EXPERIMENT 4 : SUPPOSITORY

EXPERIMENT 4 : SUPPOSITORY

TITLE:  Evaluation of the effects of different composition of substance on the characteristics
               of suppository formulation.

DATE OF EXPERIMENT: 6 MAY 2013

OBJECTIVE: To study the effects of different base composition on the physical characteristics of suppositories formed and on the release of drug from the suppository formulation.

INTRODUCTION:

Suppositories are solid dosage forms intended for insertion into body orifices (rectum, vagina, urethra) where they melt, soften, or dissolve and exert a local or systemic effect. The properties of an ideal suppository base are:
-  Melts at body temperature or dissolves in body fluids.
-  Non-toxic and non-irritant.
-  Compatible with any medicament.
-  Releases any medicament readily.
-  Easily moulded and removed from the mould.
-  Stable to heating above the melting point.
-  Easy to handle.
-  Stable on storage.

In this experiment, water-miscible base, that is polyethylene glycol (PEG) or also called macrogol is used. Polyethylene glycols are polymers of ethylene oxide and water, prepared to various chain lengths, molecular weights, and physical states. The numerical designations refer to the average molecular weights of each of the polymers. Polyethylene glycols (PEGs) having average molecular weights of 300, 400, and 600 are clear, colorless liquids, while those with molecular weights of 600-1000 are semisolids. Those having average molecular weights of greater than 1000 are wax-like, white solids with the hardness increasing with an increase in the molecular weight.

Polyethylene glycol is non-toxic, odorless, neutral, lubricating, nonvolatile and nonirritating and is used in a variety of pharmaceuticals and in medications as a solven, dispensing agent, ointment and suppository bases, vehicle, and tablet excipient.

APPARATUS:

Weighing machine                              Water bath (37^oC)

Spatula                                                            1 dialysis bag (10 cm)

1 weighing boat                                  2 strand of thread

1 beaker 50 ml                                     1 glass rod

1 beaker 100ml                                    1 set of pipet (5ml) and pipet bulb

1 measuring cylinder 5 ml                   1 plastic cuvette

1 set suppository mould                      Spectrophotometer UV

1 hotplate

MATERIALS:

Polyethylene glycol (PEG) 1000

Polyethylene glycol (PEG) 6000

Paracetamol

METHOD:

1.      1g of Paracetamol powder is weighed.

2.      Paracetamol Suppository 10g is prepared using the formulation below:

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

3.      The suppository is mould by using suppository-mould provided. The shape, texture, and colour of all the suppositories are compared and verified.

4.      One of the suppositories is inserted into a beaker containing distilled water (10ml, 37^oC) and the time taken required for it to melt is recorded.

5.      One of the suppositories is inserted into a dialysis bag and both end of the bag is tightly tied as shown in the figure below.  The dialysis bag is placed into a beaker (100ml) containing a distilled water (50ml) heated at 37^oC.

6.      Every 5 minutes interval, a small amount of sample (3-4 ml) is pipetted and the rate of diffusion of Paracetamol from the suppository is determined by using a spectrometer UV-visible. Before taking the sample, the distilled water is stirred with a glass rod.

Time taken (min)	Absorbance of UV-visible
	0	5	10	15	20	25	30	35	40	45	50	55	60
Absorbance of UV on 520 nm

RESULT & DISCUSSION:

QUESTION 1

Compare and explain on the physical appearance of the suppository formed.

Criteria Group	Group 1 (PEG 1000:6000 = 9:0)	Group 2 (PEG 1000:6000 = 6:3)	Group 3 (PEG 1000:6000 = 3:6)	Group 4 (PEG 1000:6000 = 0:9)
Texture	Smooth but less shinning	Smooth and shinning	Smooth and shinning	Smooth and shinning
Shape	Bullet-shaped	Bullet-shaped	Bullet-shaped	Bullet-shaped
Colour	White and opaque	White	White	Clear white
Hardness	A little soft and less brittle	Hard and brittle	Hard and brittle	Hard solid and and brittle
Greasiness	Very greasy	Greasy	Slightly Greasy	Least greasy

Poly ethylene glycols (PEGs) are family of water-soluble linear polymers formed by the additional reaction of ethylene oxide (EO) with mono ethylene glycols (MEG) or diethylene glycol. Polyethylene glycols are available in average molecular weight ranging from 200 to 8000 and in this experiment, polyethylene glycol with molecular weight of 1000 and 6000 were used. Polyethylene glycol is non-toxic, odorless, neutral, lubricating, nonvolatile and nonirritating and is mainly used as solvent, water soluble, binder, lubricant, plasticizer and use in ointment base, tablet coating, gelatine capsule, liquid oral medications.

