NMR detects clustering and ultra-weak excipient interactions governing monoclonal antibody viscosity in formulation-relevant conditions

H transverse relaxation rates. These experiments provided complementary information on excipient interactions with the different mAb oligomers. Lysine was identified as the best mAb binder. However, several excipients such as sucrose that do not reduce the macroscopic viscosity also bind to concentrated mAb, highlighting that excipient binding can have various consequences on the transient interactions between mAb species. Altogether, this work proposes a powerful NMR pipeline to dissect ultra-weak molecular interactions that govern viscosity and developability in therapeutic antibody formulations.