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PART - III: All 20 Questions (20 × 1 = 20)

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Quick Summary Table

D. Pharmacy 1st Year — Pharmaceutical Chemistry (ER-20-12T)

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PART - I (Attempt any SIX — 6×5 = 30)

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a. Importance of Limit Tests + Principle & Procedure of Limit Test for Chlorides

Cl⁻ + AgNO₃ → AgCl↓ (white turbidity) + NO₃⁻

1. Dissolve the specified weight of the substance in water in a Nessler cylinder (50 mL).
2. Add 1 mL of dilute nitric acid and 1 mL of AgNO₃ solution (2% w/v).
3. Make up to 50 mL with water. Mix and allow to stand for 5 minutes.
4. Prepare a standard: take the specified volume of standard chloride solution (containing 5 µg Cl⁻/mL), add the same reagents in the same quantities.
5. Compare turbidity: the test solution should not be more turbid than the standard.

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b. Acid–Base Titration with Indicators

Acid + Base → Salt + Water

• HCl + NaOH → NaCl + H₂O (strong acid vs. strong base)
• CH₃COOH + NaOH → CH₃COONa + H₂O (weak acid vs. strong base)

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c. Classification, Preparation and Uses of Haematinics

1. Iron preparations — for iron-deficiency anaemia
   • Ferrous sulphate, Ferrous gluconate, Ferric ammonium citrate
2. Vitamin B₁₂ — for megaloblastic/pernicious anaemia
   • Cyanocobalamin, Hydroxocobalamin
3. Folic acid — for megaloblastic anaemia
4. Erythropoietin — for anaemia of chronic renal failure

• Iron is dissolved in dilute sulphuric acid
• The resulting solution is concentrated and crystallised
• Blue-green crystals are obtained

• Treatment of iron-deficiency anaemia
• Prophylaxis in pregnancy, infancy, and growing children
• Vitamin B₁₂ — pernicious anaemia, subacute combined degeneration of spinal cord
• Folic acid — neural tube defect prevention in pregnancy

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d. Nomenclature of Heterocyclic Compounds (up to Three Rings)

• Ring size is indicated by a prefix; heteroatom by a specific prefix
• Nitrogen → aza, Oxygen → oxa, Sulphur → thia
• Unsaturation is indicated by -ene or absence of -ane

• Pyrrole — 5-membered ring with 1 N (azole)
• Furan — 5-membered ring with 1 O (oxole)
• Thiophene — 5-membered ring with 1 S (thiole)
• Pyridine — 6-membered ring with 1 N
• Quinoline — bicyclic: benzene fused with pyridine (2 rings)
• Acridine — tricyclic: benzene + pyridine + benzene (3 rings)
• Indole — bicyclic: benzene + pyrrole
• Purine — bicyclic: pyrimidine + imidazole (important in nucleotides)

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e. Classification of Drugs Acting on CNS + Two Sedatives and Hypnotics

1. CNS Depressants
   • General anaesthetics (ether, halothane)
   • Sedatives & hypnotics (barbiturates, benzodiazepines)
   • Anxiolytics (diazepam)
   • Antipsychotics (chlorpromazine)
   • Antidepressants (amitriptyline)
   • Opioid analgesics (morphine)
   • Antiepileptics (phenytoin)
2. CNS Stimulants
   • Amphetamine, caffeine, methylphenidate
3. Drugs acting on autonomic nervous system (indirectly affecting CNS)

• Mechanism: Enhances GABA-A receptor activity → prolongs Cl⁻ channel opening
• Uses: Sedation, epilepsy, insomnia (now less common)
• Low dose = sedative; high dose = hypnotic

• Mechanism: Binds GABA-A receptor at benzodiazepine site → increases frequency of Cl⁻ channel opening
• Uses: Anxiety, insomnia, muscle relaxation, status epilepticus, alcohol withdrawal
• Safer therapeutic index than barbiturates

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f. Sympathomimetic Agents — Classification and Examples

1. Direct-acting — act directly on adrenoceptors: Adrenaline, Noradrenaline, Salbutamol
2. Indirect-acting — release noradrenaline from nerve terminals: Amphetamine, Tyramine
3. Mixed-acting — both mechanisms: Ephedrine, Pseudoephedrine

• Anaphylaxis (Adrenaline)
• Bronchial asthma (Salbutamol)
• Nasal decongestant (Xylometazoline)
• Hypotension/shock (Noradrenaline, Dopamine)
• Cardiac arrest (Adrenaline)

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g. Anti-arrhythmic Drugs — Classification and Uses

• SVT (supraventricular tachycardia): Verapamil, Adenosine
• Atrial fibrillation: Amiodarone, Digoxin
• Ventricular tachycardia/fibrillation: Lignocaine, Amiodarone
• Post-MI prophylaxis: Propranolol

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PART - II (Attempt any TEN — 10×3 = 30)

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i. Accuracy and Precision

• Example: If the true value of a drug content is 100 mg and the test gives 99.8 mg → high accuracy.

