The Active Pharmaceutical Ingredient (API) is the part of any drug that is active. Some drugs, such as combination therapies, have multiple active ingredients to treat different diseases. While production of APIs has traditionally been done by the pharmaceutical companies themselves in their home countries, in recent years many corporations have opted to send manufacturing overseas to cut costs. This has caused significant changes to how these drugs are regulated, with more rigorous guidelines and inspections put into place.
All drugs are made up of two core components: the API, which is the central ingredient, and the excipient, the substance inside the drug that helps deliver the medication to your system. Excipients are inactive substances, such as mineral oil, and not chemically active.
Manufacturers use certain standards to determine how strong the API is in each drug. However, the standard can vary widely from one brand to another. One brand might use one test, another a different one.