Both pharmaceutical intermediates and APIs belong to the category of fine chemicals. Intermediates are produced in the process steps of APIs and must undergo further molecular changes or refining to become APIs. Intermediates can be separated or not.
Active Pharmaceutical Ingredient (API): Any substance or mixture of substances intended to be used in the manufacture of a drug and which, when used in a drug, becomes an active ingredient of the drug. Such substances have pharmacological activity or other direct effects in the diagnosis, treatment, symptom relief, treatment or prevention of diseases, or can affect the function and structure of the body.