate the HLB value, we use this formula:

         Emulsions contains materials of different densities.During the centrifugation process of emulsion at 4500rpm for 10 minutes, creaming, flocculation and coalescence will occur . Mineral oil has lower density (0.8/cm3)  than water (1.0g/cm3). The mineral oil droplets rise and concentrate, which appears at the top. Finally, the drops will coalesce to form a separate layer of oil on top from water causing phase separation.

Discussion

       The HLB of an emulsifier is related to its solubility. Thus, an emulsifier having a low HLB will tend to be oil-soluble, and one having a high HLB will tend to be water-soluble, although two emulsifiers may have the same HLB and yet exhibit quite different solubility characteristics.

       Generally, the emulsion of  will separate into two phases within shortest time if the surfactants (Span 20 or Tween 80) are not used in the formulation. This is due to the absence of the surfactant which play a role in dispersing the oily phase into the aqueus phase or otherwise. If a single susfactant is used in the emulsion formulation, the product produced is not so stable compared to the emulsion with combination of 2 surfactants.

           In fact, surfactant is used in formulating the emulsion to stabilise both the oil and aqueus phases which are not immiscible. Micelle consists of the hdrophillic head and hydrophobic tail. It will try to keep the hydrophobic drug particles in the core of the micelle with the tail points inward to the center of the micelle and the head will remain in the aqueus phase. The adsorbtion of the surfactant at the interface between the two immiscible phases will lower the interfacial tension, the process of emulsification will be made easier and the stability may be enhanced.

           However, there may be some experimental errors that can make the results inaccurate. The surfactants added are measured by drops which is not so accurate. There maybe also parallax errors when observing the phase separation in the test tubes. Different observers for different test tube may also resulted in inacurate result.

diagrams of mineral oil emulsion under light microscope 

       Sudan solution is used to show the shape and physical characteristic of oily emulsion. It can show the emulsion whether is oily-in-water emulsion or water-in-oil emulsion by comparing the amount of the globules in red color and the colorless globules. Sudan solution, which is red in color, is dissolved in the oily phase in the emulsion. This makes the oily globules red in color.

non-homogenized and homogenized emulsion

                                              Non-Homogenized Emulsion (magnification x10)

                                           Homogenized emulsion (magnification x10)

          Homogenization is a process of increasing the stability of existing emulsion by decreasing the size of droplets either by impact or shearing the emulsion further. During the homogenization process, droplet deformation occurs where the droplets of emulsion are broke up into smaller droplets and the surfactant that previously attach to the droplet is also separated from the droplet. Stabilization  takes place after homogenization where the surfactant will adsorp onto the surfact and prevent the small droplets from fusing back together.

        For non homogenous emulsion, the size of the droplets appears bigger than the homogenized emulsion due to the impact or shearing of the emulsion to smaller size.The average size of the droplets of on to the surfactant homogenized emulsion is less even than the droplet of homogenized emulsion. distribution of the droplets. The texture of a non homogenized emulsion is less creamy than the homogenized emulsion as the dispersed phase is less distributed compared to homogenized emulsion. The non homogenized emulsion is also less viscous than the non homogenized emulsion. The more even distribution of the dispersed phase in homogenized emulsion also made the colour of the homogenized emulsion to appear more even than the non homogenized emulsion. 

        

Plot and discuss

     i) Graph of sample viscosity before and after the temperature cycling vs the different content of Mineral oil.

        The exaggeration of the temperature fluctuations subjected to the emulsion in the normal storage conditions is used to compare the physical instabilities of the emulsion. The emulsion is subject to freeze-thaw cycling which involved heating the sample at 45°C for 30 minutes, freezing it at 4°C for 30 minutes and lastly let the sample to achieve room temperature before measuring its viscosity. From the results, it shows that the viscosity of emulsion increase after the temperature cycling. Viscosity of emulsion increase as the result of extensive droplet aggregation which may cause by a number of physicochemical mechanisms. First, when the emulsion was placed in the freezer, some of its water crystallized. This caused the dispersed oil droplets to come into closer proximity because the oil droplets were confined to the non frozen regions remaining in the aqueous phase. When there was no presence of sufficient free water to fully hydrate the oil droplet surfaces, the droplet–droplet interactions was forced closer together to effect coalescence to occur. Second, ice crystallization led to an increase in the ionic strength of the freeze-concentrated non-frozen aqueous phase surrounding the emulsion droplets. Third, it is possible that ice crystals formed during freezing may have penetrated into the oil droplets and disrupted their interfacial membranes. This allowed the oil droplets more prone to coalescence between them. Fourth, cooling may have caused some of the fat in the emulsion droplets to crystallize promoting partial coalescence due to penetration of a fat crystal from one droplet through the membrane of another droplet.

