Stability study for Peptide A Pharmaceutical development was triggered for Peptide A, sequence H{d}SQGTFTSDK(γEγEC16)SKYLDARAAQDFVQWLLDT-NH2, necessitating the design of a robust and safe formulation with optimized chemical and physical stability. Early in development it was determined that Peptide A had risks in both its chemical and physical stabilities. The primary chemical degradation products were aspartic acid isomerization at multiple sites and reactivity at the N-terminal histidine. Fibrillation was identified as the primary mechanism of physical degradation. Optimizing the formulation for Peptide A was a balancing act due to the contrasting pH dependent trends necessary for chemical and physical stability. The chemical stability and key degradation products were observed to be accelerated under more alkaline conditions for the pH range evaluated (7.0-8.7). In contrast, the physical stability was inverted where Peptide A was stabilized by more alkaline conditions tending to form fibrils at neutral or acidic pH's.