KMR ADVICE

B.Pharm Exam Strategy & Important Questions Guide

Mr. K. Mallikarjuna Reddy

Associate Professor, M. Pharma (Pharmacology)

kmradvice.com

EXAM STRATEGY & IMPORTANT QUESTIONS GUIDE

1.4 BP104T · PHARMACEUTICAL INORGANIC CHEMISTRY (THEORY)

Complete PCI B.Pharm Semester I syllabus coverage with detailed answers, star-rated importance, and key terms highlighted.
Based on real university question-paper analysis (JNTU-H/K, AKTU, KUHS, Paru, RGUHS, Anna Univ).

📖 HOW TO USE THIS GUIDE

🔵 Click any blue tag for abbreviation + brief note.

🟣 Click any purple term for a plain-English explanation.

🔊 Click the speaker icon for pronunciation.

⭐ Stars reflect real past-paper repeat frequency.

✍️ Every answer opens with a short Opening Line — copy it as your first paragraph.

⚡ Each question ends with a compact At-a-Glance Summary.

PRIORITY READING GUIDE

🔴 TOP PRIORITY

Limit tests (Cl⁻, SO₄²⁻, Fe, As, Pb, Heavy metals) — principles + procedures.

Buffers — Henderson-Hasselbalch equation, buffer capacity, buffered isotonic solutions.

Antacids — ideal properties + NaHCO₃, Al(OH)₃ gel, Mg(OH)₂.

Electrolytes + ORS — roles, preparation of ORS, acid-base balance.

Haematinics — FeSO₄ preparation, assay, uses.

Antimicrobials — KMnO₄, H₂O₂, chlorinated lime, iodine.

🟡 MEDIUM PRIORITY

Dental products — dentifrices, fluoride, ZnO eugenol.

Cathartics — MgSO₄, Na₂HPO₄, kaolin, bentonite.

Poisons + Antidotes — Na₂S₂O₃, Na nitrite (cyanide), activated charcoal.

Radiopharmaceuticals — α/β/γ, half-life, ⁱ³ⁱI.

🔵 LOW PRIORITY

Emetics, Expectorants, Astringents — CuSO₄, KI, ZnSO₄, potash alum.

Acidifiers — NH₄Cl + dil HCl.

Modified limit tests for Cl / SO₄.

UNIT I

Impurities & Limit Tests (10 h)

Write a note on the history of pharmacopoeia 🔊, and the sources and types of impurities in pharmaceutical substances.

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10MLong Essay

Detailed Answer:

✍️ OPENING LINE A pharmacopoeia is the legal reference book that specifies the identity, purity and strength of every drug sold in a country; its evolution mirrors the evolution of modern pharmacy itself. Because every drug substance carries some impurities that can alter efficacy or safety, the pharmacopoeias prescribe strict limit tests to keep such impurities within acceptable limits.

History of Pharmacopoeia:
The earliest drug lists appear in ancient texts such as the Egyptian Ebers Papyrus 🔊 (about 1500 BC), the Chinese Pen T'sao and the Indian Charaka and Sushruta Samhita.
The Florentine Pharmacopoeia (1498) 🔊, published in Italy, was the first printed official pharmacopoeia. The London Pharmacopoeia (1618) was ordered by King James I. The United States Pharmacopeia (USP), 1820, is the oldest pharmacopoeia still in continuous use. The British Pharmacopoeia (BP), 1864, and the Indian Pharmacopoeia (IP), 1955 (now in its 9th edition, IP 2022, published by the IP Commission, Ghaziabad) followed. Other important compendia are the European Pharmacopoeia (Ph.Eur., 1964), the International Pharmacopoeia (WHO, 1951) and the Japanese Pharmacopoeia (JP, 1886).

Sources of Impurities:
Impurities can enter a drug substance at many stages from raw material to finished product.
(1) Raw materials themselves may be impure (for example, rock salt contains Mg²⁺, Ca²⁺ and SO₄²⁻).
(2) Reagents used in manufacturing can leave residues or catalyst traces.
(3) Solvents may leave traces of heavy metals or residual organic solvents.
(4) Manufacturing equipment can introduce impurities through corrosion or leaching from iron or copper vessels.
(5) Atmospheric contamination — oxygen, carbon dioxide, moisture and microbes.
(6) Inadequate washing after a reaction leaves behind unreacted reagents.
(7) Chemical process can give side reactions, degradation products and polymerisation.
(8) Packaging materials such as plastic plasticisers and alkaline glass.
(9) Storage promotes hydrolysis, oxidation, photolysis and racemisation.
(10) Microbial contamination during manufacture or storage.

Types of Impurities:
A. Inorganic impurities: chloride (Cl⁻), sulphate (SO₄²⁻), iron (Fe), arsenic (As), lead (Pb) and other heavy metals (Hg, Bi, Sb, Cu), along with calcium and magnesium salts.
B. Organic impurities: unreacted starting materials, intermediates, degradation products and by-products.
C. Residual solvents: methanol, ethanol, benzene and toluene, classified by ICH Q3C into Classes 1 – 3.
D. Microbial impurities: bacteria, yeasts, moulds and pyrogens.
E. Particulate matter, especially important for parenteral products.

