Explore the general test procedures for uniformity of weight as per USP, BP, and IP. Enhance your understanding of pharmaceutical quality assurance.

Uniformity of Weight – General Test Procedure

1.0     Objective

• • The objective of this General Test Procedure is to describe the procedure to be checking Uniformity of Weight by using calibrated analytical balance.

2.0     Principle/Reaction

• • This test is applicable for tablets and capsules for checking Average weight by using calibrated analytical balance.

3.0     Requirements:

• • Calibrated Analytical balance

• • Tablets / Capsules

• • Powders for oral suspensions

4.0     Test Procedure of Uniformity of Weight:

• Weight Variation (Uniformity of Weight) of Hard gelatin capsules

  • Hard gelatin capsules have shells consisting of two prefabricated, cylindrical sections, each of which has one rounded, closed end and one open end.

• • Hard gelatin capsules contain the medicament(s) in the form of powders, pellets or granules, semisolids or liquids etc.

• • Where two mutually incompatible drugs are present in the mixture, one of the drugs can be put as a tablet or pellet or in small capsule and then encapsulated with the other drug in a larger capsule.

• • Average weight & Uniformity of weight as per IP & BP – Capsule

  • Procedure: As per IP/BP/IH 

• • Select 20 Capsules at random from a particular lot or batch.

• • Weigh an intact capsule.

• • Open the capsule without losing any part of the shell and remove the contents as completely as possible.

• • Weigh the shell.

• • The weight of the contents is the difference between the weighing’s of the   intact capsule and emptied capsule shell.

• • Repeat the procedure with a further 19 capsules.

• • Determine the average weight of capsule contents by the following formula:-

Average weight ⁼ W₁+W₂+W₃+. …………+W₂₀  

20

Where,

W₁, W₂, W₃,……., W₂₀  = weight of the contents of capsules 1,2,3………….… 20.

20   = Total no. of capsules taken.

• • Calculate the % deviation of individual weight of capsules (contents of capsule) from average weight

• •  Not more than two of the individual weights deviate from the average weight by more than the percentage deviation show in the table and none deviates by more than twice that percentage.

Average weight of capsule contents	Percentage deviation
Less than 300 mg          300 mg  or more	10                      7.5

• Procedure for Uniformity of weight as per USP

  • Weight Variation Of Dietary Supplements:

• • The following tests provide limits for the permissible variations in the weights of individual capsules, expressed in terms of the allowable deviation from the average weight of a sample.
  • Separate procedures and limits are described herein for capsules that are intended for use as dietary supplements.  

• • Capsules: Capsules meet the requirements of the following test with respect to variation in weight of contents.

• • Uniformity of Weight – Hard shell Capsules:

• • Weigh 20 intact capsules individually, and determine the average weight.

• • The requirements are met if each of the individual weights is within the limits of 90% and 110% of the average weight.

• • If not all of the capsules fall within the aforementioned limits, weigh the 20 capsules individually, taking care to preserve the identity of each capsule, and remove the contents of each capsule with the aid of a small brush or pledged of cotton.

• • Weigh the emptied shells individually, and calculate for each capsule the net weight of its contents by subtracting the weight of the shell from the respective gross weight.

• • Determine the average net content from the sum of the individual net weights.

• • Then determine the difference between each individual net content and the average net content: the requirements are met if (a) not more than 2 of the differences are greater than 10% of the average net content and (b) in no case is the difference greater than 25%.

• • If more than 2 but not more than 6 capsules deviate from the average between 10% and 25%,

• • determine the net contents of an additional 40 capsules, and determine the average content of the entire 60 capsules.

• • Determine the 60 deviations from the new average: the requirements are met if (a) not more than 6 of the 60 capsules have differences that are greater than 10% of the average net content and (b) in no case does the difference exceed 25%.

• • Uniformity of Weight – Soft shell Capsules:

• • Proceed as directed under Hard shell Capsules, but determine the net weight of the contents of individual capsules as follows.

• • Weigh the intact capsules individually to obtain their gross weights, taking care to preserve the identity of each capsule.

• • Then cut open the capsules by means of a suitable clean, dry cutting instrument, such as scissors or a sharp open blade, and remove the contents by washing with a suitable solvent.

• • Allow the occluded solvent to evaporate from the shells at room temperature over a period of about 30 min, taking precautions to avoid uptake or loss of moisture.

• • Weigh the individual shells, and calculate the net contents. The requirements are as stated under Hard shell Capsules.

• Uniformity of Weight – Tablets

  • Tablets are solid dosage forms each containing a unit dose of one or more medicaments.

• • They are intended for oral administration.

