Which dosage strength is the worst case for forced deg study

[darasc0211]

Hi, I am validating a stability indicating HPLC method that will quantitate both assay and impurities for 2mg/ml and 0.75mg/ml liquid drug product.

Which strength (2 mg/ml or 0.75mg/ml) shall I pick for forced degradation study? Why? I believe i only need to stress the worst worst case dosage instead of both.

Thanks in advance.

[DR]

It can really go either way, so you will have to study both strengths initially. For solid dosage forms of several strengths, you can base your work on the extreme cases (highest & lowest % API formulations) but for 2 strengths, test both (IMHO).