   ii) Graph of the viscosity difference (%) versus various amount of mineral oil

       In this experiment, emulsion containing 30ml of mineral oil shows the greatest difference in the viscosity, that is 409.62%. The smallest difference in viscosity, which is 1.95%, is shown by the emulsion containing 20ml of mineral oil. The higher the difference in viscosity, the less stable is the emulsion. From the results obtained in this experiment, emulsion III  is the most unstable emulsion while emulsion I is the most stable one. This is because when there is a higher oily phase present in an emulsion (emulsion with 30ml of mineral oil), the emulsion is more unstable as the oil droplets tend to aggregate especially after the freeze-thawing cycle. Theoretically, emulsion IV with 35ml of mineral oil should show highest viscosity difference. However, it only has 19.13% of viscosity difference, this show that error has occurred. 

Plot a ratio separation phase as a result of centrifugation process on different amount of mineral oil. Describe.

      Based on the graph above, the separation phase ratio decreases as the volume of mineral oil increase. When the separation phase ratio of the emulsion decreases, this indicate the stability of emulsion is higher as the emulsion is more stable from undergoing the process of creaming, flocculation, and coalescence through the centrifugation process. Less amount of phase separation will occur. This indicate the higher the amount of mineral oil, the lower the separation phase ratio of the emulsion, and the more stable of the emulsion, until it achieves the optimum amount of mineral oil or ratio of mineral oil with water in the emulsion.


What is the function of each ingredient used in the preparation of the emulsion? How is the usage of different ingredients would affect the physical properties and stability of an emulsion formulation?
        Mineral oil act as the active ingredient of the dosage form. Acacia act as emulsifying agent that can provide electrostatic between the oil droplets to prevent them from coalescence in the vehicle, making the emulsion to be more stable.Syrup functions to provide a sweet flavour as well as masking the unpleasant taste of mineral oil. Vanillin act as flavouring agent and make the emulsion taste better.Alcohol also act as emulsifierand stabilize the emulsion. Distilled water act as solvent and act as vehicle for all the ingredients of the emulsion.

Conclusion
The HLB values for the mineral oil are different from each other due to the differences of quantity tween 80 and span 20 that was added into the sample.  From the result of viscosity test, it shows that the viscosity of emulsion increase after the temperature cycling as the result of extensive droplet aggregation.
For the experiment of viscosity that involving different content of mineral oil, emulsion containing 30ml of mineral oil shows the greatest difference in the viscosity, that is 409.62%. The smallest difference in viscosity, which is 1.95%, is shown by the emulsion containing 20ml of mineral oil. For the experiment of separation phase ratio, the result that we obtained show that the separation phase ratio decreases as the volume of mineral oil increase.


References
1) Lab (7) Preparation of a pharmaceutical emulsion, Jordan University of Science and Technology, Faculty of Pharmacy,Department of Pharmaceutical Technology, Retrieved from http://www.just.edu.jo/~sfg/Lab72.htm

2. R. L.Earle, Emulsification,Unit Operation in Food Processing , Retrieved from http://www.nzifst.org.nz/unitoperations/sizereduction2.htm

3. Klein K., Stability Testing…So What’s Adequate?, Cosmetech Laboratories Inc., Retrieved from
http://www.zenitech.com/documents/Stability%20Testing.pdf

4. Emulsion Stability and Testing, Particle Sciences, Retrieved from
 http://www.particlesciences.com/news/technical-briefs/2011/emulsion-stability-and-testing.html