Stability and sterility of the drug?

What r the factors that impact sterility and stabity of a product?

Stability is demonstrated by being compliant with ICH Q1x guidelines. As related substances’ concentration grow with time the potency of the API decreases. Eventually this potency will reach your expiry limits.

Sources of a related substance can be;

  1. Molecules found in the raw material (example = intermediate)
  2. The API disintegrating (monomolecular)
  3. Polymerization of the API
  4. Reaction product between the API and the formulation (bimolecular)
  5. Reaction product between the API and the container closure system (bimolecular)

Both time and temperature affect and control the rate of growth of the related substances and thus your expiry period. See the Arhenius equation.