Effects of Impurities:
Impurities reduce the therapeutic potency of a drug and may introduce toxicity. They can cause physical changes in colour, odour and taste; chemical changes that affect stability; and toxic effects — for example, chronic toxicity from heavy metals such as lead, mercury and arsenic.

⚡ AT-A-GLANCE SUMMARY

Oldest printed: Florentine 1498; oldest in use: USP 1820; BP 1864; IP 1955.
Sources: raw materials, reagents, equipment, atmosphere, packaging, storage, microbes.
Types: inorganic, organic, residual solvents, microbial, particulate.
Effects: reduced potency, toxicity, altered appearance and reduced stability.

Explain the principle and procedure of limit tests for Cl⁻, SO₄²⁻, iron, arsenic, lead and heavy metals.

★★★★★

10MLong Essay

Detailed Answer:

✍️ OPENING LINE Limit tests are simple, semi-quantitative comparison tests carried out in matched Nessler cylinders 🔊 to ensure that a trace impurity in a drug substance does not exceed the pharmacopoeial limit. Each test produces a characteristic opalescence, colour or stain that is matched against a standard prepared with a known amount of the impurity.

1. Limit Test for Chloride (Cl⁻):
Principle: Chloride reacts with silver nitrate in dilute nitric acid to give a white curdy precipitate of silver chloride that appears as an opalescence.
Cl⁻ + AgNO₃ → AgCl↓ (white) + NO₃⁻ Procedure: Equal volumes of test and standard (prepared from NaCl to give the permitted Cl⁻ level) are placed in matched Nessler cylinders; 1 mL of dilute HNO₃ and 1 mL of AgNO₃ are added to each, mixed and kept for 5 minutes. The sample passes if its opalescence is not more than that of the standard.

2. Limit Test for Sulphate (SO₄²⁻):
Principle: Sulphate reacts with barium chloride in the presence of dilute HCl to give a fine white turbidity of barium sulphate. A small amount of potassium sulphate is added to seed uniform nucleation.
SO₄²⁻ + BaCl₂ → BaSO₄↓ (white) + 2 Cl⁻ Procedure: Test and standard (0.1087 g K₂SO₄/L) are placed in Nessler cylinders; 2 mL of ethanolic BaCl₂, 1 mL of dilute HCl and 0.15 mL of the K₂SO₄ reagent are added, mixed, and the turbidities are compared after 5 minutes against a dark background.

3. Limit Test for Iron (Fe):
Principle: In an ammoniacal medium (pH 9), Fe³⁺ combines with thioglycollic acid 🔊 to give a stable pink to violet complex. If ferrous ions are present, citric acid first oxidises them to ferric, and thioglycollic acid then reduces Fe³⁺ back to Fe²⁺ inside the complex.
2 Fe³⁺ + 2 HSCH₂COOH → [Fe(SCH₂COO)]²⁺ + 2 H⁺ Procedure: Sample is dissolved in water and mixed with iron-free citric acid, thioglycollic acid and dilute ammonia, and the colour is compared in a Nessler cylinder with a standard containing 20 µg of iron.

4. Limit Test for Arsenic (As) — Gutzeit Test:
Principle: In the Gutzeit test 🔊, arsenic compounds are reduced to arsine 🔊 gas by nascent hydrogen (Zn + dilute H₂SO₄), and the arsine gas then reacts with mercuric chloride paper to give a yellow-to-brown stain whose intensity depends on the amount of arsenic.
As³⁺ + 3 H → AsH₃↑; AsH₃ + 2 HgCl₂ → As(HgCl)₃ (yellow-brown) + HCl Apparatus: The Gutzeit apparatus is a wide-mouthed bottle fitted with a glass tube that holds a lead-acetate cotton plug (which absorbs any H₂S) and, at its upper end, a strip of mercuric chloride paper.
Procedure: Sample, KI, SnCl₂, zinc and dilute H₂SO₄ are placed in the bottle and the apparatus assembled quickly; reaction is allowed to proceed for 40 minutes at 40 °C, and the stain is compared with a standard stain obtained from 10 µg of arsenic.

5. Limit Test for Lead (Pb):
Principle: In an alkaline medium (pH 8.5 – 11.5), Pb²⁺ is extracted as the violet-red lead dithizonate complex into chloroform, using ammonium citrate as masking buffer and dithizone 🔊 as chelating reagent.
Procedure: The sample is dissolved, the pH is adjusted with ammonia, and KCN is added to mask Cu²⁺ and Zn²⁺; the solution is extracted with dithizone in chloroform, and the red colour of the organic layer is compared with that obtained from a standard lead solution.

