Evaluation of Suppositories Pharmaceutics B.Pharmacy 1st semester Notes

EVALUATION OF SUPPOSITORIES

Suppositories are semisolid preparations administered through the orifices, each contain one or more medicaments.

They are normally administered as a single dose for local or systemic action.

TESTS FOR THE EVALUATION OF SUPPOSITORIES

Appropriate test methods and specifications are developed, which are capable of guaranteeing that the purpose for which suppositories are used will be fulfilled.

TESTS FOR SUPPOSITORIES ARE

• Uniformity of weight
• Disintegration test.
• Content uniformity test.
• Melting point determination test.
• General appearance test.
• Assay of active contents.

1). UNIFORMITY OF WEIGHT

• Weigh 20 suppositories individually.
• Determine their average weight.
• Not more than two of individual weights should deviate from the average weight more than 5% and none deviates by more than 10%.

2). DISINTEGRATION TEST

Apparatus: 

• A transparent sleeve of glass or suitable plastic of height 60mm with an internal diameter of 52mm.
• A metal device consisting of two stainless discs each of which contain 39 holes, each 4mm in diameter.
• Diameter of the disc is closely similar to the internal diameter of the sleeve.
• Discs are separated by a distance of 30mm. Metal device is attached to outer sleeve by means of three equally spaced hooks.

Method: 

• Place a suppository on the lower perforated disc of metal device and then insert the device into the cylinder and attach this to the sleeve.
• Repeat the same operation with further two suppositories, metal device and sleeve. 
• Place each piece of apparatus in a vessel containing at least five liters of water at 37C and fitted with a slow stirrer and by means of holding the top of apparatus 90 mm below the surface of water. 
• After every 10 minutes invert each apparatus without removing it from water.
• Disintegration is complete when molded suppositories are:
• Completely dissolved.
• Dispersed into its components.
• Have become soft.
• Disintegration occurs in not more than 30 minutes for fat based suppositories and for water-soluble suppositories disintegration occurs in not more than 60 minutes.

3). CONTENT UNIFORMITY TEST

• Take 10 suppositories; determine the active ingredients of each of the 10 suppositories by using a suitable analytical method.
• If not more than one of the individual values thus obtained is outside the limit i.e.% of the average value and none of them is outside the limit i.e. 25% of the average value.
• Repeat the test by using another 20 suppositories taken at random. If out of 30 suppositories not more than 3 individual values are outside the limit 15% of the average values and none is outside the limit 25% of the average value, then the test is O.K, otherwise failed.

4). MELTING POINT DETERMINATION TEST

• Melt the suppositories rapidly at a temperature not more than 10C above the point of complete fusion. Insert one end of glass capillary tube into the melted substance so that a column of substance become 8-12 high rise into it. Cool the tube to 15C and maintain the temperature at 15-17C for not less than 16 hours. Attached the tube to thermometer in the heating vessel containing water at 15C so that the lower end of the column of substance is 30mm below the surface of water. Heat the water with constant stirring, so that the temperature rise at a rate of 2C per minute.
• The temperature at which partially melted substance begins to rise in the tube is regarded as the melting point. The melting point of suppositories should not rise more than that given in the monograph.

5). GENERAL APPERANCE

• When cut longitudinally, the internal and external surface should be same.

6). ASSAY OF ACTIVE CONTENTS:

• Official limit for the active contents is 95- 105% e.g. Glycerol Suppositories.
• Dissolve a number of suppositories equivalent to 8 grams of glycerol in 50 ml of water and add quantity sufficient to produce 250ml.
• Take 5ml of this solution and 150ml of water and 0.25ml of Bromocresol purple solution and add 0.1M.NaOH to neutralize the blue color of indicator.
• Add 1.6 grams of sodium metaphenolate and allow to stand for 15 minutes and titrate with 0.1M NaOH to same blue color.
• Each ml of 0.1M NaOH=0.00921 grams of glycerol.