The variability of dosage form (solid) is controlled and assessed by the content uniformity tests. It is recommended to go for a

random sampling.

The size range of the dosage form is less than or equal to 50mg

Tablets:

30 units are kept aside.

• 10 tablets are assayed.

Results are interpreted as follows

All tablets- 85%-115%- RSD</= 6

If the above condition is not achieved, the results should be as follows inorder to pass the test

Percentage purity should be within 75%-125%

• 20 tablets (remaining) are assayed.

Out of 30 tablets, 1 tablet can be outside 85-115%

Not even one should be above 75%-125%

RSD</= 7.8%

Capsules:

• 10 capsules are taken and subjected to assay.

They will pass the test if

All capsules- 85%-115%- RSD</= 6

If the above condition is not satisfied still they can pass the test under following conditions

Percentage purity should be within 75%-125%

• 20 tablets (remaining) are assayed.

Out of 30 tablets, <3 tablets can be outside 85-115%

Not even one should be above 75%-125%

RSD<7.8%

Reference:
Pharmaceutical statistics: practical and clinical applications, Part 1
By Sanford Bolton, Charles Bon ,page 408