6. Limit Test for Heavy Metals:
Principle: Heavy metals such as Hg, Bi, Sb, Pb, Cd, Ag and Cu react with H₂S (or thioacetamide) in an acidic or buffered medium to give coloured sulphides ranging from brown to black.
Procedure: The sample is dissolved, buffered to pH 3.5 with acetate buffer; H₂S gas is passed or thioacetamide reagent is added; the colour of the resulting sulphide is compared with that obtained from a standard lead solution.
The IP limit is usually expressed as 20 ppm of heavy metals calculated as lead.

⚡ AT-A-GLANCE SUMMARY

Chloride: AgNO₃ + dilute HNO₃ → white AgCl opalescence.
Sulphate: BaCl₂ + dilute HCl → BaSO₄ turbidity.
Iron: thioglycollic acid + ammonia → pink-violet complex (20 µg Fe standard).
Arsenic (Gutzeit): Zn + H₂SO₄ → AsH₃; HgCl₂ paper → yellow-brown stain (10 µg As standard).
Lead: dithizone in chloroform at pH 8.5 → violet-red complex.
Heavy metals: H₂S or thioacetamide → brown-to-black sulphide; IP limit 20 ppm as Pb.

Write a short note on modified limit tests for chloride and sulphate.

★★★★

5MShort Note

Detailed Answer:

✍️ OPENING LINE Some pharmaceutical substances — especially those that are intensely coloured, reducing or poorly soluble — interfere with the regular limit test. Modified limit tests are developed for such cases, usually by pre-treating the sample to remove the interfering property before applying the standard procedure.

Modified Limit Test for Chloride:
The modification is used when the sample itself would reduce AgNO₃ or is deeply coloured — for example, ferrous sulphate, iodides and sulphites.
Procedure: The sample is first boiled with dilute nitric acid, which destroys the reducing matter and removes colour; the mixture is then cooled and filtered, and the filtrate is treated in the usual way with AgNO₃ in dilute HNO₃.
Example: For the chloride limit test in ferrous sulphate, Fe²⁺ is first oxidised to Fe³⁺, otherwise Ag⁺ would be reduced to metallic silver and the opalescence would not represent the chloride content.

Modified Limit Test for Sulphate:
The modification is used when the sample contains barium salts, colouring agents or significant organic matter.
Procedure: The sample is first dissolved in dilute HCl (to prevent precipitation of carbonate or phosphate) and filtered if necessary. BaCl₂ is then added in the presence of a small quantity of K₂SO₄ reagent to initiate uniform nucleation of the BaSO₄ precipitate, so that the turbidity is reproducible regardless of the nature of the sample.
Example: For sulphate in alkaline pharmaceuticals, the solution is first acidified; and heavily coloured samples are decolourised with activated charcoal before comparison.

⚡ AT-A-GLANCE SUMMARY

Modified limit test: regular procedure with suitable sample pre-treatment to remove interference.
Chloride modification: oxidise any reducing matter with dilute HNO₃ (example — FeSO₄).
Sulphate modification: acidify with HCl and add K₂SO₄ reagent (for coloured or alkaline samples).

UNIT II

Acids, Bases, Buffers · Electrolytes · Dental Products (10 h)

Define a buffer solution. Derive the buffer equation. Explain buffer capacity and buffered isotonic solutions.

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10MLong Essay

Detailed Answer:

✍️ OPENING LINE A buffer is a solution that resists sudden changes in pH on the addition of a small amount of acid or base, and it is indispensable in pharmaceutical preparations to ensure drug stability, patient comfort and efficacy. A buffer is prepared by mixing a weak acid with its conjugate base (or a weak base with its conjugate acid) in a suitable proportion.

Components of a Buffer:
An acidic buffer consists of a weak acid together with its salt with a strong base; a typical example is acetic acid with sodium acetate.
A basic buffer consists of a weak base together with its salt with a strong acid; a typical example is ammonium hydroxide with ammonium chloride.

Derivation of the Buffer Equation (Henderson–Hasselbalch):
For a weak acid HA dissociating as HA ⇌ H⁺ + A⁻, the acid dissociation constant is K_a = [H⁺][A⁻] / [HA]. Rearranging gives [H⁺] = K_a × [HA] / [A⁻]. Taking the negative logarithm of both sides:
−log [H⁺] = −log K_a + log ([A⁻] / [HA]) which leads directly to the Henderson–Hasselbalch equation 🔊
pH = pK_a + log ([salt] / [acid]) (acidic buffer) For a basic buffer, the analogous equation is pOH = pK_b + log ([salt] / [base]), with pH obtained from pH = 14 − pOH.

Buffer Capacity (β):
Buffer capacity (symbol β, the Van Slyke 🔊 measure) is defined as the number of moles of strong acid or strong base required to produce a unit change in the pH of 1 L of buffer — that is, β = ΔB / ΔpH. Buffer capacity is maximum when pH = pK_a (at which point [salt] = [acid]), and the useful buffering range lies within pK_a ± 1. The capacity also increases with the total concentration of the buffer components.

