Suppository

Title:

To investigate the effect on characteristic of suppositories formulation by using different portion of ingredient.

Introduction:

Suppositories is a solid formulation with different size and shape suitable for rectal administration. Good suppositories must melt and dissolve after administer to the rectal and dispersed the drug for local or systemic effect.

Drug must be dispersed in a suitable suppositories base. Good base must not toxic, do not give irritation; do not interact with other drug and also easy to be shape to become a suppository. The different base composition will affect the rate and dispersion of the drug from the suppositories.

In this experiment, effects on different base composition towards the physical characteristic of the suppositories that produce and the effect toward drug release from the suppositories have been investigated.

Apparatus:

Electronic balance, 1 weighing boat, spatula, 50 ml beaker, 100 ml beaker, hot plate, 5 ml measuring cylinder, suppository mould, water bath 37  ̊C, dialysis bag 10 cm, 2 strand, glass rod, 5 ml pipette and pipette bulb, plastic cuvette, spectrophotometer UV.

Materials:

Polyethylene glycol (PEG) 1000

Polyethylene glycol (PEG) 6000

Paracetamol

Procedure:

1.       Saturated of paracetamol stock solution was prepared. (10g in 5ml distilled water)

2.       Paracetamol suppositories were formulated. (1g by using this formula) :

Suppository	Group	Ingredient (g)		Paracetamol stock solution (1g)	Total (g)
		PEG 1000	PEG 6000
I	1, 5, 9	9	0	1	10
II	2, 6, 10	6	3	1	10
III	3, 7, 11	3	6	1	10
IV	4, 8, 12	0	9	1	10

3.       Suppositories were shaped by using suppository-mould. Shape, texture, and colour produced were described and compared.

4.       1 suppositories was put into a beaker that contains distilled water (10 ml, 37  ̊C) and time that need for the suppositories to melt was recorded.

Content PEG 6000 (g)	0	3	6	9
Time (min)	65	10	60	74
	58	65	43	61
Average ± SD	61.5±4.95	37.5±38.89	51.5±12.02	67.5±9.19

5.       1 suppository was inserted into a dialysis bag and make sure both end were tied tightly as shown below in the diagram. Dialysis bag was place in a beaker (100 ml) that contains distilled water (50 ml, 37 ̊C).

6.       3-4 ml aliquot sample was pipetted for every 5 minute for about 30 minutes. Dispersion of paracetamol from the suppositories was recorded by using UV-visible spectrometer. Make sure the distilled water were stirred using a glass rod before taking the sample.

Time (min)/ Group	Average of UV absorption at 520 nm (x ± SD
	0	5	10	15	20	25	30
1	0.013	0.197	0.217	0.208	0.211	0.225	0.297
5	0.0013	0.0045	0.0074	0.0068	0.0082	0.0112	0.0110
2	0.020	0.025	0.031	0.034	0.034	0.035	0.036
6	0.0006	0.0012	0.014	0.011	0.012	0.011	0.016
3	0.002	0.003	0.004	0.007	0.021	0.013	0.019
7	0.02	0.033	0.030	0.010	0.023	0.013	0.013
4	0.000	0.002	0.003	0.003	0.004	0.004	0.005
8	0.010	0.018	0.078	0.033	0.046	0.044	0.046

Results:

Content PEG 6000 (g)	0	3	6	9
Time (min)	65	10	60	74
	58	65	43	61
Average ± SD	61.5±3.5	37.5±27.5	51.5±8.5	67.5±6.5

Time (min)/ Group	Average of UV absorption at 520 nm (x ± SD)
	0	5	10	15	20	25	30
1	0.013	0.197	0.217	0.208	0.211	0.225	0.297
5	0.0013	0.0045	0.0074	0.0068	0.0082	0.0112	0.0110
2	0.020	0.025	0.031	0.034	0.034	0.035	0.036
6	0.0006	0.0012	0.014	0.011	0.012	0.011	0.016
3	0.002	0.003	0.004	0.007	0.021	0.013	0.019
7	0.02	0.033	0.030	0.010	0.023	0.013	0.013
4	0.000	0.002	0.003	0.003	0.004	0.004	0.005
8	0.010	0.018	0.078	0.033	0.046	0.044	0.046

