THE USE OF WETTING AGENT IN SUSPENSION

UNIVERSITI KEBANGSAAN MALAYSIA

 

 

 

LABORATORY REPORT

DEVELOPMENT OF PHARMACEUTICAL PRODUCTS 1

(NFNF 2213)

 

TITLE                        : THE USE OF WETTING AGENT IN SUSPENSION

GROUP                     : 2

NAME                       : MUHAMMAD RASYDAN BIN BUCHEK     A168185

                                  FARINA ZAHIDAH BINTI ABD AZIZ          A168417

                                  NUR AQILAH BINTI ABDUL KADIR          A169046

                                  LILLIAN YEO FANG FANG                        A167802

 

LECTURER’S NAME  : PROF. MADYA DR. HALIZA BINTI KATAS

 

SEMESTER I, SESSION 2019-2020

FACULTY OF PHARMACY

 

TITLE:

The use of wetting agent in suspension  

 

DATE:

3rd October 2019  

 

OBJECTIVES:

To identify the effect of concentration of tragacanth to the rate of sedimentation of suspensions.  

 

INTRODUCTION:

      The suspension is a heterogeneous mixture where the solute is not dissolved in the solvent but it is suspended in the continuous phase either in liquid or gas form. Mostly, suspension is used for drugs that is not soluble to water and drugs having unpleasant taste and odour. Suspension can be used in oral administration as a flavoured and sweetened formulation which patients able to use them. It is also can be used for non oral administration such as lotion and parenteral medication. 

      Suspension is physically unstable due to they tend to settle after a period of time without agitation. This may lead to lack of uniformity of the drug dispersity and might lead to therapeutic effects. A good suspension should be easily homogeneously dispersed when shaken to prevent therapeutic effects, pourable, have pleasant taste and texture and also uniform particle size. Besides, they should also easy to redispersion of settled solid particles, physically and chemically stable and resistant against microbial contamination. To produce better suspension, a few important aspects regarding particle size distribution, specific surface area, inhibition of crystal growth and changes in the polymorphic form should’ve been given attention. This to make the suspension keep stable even after a long period of storage.

      The amount of suspending agent used in formulation is depends on the volume of vehicle used. It does not vary with the amount of powder in the preparation. A suspending agent function is to increase the viscosity of the vehicle and therefore reduces sedimentation rates and reduce the surface tension. Another way to reduce the sedimentation rate is by decreasing the particle size of the powder in suspension. The most common suspending agents used Tragacanth and sodium lauryl sulphate. For this experiment we are using tragacanth as suspending agents to observe the relationship between concentration of tragacanth and sedimentation rate of suspension.  

 

APPARATUS:

1 x 1 mL graduated pipette	1 x 100 mL beaker
1 x pipette bulb	Parafilm®
1 x weighing boat	1 x Weighing balance
1 x set of mortar and pestle	1 x Viscometer
1 x 50 mL graduated cylinder
1 x 200 mL graduated cylinder

 

MATERIALS:

Chalk	Double strength chloroform water
Tragacanth	Distilled water
Concentrated peppermint water (or any flavoring agent)	Syrup BP

 

PROCEDURE:

1. A suspension of Pediatric Chalk Mixture (150 mL) was prepared according to the following formula:

INGREDIENT		Suspension
	A	B	C	D	D
Chalk (g)	3	3	3	3	–
Tragacanth (g)	0.0	0.01	0.03	0.05	0.1
Concentrated peppermint water (mL)	0.5	0.5	0.5	0.5	0.5
Syrup BP (mL)	15	15	15	15	15
Double Strength Chloroform water (mL)	75	75	75	75	75
Distilled water q.s. (mL)	150	150	150	150	150

 

2. 5 mL of the suspension was poured into a weighing boat and each formulation was labelled.   The texture ,clarity and color of each suspension were observed and compared.