Buffers in Pharmaceutical Systems:
Buffers maintain the pH required for drug stability and for physiological compatibility. Intravenous injections are buffered close to pH 7.4; eye drops are buffered to pH 7.4 (the pH of lacrimal fluid); nasal preparations to pH 6 – 7; oral syrups to pH 4 – 7; and topical products to pH 5 – 6.5 (matching skin). The common pharmaceutical buffers are phosphate, citrate, acetate, borate, Tris and bicarbonate.

Buffered Isotonic Solutions:
An isotonic solution exerts the same osmotic pressure as body fluids (approximately 310 mOsm/L). In pharmaceutics, the pH (buffered) and tonicity are adjusted simultaneously for parenteral and ophthalmic products. The main methods of assessing tonicity are the ΔT_f method (body fluid = −0.52 °C), the haemolytic method, the sodium chloride equivalent (E) method and the L_iso method. The most commonly used buffered isotonic preparation for ophthalmics is Sorensen's phosphate buffer 🔊, which covers pH 5 – 8.

💡 EASY FORMAT — Worked Example

Prepare an acetate buffer of pH 4.5 from 0.1 M acetic acid (pK_a = 4.76) and 0.1 M sodium acetate.
Using pH = pK_a + log ([salt]/[acid]): 4.5 = 4.76 + log(S/A), which gives log(S/A) = −0.26, and therefore S/A ≈ 0.55. The buffer is prepared by mixing the salt and acid in the ratio 1 : 1.82 approximately.

⚡ AT-A-GLANCE SUMMARY

Buffer: weak acid + conjugate salt (acidic) OR weak base + conjugate salt (basic).
Henderson–Hasselbalch equation: pH = pK_a + log ([salt] / [acid]).
Buffer capacity (β): maximum at pH = pK_a; useful range pK_a ± 1.
Common buffers: phosphate, acetate, citrate, borate, Tris, bicarbonate.
Buffered isotonic: Sorensen's phosphate buffer for ophthalmics (pH 5 – 8).
ΔT_f of body fluid = −0.52 °C.

Discuss the functions of the major extracellular and intracellular electrolytes 🔊. Describe the preparation and role of ORS.

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10MLong Essay

Detailed Answer:

✍️ OPENING LINE Electrolytes are ionic substances in body fluids that maintain osmotic pressure, acid-base balance, nerve conduction and muscle contraction. An imbalance — caused by vomiting, diarrhoea, sweating or diuretics — can be life-threatening and must be corrected by oral or intravenous replacement therapy such as ORS.

Major Electrolytes and Their Functions:
The principal electrolytes, their location, their plasma concentration and their main function are summarised below.

Ion	Location	Normal plasma value	Key function
Na⁺	Chief ECF cation	135 – 145 mEq/L	Osmotic pressure, fluid balance, nerve impulse conduction
K⁺	Chief ICF cation	3.5 – 5 mEq/L	Resting membrane potential, cardiac and skeletal muscle contraction
Ca²⁺	ECF (99 % in bone)	8.5 – 10.5 mg/dL	Muscle contraction, coagulation, neurotransmission, bone formation
Mg²⁺	ICF (second)	1.5 – 2.5 mEq/L	Cofactor for more than 300 enzymes, ATP stabilisation, muscle function
Cl⁻	Chief ECF anion	98 – 110 mEq/L	Fluid and acid-base balance, gastric HCl
HCO₃⁻	ECF	22 – 28 mEq/L	Main blood buffer; acid-base balance
HPO₄²⁻	ICF (main)	2.5 – 4.5 mg/dL	Intracellular buffer; ATP, DNA and RNA

Sodium Chloride (NaCl):
Preparation: sodium chloride is obtained from sea water or rock salt and purified by recrystallisation.
Assay: by Mohr's method 🔊 using 0.1 M AgNO₃ with potassium chromate indicator; the end-point is a red-brown colour of silver chromate.
Uses: 0.9 % w/v solution (normal saline) for intravenous infusion and wound irrigation; it is also a component of ORS and of Ringer's solution.

Calcium Gluconate:
Preparation: calcium carbonate is reacted with gluconic acid to give calcium gluconate.
Assay: by complexometric titration with EDTA at pH 12 using murexide as indicator, with a colour change from pink to violet.
Uses: in the treatment of hypocalcaemia, osteomalacia and allergic conditions.

Oral Rehydration Salt (ORS):
Purpose: to replace fluid and electrolytes lost in diarrhoea, vomiting or cholera. ORS works on the principle of sodium–glucose co-transport in the small intestine.
WHO Low-Osmolarity Formula (2002) per litre of clean water contains: sodium chloride 2.6 g, potassium chloride 1.5 g, trisodium citrate dihydrate 2.9 g and anhydrous dextrose 13.5 g, giving an osmolarity of about 245 mOsm/L.
Mechanism: glucose drives active absorption of Na⁺ across the intestinal villi through the SGLT-1 co-transporter, and water follows the absorbed sodium osmotically.
Use of sachet: the contents are mixed in 1 L of clean water and the reconstituted solution is consumed within 24 hours.

