The purpose of stability testing in drug development is to provide evidence on how the quality of an active substance or pharmaceutical product varies with time under the influence of a variety of environmental factors such as temperature, humidity, and light.
The first stability studies performed are usually forced degradation studies. These are carried out to understand the primary degradation products of the molecule and to aid analytical method development. The next stage is to perform accelerated stability testing for excipient compatibility studies during formulation development and to support assignment of initial shelf lives/storage conditions for early toxicological and clinical studies. Long-term stability studies will also be initiated on both the active pharmaceutical ingredient (API) and the drug product, generally following many of the principles contained in the ICH stability guidelines, with storage at accelerated and long-term conditions.