An optimised excipient would be a large, branched compound which is highly polar (i.e., with several oxygen atoms) and also some hydrophobic character. Practically, this could be achieved by the incorporation of multiple PEG chains into the excipient design, around a central scaold and at least one aliphatic chain. This is broadly descriptive of a polysorbate compound, and this is perhaps unsurprising considering their performance, but is also indicative that there is chemical space that is underutilised by the current anti-aggregation excipient design paradigm. It implies that the exact degree of hydrophobic content is not signicant, provided that there is some present in a localised area in order to provide amphiphilic character to the excipient. The ndings suggest that perhaps a lighter compound with a higher number of short branches would be more eective in APR shielding than heavier compounds with a small number of large chains.