Basically all the suppositories formed are shinning and smooth and are bullet-shaped. All the suppositories formed are white in colour but for Group 1, it is opaque whereas for group 4, the suppositories formed are clear white. This is due to increasing amount of PEG 6000 and decreasing amount of PEG 1000 used. The colour of PEG 1000 is white paste which is opaque and the colour of PEG 6000 is white flake, which is slightly clear.

The hardness of PEGs increases with increasing molecular weight. Group 4 suppositories are hard due to the use of 100% PEG 6000 and Group 1 suppositories are a little soft because of 100% PEG 1000 used. Besides that, those with molecular weights of 600-1000 are semisolids. Higher proportions of high molecular weight polymers produces preparations which release the drug slowly and are also brittle. Less brittle products which release the drug more readily can be prepared by mixing high polymers with medium and low polymers. Degree of greasiness decreases as amount of PEG 1000 used decreases and amount of PEG 6000 increases this is because those having average molecular weights of greater than 1000 are wax-like.

QUESTION 2

Plot the graph of time needed to melt the suppository versus the amount of PEG 6000 in the formulation. Compare and discuss the result.

PEG 6000 ( g ) content	0	3	6	9
Time ( min )	Group 1 : 55min 14s	Group 2 : 30min	Group 3 : 36min 46s	Group 4 : 55min 47s
	Group 5 : 37min 37s	Group 6 : 56min 18s	Group 7 : 30min 14s	Group 8 : 55min 52s
Average Time ( min ) (x ± SD)	46.43±12.46	43.15±18.6	33.5±4.26	55.83±0.06

The graph shows the average time required to melt the suppository against the amount of PEG 6000 used in the formulation. The polyethylene glycol PEG acts as the suppository base in the formulation.  Two different PEGs are used in the formulation, PEG 1000 and PEG 6000. Since the molecular weight of the PEG 6000 is greater than PEG 1000, formulation with a higher PEG 6000 content will be more solid and harder. Theoretically, higher PEG 6000 content (with greater molecular weight) in the suppository has higher meting point and lower dissolution rate. This is because the stronger bonding within the suppository leads to lesser interaction of the base with the surrounding water molecule. Thus, longer time should be required to melt the suppository with greater amount of PEG 6000.

However, the results obtained from the experiment were not compatible to the theory. Based on the graph plotted, suppository with 6g of PEG 6000 recorded the shortest time to melt with average of 33.5 minutes whereas suppository with 9g of PEG 6000 charted the longest time required, with 55.82 minutes. There is a decrease in the time required form 0g to 6g content of the PEG 6000 content. The different in the result may be due to the large standard deviation calculated and is believed to be resulted from some errors that had been done in the experiment.

The suppository produced may contain different amount of the base and the active ingredient from the stated amount in the table due to the improper procedure and technique. Error in the measuring and transferring process may decrease the mass of suppositories produced and thus less time required for melting.  The suppository may also be damaged when it was taken out from the mould. Insufficient solidification of the suppository may cause the internal structure remained liquefied and make it easier to dissolve when the outer layer had dissolved in the water. Also, different technique used by different groups such as stirring can increase the rate of dissolution of the suppository.

            Generally, melting point of PEG is above of the body temperature. When it is administrated via the rectal route, it can dissolve and disperse the medication slowly, providing a sustained effect in the body.

QUESTION 3

Plot the graph of UV absorption versus time. Give explaination.

	Time (min)	UV-Visible Absorption at 520 nm
	0	0.000
	5	0.039
	10	0.043
	15	0.046
	20	0.049
	25	0.051
	30	0.063
	35	0.077
	40	0.085
	45	0.084
	50	0.098
	55	0.107
	60	0.124

The graph above shows the UV absorption at 520nm for suppository 3 which contain 3g of PEG 1000 and 6g of Peg 6000. We can observe that the graph fluctuates (up and downs) as time goes by. Theoretically, the graph should show a sigmoidal shape. This is because the suppository will dissolve slowly and the drugs are released slowly at body temperature. So that, the concentration of drugs in the water is increases with time 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.

            From the graph obtained, the graph are keep on increasing of UV absorption with time except at the time of 45minutes there shows a little bit drop of the value. This slightly deviates from the theory. The error may due to some errors that occur during 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. 

QUESTION 4

Plot the graph of UV absorption versus time for the suppository formulation which have different composition. Compare and discuss the result.

