Active pharmaceutical intermediates (APIs) are chemical compounds that are used in the production of pharmaceutical drugs. They are intermediate compounds that are used as building blocks in the synthesis of a wide range of pharmaceuticals, including prescription drugs, over-the-counter drugs, and dietary supplements. APIs are typically small, high-value molecules that are produced in relatively small quantities and are used as intermediates in the manufacture of a variety of pharmaceutical products.

APIs can be classified according to the type of chemical reactions used to synthesize them, such as condensation reactions, substitution reactions, and oxidation reactions. They can also be classified according to their therapeutic use, such as anti-inflammatory drugs, cardiovascular drugs, and central nervous system drugs.

APIs are an important component of the pharmaceutical industry, as they are used as starting materials for the manufacture of a wide range of drugs. They are typically synthesized in specialized chemical plants and are used in the production of a variety of pharmaceutical products.