Physiological Acid-Base Balance:
Blood pH is maintained within the narrow range 7.35 – 7.45 by three integrated systems. Buffer systems — HCO₃⁻/H₂CO₃ (the main ECF buffer), HPO₄²⁻/H₂PO₄⁻ (ICF) and protein buffers such as haemoglobin in red blood cells — act within seconds. The respiratory system removes CO₂ through the lungs over minutes to hours. The renal system excretes H⁺ and reabsorbs HCO₃⁻ over hours to days.

⚡ AT-A-GLANCE SUMMARY

Na⁺: chief ECF cation (140 mEq/L) — fluid balance and nerve conduction.
K⁺: chief ICF cation — muscle and cardiac function.
Ca²⁺: 9 mg/dL — muscle, clotting and bone.
Cl⁻: 100 mEq/L — chief ECF anion; gastric HCl.
NaCl assay by Mohr's method (AgNO₃ + K₂CrO₄ → red-brown).
Calcium gluconate: EDTA complexometric titration at pH 12 with murexide.
ORS (WHO 2002): NaCl 2.6 g + KCl 1.5 g + Na citrate 2.9 g + glucose 13.5 g per litre.
ORS mechanism: SGLT-1 cotransports Na⁺ and glucose; water follows.

Write a note on dental products — dentifrices 🔊, the role of fluoride in dental caries 🔊, desensitising agents, calcium carbonate, sodium fluoride, and zinc eugenol cement.

★★★★

10MLong Essay

Detailed Answer:

✍️ OPENING LINE Dental products are pharmaceutical preparations designed for the hygiene and therapeutic care of teeth and oral tissues. They include toothpastes, mouthwashes, fluoride treatments, desensitising agents and dental cements, each of which addresses a specific oral problem.

Dentifrices:
Dentifrices are preparations used with a toothbrush to clean the teeth, and are available as powders, pastes, gels or liquids.
Their typical components are: (1) abrasives such as calcium carbonate, dicalcium phosphate, silica and sodium bicarbonate, which remove plaque; (2) humectants such as glycerol and sorbitol that prevent drying; (3) detergents or foaming agents, mainly SLS; (4) binders and thickeners such as CMC and carrageenan; (5) flavours and sweeteners such as peppermint oil and saccharin; (6) preservatives such as parabens; and (7) therapeutic agents such as fluoride (0.15 % w/w), triclosan and zinc citrate (antiplaque).

Role of Fluoride in Dental Caries:
Dental caries develops when acid produced by bacterial fermentation of dietary sugars demineralises the hydroxyapatite of tooth enamel.
The cariostatic action of fluoride is threefold. Firstly, fluoride replaces OH⁻ in hydroxyapatite to form the much more acid-resistant fluorapatite, Ca₁₀(PO₄)₆F₂. Secondly, it promotes remineralisation of early carious lesions. Thirdly, it inhibits bacterial enolase, reducing acid production in plaque.
Sources of fluoride include drinking water (optimal 0.7 – 1.2 ppm), toothpaste (NaF 0.32 %), mouth rinses, gels and varnishes.
Toxicity: above 2 ppm in drinking water produces dental fluorosis 🔊, and above 10 ppm produces skeletal fluorosis.

Desensitising Agents:
Desensitising agents block the exposed dentinal tubules and thereby reduce tooth sensitivity to hot, cold and sweet stimuli. Common agents include 10 % strontium chloride, 5 % potassium nitrate, stannous fluoride, calcium phosphate, oxalates and zinc chloride.

Calcium Carbonate (CaCO₃):
Preparation: calcium hydroxide reacts with carbon dioxide to give precipitated calcium carbonate, which is then purified.
Ca(OH)₂ + CO₂ → CaCO₃↓ + H₂O Uses: abrasive in dentifrices, antacid, calcium supplement and filler in ORS.

Sodium Fluoride (NaF):
Preparation: hydrofluoric acid reacts with sodium carbonate.
2 HF + Na₂CO₃ → 2 NaF + CO₂↑ + H₂O Assay: precipitation as lead chloro-fluoride.
Uses: 0.05 % rinse for daily caries prevention, 0.2 % weekly rinse, 2 % gel for professional application, and community water fluoridation. The lethal oral dose is greater than 5 g.

Zinc Eugenol Cement:
Zinc eugenol cement is used as a temporary dental filling, as a cavity liner and as a root-canal sealer.
Composition: zinc oxide powder mixed with eugenol 🔊 (4-allyl-2-methoxyphenol, from clove oil); on mixing, a zinc eugenolate cement is formed that hardens in 2 – 5 minutes.
Properties: sedative and analgesic action on the pulp, antimicrobial activity and easy removal. It cannot, however, be used beneath composite resin fillings because eugenol interferes with polymerisation.

