ABSTRACT
A major challenge to the formulation of peptides and proteins into efcacious dosage forms is to ensure their stability over their shelf life (Manning, Chou, Murphy, Payne, & Katayama, 2010). Typically, a shelf life of at least 1.5-2 years at room temperature storage or refrigeration storage is desirable. Storage stability in the frozen state is less relevant as commercial distribution channels are not equipped for frozen products. Most proteins are marketed as lyophilized products, and most of these need refrigerated storage (Nail, Jiang, Chongprasert, & Knopp, 2002). The safety and efcacy of the product must be maintained over the shelf life during storage and handling, and it is realized that some degradation takes place. Some degradation products may have more impact on safety than others and therefore should be treated differently. Impurities resulting from deamidation and aggregation are relatively common, and the percent impurity allowed can be discussed with the Food and Drug Administration (FDA) on a case-by-case basis at an early stage. There are currently no regulatory guidelines for acceptable levels of such impurities. Toxicity testing may be required if the impurity levels are high and/or if the degradation products may likely be toxic.
