USP publishes revision of chapter <111> Design and Analysis of Biological Assays

Bioassays/Potency Assays – Regulatory Requirements, Development and Routine Use

Recommendation

25 November 2025
Neuss, Germany

Bioassays/Potency Assays – Regulatory Requirements, Development and Routine Use
This conference is part of PharmaLab Congress 2025

The USP recently published a draft revision of Chapter <111> on the development and analysis of biological tests. This proposal is based on the official version of the chapter dated 1 August 2020. When revising ‘Analysis of Biological Tests’ <1034>, the Biological Testing Subcommittee decided that one of the three options for combining the results of independent tests contained in <111> should be deleted from <1034>. The chi-square test option has been omitted from the revised version. The other two options and the remaining sections of this chapter have not been revised.

Purpose and content

For a whole range of products listed in the pharmacopoeia, bioactivity must be determined by bioassays. The aim of this chapter is to provide a brief overview of the identification of outliers, confidence intervals for relative efficacy measurements and the combination of independent assays. For bioassays not included in the USP-NF, other methods may be suitable. Options for outlier testing, including the Dixon test and the Grubbs test, are explained in more detail.

One section of the chapter also discusses how to deal with or reject deviating results (outliers) during an assay, both when they are immediately noticeable and when they are only recognised when the results are listed in a table. However, such values should only be rejected after thorough examination. Options for outlier tests for evaluation, including the Dixon test and the Grubbs test, are explained in detail.

Further information on the development and statistical analysis of bioassays can be found in the new, not yet effective chapters ‘Design and Development of Biological Assays’ <1032> and ‘Analysis of Biological Assays’ <1034> (USP 1 October 2026), which can serve as helpful but non-binding guidelines. We have already reported on their current revision elsewhere.

The USP is thus continuing the reorganisation of the chapters on bioassays, which, in addition to the above-mentioned chapters, also includes <1033> ‘Validation of Biological Assays’.

Further details on chapter <111> can be found at the Website of the USP.