• • Tablets are obtained by compression of uniform volumes of powders or granules or beads or pellets by applying high pressure and using punches and dies.

• • Weight Variation of Tablet as per IP/BP/IH

  • Select 20 tablets at random from a particular lot or batch.

• • Weigh the tablets individually.

• • Determine the average weight of the tablets by the following formula

Average weight = W₁+W₂+W₃+  …………+W₂₀

20

Where,

W₁, W₂, W₃,……., W₂₀  =Weight  of the tablets 1,2,3…………………20.   

20   =Total No. of the tablets taken.

• • Calculate the % deviation of individual weight of tablets from average weight.

• • Not more than two of the individual weights deviate from the average weight by more than the percentage shown in the table and none deviates by more than twice that percentage.

Average weight of tablets	Percentage deviation
80 mg or less More than 80 mg but less than 250 mg 250 mg or more	10                7.5                 5

•  Uniformity of Weight as per USP

  • Weight Variation of dietary supplements:

• • The following tests provide limits for the permissible variations in the weights of individual tablets expressed in terms of the allowable deviation from the average weight of a sample.

• • Separate procedures and limits are described herein for uncoated tablets, coated tablets that are intended for use as dietary supplements.

• • Tablets: Tablets conform to the criteria given in the accompanying table.

• • Uniformity of Weight – Uncoated Tablets and Film-Coated Tablets:

• • Weigh 20 whole tablets individually, and calculate the average weight.

• • The requirements are met if the weights of not more than 2 of the tablets differ from the average weight by more than the percentage listed in the accompanying table and no tablet differs in weight by more than double that percentage.

• • Uniformity of Weight – Coated Tablets (Other Than Film-Coated Tablets):

• • Weigh 20 whole tablets individually, and calculate the average weight.

• • If the coated tablets do not conform to the criteria in the accompanying table, place 20 tablets in a beaker of water at 37°and swirl gently for not more than 5 min.

• • Examine the cores for evidence of disintegration and repeat the procedure for a shorter time if disintegration has begun.

• • Dry the cores at 50° for 30 min. Accurately weigh 20 individual tablet cores, and calculate the average weight.

• • The requirements are met if the weights of not more than 2 of the tablets differ from the average weight by more than the percentage listed in the accompanying table and no tablet differs in weight by more than double that percentage.

• • Acceptance Criteria:

• • Weight Variation Tolerances for Uncoated Tablets, Film-Coated Tablets, and Coated Tablets (Other Than Film-Coated Tablets)

Average Weight of Tablet (mg)	Difference (%)
130 or less From 130 through 324 More than 324	10                                  7.5                      5

• Weight Variation – Powders for Oral Suspensions

  • Uniformity of Weight Procedure as per IP/IH for Powders for Oral Suspensions

  • Oral suspensions are Oral liquids containing one or more active ingredients suspended in a suitable vehicle.

• • Suspended solids may slowly separate on keeping but are easily redisposed.

• • In the manufacture of oral suspensions containing dispersed particles, measures shall be taken to ensure a suitable and controlled particle size with regard to the intended use of the product.

• • Average weight & Uniformity of weight

• • Select a sample of 10 filled containers at random from a particular lot or batch.

• • Clean and dry the outer surfaces of the containers and weight each container.

• • Remove quantitatively the contents from each container.

• • If necessary, cut open the container and wash each empty container with a suitable solvent, taking care to ensure that the closure and other parts of the container are retained.

• • Dry and again weight each empty container together with its part, which may have been removed.

• • The difference between the two weights is the net weight of the contents of the container.

• • Determine the average weight of the contents of the container by the following formula:-

Average weight   = W₁+W₂+W₃+. …………+W₁₀

10

Where,

W₁, W₂, W₃,……., W₁₀    = weight of the contents of the container 1,2,3………… 10.

10     = Total no. of container taken.

• • Calculate the % deviation of individual weight of contents of the container from average weight.

• • The average net weight of the contents of the 10 containers is not less than the labelled amount and the net weight of the contents of any single container is not less than 90 per cent of the labelled amount where the labelled amount is 60 g or 60 ml or less, or not less than 95 per cent of the labelled amount where the labelled amount is more than 60 g or 60 ml.

• • If this requirement is not met, determine the net weight of the contents of 20 additional containers.

• • The average net weight of the contents of the 30 containers is not less than the labelled amount, and the net weight of the contents of not more than 1 of the 30 containers is less than 90 per cent of the labelled amount where the labelled amount is 60g or 60 ml or less, or less than 95 per cent of the labelled amount is more than 60g or 60 ml.

• • None of individual weights deviates by more than twice that of respective minimum percentage limit.

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