Physical stability of pharmaceutical formulations: solid-state characterization of amorphous dispersions

•A concise review of physical attributes of different pharmaceutical-dosage forms.•Recent FDA drug recalls due to physical defects and instability issues.•A general review of solid-state analytical techniques.•The benefits and physical stability challenges of amorphous solid dispersions.

The acceptable stability of the drug formulations is one of the basic requirements for pharmaceutical development and commercialization. The increasing application of enabling delivery techniques poses even more challenge to the drug physical stability of pharmaceutical formulations. After a brief review of regulatory requirements and recent drug recalls due to physical instability, we discuss the physical stability of the solid-state drug in amorphous dispersions with focus on analytical techniques, amorphous molecular mobility, drug-excipient interaction, and the effect of water.