Use of chemicals for therapeutic effect is called chemotherapy.
2. Why do we need to classify drugs in different ways ?
It is useful for doctors because it provides them the whole range of drugs available for the treatment of a particular type of problem.
3. How are drugs classified?
(a) On the basis of pharmacological effect
For example, analgesics have pain killing effect.
(b) On the basis of drug action
It is based on the action of a drug on a particular biochemical process. For example, antihistamines inhibit the action of histamine which causes inflammation in the body. (c) On the basis of chemical structure
Drugs classified in this way share common structural features and often have similar pharmacological activity. For example, sulphonamides have common structural feature. (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.
4. Name the macromolecules that are chosen as drug targets.
Carbohydrates, lipids, proteins and nucleic acids are chosen as drug targets.
5. Explain the term, target molecules or drug targets as used in medicinal chemistry. Drugs usually interact with biomolecules such as carbohydrates, lipids, proteins and nucleic acids. These are called target molecules or drug targets.
6. Why should not medicines be taken without consulting doctors ? (or) Sleeping pills are recommended by doctors to the patients suffering from sleeplessness but it is not advisable to take its doses without consultation with the doctor. Why ? Most of the drugs taken in doses higher than recommended may cause harmful effect and act as poison.
7. How do drugs act as inhibitors of enzymes?
i) Drugs compete with the natural substrate for their attachment on the active sites of enzymes. Such drugs are called competitive inhibitors ii) Some bind to a different site of enzyme which is called allosteric site. This changes the shape of the active site in such a way that substrate cannot recognise it.
8. Define the terms agonist and antagonist.
Drugs that bind to the receptor site and inhibit its natural function are called antagonists. These are useful when blocking of message is required. Drugs that mimic the natural messenger by switching on the receptor, these are called agonists. These are useful when there is lack of natural chemical messenger.
9. What are antacids? Give examples
Antacids are drugs which act against acidity in the stomach. They include sodium hydrogencarbonate or a mixture of aluminium and magnesium and antihistamines like cimetidine and ranitidine.
10. Why are cimetidine and ranitidine better antacids than sodium hydrogencarbonate or magnesium or aluminium hydroxide ? The drug cimetidine and ranitide are designed to prevent the interaction of histamine with the receptors present in the stomach wall. This results in release of lesser amount of acid.
11. How are metal hydroxides better alternatives than ydrogen carbonates? Excessive hydrogencarbonate can make the stomach alkaline and trigger the production of even more acid. Metal hydroxides are insoluble, and do not increase the pH above neutrality.
12. While antacids and antiallergic drugs interfere with the function of histamines, why do these not interfere with the function of each other ? Antiallergic and antacid drugs work on different receptors.
13. What are anti allergic drugs? Give examples.
Anti allergic drugs are antihistamines which bind to receptors of histamine and prevent allergic reactions. Eg- brompheniramine (Dimetapp) and terfenadine (Seldane).
14. With reference to which classification has the statement, “ranitidine is an antacid” been given? This statement...