Active Pharmaceutical Ingredients (APIs): Definition and Overview

a scientist in a sterile white lab coat holds a small transparent vial containing a glowing blue liquid symbolizing the Active Pharmaceutical Ingredient (API)

Definition: An Active Pharmaceutical Ingredient (API) is the biologically active component of a drug responsible for its therapeutic effect. In a finished medication (tablet, capsule, injectable, etc.), the API provides the intended pharmacological action, while inactive excipients aid stability, delivery, and manufacturability. In regulatory terms, ICH defines an API as “any substance… that, when used … Read more