Validation of USP Methods

In the first supplement of the USP 32, the revised, general chapter <1225> - Validation of Compendial Methods - was published. This chapter describes the requisite performance characteristics that should be considered to prove the validation of a method in the case of its submission to the Pharmacopoeia.

It is striking that terms coming from ISO standards have also been incorporated, although the wording in pharmaceutical surroundings was until now oriented towards the ICH Guidelines, especially ICH Q2(R1).

This was also the topic of the publication entitled "Making Sense of Trueness, Precision, Accuracy, and Uncertainty" in the Pharmacopoeial Forum of May-June 2008. This article reviews the differences between the terms when used in ICH and ISO. It also states that the terms "trueness" and "uncertainty" do not even exist in the ICH and the USP. The conclusions drawn in this article are as follows: The terms should be clarified in the USP. These clarifications could easily be added to the General Chapters <1010> und <1225>. In the longer term, the USP encourages continued harmonisation of terminology among the involved parties (ISO, ICH, VIM - International Vocabulary of Metrology) and other interested parties.

In the revised chapter <1225> of the first supplement to USP 32, these terms have now been incorporated from ISO 5725-1 and ISO 3534-1.

And the term "reportable value", established from the OOS discussions in recent years, is now also incorporated in this USP chapter.

The requisite performance characteristics to be considered in validation of the types of methods in order to prove their suitability for the USP (accuracy, precision, specificity, detection limit, quantitation limit, linearity, range and ruggedness) remained unchanged.

And when is it necessary to revalidate? Revalidation may become necessary when a revised analytical method is submitted to the USP or when an established, general method is to be used for a new product or for a new starting material.