 

3. The sedimentation rate of each suspension was determined. The suspension was shook vigorously to make sure all of the particles were uniformly suspended, and the time wass noted. The boundary between the sediment and the supernatant was observed and  the time took for the boundary to pass each 10 mL graduation until the volume of sediment reached 80 mL was recorded. 

 

**The best way to observe the boundary is to view it directly in front of a light source. A clear and distinct boundary or no obvious boundary was noted.

 

4. The graduated cylinder was set down on the lab bench, and the lab timer was started at this point.

 

5. For suspensions A to D, the sedimentation volume of the suspensions were recorded at time, t=0, 2, 5, 10, 15, and      30 min.

 

6. The obtained data was recorded  in the table.

 

7. The sedimentation volume ratio was calculated using the following formula  :

     Sedimentation volume ratio = Hu/Ho

     Hu: ultimate height of the sediment, the height of the sediment at a particular

              time

     Ho: initial height of the total suspension

 

8. The ease of re-dispersibility of each formulation was examined after the last measurement. To do this:

I. The Parafilm® was made sure to snug on the mouth of the graduated cylinder, and the seal is re-enforce with gloved hand.

II. The number of inversions it takes to completely re-disperse the drug was counted .

III. The observations were recorded.

 

9. 95 mL of suspension was poured  into a 100 mL beaker and the viscosity of the suspension was determined using viscometer at 12 000 rpm for 2 minutes.

 

10.  The data was recorded in the table.

 

11.  Each suspension was poured  into a plastic bottle. After storing all the suspensions for a period of 4 days,  the ease of redispersion and which system was most acceptable were determined in each system was determined.

 

RESULTS:

1. Texture, clarity and colour

Observations	Texture	Clarity	Colour
A	Watery	Not clear	White
B	Thicker than A	Not clear	White
C	Thicker than A	Not clear	White
D	Watery	Translucent	Colourless

 

2. Volume of sendiment

Volume of Sediment	Time taken (s)
	150mL	140mL	130mL	120mL	110mL	100mL	90mL	80mL
A	0	46	87	113	141	215	248	293
B	0	–	–	–	–	–	–	–
C	0	–	–	–	–	–	–	–
D	0	–	–	–	–	–	–	–

 

3. Sedimentation volume at pre-determined time 

Suspension	Sedimentation volume (mL) at pre-determined time (min)						Distinct boundary (yes/no)
	0	2	5	10	15	30
A	150	150	75	27	26	12	Yes
B	150	150	150	150	150	150	No
C	150	150	150	149	148	148	No
D	150	150	150	150	150	150	No

 

4. Sedimentation volume ratio

For Suspension A:

Time (min)	Sedimentation volume ratio
0	150/150 = 1
2	150/150 = 1
5	75/150 = 0.50
10	27/150 =0.18
15	26/150 = 0.17
30	12/150 = 0.08

  For Suspension B:

Time (min)	Sedimentation volume ratio
0	150/150 = 1
2	150/150 = 1
5	150/150 = 1
10	150/150 = 1
15	150/150 = 1
30	150/150 = 1

  For Suspension C:

Time (min)	Sedimentation volume ratio
0	150/150 = 1
2	150/150 = 1
5	150/150 = 1
10	149/150 = 0.99
15	148/150 = 0.99
30	148/150 = 0.99

  For Suspension D:

Time (min)	Sedimentation volume ratio
0	150/150 = 1
2	150/150 = 1
5	150/150 = 1
10	150/150 = 1
15	150/150 = 1
30	150/150 = 1

 

Suspension	Sedimentation volume (mL) at pre-determined time (min)						Distinct boundary (yes/no)
	0	2	5	10	15	30
A	1	1	0.5	0.18	0.17	0.08	Yes
B	1	1	1	1	1	1	No
C	1	1	1	0.99	0.99	0.99	No
D	1	1	1	1	1	1	No

 

5. Ease of redispersibility

A = Easy

B = Easy

C = Easy

D = Easy

B,C and D are easy to disperse because the sediment formed was in small value.

