1. Drugs and their Classification

Chapter 15: Chemistry in Everyday Life

1.   Introduction to Drugs and Chemotherapy :

In general the drug may be defined as the substances used in the prevention, diagnosis, treatment or cure of disease in man or animals.

When administered to the ailing individual, its action should be localised at the site where it is desired to act. (In actual practice, there is no drug which behaves in this manner).

Chemotherapy :

“The use of chemicals to destroy infectious micro organisms without causing any injury to the host is called as chemotherapy” .

Drugs and Classification of drugs

(a) On the basis of Pharmacological effect

(b) On the basis of drug action

(c) On the basis of chemical structure

(d) On the basis of molecular targets

Drug Target Interaction :

Macromolecules of biological origin perform various functions in the body for example proteins which perform the role of biological catalysts in the body are called enzymes, and those which are crucial to communication system in the body are called receptors.

Enzymes as Drug Targets :

(a) Catalystic action of enzymes : 

In catalytic activity, enzymes perform two major functions as follows

(i) To hold the substrate for chemical reaction :

(ii) The second function of the enzyme is to provide functional group which will attacks the substrate to carry out chemical reaction.

Receptors as Drug Targets :

Receptors are proteins that are crucial to body’s communication process.