**5. Drug excipient compatibility**

Excipients are added along with the active pharmaceutical ingredient in formulations. Most excipients possess biological activity but having role in administration, mediating the release of the active component, and providing stability against degradation. However, inappropriate excipients can also give rise to inadvertent and/or unintended effects, which can affect the chemical nature, the stability, and the bioavailability of the API, and consequently, their therapeutic efficacy and safety. So study about interaction between active ingredient and inactive ingredient can provide idea about type of incompatibility and the justification behind the inactive ingredient selection [14].


In general, one can say that drug-excipient incompatibility may result in change in physical, chemical, microbiological, or therapeutic properties of formulation.