 

6. Viscosity

X = mean

∑ X = sum of viscosity

n = no of recording recorded

   

Suspension	Viscosity (cP)			Mean	Standard Deviation
A	0.66	1.20	0.72	0.86	0.0876
B	1.02	1.68	1.14	1.28	0.1236
C	0.48	0.36	0.54	0.46	0.0084
D	1.32	1.62	1.38	1.44	0.0252

 

7. Ease of redispersion after 4 days storage

A = Hard, required 13 inversions

B = Quite hard, required 10 inversions

C = Quite easy, required 6 inversions

D = Easy, required 3 inversions

 

DISCUSSION:

1. Compare and discuss the physical appearances of all suspensions produced.

In this experiment, four suspensions are prepared with varying amount of tragacanth as wetting agent. The physical appearance in terms of texture, clarity and colour is observed. Tragacanth can give viscosity to the suspension as it has great importance for stability and pourability of suspensions. The presence of wetting agent facilitates the distribution and dispersion of the lyophobic powders. Absence of the tragacanth as the suspending agent causes the suspensions to sediment very fast and the particles are separated into two distinct boundaries.

Based on the observation, Suspension A has the clearest clarity, least viscous and milky suspension among suspension B, C and D. This is due to the absence of tragacanth powder that serves as a viscosity increasing agent. The absence of the tragacanth as suspending agent causes suspension A to sediment very fast. Therefore it shows the clearest distinct boundaries.

In suspension B, the suspension is less viscous than C due to the presence of small amount of tragacanth. It is a bit cloudy due to the insoluble chalk powder which does not dissolve in the solution. The viscosity contributes by the tragacanth gives the colour of milky white. The rate of sedimentation in suspension B is much slower than suspension A. This is due to the presence of the tragacanth as suspending agent which helps to prevent settlement of the suspended solids under gravity. The clarity of this suspensions iss opaque compared to clearer suspensions A because the suspensions does not seem to separate into two separate layers.

Suspension C has greater viscosity compared to B but lower compared to A because of increased amount of tragacanth. The texture is very smooth and cloudy because tragacanth helps to suspend and distributes the insoluble particle evenly. The colour of milky white is due to the viscosity and the chalk powder. The sedimentation rate of suspension C is higher than suspension B due to greater amount of tragacanth added. 

Suspension D is the most vicious because it contains the highest amount of tragacanth with no chalk. It has the thickest texture. This is because suspension D contained the highest amount of tragacanth but does not contain chalk, the active ingredient to be suspended in aqueous phase. Due to the absent of tragacanth, the chalk particles tend to sediment quickly and left the top part free from chalk particles.

 

2.Plot Hu/Ho vs time for each of the suspension ( Table 1 ). Discuss the findings. 

Sedimentation volume ratio is the ratio of the ultimate height or volume of sediment (Hu) to the original height or volume of sediment (Vo) before settling. 

From the graph shown above, the sedimentation volume ratio for suspension A increases a little then decreases with time. This is due to absence of tragacanth which act as wetting agent and suspending agent which can stabilize and disperse the indiffusible solid uniformly in the suspension. Therefore, sedimentation occurs the fastest in suspension A. However, as time goes by, the graph decreases sharply and slightly towards the end. This is because the suspension starts to form sediment or flocculation system. As the flocs is pulled down to the bottom, it will form flocs and start to compact. Eventually, sediment is formed. 

Sedimentation volume ratio for suspensions B, C and D are quite constant with time. This may due to the presence of tragacanth, which act as wetting agent or suspending agent. So, the indiffusible solid chalk particles can disperse uniformly in the suspension and less tendency or slower to form sedimentation. The reason for graph to show almost constant value may be because sedimentation did not occur during that period of time. The suspension may require a longer time to sediment.

 

3. Briefly explain the principle of analysis using viscometer. Plot the viscosity vs  tragacanth content (Table 2 ). Discuss the findings.

