Unit 16 · JEE Advanced Quick Reference · Drugs · Food · Cleansing Agents
Enzymes: (1) hold substrate at active site, (2) provide functional groups to react.
Binding forces: ionic, H-bonding, van der Waals, dipole–dipole.
Competitive inhibitor → competes with substrate at active site.
Non-competitive inhibitor → binds allosteric site → shape of active site changes → substrate can't bind.
Covalent (irreversible) → enzyme permanently blocked → body degrades complex → synthesises new enzyme.
Receptors = proteins embedded in cell membrane. Active site projects outside cell.
Chemical messengers bind → shape change → message transferred without messenger entering cell.
Different receptors → different shape, structure, amino acid composition → selectivity.
Antagonist → blocks receptor (used when blocking needed).
Agonist → mimics messenger, activates receptor (used when natural messenger is deficient).
| Class | Drug / Example | Brand | Mechanism / Key Note | Uses |
|---|---|---|---|---|
| Antacids Antacid |
NaHCO₃, Al(OH)₃, Mg(OH)₂ Cimetidine, Ranitidine |
Tegamet Zantac |
Metal hydroxides better (insoluble, don't raise pH above neutral). Cimetidine/Ranitidine = H₂ receptor antagonists → block histamine from stimulating acid in stomach wall. | Hyperacidity, stomach ulcers |
| Antihistamines Antiallergic |
Brompheniramine Terfenadine |
Dimetapp Seldane |
Compete with histamine at allergy receptor binding sites. Act on different receptors than antacids → don't reduce acid secretion. | Nasal congestion, allergic response, common cold, pollen allergy |
| Tranquilizers Neurological |
Iproniazid, Phenelzine Chlordiazepoxide, Meprobamate Equanil, Valium, Serotonin Barbiturates: veronal, amytal, nembutal, luminal, seconal |
Nardil — |
MAO inhibitors (Iproniazid, Phenelzine) → inhibit enzymes degrading noradrenaline → longer activation → counteracts depression. Barbiturates = hypnotic (sleep-producing). Valium, serotonin also tranquilizers. | Depression, anxiety, stress, hypertension, sleeping pills |
| Non-narcotic Analgesics Non-addictive |
Aspirin, Paracetamol | — | Aspirin inhibits synthesis of prostaglandins (cause inflammation + pain). Antipyretic. Anti-platelet coagulation → prevents heart attacks. | Skeletal pain, arthritis, fever reduction, heart attack prevention |
| Narcotic Analgesics Addictive |
Morphine, Heroin, Codeine | Opiates | From opium poppy. Relieve pain + produce sleep at med doses. Poisonous doses → stupor, coma, convulsions, death. Highly addictive. | Post-op pain, cardiac pain, terminal cancer, childbirth |
| Antibiotics (Broad) Broad Spectrum |
Chloramphenicol (1947) Ampicillin, Amoxycillin Vancomycin, Ofloxacin |
— | Kill/inhibit both Gram+ve and Gram–ve bacteria. Chloramphenicol rapidly absorbed orally. Ampicillin/Amoxycillin = synthetic mods of penicillin. Dysidazirine → toxic to some cancer cells. | Typhoid, dysentery, meningitis, pneumonia, UTI, fever |
| Antibiotics (Narrow) Narrow Spectrum |
Penicillin G | — | Fleming 1929, from Penicillium fungus. Nobel Prize 1945 (Fleming + Florey). Test allergy before giving. Bactericidal. Made at Hindustan Antibiotics, Pimpri in India. | Specific bacterial infections |
| Antiseptics Living Tissue |
Dettol (chloroxylenol + terpineol) Bithionol (soaps), Iodoform Tincture of iodine (2–3% I₂) Boric acid (dilute) — weak, eyes |
— | Applied to living tissues (wounds, cuts, skin). NOT ingested. Furacine, soframicine = other examples. | Wound dressing, skin infections, eye wash |
| Disinfectants Inanimate |
Phenol 1% · Cl₂ (0.2–0.4 ppm) SO₂ (very low conc.) |
— | Applied to inanimate objects. Phenol: 0.2% = antiseptic, 1% = disinfectant — concentration-dependent switch. | Floors, drainage, instruments |
| Antifertility Hormonal |
Norethindrone Ethynylestradiol (Novestrol) |
— | Birth control pills = synthetic estrogen + synthetic progesterone together. Progesterone suppresses ovulation. Synthetic derivatives more potent. Norethindrone = most widely used. | Contraception / family planning |
Arsenic-based compounds for syphilis. Developed Arsphenamine (Salvarsan) — first effective treatment for syphilis. Noted –As=As– resembles –N=N– of azodyes → searched azodye-like antibacterial compounds.
Ehrlich prepared prontosil, first effective antibacterial agent. Structurally resembles salvarsan. In body: prontosil → sulphanilamide (actual active compound). → Sulpha drug era began. Best: Sulphapyridine.
