Drug class
Substances that can exert a pharmacological effect on a living organism are commonly assigned to different classes of active substances , also known as groups of active substances , for reasons of clarity . Common classifications, such as the ATC classification system , differentiate according to the organ system in which the substance predominantly develops its effect, the type of effect and the type of chemical compound . The type of effect can be further subdivided according to clinical aspects, i.e. the effects that can be observed directly on the patient, and the reactions triggered on a biochemical level.