Pharmaceutical intermediates are intermediate chemicals produced during the synthesis of chemical drugs. Their upstream industry is the basic chemical raw material manufacturing industry, and their downstream industry is the chemical pharmaceutical raw material and preparation manufacturing industry. The quality requirements for pharmaceutical intermediates are extremely high, especially the control of impurities, which directly affects the quality and safety of active drugs.

An active pharmaceutical ingredient (API) is any substance or mixture of substances used in the manufacture of pharmaceuticals that has pharmacological activity or other direct effects in the diagnosis, treatment, symptom relief, management, or prevention of disease, or that can affect the function or structure of the body.

Pharmaceutical excipients refer to the excipients and additives used in the production of drugs and the preparation of prescriptions; they are substances, other than the active ingredient, that have undergone reasonable safety assessments and are included in pharmaceutical formulations. Besides acting as excipients, carriers, and improving stability, pharmaceutical excipients also have important functions such as solubilization, co-solubilization, and sustained-release, and are important components that may affect the quality, safety, and efficacy of drugs.

Coordination compounds are a class of compounds with characteristic chemical structures, which are formed by the complete or partial combination of a central atom (or ion, collectively referred to as the central atom) and the molecules or ions surrounding it (called ligands) through coordinate bonds.