Physical stability of <scp>RNA</scp> –lipid nanoparticles under agitation, freeze–thaw and accelerated stability testing

Abstract BACKGROUND The choice of excipient is important in enhancing stability of liquid formulations containing lipid nanoparticles (LNPs) used in RNA delivery where the ability to survive unplanned excursions to higher and lower temperature and vibration is an important attribute. In this study, established parenteral excipients were tested for their capacity to protect LNP structures in solution. RESULTS LNPs are very susceptible to damage during freeze–thaw cycles. The most promising excipients to reduce ice crystal damage were sucrose and glycerol. Poloxamer 188 (PX188), polysorbate 80 (PS80), bovine serum albumin (BSA) and trehalose did not perform as well as sucrose and glycerol. Accelerated stability testing (35 °C) observed an increase in hydrodynamic diameter of LNPs. BSA and PS80 were deleterious to LNP stability at 35 °C with a large rise in the polydispersity index. Trehalose, sucrose and glycerol performed better at 35 °C than the other treatment groups. Mild agitation had little effect on LNP structures. CONCLUSIONS The excipients of choice for liquid formulation based on freeze–thaw and accelerated testing are sucrose and glycerol. Sucrose is known to be effective in formulations of liposomes and LNPs. Glycerol, however, is rarely used for liposomes and LNP liquid formulations. PS80 and BSA were deleterious to LNP stability during freeze–thaw and accelerated testing. PX188 conferred some protection during freezing, and since its structure and mode of action are radically different from those of sucrose and glycerol it could prove to be synergistic. © 2026 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry (SCI).