Time		UV absorption average at 520nm (x ± SD)
		0	5	10	15	20	25	30	35	40	45	50	55	60
suppository	I	0	0.022	0.023	0.024	0.0255	0.0265	0.0295	0.0385	0.040	0.0435	0.0465	0.056	0.06
		±	±	±	±	±	±	±	±	±	±	±	±	±
		0	0.0127	0.0141	0.0156	0.0148	0.0148	0.0177	0.0219	0.0212	0.0205	0.0233	0.0226	0.0184
	II	0	0.0575	0.0295	0.0365	0.0350	0.0535	0.0530	0.0625	0.072	0.07	0.0815	0.079	0.107
		±	±	±	±	±	±	±	±	±	±	±	±	±
		0	0.03606	0.00919	0.00636	0.01697	0.00919	0.00707	0.01485	0.02687	0.01838	0.02899	0.01414	0.01556
	III	0	0.0305	0.034	0.036	0.038	0.0445	0.0525	0.06	0.066	0.067	0.0745	0.0815	0.0935
		±	±	±	±	±	±	±	±	±	±	±	±	±
		0	0.01202	0.01273	0.01414	0.01556	0.01485	0.01202	0.024	0.0269	0.024	0.0332	0.0361	0.0431
	IV	0	0.0175	0.0205	0.0255	0.03	0.034	0.0365	0.0375	0.044	0.051	0.059	0.0625	0.0655
		±	±	±	±	±	±	±	±	±	±	±	±	±
		0	0.00636	0.00778	0.00212	0.00141	0.00424	0.00778	0.0064	0.0085	0.0085	0.0099	0.0092	0.0050

In this experiment, the graph shows a wide range of variation which do not follow the theoretical principle. The error is occurred because of the presence of the impurities, parallax error, and equipment used give inaccurate readings, uneven temperature of the water bath and others. Besides that, the distilled water is not properly stirred before sample is collected is also among the reason .Different composition will give different results.

            Theoretically the suppository with the highest amount of PEG 6000 will have the slowest release rate due to the stronger hydrogen bonds (intermolecular forces) formed with Paracetamol which will hinder the release of Paracetamol.  Suppository I should has the highest rate of release  because of the lowest proportion or amount of PEG 6000 in the formulation. In the general, the rate of drug release which can be determine for the UV absorption show a gradual increase until a certain point where the drugs release will become constant. , and this applies to all the suppository formulation.

QUESTION 5

What are the functions of each ingredients used in the formulation of suppositories. And how the use of different amount of PEG 1000 and PEG 6000 will affect the physical characteristics of the formulation of suppositories and rate of release of the drug?

Polyethylene glycol  also known as macrogols and act as base. PEG 1000 and PEG 6000,means Polyethylene glycol have different molecular weight of each polymers. These PEGs can be blended  together to produce suppository bases with varying melting points, dissolution rates and physical characterisics. Suppositories of varying melting point and solubility characteristics can be prepared by adding different amount of PEG 1000 and PEG 6000. While, Paracetamol acts as active ingredient in the formulation of suppositories.

In our formulation, we are using 3g of PEG 1000 and 6g PEG 6000. The hardness of PEGs increases with increasing molecular weight. So when we compared the hardness of our suppositories of with other group, our suppositories are more hard and brittle compared with other group which use 9g of  PEG 1000 and 0 g of PEG 6000 which their suppositories are more soft and less brittle. It is means that, our suppositories(3g of PEG 1000 and 6g PEG 6000) have higher melting point and low solubility. Suppositories are formulated to melt at body temperature  and releases drug for effect.

Drug release depends on the base dissolving rather than melting. Higher proportions of high molecular weight polymers produce preparations which release the drug slowly and are also brittle. Melting point above body temperature cause the base disslove in the body and disperse the medication slowly, providing a sustained effect. 

CONCLUSION:

At the end of the experiment, we are able to investigate the effects of different base composition onto the physical characteristics of the the suppositories formed and also the effect of release of the drug from the formulation.

1.      Increasing the amount of PEG 6000 and decreasing the amount of PEG 1000 will result in increased shining and hardness, decreased greasiness and producing clear, white and less opaque suppositories.

2.      The highest the amount of PEG 6000 in the suppository formulation, the highest its melting point and longest the time required for melting. It can be affected by other factors in vivo such as body temperature and anatomical and physiological factors of the rectum mucosa.

3.  The drug is released slowly from the suppository with increasing time at the body temperature until equilibrium is reached.

4.  Higher melting point and low solubility of suppository cause the  release of active ingredient from the formulation much slower.