Chemistry in Everyday life

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Reginald McLaughlin
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Therapeutic Action of drugs Chemistry in Everyday life Question 1 What are competitive inhibitors? Drugs inhibit the attachment of substrate on active site of enzymes by specific ways.

1 Therapeutic Action of drugs Chemistry in Everyday life Question 1 What are competitive inhibitors? Drugs inhibit the attachment of substrate on active site of enzymes by specific ways. When the drugs compete with the natural substrate for their attachment on the active sites of enzymes, such drugs are called Competitive inhibitors. Question 2 How substrate binds to the active site of the enzyme? Substrates bind to the active site of the enzyme through a variety of interactions such as ionic bonding, hydrogen bonding, van der Waals interaction or dipole-dipole interaction. Question 3 Explain the role of receptors as drug target? How the receptor receives the chemical messenger? Receptors are proteins that are crucial to body's communication process. Majority of these are embedded in cell membranes.

Message between two neurons and that between neurons to muscles, in the body is communicated through certain chemicals known as chemical messengers.

Thus even without entering the cell the chemical messenger passes the message.

2 Message between two neurons and that between neurons to muscles, in the body is communicated through certain chemicals known as chemical messengers. These are received at the binding sites of the receptor proteins. Shape of the receptor site changes when it accommodates a messenger so as to ease the transfer of message to the cell. Thus even without entering the cell the chemical messenger passes the message. Based on the shape, structure and amino acid composition of the binding site, the receptors shows selectivity for the chemical messengers. Hence different receptors in the body interact with different chemical receptors. Question 4 What are receptors? Receptors are proteins that are crucial to body s communication process. Majority of these are embedded in cell membranes.receptor proteins are embedded in the cell membrane in such a way that their small part possessing active site projects out of the surface of the membrane and opens on the outside region of the cell membrane.

Question 5 How the drug interacts with the enzyme? Drugs can block the binding site of the enzyme and prevent the binding of substrate, or can inhibit the catalytic activity of the enzyme.

Drugs inhibit the attachment of substrate on active site of enzymes in two different ways (i) Drugs compete with the natural substrate for their attachment on the active sites of enzymes.

3 Question 5 How the drug interacts with the enzyme? Drugs can block the binding site of the enzyme and prevent the binding of substrate, or can inhibit the catalytic activity of the enzyme. Such drugs are called enzyme inhibitors. Drugs inhibit the attachment of substrate on active site of enzymes in two different ways (i) Drugs compete with the natural substrate for their attachment on the active sites of enzymes. Such drugs are called competitive inhibitors. Some drugs do not bind to the enzyme s active site. These bind to a different site of enzyme which is called allosteric site. This binding of inhibitor at allosteric site changes the shape of the active site in such a way that substrate cannot recognise it. If the bond formed between an enzyme and an inhibitor is a strong covalent bond and cannot be broken easily, then the enzyme is blocked permanently. The body then degrades the enzyme-inhibitor complex and synthesises the new enzyme.

4 Question 6 What are enzyme inhibitors? Drugs inhibit any of the above mentioned activities of enzymes. These can block the binding site of the enzyme and prevent the binding of substrate, or can inhibit the catalytic activity of the enzyme. Such drugs are called Enzyme inhibitors. Question 7 What are receptors and how are they different from enzymes? 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, those which are crucial to communication system in the body are called Receptors. Question 8 What are the ways of classification of drugs? Drugs can be classified mainly on criteria outlined as follows: (a) On the basis of pharmacological effect On the basis of pharmacological effect, drugs are classified. For example, Analgesics are drugs which have pain killing effect. For example Aspirin and Morphine acts on different targets and have no structural relationship. To resist or kill the growth of microorganisms antiseptics are used. (b) Second the drugs are classified on the basis of drug action, i.e. whether they act on a particular bio-chemical process. For example, Antihistamines inhibit the action of the inflammatory agent Histamine in the body. (c) Third method of classifying drugs is by their chemical structure. Drugs classified in this way share a common structural features and often have similar pharmacological activity. For example, Penicillins contains a beta-lactum ring and kills bacteria by the same mechanism. (d) Finally classifying drugs according to their molecular targets. Drugs usually interact with biomolecules and these are called target molecules or drug targets. These drugs possesses some common structural features hence have the same mechanism of action on targets. Question 9 What are Antagonists and Agonists in drug action? Antagonists are the drugs that binds to the receptor site to inhibit its function and are useful when blocking of message is required. Agonists are the drugs that mimic the natural messenger by switching on the receptor and are useful when there is lack of natural chemical messenger.

Question 10 What is meant by Chemotherapy? Drugs are the chemical substances that are used for curing diseases and reducing suffering from pain are called medicines or drugs.

