You can estimate the shelf life (90% degradation) from the reaction rate kψ and t90. Usually, determine the reaction rate at higher temperatures and extrapolate to 25 oC. However, FDA requires the shelf life to be established based on stability data.

t90=ln⁡(1/0.9)/kψ =0.105/kψ

log (t90(RT))/(t90(T)) = Ea/2.303R(1/298-1/T)

Hi

This guideline could be useful as well, ICH Topic Q 1 E Evaluation of Stability Data

https://www.ema.europa.eu/en/documents/scientific-guideline/ich-q-1-e-evaluation-stability-data-step-5_en.pdf

Best regards

Tomasz

Please look at the following below links which may help you in your analysis:

https://www.pharmaceuticalonline.com/doc/an-introduction-to-forced-degradation-studies-for-drug-substance-drug-product-0001

http://medcraveonline.com/JAPLR/JAPLR-03-00073.pdf

Thanks

Forced degradation studies, also called “stress tests,” have been used in the pharmaceutical industry for a long time, but the International Conference on Harmonization (ICH) only issued the formal request Q1A with a guideline “Stability Testing of New Drug Substance and Products” in 1993. ICH Q3A and Q3B guidelines are addressed for registration applications about the content and qualification of impurities classified as degradation products, which are observed during manufacturing or stability studies of the new drug products. ICH recommended degradation should be between 10 to 30% of the API.

Please refer for more information, Expert Committee on Specifications for Pharmaceutical Preparations from ICH guidelines.

100years old raw material is subjected for formulation-?

then calculate for different constituents, what will be the result.

also expired tablets collected from market & repacked with new seal then distributed as physian sample, then what will be the result@