Drug substance refers to the drug substance used in the production of various preparations. It is the effective ingredient in the preparations. It is the powder, crystal, extract, etc. prepared by chemical synthesis, plant extraction or biotechnology and used as medicine, but cannot be taken directly by patients.
The perfect definition of API in ICH Q7A: any substance or mixture of substances intended to be used in the manufacture of drugs and become an active ingredient of drugs when used in pharmaceuticals. This substance has pharmacological activity or other direct effects in the diagnosis, treatment, symptom relief, treatment or disease prevention of diseases, or can affect the function or structure of the body.
The meaning of pharmaceutical intermediates is that two or more different substances have special properties of products through systematic chemical reactions in appropriate proportions. It retains the unique efficacy of its own raw materials, overcomes the defect of using a single raw material, and improves the efficacy and safety of the drug.