Classification Of Drugs - Practice Questions & MCQ

All medicines are drugs but all drugs are not medicines. A drug may be habit-forming, causing addiction while a medicine is safe to use and does not cause addiction. Drugs may be a single chemical substance or a combination of two or more different substances. An ideal drug should satisfy the following requirements:

• When administered to the ailing individual or host, 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.
• It should act on a system with efficiency and safety.
• It should have minimum side effects.
• It should not injure host tissues or physiological processes.
• The cells should not acquire resistance to the drug after sometime.

Classification of Drugs
Drugs may be classified in a number of different ways. Some of these are mentioned below:

1. On the basis of pharmacological effect: This classification is based on the 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 disease or infection. For example, analgesics have pain killing effect while antiseptics kill or arrest the growth of microorganisms.
2. 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 histamine which causes inflammation in the body. There are various ways in which action of histamines can be blocked.
3. On the basis of chemical structure: It is based on the chemical structure of the drug because drugs have common structural features and often have similar pharmacological activity. For example, sulphonamides having common structural feature as given below are mostly antibacterial.