5 Question 10 What is meant by Chemotherapy? Drugs are the chemical substances that are used for curing diseases and reducing suffering from pain are called medicines or drugs. The branch of science that deals with the treatment of diseases using suitable chemicals is known as Chemotherapy. Classes of drugs Question 1 What are analgesic medicines? How are they classified and when are they commonly recommended for use? Analgesic medicines are those medicines which reduce or abolish pain causing impairment of consciousness, mental confusion, incoordination or paralysis or some other disturbances of nervous system. These are classified as follows: (i) Non-narcotic (non-addictive) analgesics: These drugs are effective in relieving skeletal pain such as that due to arthritis and preventing platelet coagulation. (ii) Narcotic drugs: These analgesics are chiefly used for the relief of severe pain like postoperative pain, cardiac pain and pains of terminal cancer, and in child birth. Question 2

6 Question 3 What are Tranquilisers? Drugs that acts on the central nervous system and helps in reducing anxiety and stress are known as tranquilizers. They are psychotherapeutic drugs used in the treatment of mental diseases. These are used for making sleeping pills. Question 4 What are oral-contraceptives? Give an example. The techniques used to prevent pregnancy by the woman are called contraceptives and the suppression of the activity of the Pituatory by the use of pills are called oral- Contraceptives. Example is Envoid-E that contains a mixture of Estrogen-Mestranol and Progestrogen-Norethynodrel. Question 5 What is Aspirin? Aspirin is Acetyl Salicylic acid and is an analgesic used for relief of pain like headache, bodyaches, Arthritis. Question 6 Give an example of a Tranquilizer. Seconal, Reserpine are examples of Tranquilizer. Question 7 Which Antibiotic is used in the treatment of Typhoid fever? Chloramphenicol is used in the treatment of typhoid fever. Question 8 Name one substance that acts as both Antiseptic and Disinfectant? Phenol acts as both Antiseptic and Disinfectant. Question 9 What is the name given to the medicine used for getting relief from pain? Analgesics are the medicines used for getting relief from pain.

7 Question 10 Penicillin is what type of drug? Penicillin is a type of antibiotic. It is a narrow-spectrum antibiotic, produced from microorganism and effective in killing other harmful micro-organisms. Question 11 Name the chemicals responsible for the antiseptic property in dettol. Chemicals Chloroxylenol and Terpineol present in dettol are responsible for the antiseptic property in it. Question 12 How Antiseptics differ from Disinfectants? Drugs that are produced from micro-organisms and are used to kill other harmful microorganisms are known as Antibiotics. Disinfectants are chemical substances which kill micro-organisms but are not safe to be applied on living tissues. These are used to kill the micro-organisms present in the drains, toilets etc. Food additives and cleansing agents Question 1 Describe the following giving one example for each: (i) Detergents (ii) Food preservatives (iii) Antacids Solution 27. (i) Detergents: A detergents is a surfactant or a mixture of surfactants having cleaning properties in dilute solution. Commonly, detergent refers to alkylbenzenesulphonates. For example: Sodium dodecylbenzene sulphonate (ii) Food preservatives: Food preservatives are chemicals that prevent food from spoilage due to microbial growth. Table salt, sugar, vegetable oil, sodium benzoate (C 6 H 3 COONa), and salts of propanoic acid are some examples of food preservatives. (iii) Antacids: Any drug that is used to counteract the effects of excess acid in the stomach and raise the ph to an appropriate level is called an antacid. Example: Omeprazole

8 Question 2 What is the need of artificial-sweetening agents? Artificial sweetening agents are useful to diabetic person and to people who need to control intake of calories. Question 3 Why detergents are preffered over soap? Detergents are preffered over soap as it works on hard water i.e. it forms foam in both hard and soft water, unlike soap. Synthetic detergents contains the properties of soap without having soap. Question 4 How the synthetic detergents are classified? Synthetic detergents are classified as cationic, anionic and non-ionic detergents. Question 5 What are food preservatives? Give example. Food preservatives prevent spoilage of food due to microbial growth. For example table salt, sugar, vegetable oil and Sodium benzoate. Question 6 Give an example of artificial sweetening agent? Aspartame is an artificial sweetening agent Question 7 Why are chemicals added to food? Chemicals are added to food for preservation, enhancing their appeal, and adding nutrititive value in them.

9 Question 8 What causes hardness of water? Why soap fails to work in hard water? Hardness of water is due to the presence of calcium and magnesium salts. These ions form insoluble calcium and magnesium soaps when sodium or potassium soaps are dissolved in water. The insoluble soap separates as scum in water and are useless as cleansing agents. Question 9 What are cationic detergents? Which cationic detergent is used in hair conditioner? Cationic detergents are quarternary ammonium salts of amines with Acetates, Chlorides and Bromides as substrates. Cetyltrimethylammonium bromide is the cationic detergent that is used as hair-conditioner. Question 10 What are non-ionic Detergents? Detergents which does not contain any ion in their constitution are non-ionic detergents. Example of such a detergent is formed when Stearic acid reacts with Polyethylene glycol. Question 11 What is Saponification process? Soaps containing sodium salts are formed by heating fat i.e. glyceryl ester of fatty acids with aqueous Sodium hydroxide solution. The reaction is known as Saponification reaction. In such reaction esters of fatty acids are hydolysed and the soap remains in colloidal form. It is precipitated from the solution by adding Sodium chloride. The solution left after removing the soap contains

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Downloaded from Question 16.1: Why do we need to classify drugs in different ways? The classification of drugs and the reasons for classification are as follows: (i) On the basis of pharmacological effect: This classification