MD simulations have been employed to investigate the ecacy of excipients as anti-aggregation agents and probe the importance of APR interaction as a mechanism for the prevention of biotherapeutic aggregation. The APRs of HSA have been identied using an experimentally- Generally, molecules with a high degree of PEG content reduced the SASA of APRs, with little impact from any dierences in hydrophobic content within ethoxylated compounds and almost no change between HSA and compounds with high hydrophobic content that lack PEG. This suggests that the interaction between the protein and the polar PEG chains that constitute the head group is driving the overall increase in interaction, a nding that is supported by the literature.