In the final dosage form the active pharmaceutical ingredient (API) is in contact with one or more excipients, this interaction can affect the bioavailability as well as the stability of the drug product. The study consists of a weighed amount of API that will be mixed well with a proposed percentage of  a single or binary mixture of excipient(s). A time-zero assay will be completed to compare differences if noted in the scheduled time-points.

Example of a Drug-Excipient time-point testing schedule

X=HPLC Assay
Y=Microscope, DSC and TGA (if needed)