1929: Discovered antibacterial properties of Penicillium fungus. Isolation + purification took 13 years. Shared Nobel with H.W. Florey. Real revolution in antibacterial therapy.
| Sweetener | Sweetness vs Cane Sugar | Chemical Nature | Key Note |
|---|---|---|---|
| Aspartame | 100× | Methyl ester of dipeptide (aspartic acid + phenylalanine) | Most widely used. Unstable at cooking temperature — cold foods and soft drinks only. |
| Saccharin | 550× | Ortho-sulphobenzimide | First popular artificial sweetener (discovered 1879). Excreted unchanged in urine. Useful for diabetics. |
| Sucralose | 600× | Trichloro derivative of sucrose | Stable at cooking temperature. Looks and tastes like sugar. Zero calories. |
| Alitame | 2000× | High potency sweetener | More stable than aspartame. Problem: difficult to control sweetness of food. |
| Property | Soaps | Synthetic Detergents |
|---|---|---|
| Chemical nature | Na/K salts of long-chain fatty acids (stearic, oleic, palmitic) | Sodium salts of sulphonated long-chain alcohols/hydrocarbons, or ammonium salts, or polyglycol esters |
| Preparation | Saponification: fat + 3NaOH → 3 RCOONa + glycerol. NaCl added to precipitate soap. Glycerol recovered by fractional distillation. | Long-chain alcohol + H₂SO₄ → alkyl H₂SO₄ → NaOH → anionic detergent. Or alkylbenzene sulphonic acid + NaOH. |
| Hard water | Fails in hard water. Ca²⁺/Mg²⁺ form insoluble soaps (scum). Gummy mass on fabric. Dull hair. Uneven dye absorption. | Works in hard water (and ice cold water for some types). |
| Biodegradability | Biodegradable | Straight chain = biodegradable (preferred). Branched chain = non-biodegradable → accumulates → river/pond foaming → pollution. |
| Cleansing action | Both: micelle formation. Hydrophobic tails trap grease/oil in core. Hydrophilic heads face water. Grease dispersed and removed. | |
Anionic part does the cleansing.
Na salts of sulphonated long-chain alcohols or alkylbenzene sulphonates.
E.g. Sodium dodecylbenzenesulphonate
(dodecylbenzene + H₂SO₄ → sulphonic acid + NaOH → product)
Use: Household cleaning, toothpastes
Quaternary ammonium salts of amines. Long hydrocarbon chain + positive N (acetates, chlorides, bromides as anions).
E.g. Cetyltrimethylammonium bromide
Have germicidal properties. Expensive → limited use.
Use: Hair conditioners
No ions in structure.
E.g. stearic acid + polyethyleneglycol → product
Same micelle cleansing mechanism (removes grease/oil).
Use: Liquid dishwashing, emulsifying agents, wetting agents
| Name | Brand/Alias | Class | Key Identity Fact |
|---|---|---|---|
| Cimetidine | Tegamet | Antacid | First H₂ receptor antagonist. Was world's largest-selling drug until ranitidine. |
| Ranitidine | Zantac | Antacid | Replaced cimetidine. Blocks histamine H₂ receptors in stomach wall. |
| Brompheniramine | Dimetapp | Antihistamine | Competes with histamine at allergy receptors. Doesn't reduce acid secretion. |
| Terfenadine | Seldane | Antihistamine | Same mechanism as brompheniramine. Antiallergic, not antacid. |
| Iproniazid | — | Antidepressant | MAO inhibitor → slows degradation of noradrenaline → longer receptor activation. |
| Phenelzine | Nardil | Antidepressant | Same MAO inhibitor mechanism as iproniazid. |
| Equanil | Meprobamate | Tranquilizer | Controls depression and hypertension. |
| Chlordiazepoxide | — | Tranquilizer | Mild tranquilizer for relieving tension. Relatively safe. |
| Aspirin | — | Non-narcotic | Inhibits prostaglandin synthesis. Antipyretic + anti-platelet → prevents heart attacks. |
| Morphine / Heroin / Codeine | Opiates | Narcotic | From opium poppy. Pain relief at med doses. Stupor/coma/death at high doses. Addictive. |
| Arsphenamine (Salvarsan) | — | Antibacterial | Paul Ehrlich. First effective treatment for syphilis. Arsenic-based. Nobel 1908. |
| Prontosil | — | Sulpha drug | 1932, Ehrlich. First effective antibacterial agent. Converted to sulphanilamide in body. |
| Sulphanilamide → Sulphapyridine | — | Sulpha drug | Real active compound of prontosil. Sulphapyridine = most effective sulphonamide analogue. |
| Penicillin G | — | Narrow spectrum | Fleming 1929, from Penicillium fungus. Nobel 1945. Made at Hindustan Antibiotics, Pimpri. |
| Chloramphenicol | — | Broad spectrum | Isolated 1947. Rapidly absorbed orally. Typhoid, dysentery, meningitis, pneumonia. |
| Norethindrone | — | Antifertility | Most widely used synthetic progesterone derivative. Suppresses ovulation. |
| Ethynylestradiol | Novestrol | Antifertility | Synthetic estrogen. Used with norethindrone in birth control pills. |
| Saccharin | — | Sweetener | Ortho-sulphobenzimide. 550×. First popular artificial sweetener (1879). Diabetics. |
| Aspartame | — | Sweetener | 100×. Dipeptide ester (Asp+Phe). Unstable at high T → cold drinks only. |
| Sucralose | — | Sweetener | 600×. Trichloro sucrose. Stable at cooking T. Zero calories. |
| Alitame | — | Sweetener | 2000×. Stable. Problem: hard to control sweetness of food. |
| Sodium benzoate | C₆H₅COONa | Preservative | Most common synthetic preservative. Metabolised in body. Limited quantities. |
| Dettol | — | Antiseptic | Mixture of chloroxylenol + terpineol. |
| Bithionol | Bithional | Antiseptic | Added to soaps to impart antiseptic properties. |
| Tincture of iodine | — | Antiseptic | 2–3% I₂ solution in alcohol-water. Powerful antiseptic for wounds. |
| Iodoform | CHI₃ | Antiseptic | Used as antiseptic for wounds. |
| Cetyltrimethylammonium bromide | — | Cationic detergent | Popular cationic detergent. Germicidal. Used in hair conditioners. |