Drugs — analgesics, antibiotics, antiseptics, antacids (mechanism overview)

4.7.1 · Chemistry › Chemistry in Everyday Life (compressed)

Hum is classification ki zaroorat kyun rakhte hain?

Drugs ko group kiya jaata hai woh kya karte hain (analgesic = dard khatam karna) aur woh kaise kaam karte hain (mechanism) ke basis par. Mechanism jaanne se tum side-effects predict kar sakte ho aur behtar drugs design kar sakte ho — yahi is poore topic ka 80/20 core hai.

Target type: enzyme ya receptor.
Action type: inhibitor (enzyme block karta hai) ya antagonist/agonist (receptor ko block/trigger karta hai).

Chaar families (mechanism overview)

Figure — Drugs — analgesics, antibiotics, antiseptics, antacids (mechanism overview)

1. Analgesics — dard kam karna

Non-narcotic (non-addictive): aspirin, paracetamol, ibuprofen.
- HOW: yeh COX enzyme ko inhibit karte hain, prostaglandin synthesis rokke. Aspirin khoon bhi patla karta hai (anti-clotting) → heart attacks rokne ke liye use hota hai.
Narcotic / opioid: morphine, codeine, heroin.
- HOW: yeh brain mein opioid receptors se bind karte hain (agonists), dard ki perception block karte hain; neend/euphoria produce karte hain; zyada doses mein addictive hote hain.

2. Antibiotics — bacteria ko maaro ya rokho

Selective kyun hain: yeh un structures par attack karte hain jo bacteria mein hote hain lekin humans mein nahi (jaise bacterial cell wall, ya bacterial ribosomes).
HOW (examples):
- Penicillin cell-wall synthesis ko inhibit karta hai → bacterium phoot jaata hai (bactericidal).
- Chloramphenicol / tetracycline bacterial protein synthesis ko block karte hain (bacteriostatic).
Range: broad-spectrum (kaafi bacteria, jaise tetracycline) vs narrow-spectrum (kuch hi).

3. Antiseptics & Disinfectants — surfaces par microbes ko destroy/inhibit karna

Term	Kahan lagaate hain	Concentration
Antiseptic	living tissue (skin, wounds)	mild
Disinfectant	non-living surfaces (floors, instruments)	strong

Wahi compound dono ho sakta hai, concentration ke hisaab se. Dettol = chloroxylenol + terpineol. Phenol ( $\sim 0.2%$ = antiseptic, $\geq 1%$ = disinfectant). Tincture of iodine ( $2$ – $3%$ I $_{2}$ in alcohol/water).

4. Antacids — pet mein zyada acid neutralise karna

HOW (neutralisers): weak bases HCl ke saath react karte hain. $NaHCO_{3} + HCl ⟶ NaCl + H_{2} O + CO_{2}$ $Mg(OH)_{2} + 2 HCl ⟶ MgCl_{2} + 2 H_{2} O$ $Al(OH)_{3} + 3 HCl ⟶ AlCl_{3} + 3 H_{2} O$
HOW (production blockers): ranitidine (Zantac), cimetidine ==histamine H $_{2}$ -receptor antagonists== hain. Histamine acid release trigger karta hai; receptor block karo → kam acid banta hai. Omeprazole seedha proton pump ko block karta hai.

Worked examples

Common mistake Classic errors ko steel-man karna

Error 1: "Antiseptics aur antibiotics ek hi cheez hain." Kyun sahi lagta hai: dono germs se ladte hain. Fix: antibiotics internally liye jaate hain aur microbe-derived chemicals hain jo bacteria ko selectively target karte hain; antiseptics external living tissue/surfaces par lagaaye jaate hain aur proteins denature karke microbes ko non-selectively maarte hain. Galat jagah, galat selectivity.

