Effect of arginine on the aggregation of protein in freeze-dried formulations containing sugars and polyol. 1. Formulation development

L-arginine was introduced into protein-based freeze-dried formulations to study the ability of arginine to reduce / prevent from protein aggregation during manufacturing, storage and reconstitution of lyophilized protein-based pharmaceuticals. As L-arginine is known to be very hygroscopic, additional excipients which could provide a moisture buffering capacity need to be introduced into the formulation. In the first part of our study – excipient formulation development – the screening of a number of sugars/polyols has been done in order to select the best combination of excipients that, in a complex with L-arginine, can i) produce freeze-dried cakes with elegant appearance, adequate mechanical properties and reconstitution times, and ii) resist/minimize the moisture sorption. Various freeze-dried cakes containing L-arginine in combination with mannitol, trehalose, lactose, and sucrose were produced and analyzed by TGA, DSC, texture analysis, moisture sorption, cake shrinkage, TVIM and SEM. The non-linear dependencies of the physicochemical properties of the freeze-dried cakes on the sugar-to-mannitol ratios were found. The best combinations of excipients (L-arginine, mannitol and trehalose) were selected to be used in the second part of this work, in which the impact of each selected formulation will be studied in relation to the aggregation of a protein.