Bracketing and Matrixing Designs for Stability Testing

Reduced study designs, in the context of pharmaceutical development and stability testing, refer to approaches that allow for a reduction in the number of samples and/or time points for testing while still ensuring the reliability and validity of the data.
The concept of reduced study designs aligns with the guidelines provided by the ICH.. These designs can help save time and resources without compromising the quality, safety, and efficacy of pharmaceutical products.

ICH has outlined certain principles and guidelines related to reduced study designs, which include Bracketing and matrixing:

Pharmaceutical researchers use bracketing and matrixing as strategies in the design of stability studies to reduce the number of samples for testing, ensuring the scientific validity of the obtained data. ICH).


Bracketing involves the design of a stability schedule where only samples on the extremes of certain design factors are tested at all time points throughout the study. These factors can include different strengths, container sizes, or other relevant parameters. Assuming the stability of the intermediate samples based on demonstrating the stability of the most extreme samples.This approach can significantly reduce the number of samples required for testing, thus saving resources and time during the stability study.


Testing only a subset of the total samples at predetermined time points throughout the study constitutes the design of matrixing. The samples chosen for testing represent a subset of the total number of samples, based on a predefined statistical approach. This approach allows for a reduction in the total number of samples tested at each time point, thus leading to a more efficient stability study design.


Regulatory authorities accept both bracketing and matrixing as valid approaches to streamline stability testing while maintaining the necessary scientific rigor.

However, it is essential to adhere to the specific guidelines and recommendations provided by the ICH, as well as any additional regulations from relevant regulatory agencies. In situations where testing would otherwise require a large number of samples, implementing these approaches can significantly save time and costs during the stability testing process.

Also refer: Stability Studies as per ICH

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