An active pharmaceutical ingredient (API) is the biologically active component in a medication that produces its therapeutic effect. The drug product itself contains the API plus inactive excipients, binders, and coatings. The U.S. imports approximately 85% of the APIs used in its patented pharmaceutical products, primarily from China and India. Because APIs are the core input in drug manufacturing, foreign dependence on API supply chains is the central national security argument used to justify pharmaceutical tariffs.