Mass balance in drug product stability ensures that API loss is scientifically accounted for during shelf-life.
What it means (technically) relationship between assay and in degradation products.
Expressed as:
Assay (%) + Total impurities (%) ≈ 100% (± justified loss)
Why it matters:
- Confirms stability-indicating analytical methods
- Demonstrates no hidden or uncharacterized degradation
- Supports impurity qualification & shelf-life justification
Regulatory expectations:
- Applicable for long-term, accelerated, and stress studies
- Significant imbalance requires root-cause investigation (volatile loss, adsorption, extraction efficiency, analytical bias)
Poor mass balance is often flagged during EMA/FDA quality reviews.
Read also: Forced Degradation Studies in Pharmaceutical Industry
Resource Person: Chetan Rajak
