Many of today's biopharmaceutical formulations may potentially suffer from oxidation to some degree. Large molecule formulations are relatively more delicate and may be prone to degrade in the presence of oxygen. Besides a loss of efficacy and reduction in shelf life, exposure of such products to oxygen can result in product discoloration, changes in dissolution rate and profile, and even toxicity or other pharmacological properties associated with negative side effects. During the development of an oxygen-sensitive product, studies are performed that investigate the formulation’s interaction with oxygen. End-of-shelf-life stability studies verify that the product indeed retains efficacy under specified headspace oxygen levels. Such studies allow for the specification of appropriate initial headspace oxygen levels in the primary packaging.