• Example: If repeated tests give 98.1, 98.2, 98.0 mg consistently → high precision (but may not be accurate).

A method can be precise without being accurate, but a truly accurate method must also be precise.

• Accuracy → % error = [(measured − true)/true] × 100
• Precision → Relative Standard Deviation (RSD) or Coefficient of Variation (CV)

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ii. Volumetric Analysis — Definition and Advantages

1. Simple, rapid, and inexpensive
2. Suitable for routine quality control in pharmaceutical labs
3. High accuracy and precision
4. Can be used for wide range of substances (acids, bases, oxidising agents, reducing agents, complexes)
5. Requires simple apparatus
6. Both organic and inorganic substances can be analysed

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iii. Limit Test for Sulphates

SO₄²⁻ + BaCl₂ → BaSO₄↓ (white turbidity) + 2Cl⁻

1. Dissolve the substance in water in a Nessler cylinder.
2. Add 2 mL of dilute HCl and 2 mL of BaCl₂ solution (25% w/v).
3. Make up to 50 mL. Allow to stand 10 minutes.
4. Prepare standard: a specified volume of standard sulphate solution + same reagents.
5. Compare: turbidity of test should not exceed standard.

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iv. Complexometric Titration

Ca²⁺ + EDTA → [Ca-EDTA] complex Used to determine calcium and magnesium in water hardness tests.

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v. Short Note on Antacids

• Al(OH)₃ → constipation
• Mg(OH)₂ → diarrhoea
• NaHCO₃ → systemic alkalosis, CO₂ belching

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vi. Cathartics — Definition and Two Examples

1. Bulk-forming: Isabgol, Methylcellulose
2. Osmotic/Saline: Magnesium sulphate, Lactulose
3. Stimulant/Irritant: Castor oil, Senna, Bisacodyl
4. Lubricant: Liquid paraffin
5. Stool softeners: Docusate sodium

1. Magnesium sulphate (Epsom salt): Osmotic cathartic; retains water in gut by osmosis → increases peristalsis.
2. Castor oil: Stimulant cathartic; converted to ricinoleic acid in intestine → irritates mucosa → increased peristalsis.

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vii. Dental Products — Definition and Examples

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viii. Beta-blockers — Two Examples

• Non-selective (β₁ + β₂): Propranolol, Sotalol
• Cardioselective (β₁): Atenolol, Metoprolol, Bisoprolol
• With intrinsic sympathomimetic activity: Pindolol

1. Propranolol — non-selective β-blocker; used in hypertension, angina, arrhythmias, thyrotoxicosis, migraine prophylaxis
2. Atenolol — cardioselective β₁-blocker; used in hypertension, angina, post-MI

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ix. Hypoglycemic Agents

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x. Classification of Anti-infective Agents

Anti-infective Agents
├── Antibacterials
│   ├── Antibiotics (Penicillin, Streptomycin, Tetracycline)
│   └── Sulfonamides (Sulfadiazine, Co-trimoxazole)
├── Antifungals
│   ├── Polyenes (Amphotericin B, Nystatin)
│   ├── Azoles (Fluconazole, Clotrimazole)
│   └── Allylamines (Terbinafine)
├── Antivirals
│   ├── Nucleoside analogues (Acyclovir, Zidovudine)
│   └── Protease inhibitors (Ritonavir, Lopinavir)
├── Antiprotozoals
│   ├── Antimalarials (Chloroquine, Quinine)
│   └── Antiamoebics (Metronidazole)
├── Anthelmintics (Albendazole, Mebendazole)
└── Antitubercular (Isoniazid, Rifampicin, Pyrazinamide)

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xi. Sulfonamides — Definition and Two Examples

Bacteria cannot absorb exogenous folate → folic acid synthesis is essential → sulfonamides selectively inhibit bacteria (human cells use preformed folate from diet).

1. Sulfadiazine
   • Uses: Urinary tract infections, burns (silver sulfadiazine), toxoplasmosis, meningococcal meningitis prophylaxis
2. Sulfamethoxazole (combined with Trimethoprim as Co-trimoxazole)
   • Uses: UTI, respiratory tract infections, Pneumocystis jirovecii pneumonia (PCP), typhoid

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PART - II: All 11 Questions (10×3 = 30)

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i. Define Accuracy and Precision with Examples

• Example: True content = 100 mg; test result = 99.8 mg → highly accurate.

