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/Ludwig Kuhlmann

HomepageLudwig Kuhlmann
Variability of analysis methods - the crux of the matter with individual values

Online lecture by Ludwig Kuhlmann on 19 September 2023, 3-4 pm

Moderation: Eberhard Ehlers

The results of analytical methods often have to be evaluated statistically.

In general, the statement applies that the mean value of many individual values comes closest to the "true" value. Nevertheless, many people are also familiar with the statement that if someone "stands with one foot on a hot hob and the other foot in ice water, they should feel comfortable on average". This makes it clear that the individual values must have a meaning.

This point is elaborated using the example of drug testing. Both the manufacturing and testing of medicinal products require validated processes and methods. This ensures that accuracy and reliability are guaranteed. In addition to accuracy, specificity, limit of detection and limit of quantification, the robustness of analytical methods must be described as part of validation. Of particular importance is the variability of the method, which includes repeatability, reproducibility and long-term precision.

In the context of the authorisation of medicinal products, acceptance criteria are defined that must be met by every batch of a medicinal product. The guidelines of the authorities also stipulate that the individual values are also subject to certain criteria. This is illustrated in more detail using the example of testing for content uniformity in tablets or comparable preparations.

The variability of the analysis methods plays a major role in stability tests that are carried out over many years with one or more batches. Over such long periods of time, the variability of the analysis methods is particularly high, as many factors have an influence on the analysis methods. This becomes clear from the fluctuation range of the individual values.

It is particularly important in stability studies to make predictions about the shelf life of the medicinal product that show whether the set acceptance criteria can be met. This is demonstrated using the example of a medicinal product, whereby the significance of the individual values is illustrated.
Radionuclides - human helpers

Online lecture by Ludwig Kuhlmann on 18 January 2022, 3-4 pm

Moderation: Eberhard Ehlers

The focus is on the diagnostic application of radioactively labelled substances that are introduced into the body, detected as γ-radiation outside the body using specific camera systems (single photon emission computed tomography (SPECT) or positron emission tomography (PET)) and converted into images. Nuclear medicine diagnostics are functional diagnostics.

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