Pharmacokinetics mainly studies the process of drug disposal by the body. Including absorption, distribution, biotransformation (or metabolism), excretion and the change of blood drug concentration with time. Pharmacodynamics mainly studies the effects and laws of drugs on the body and expounds the mechanism of drug prevention and treatment of diseases. Toxicology research refers to observing the possible side effects, toxic reactions, allergic reactions, side effects and other adverse reactions caused by drugs when studying and investigating the efficacy of drugs. Clinical research of new drugs includes evaluating the safety and effectiveness of new drugs, reevaluating the drugs on the market and monitoring the adverse drug reactions. The study of drug interaction refers to the study of the changes in the intensity and properties of drug action caused by the combined or sequential use of two or more drugs.