Error 2: "Antiseptic aur disinfectant alag chemicals hain." Kyun sahi lagta hai: alag naam hain. Fix: aksar wahi compound alag concentrations mein hota hai — phenol $0.2%$ (antiseptic) vs $\geq 1%$ (disinfectant). Yeh dose + surface ka mamla hai, identity ka nahi.

Error 3: "Antacids acid production kam karte hain." Kyun sahi lagta hai: dono acidity kam karte hain. Fix: saadhe antacids (NaHCO $_{3}$ , Mg(OH) $_{2}$ ) pehle se maujood acid neutralise karte hain; sirf H $_{2}$ -antagonists/proton-pump inhibitors production kam karte hain.

Error 4: "Saare analgesics addictive hote hain." Fix: Sirf narcotic (opioid) wale hote hain. Non-narcotic (aspirin/paracetamol) nahi hote.

Recall Feynman: 12 saal ke bachche ko samjhao

Tumhare body mein chhoti chhoti machines (proteins) hain. Ek drug ek chhoti si chabi hai.

Dard ki goliyan (analgesics): us machine ko jam kar deti hain jo "ouch" chemicals banati hai.
Antibiotics: ek aisi deewar tod dete hain jo sirf bacteria ke paas hoti hai, toh germs phoot jaate hain — lekin tumhare cells safe rehte hain.
Antiseptics: soap-jaisi chemicals jo tumhari skin ya floor par germs ko pighal deti hain.
Antacids: tumhare pet mein acid hota hai; yeh baking soda jaisi cheez hain jo acid ko fizz karke khatam kar deti hain, ya ek "stop" switch jo kam acid banata hai. Har jagah wahi trick: sahi machine dhoondo aur use jam kar do.

Flashcards

Non-narcotic analgesics kaun si enzyme inhibit karte hain, aur woh kya banati hai?

Cyclooxygenase (COX); yeh prostaglandins banati hai (dard/fever/inflammation).

Morphine jaisi narcotic analgesics kaise kaam karti hain?

Yeh brain mein opioid receptors se bind karti hain (agonists), dard ki perception block karti hain; addictive hoti hain.

Penicillin ka mechanism?

Bacterial cell-wall synthesis inhibit karta hai → bacterium phoot jaata hai (bactericidal).

Bactericidal vs bacteriostatic?

Bactericidal bacteria ko maarta hai; bacteriostatic sirf unki growth/multiplication rokta hai.

Antiseptic vs disinfectant — key difference?

Antiseptic living tissue par (mild); disinfectant non-living surfaces par (strong); aksar wahi compound, alag concentration.

Phenol ki do uses ke liye concentrations?

~0.2% antiseptic; ≥1% disinfectant.

Acidity treat karne ke do mechanisms?

(1) Acid neutralise karo (NaHCO₃, Mg(OH)₂, Al(OH)₃); (2) acid production kam karo (ranitidine/cimetidine = H₂-antagonists; omeprazole = proton-pump inhibitor).

1 mol Al(OH)₃ kitne mol HCl neutralise karta hai?

3 mol HCl.

Ranitidine ka mechanism kya hai?

Histamine H₂-receptor antagonist → kam acid secretion.

Antibiotic ki definition?

Ek chemical jo wholly/partly microorganisms dwara produce hota hai jo low concentration mein doosre microbes ko maarta ya unki growth inhibit karta hai.

Competitive vs non-competitive inhibitor?

Competitive substrate jaisa hota hai aur active site ke liye compete karta hai; non-competitive ek allosteric site se bind karta hai, enzyme ki shape badal deta hai.

Aspirin heart ki protection kyun karta hai?

COX inhibition thromboxane kam karta hai → platelet aggregation kam → anti-clotting.

Connections

Enzymes and active sites — drug = enzyme inhibitor mechanism
Receptors and signal transduction — agonists/antagonists
Acid–base neutralisation — antacid stoichiometry
Prostaglandins and inflammation
Chemotherapy and drug design
Soaps and detergents — membrane disruption parallels antiseptics