Ultimate Guide: Content Uniformity Test in Pharmaceutical Analysis USP<905>

What is Content Uniformity in Pharma?

Content uniformity is a standardized test that verifies every tablet, capsule, or unit dose delivers consistent amounts of the active pharmaceutical ingredient (API).

Content uniformity involves assaying each individual unit using an analytical method and comparing the results against established acceptance criteria from the USP.

How the Content Uniformity Test Works

1. Solid Dosage Forms

   • Assay 10 units individually using an appropriate analytical method

   • Calculate the acceptance value

2. Liquid Dosage Forms

   • Assay 10 units individually using an appropriate analytical method

   • Perform assay on the well-mixed material removed from an individual container in conditions of normal use

   • Report results as delivered dose

   • Calculate the acceptance value

Requirement to pass content uniformity

• Acceptance value must be less than or equal to L1%

• If acceptance value > L1%, test additonal 20 units and calculate acceptance value. The requirements are met if the final acceptance value of the 30 dosage units is ≤ L1%, and no individual content of any dosage unit is less than [1 − (0.01)(L2)]M nor more than [1 + (0.01)(L2)]M

• The acceptance value is |M-X| + ks, with the terms defined in the table below from USP <905>.

Reference: USP <905) Uniformity of Dosage Units

Read related article on Weight Variation in Pharmaceutical Analysis.

Feeling overwhelmed? Simplify the process with our content uniformity calculator. Quickly perform these calculations and make your life easier!

Content Uniformity Calculator Preview

Enter the % Label Claims for 10 dosage units, and the template will automatically calculate the acceptance value. It will also indicate whether the data passes or fails the test based on USP <905>.

Frequently Asked Questions

• What is Content Uniformity according to USP <905>?

  Content uniformity is a test described in USP <905> that evaluates whether individual dosage units contain the intended amount of API. The test ensures that each unit in a batch delivers a consistent dose to the patient.

• How many dosage units are tested in USP <905>?

  10 dosage units are tested first. If the batch fails, 20 additional units are tested (total of 30).

• What is the acceptability constant (k) used in USP <905>?

  The value of k depends on the number of dosage units tested. For a sample size of 10, k = 2.4, while for a sample of 30, k = 2.0

• What is the reference value (M) in USP <905> acceptance value calculation

  The reference value (M) represents the target content used in the Acceptance Value calculation. It is typically determined based on the mean of the sample results relative to the labeled claim.

  In many cases:

  • If the mean result is between 98.5% and 101.5%, then M equals the sample mean.

  • If the mean falls outside this range, M is set to the nearest limit.

• What are the individual unit limits in Content Uniformity testing?

  USP <905> also sets limits on individual dosage units:

  • No individual unit should be outside 75–125% of label claim.

  • In Stage 2 testing, not more than one unit may fall outside 85–115% of label claim.

  These criteria ensure that extreme variability does not occur even if the AV passes.

• What is the difference between content uniformity and weight variation?

  Both tests evaluate dosage unit consistency but differ in approach:

   Content Uniformity

  • Measures actual drug content in each unit

  • Used for low-dose formulations

  Weight Variation

  • Measures total unit weight

  • Used when the API represents a large proportion of the dosage form