Biochemical reactions happen within a cell and involve the breakdown of molecules, called a catabolic reaction or the building up of molecules, called an anabolic reaction. This occurs in the body all of the time. An example of an anabolic biochemical reaction is amino acids combining to form protein in the body.
Pharmaceutical chemical reactions is the way that medication interacts with the human body. This is extremely important to the health care profession because researchers need to understand why medications work the way that they do or why they don't work and what possible side effects may occur. An example of why pharmaceutical reactions are important would be the effect of taking both risperidone and tegretol is that the tegretol can decrease the effectiveness of the risperidone.
Diagnostic chemical reactions are those used for medical testing purposes such as a glucose tolerance test. A chemical is introduced to the body in order for the physicians to measure the results of the chemical interaction. In this case, a patient would consume a drink with a high concentration of glucose and blood would be drawn before and after consumption to monitor how the body reacts to the influx of glucose.