                             

                                       

Questions:

1.      Compare the physical appearance of the suppository formed.

Suppository	Group	Shape	Hardness	Greasiness	Colour
I	1,5 9g PEG 1000 0g PEG 6000	Bullet	soft	greasy, oily	Intense white
II	2,6 6 g PEG 1000 3 g PEG 1000	Bullet	medium	Greasy	Clearly white
III	3,7 3g PEG 1000 6g PEG 6000	Bullet	hard	Not so greasy	Milky white
IV	4,8 0g PEG 1000 9g PEG 6000	Bullet	Very hard	Less greasy	Clearly white

All suppositories are bullet-shaped because same type of mould is used to make the suppositories. From suppositories I to IV, the content of PEG 1000 decreases while the content of PEG 6000 is increasing. The hardness of the suppositories increases from I to IV. This is because increasing the content of PEG 6000 increases the number of hydrogen bonds between the molecules. Therefore, hardness and strength of suppositories increases. PEG 6000 less oily and this make the contents of the suppositories less oily and drier.

2)  Plot a graph of time needed to melt the suppository against the quantity of PEG 6000 in the formulation. Compare and discuss the result.

Amount of PEG 6000 (g)	0		3		6		9
Group	1	5	2	6	3	7	4	8
Time taken to melt (min)	65	58	10	65	60	43	74	61
Average time (min) (x±SD)	61.5±3.5		37.5±27.5		51.5±8.5		67.5±6.5

          Graph above shows the time needed to melt the suppository against the quantity of PEG 6000 in the formulation.

          PEG 6000 also known as Polyethylene Glycol 6000, it has high molecular weight of ethylene oxide and it is a water-soluble. The amount of PEG 6000 will affect the in vivo release of the drug in the body because due to its solubilizing character of this base and its low dielectric constant. By using greater amount of PEG 6000, drugs may tend to remain in the base and slow down the release of acetylsalicylic acid from suppository.

        Therefore, increasing amount of PEG 6000 will slow down the rate of release of acetylsalicylic acid from suppository. The suppository IV with greatest amount of PEG 6000 (9g) take the longest average time (67.5 mins) in order to melt in body temperature of 37°C. For suppository I with absence of PEG 6000, it takes longer time (61.5 mins) to melt than suppository II and III with immediate amount of PEG 6000 (3g and 6g). It is because suppository I contains high amount of PEG 1000 although it does not contain PEG 6000.

          Besides, there are some errors occurring during the experiment has affect the accuracy of result. For example, amount of ingredients is not accurate during production of suppository and temperature of water bath is not constant. 

3. Plot a graph of UV absorption against time. Analyse it.

Time(min)	Absorption of Visible-UV
	0	5	10	15	20	25	30
UV absorption at 520nm	0.013	0.197	0.287	0.208	0.211	0.226	0.297

From the graph above, the UV absorption at 520nm is in an increasing order except a slightly drop during the 10 minute. Theoretically or in ideal condition, negative value should not appear. The longer the period the dialysis bag stays in the solution, the more the amount of paracetamol diffuses out of it, and hence the higher the value of UV absorption because more UV light is absorbed. In this experiment, dialysis bag resembles the lipid bilayer membrane while the distilled water simulates the human plasma which represents the drug diffussion mechanism in our body. At 37 ^oC, the drug in the suppositories will diffuse into the systemic circulationdue to the concentration gradient between the melted suppositories in the dialysis bag and dilutes solution outside the dialysis bag. This may due to some error in handling the sample and inapproriately use of machine. Other reason may be impurities in the sample container due to incomplete washing.

4. Plot the graph of UV against time for the suppository formulation with different compositions. Compare and discuss the result.