⚡ AT-A-GLANCE SUMMARY

Dentifrice components: abrasive, humectant, detergent, binder, flavour, preservative, therapeutic (fluoride).
Fluoride action: hydroxyapatite → fluorapatite (acid-resistant); inhibits bacterial enolase.
Optimal water fluoride: 0.7 – 1.2 ppm; above 2 ppm produces dental fluorosis.
Desensitising agents: 10 % SrCl₂, 5 % KNO₃, stannous fluoride, calcium phosphate.
CaCO₃: dentifrice abrasive and antacid.
NaF: 0.05 % daily / 0.2 % weekly rinse; lethal dose > 5 g.
Zinc eugenol: ZnO + eugenol → ZnO-eugenolate; temporary filling and sealer; sedative and antimicrobial.

UNIT III

Gastrointestinal Agents (10 h)

Define antacids 🔊. List ideal properties and discuss the preparation, properties and uses of sodium bicarbonate, aluminium hydroxide gel and magnesium hydroxide mixture.

★★★★★

10MLong Essay

Detailed Answer:

✍️ OPENING LINE Antacids are basic inorganic compounds that neutralise excess gastric hydrochloric acid, raise the intragastric pH and thereby relieve the burning discomfort of dyspepsia 🔊, gastritis and peptic ulcer. An ideal antacid should act rapidly and for a prolonged period, should not cause systemic alkalosis, should not disturb electrolyte balance, and should not produce excessive CO₂ or cause constipation or diarrhoea.

Ideal Properties of an Antacid:
The antacid should have a rapid onset and a long duration of action. It should have a high acid-neutralising capacity and should not be absorbed systemically, so that metabolic alkalosis is avoided. It should produce no rebound hyperacidity, no CO₂ release (which would cause distension), and no effect on electrolyte or mineral balance. It should be palatable, economical, compatible with other drugs, and should not cause constipation or diarrhoea.

Combinations of Antacids:
A single antacid rarely meets all these criteria, so combinations are used to balance complementary effects. The combination of aluminium hydroxide (which causes constipation) with magnesium hydroxide (which causes diarrhoea) gives a balanced bowel effect; common examples are Gelusil, Digene and Mucaine. Simethicone 🔊 (antifoam) and alginate (raft-former) are often added.

1. Sodium Bicarbonate (NaHCO₃):
Preparation (Solvay process): brine is saturated with ammonia, then carbon dioxide is bubbled through to precipitate sodium bicarbonate.
NaCl + NH₃ + CO₂ + H₂O → NaHCO₃↓ + NH₄Cl Assay: by titration with 0.5 N H₂SO₄ using methyl orange indicator.
2 NaHCO₃ + H₂SO₄ → Na₂SO₄ + 2 CO₂↑ + 2 H₂O Reaction with gastric HCl:
NaHCO₃ + HCl → NaCl + H₂O + CO₂↑ Advantages: rapid and cheap.
Disadvantages: systemic absorption can produce metabolic alkalosis; liberated CO₂ causes gastric distension and belching; the sodium load is dangerous in hypertension and heart failure; it causes rebound acidity and, with heavy milk intake, the milk-alkali syndrome.
Uses: antacid, systemic alkaliser (for urinary alkalinisation), ingredient of effervescent formulations and dentifrices.

2. Aluminium Hydroxide Gel (Al(OH)₃):
Preparation: aluminium sulphate is treated with sodium carbonate (or NaOH) to precipitate aluminium hydroxide, which is washed, purified and dispersed as a gel.
Al₂(SO₄)₃ + 3 Na₂CO₃ + 3 H₂O → 2 Al(OH)₃↓ + 3 Na₂SO₄ + 3 CO₂↑ Assay: the gel is dissolved in HCl and the aluminium is titrated with EDTA (complexometric).
Reaction with gastric HCl:
Al(OH)₃ + 3 HCl → AlCl₃ + 3 H₂O Advantages: non-systemic, slow and prolonged action, no CO₂ release.
Disadvantages: causes constipation, binds phosphate in the gut leading to hypophosphataemia, and interferes with the absorption of tetracyclines and fluoroquinolones.
Uses: peptic ulcer, hyperphosphataemia in chronic kidney disease, and as a vaccine adjuvant.

3. Magnesium Hydroxide Mixture (Milk of Magnesia):
Preparation: magnesium sulphate is treated with sodium hydroxide to precipitate magnesium hydroxide, which is washed and suspended in water.
MgSO₄ + 2 NaOH → Mg(OH)₂↓ + Na₂SO₄ Assay: by back-titration of HCl used to dissolve the base.
Reaction with gastric HCl:
Mg(OH)₂ + 2 HCl → MgCl₂ + 2 H₂O Advantages: rapid onset with good neutralising capacity.
Disadvantages: causes diarrhoea and, in renal failure, hypermagnesaemia.
Uses: antacid, saline laxative (at larger doses), and topically for skin irritation.

⚡ AT-A-GLANCE SUMMARY

Ideal antacid: non-absorbed, rapid and long-acting, no CO₂, no electrolyte imbalance, palatable.
Combination: Al(OH)₃ (constipating) + Mg(OH)₂ (laxative) = balanced bowel effect.
NaHCO₃: prepared by Solvay process; rapid but causes alkalosis, CO₂ and sodium load.
Al(OH)₃: slow, non-systemic; causes constipation and binds phosphate.
Mg(OH)₂: rapid; laxative at larger doses; avoid in renal failure.
General reaction: antacid + HCl → salt + H₂O (with CO₂ only from NaHCO₃).

