ASDs of PROTACs: Spray-dried solid dispersions as enabling formulations

Proteolysis targeting chimeras (PROTACs) are a promising class of pharmaceutical agents with a unique mode of action. PROTACs enable the targeting of a broad variety of structures including transcription factors and other "undruggable" targets. The poor solubility and slow dissolution of PROTACs currently limit the extensive use of their potential. Up to date, only very limited drug delivery options have been examined to address this challenge. Therefore, we explored the potential of amorphous solid dispersions (ASDs) by spray drying a model PROTAC with different polymers. The resulting formulations were assessed in terms of purity, solid state, dissolution performance, and stability. A strong increase in supersaturation compared to the physical mixture was provided, although in both systems the PROTAC molecule itself was already in the amorphous state. Evaluation of the reasons for the superiority of the ASD formulations revealed that the major factor was the homogeneous, molecular distribution of the active pharmaceutical ingredient (API) in the polymer matrix, as well as improved wettability of the formulation containing Soluplus compared to the physical mixture. The manufactured formulations were stable over a minimum of 8 weeks when protected from light and humidity.