• Example: Repeated results = 98.1, 98.0, 98.2 mg → highly precise (consistent), but not necessarily accurate.

Key distinction: A result can be precise but inaccurate (systematic error), but a truly accurate method must also be precise.

• Accuracy expressed as: % Error = [(Measured − True) / True] × 100
• Precision expressed as: Relative Standard Deviation (RSD) or Coefficient of Variation (CV)

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ii. Volumetric Analysis — Definition and Advantages

1. Simple, rapid, and economical
2. High accuracy and precision
3. Wide applicability — acids, bases, redox compounds, complexes
4. Suitable for routine pharmaceutical QC analysis
5. Requires minimal, inexpensive apparatus
6. Both organic and inorganic substances can be analysed

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iii. Limit Test for Sulphates

SO₄²⁻ + BaCl₂ → BaSO₄↓ (white turbidity) + 2Cl⁻

1. Dissolve the test substance in distilled water in a Nessler cylinder.
2. Add 2 mL dilute HCl + 2 mL of 25% BaCl₂ solution.
3. Make up to 50 mL, mix, stand for 10 minutes.
4. Prepare standard: specified volume of standard sulphate solution + same reagents.
5. Compare turbidity — test must not exceed standard.

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iv. Complexometric Titration with Example

• Before endpoint: wine red (metal-indicator complex)
• At endpoint: blue (free indicator, as EDTA displaces it)

Ca²⁺ + EDTA → [Ca–EDTA] stable complex Used to determine water hardness (Ca²⁺ + Mg²⁺).

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v. Short Note on Antacids

• Al(OH)₃ → constipation
• Mg(OH)₂ → diarrhoea (so often combined)
• NaHCO₃ → CO₂ gas, systemic alkalosis

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vi. Cathartics — Definition and Two Examples

• Poorly absorbed → retains water by osmosis in gut lumen
• Increases peristalsis → rapid bowel emptying
• Used in: constipation, before bowel surgery, poisoning

• Hydrolysed to ricinoleic acid in small intestine
• Irritates intestinal mucosa → stimulates peristalsis
• Used in: constipation, before radiological procedures

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vii. Dental Products — Definition and Examples

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viii. Beta-blockers — Two Examples

• Uses: Hypertension, angina, arrhythmias, thyrotoxicosis, migraine prophylaxis, anxiety (tremors)
• Caution: Contraindicated in asthma (blocks β₂ → bronchospasm)

• Uses: Hypertension, stable angina, post-MI, arrhythmias
• Advantage: Safer in asthmatics than propranolol

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ix. Note on Hypoglycemic Agents

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x. Classify Anti-infective Agents

ANTI-INFECTIVE AGENTS
│
├── 1. ANTIBACTERIALS
│       ├── Antibiotics → Penicillin, Streptomycin, Tetracycline, Erythromycin
│       └── Sulfonamides → Sulfadiazine, Co-trimoxazole
│
├── 2. ANTIFUNGALS
│       ├── Polyenes → Amphotericin B, Nystatin
│       ├── Azoles → Fluconazole, Clotrimazole, Ketoconazole
│       └── Others → Griseofulvin, Terbinafine
│
├── 3. ANTIVIRALS
│       ├── Anti-herpes → Acyclovir
│       ├── Anti-HIV (ARVs) → Zidovudine, Nevirapine, Ritonavir
│       └── Anti-influenza → Oseltamivir
│
├── 4. ANTIMALARIALS → Chloroquine, Quinine, Artesunate, Primaquine
│
├── 5. ANTIAMOEBICS/ANTIPROTOZOALS → Metronidazole, Tinidazole
│
├── 6. ANTHELMINTICS → Albendazole, Mebendazole, Ivermectin
│
└── 7. ANTITUBERCULAR → Isoniazid (INH), Rifampicin, Pyrazinamide, Ethambutol

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xi. Sulfonamides — Definition and Two Examples

PABA → (sulfonamide blocks here) → Dihydrofolic acid → Tetrahydrofolic acid (needed for DNA/RNA synthesis)

• Short-acting sulfonamide
• Uses: UTI, burns (as silver sulfadiazine), toxoplasmosis, meningococcal prophylaxis

• Combined preparation for double blockade of folate synthesis
• Uses: UTI, respiratory infections, typhoid, Pneumocystis jirovecii pneumonia (PCP in HIV)