Write short notes on cathartics 🔊 — magnesium sulphate, sodium orthophosphate, kaolin and bentonite.

★★★★

5MShort Note

Detailed Answer:

✍️ OPENING LINE Cathartics, or laxatives, are agents that promote bowel evacuation. They are classified as osmotic (salts and sugars), stimulant (senna, bisacodyl), bulk-forming (psyllium, ispaghula), emollient (liquid paraffin) and lubricant. Inorganic cathartics are mostly osmotic or saline laxatives, which draw water into the intestinal lumen by osmosis.

1. Magnesium Sulphate (Epsom Salt, MgSO₄·7H₂O):
Preparation: from magnesite by the action of dilute H₂SO₄.
MgCO₃ + H₂SO₄ → MgSO₄ + H₂O + CO₂↑ The product is crystallised as the heptahydrate (Epsom salt).
Assay: by complexometric titration with EDTA at pH 10 using EBT as indicator.
Mechanism: osmotic — magnesium sulphate draws water into the intestinal lumen and also stimulates the release of CCK.
Uses: as a saline cathartic (5 – 15 g in warm water on an empty stomach, producing a purge in 1 – 2 hours); as an intravenous anticonvulsant in eclampsia 🔊; and as a topical soak for sprains and boils.

2. Sodium Orthophosphate (Na₂HPO₄, "Phosphate of Soda"):
Mechanism: osmotic saline laxative of mild strength.
Uses: 4 – 8 g orally for constipation; widely used for bowel preparation before colonoscopy or colorectal surgery; and as a mild source of phosphate in hypophosphataemia.
Caution: contraindicated in renal failure because of the risk of hyperphosphataemia and consequent hypocalcaemia.

3. Kaolin (Hydrated Aluminium Silicate):
Source: natural china clay; pharmacopoeial grades are available as light kaolin and heavy kaolin.
Mechanism: acts as an adsorbent and demulcent; it binds bacterial toxins, water and irritants. Contrary to its listing here among cathartics, kaolin is antidiarrhoeal rather than laxative, and is often combined with pectin (Kaopectate).
Uses: antidiarrhoeal (3 – 5 g orally), protective dusting powder, and ingredient of poultices.

4. Bentonite (Hydrated Aluminium Silicate Clay):
Source: natural volcanic ash composed mainly of montmorillonite.
Property: swells in water to 15 – 20 times its original volume, forming a thixotropic gel.
Uses: suspending and emulsifying agent; base for bentonite magma; component of poultices; binds aflatoxins and acts as an intestinal demulcent.

⚡ AT-A-GLANCE SUMMARY

MgSO₄: osmotic saline cathartic (5 – 15 g); IV in eclampsia; Epsom salt.
Na₂HPO₄: osmotic saline laxative; used for bowel preparation before colonoscopy.
Kaolin: adsorbent and demulcent → antidiarrhoeal (not a laxative); hydrated aluminium silicate.
Bentonite: swelling clay; suspending and emulsifying agent; base of bentonite magma.

Classify inorganic antimicrobials. Describe the preparation, properties and uses of potassium permanganate, boric acid, hydrogen peroxide, chlorinated lime and iodine.

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10MLong Essay

Detailed Answer:

✍️ OPENING LINE Inorganic antimicrobials are simple chemical agents used to kill or inhibit microorganisms on skin, wounds, mucous membranes and inanimate surfaces. They act by oxidation, halogenation, denaturation of microbial proteins or by heavy-metal poisoning of microbial enzymes.

Classification by Mechanism:
(1) Oxidising agents such as KMnO₄, H₂O₂ and chlorine-releasing compounds.
(2) Halogens — iodine and its preparations, chlorinated lime and sodium hypochlorite.
(3) Acids — boric acid.
(4) Heavy metals — silver nitrate, mercury compounds and zinc salts.
(5) Alcohols, phenols and quaternary ammonium compounds (organic, outside the scope of this inorganic syllabus).
(6) Dyes — gentian violet and acriflavine.

1. Potassium Permanganate (KMnO₄, Condy's Crystals):
Preparation: manganese dioxide is fused with KOH and KClO₃ to give potassium manganate, which is then oxidised by chlorine or electrolysis to potassium permanganate.
2 MnO₂ + 4 KOH + O₂ → 2 K₂MnO₄ + 2 H₂O
2 K₂MnO₄ + Cl₂ → 2 KMnO₄ + 2 KCl Properties: dark purple crystals; soluble in water, giving an intense purple colour.
Mechanism: in aqueous medium, permanganate is a strong oxidiser that liberates nascent oxygen and denatures microbial proteins.
MnO₄⁻ + 4 H⁺ + 3 e⁻ → MnO₂ + 2 H₂O Uses: disinfectant (1 : 4000 dilution for wounds, ulcers and eczema), deodoriser for tropical ulcers, topical application in snake bite, water purification, gargles (1 : 10 000) for throat infections, and analytical reagent.
Assay: against oxalic acid in dilute H₂SO₄ at 70 °C; the purple colour acts as its own (self-) indicator.

