86 the lack of dierentiation along the CMC of the compounds under study implies that it is not of critical importance in this context; heavy phospholipids above the CMC perform equally poorly to lighter phospholipids below it, and so other factors are more signicant in determining the extent of interaction. This concentration of 0.1% w/w was chosen to emulate industrial conditions for primarily surfactant excipients used in biotherapeutic stabilisation formulations; for other excipients such as those that include sugar residues and arginine, their working concentrations are typically higher.