A viscometer is an instrument used to measure the viscosity of a fluid. Generally, a specifically selected spindle is immersed in a sample of liquid or product and the viscosity if measured according to the torque required to rotate the spindle at a preset speed. This torque has to overcome the viscous forces of the tested substance and is therefore a measure for its viscosity. The viscometer works according to the principle of Searle and Couette. 

According to Searle Principle, the motor drives the cup while the bob is stationary to minimize the risk of turbulent flow. According to Couette Principle, the measuring bob or spindle is driven by a motor in a container filled with fluid. The driving speed is preset and the torque required to turn the measuring bob against the fluid’s viscosity is measured.

Theoretically, tragacanth content is directly proportional to viscosity. The greater the amount of tragacanth, the more viscous the suspension. Tragacanth acts as suspending agent that suspends and stabilises the active ingredient by increasing the viscosity of the suspension, preventing sedimentation as per Stokes Law. So, suspension A is the least viscous suspension and suspension D is the most viscous suspension. viscosity increases with the amount of tragacanth. This is because suspension A does not contain any tragacanth. This can cause instability, hard to redisperse and increase in sedimentation rate. Meanwhile, suspension D contains only tragacanth, thus increasing the viscosity of the liquid. 

There is an error in suspension C, which supposedly should have higher value of viscosity than suspension B but lower than suspension D. This may due to error occurs when handling the viscometer.

 

4. After storing the suspensions for a period of 4 days, determine the ease of  redispersion for each.

After storing for 4 days, the ease of redispersion are as shown:

Bottle	A	B	C	D
No. of inversion	13	10	6	3

 

After storing the suspensions for a period of 4 days, it is found that suspension D require the least number of inversions among suspensions A, B and C. This means that suspension D is the easiest to be dispersed among all the suspensions. This is because it contained the greatest amount of tragacanth as suspending agent without any chalk which suspend in the liquid. Tragacanth can also act as a wetting agent which can lower the interfacial tension of suspension liquid. Suspension A needs the highest number of inversions, thus it is the most difficult to redisperse. This is because it only contains chalk without any tragacanth as suspending agent to stabilise the suspension.

For suspension B, it needs higher number of inversions compared to suspension C because it contains less amount of tragacanth. Therefore, suspension B is less stable compared to suspension C and prone to sedimentation. So, suspension B is harder to redisperse.

 

5. Based on all observation, which product would be considered to be most  acceptable? Explain.

Based on all observations, suspension C is consider to be most acceptable. This is because suspension C contained the greatest amount of tragacanth among suspension A and B, without comparing to suspension D. The greater the amount of tragacanth, the more viscous the suspension was. The more viscous the suspension, the more stable the suspension is. Therefore, suspension C has the lowest sedimentation rate, lowest interfacial tension and most suitable viscosity. This prevent the finely insoluble chalk which suspends in the liquid to agglomerate, agitate and form cake. Besides, it also requires the least number of inversions. This shows that it is easily redisperse into original suspension. Meanwhile, suspensions A and B containes less amount of tragacanth, so they has a higher sedimentation rate and higher interfacial tension. Thus, the suspension is not stable and has a higher tendency to cause sedimentation and caking. Suspension D is not suitable as it containes only tragacanth without any chalk which act as active ingredient.

 

CONCLUSION:

The effect of concentration of tragacanth, which act as wetting agent and suspending agent can help to lower the rate of sedimentation of suspensions. The concentration of tragacanth can also changes viscosity of the suspension. The more the amount of tragacanth, the higher viscosity of suspension. Eventually, the suspension is more stable as it less likely to sediment, which is bad for pharmaceutical products. 

For this experiment, suspension D gives highest viscosity and took the longest time to sediment. However, because there was no active ingredient for suspension D and suspension C is the best sample for suspension as it exhibits like a drug suspension with chalk as active ingredient and more stable compared to suspension A and B.

 

REFERENCE:

1. https://www.slideshare.net/Muwela001/pharmaceutical-suspension

2. http://www.uobabylon.edu.iq/eprints/publication_3_31242_6264.pdf

3. http://abacus.bates.edu/~ganderso/biology/resources/centrifugation.html