After studying this Unit you will be
• visualise the importance of
Chemistry in daily life;
• explain the term ‘chemotherapy’;
• describe the basis of classification
• explain drug-target interaction of
enzymes and receptors;
• explain how various types of
drugs function in the body;
• know about artificial sweetening
agents and food preservatives;
• discuss the chemistry of cleansing
16.1 Drugs and
Chemistr y in
Ever yday Life
From living perception to abstract thought, and from this to practice. V.I. Lenin.
By now, you have learnt the basic principles of
chemistry and also realised that it influences every
sphere of human life. The principles of chemistry have
been used for the benefit of mankind. Think of
cleanliness — the materials like soaps, detergents,
household bleaches, tooth pastes, etc. will come to your
mind. Look towards the beautiful clothes — immediately
chemicals of the synthetic fibres used for making clothes
and chemicals giving colours to them will come to your
mind. Food materials — again a number of chemicals
about which you have learnt in the previous Unit will
appear in your mind. Of course, sickness and diseases
remind us of medicines — again chemicals. Explosives,
fuels, rocket propellents, building and electronic
materials, etc., are all chemicals. Chemistry has
influenced our life so much that we do not even realise
that we come across chemicals at every moment; that
we ourselves are beautiful chemical creations and all
our activities are controlled by chemicals. In this Unit,
we shall learn the application of Chemistry in three
important and interesting areas, namely – medicines,
food materials and cleansing agents.
Drugs are chemicals of low molecular masses (~100 – 500u). These interact with macromolecular targets and produce a biological response. When the biological response is therapeutic and useful, these chemicals are called medicines and are used in diagnosis, prevention and treatment of diseases. If taken in doses higher than those recommended, most of the drugs used as medicines are potential poisons. Use of chemicals for therapeutic effect is called chemotherapy,
Drugs can be classified mainly on criteria outlined as follows: (a) On the basis of pharmacological effect
This classification is based on pharmacological effect of the drugs. It is useful for doctors because it provides them the whole range of drugs available for the treatment of a particular type of problem. For example, analgesics have pain killing effect, antiseptics kill or arrest the growth of microorganisms.
(b) On the basis of drug action
It is based on the action of a drug on a particular biochemical process. For example, all antihistamines inhibit the action of the compound, histamine which causes inflammation in the body. There are various ways in which action of histamines can be blocked. You will learn about this in Section 16.3.2.
(c) On the basis of chemical structure
It is based on the chemical structure of the drug. Drugs classified in this way share common structural features and often have similar
pharmacological activity. For example, sulphonamides have common structural feature, given below.
Structural features of sulphonamides
(d) On the basis of molecular targets
Drugs usually interact with biomolecules such as carbohydrates, lipids, proteins and nucleic acids. These are called target molecules or drug targets. Drugs possessing some common structural features may have the same mechanism of action on targets. The classification based on molecular targets is the most useful classification for medicinal chemists.
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...
Please join StudyMode to read the full document