Drugs are chemicals of low molecular masses that interact with macromolecular targets and produce a biological response.
Drugs are called medicines when the biological response is therapeutic and useful.
The use of chemicals for obtaining a therapeutic effect is called chemotherapy.
Drugs can be classified on the basis of their pharmacological effect, drug action, chemical structure and molecular targets.
Drugs: Drug Target Interaction
Drugs known as enzyme inhibitors can inhibit the catalytic action of enzymes in two ways: either by competing with a substance or by blocking an enzyme.