Time (min)		Average of UV absorption at 520nm (x±SD)
		0	5	10	15	20	25	30
Suppository	I	0.0072 ± 0.0059	0.1008 ± 0.0963	0.1122 ± 0.1048	0.1074 ± 0.1006	0.1096 ± 0.1014	0.1181 ± 0.1069	0.1540 ± 0.1430
	II	0.0103 ± 0.0097	0.0131 ± 0.0119	0.0225 ± 0.0085	0.0225 ± 0.0115	0.0230 ± 0.0110	0.0230 ± 0.0120	0.0255 ±0.0100
	III	0.0110 ± 0.0090	0.0180 ± 0.0150	0.0170 ± 0.0130	0.0085 ± 0.0015	0.0220 ± 0.0010	0.0130 ± 0.0000	0.0160 ± 0.0030
	IV	0.0050 ± 0.0035	0.0100 ± 0.0080	0.0405 ± 0.0375	0.0180 ± 0.0150	0.0250 ± 0.0210	0.0240 ± 0.0200	0.0255 ± 0.0205

            

            In this experiment, theoretically, the suppository which contains the least amount of PEG 6000 should release the drug (paracetamol) more easily and rapidly and it is followed by suppository II, III and IV which have the gradual increase in the composition of PEG 6000. From the graph, suppository I has the highest UV absorption. However, it is followed by Suppository IV, II and III which deviate from the theory. PEG 6000 has higher molecular weight than PEG 1000 and it increases the hydrogen bond between the molecules in the suppository, causing the slower release of the drug from the suppository.

            Besides, the graph for the suppository should have sigmoid shape in which the concentration in the medium should increase with the time proportionally until it reaches maximum stage where most of the drug is being released from the dosage form. However, the graphs do not have sigmoid shape and show great fluctuation. This may be due to experimental errors.

           The experimental error is the incorrect way of suppositories preparation which causing non-homogenous dispersions pf paracetamol in the PEG suppository base or the presence of impurities in the suppositories. Furthermore, uneven stirring of the distilled water where the suppository is submerged before pipetting the sample attribute to the inaccuracy of the results which forming fluctuations of the graphs. The dialysis bag is not cleaned sufficiently before the analysis is carried out. The temperature is inconsistent. Impurities may present in the cuvettes which used to fill in the sample for UV spectroscopy due to improper cleaning of the cuvettes.

            Hence, some precautionary steps should be carried out to obtain the accurate result. The surface of the dialysis bag should be cleaned before immersing it into the distilled water. The cuvettes should not touched on its optical surface to avoid erratic readings. The distilled water in which the suppository is submerged in it should be stirred before taking the sample for analysis. Even temperature should be maintained.

5.      What is the function of every substance used in this suppository preparation? How can the different contents of PEG 1000 and PEG 6000 affect the physical characteristics of the formulation of a suppository and the rate of release of drug from it?

               Paracetamol is the active ingredient that has the therapeutic effects in the body. Different contents of PEG 1000 and PEG 6000 results in different effects on the physical characteristics, subsequently affecting the rate of drug released from the suppository. There are more hydrogen bonds are formed between the PEG 6000 molecules and drug molecules when the high amount of PEG 6000 is used. This will result in the increase of the hardness of the suppository and also the difficulty of the drug released from the suppository. Besides, it  contributes to the production of dry, hard, smooth, coarse, tackier and clear white suppository will be obtained.

             PEG 1000 and PEG 6000 are the water-soluble carrier bases. As PED degrades in our body after Paracetamol is administered via rectal route, the drugs will melt, diffuse out from PEG and dissolve in the body fluids. Suitable combinations of two different PEGs will allow optimum drug release rate from the suppository. This means that the drug is not too strongly sustained in the carrier bases and can be easily released. As a result, rate of absorption through the rectal mucosa and bioavailability increases as well.

            Thus, the combination ratio of PEG 1000 and PEG 6000 will affect in the physical characteristics of suppository. Thus, to avoid the production of extremely hard or soft suppository and to ensure an optimum bioavailability of the drugs, the correct combination ratio between  PEG 1000 and PEG 6000 should be used in manufacturing the suppository. 

Conclusion:

Different percentage of combination of PEG 1000 and PEG 6000 affects the physical characteristics of the suppository and the rate of release of the active ingredient. Suitable combinations of two different PEGs will allow optimum drug release rate from the suppository.

References:

1)  onlinelibrary.wiley.com/doi/10.1002/jps.2600640706/pdf

2)  http://pubs.acs.org/doi/abs/10.1021/la304847a