2. Boric Acid (H₃BO₃):
Preparation: borax is treated with HCl to yield boric acid.
Na₂B₄O₇·10H₂O + 2 HCl → 4 H₃BO₃ + 2 NaCl + 5 H₂O Properties: white pearly crystals; weakly acidic; mildly antiseptic.
Assay: titrated with 0.1 N NaOH in the presence of mannitol or glycerol (which converts the weak boric acid to the stronger mannitoboric acid) using phenolphthalein as indicator.
Uses: 3 – 4 % solution as an eye wash, mouthwash or ear drops; as a dusting powder; as a preservative in cosmetics and in honey; and in some spermicidal preparations.
Caution: absorption through broken skin can be toxic, especially in children.

3. Hydrogen Peroxide (H₂O₂):
Laboratory preparation: from barium peroxide and sulphuric acid; industrially, by the electrolytic or anthraquinone auto-oxidation process.
BaO₂ + H₂SO₄ → BaSO₄↓ + H₂O₂ Properties: clear colourless liquid; releases oxygen on contact with tissue catalase.
Commercial strengths: 3 % (10 volume), 6 %, 27 % (90 volume) and 30 % ("Perhydrol").
Mechanism: 2 H₂O₂ → 2 H₂O + O₂, catalysed by tissue catalase; the liberated oxygen is bactericidal (particularly against anaerobes), and the mechanical effervescence helps to clean wounds.
Assay: titration with 0.1 N KMnO₄ in dilute H₂SO₄.
5 H₂O₂ + 2 KMnO₄ + 3 H₂SO₄ → K₂SO₄ + 2 MnSO₄ + 8 H₂O + 5 O₂ Uses: antiseptic for wounds and ulcers (3 %), mouthwash (1.5 %), ear-wax removal, hair bleaching, surface disinfection and dental pulp bleaching.

4. Chlorinated Lime (Bleaching Powder, Ca(OCl)Cl):
Preparation: slaked lime is treated with chlorine gas.
Ca(OH)₂ + Cl₂ → Ca(OCl)Cl + H₂O Properties: white powder with a strong chlorine smell; unstable in air.
Mechanism: in the presence of moisture it releases nascent chlorine and hypochlorous acid, which are powerful oxidising and halogenating agents.
Assay: by iodometry — the sample reacts with KI to liberate iodine, which is then titrated with standard sodium thiosulphate.
Uses: water disinfection (1 – 2 ppm), sanitation of swimming pools, dairy and food industry sanitation, and bleaching of paper and cotton.

5. Iodine (I₂) and its Preparations:
Source: seaweeds and Chile saltpetre (NaIO₃).
Preparations:
Iodine Solution IP contains 2 % iodine and 2.4 % potassium iodide in water.
Iodine Tincture has the same composition in ethanol.
Strong Iodine Solution (Lugol's solution) 🔊 contains 5 % iodine and 10 % potassium iodide.
Povidone-iodine (PVP-I) is a complex of iodine with povidone that releases free iodine slowly and is less irritant to skin.
Mechanism: iodine halogenates microbial proteins and oxidises the thiol (–SH) groups of microbial enzymes.
Uses: pre-operative skin antiseptic, wound disinfection (povidone), prevention of iodine-deficiency goitre (iodised salt), mycotic skin infections, and thyroid pre-operative preparation (Lugol's solution, to reduce gland vascularity).
Assay: titrated with standard sodium thiosulphate (iodimetry) using starch as end-point indicator.

⚡ AT-A-GLANCE SUMMARY

KMnO₄: strong oxidiser; 1 : 4000 wound disinfectant; self-indicator in assay.
Boric acid: weak antiseptic 3 %; assayed with NaOH + mannitol.
H₂O₂: catalase liberates O₂; 3 % (10 vol) for wounds; assay with KMnO₄.
Chlorinated lime: Ca(OCl)Cl; releases Cl₂ and HOCl; used for water and pool disinfection.
Iodine: tincture, Lugol's, povidone-iodine; assayed with Na₂S₂O₃ using starch.

Write a short note on acidifiers — ammonium chloride and dilute hydrochloric acid.

★★★

5MShort Note

Detailed Answer:

✍️ OPENING LINE Acidifiers are chemicals administered to raise the hydrogen-ion concentration either in the stomach (gastric acidifier in achlorhydria 🔊) or in the systemic and urinary systems (systemic acidifier for correction of alkalosis, or urinary acidifier). The two classical inorganic acidifiers in pharmacy are ammonium chloride and dilute hydrochloric acid.

Ammonium Chloride (NH₄Cl):
Preparation: obtained as a by-product of the Solvay ammonia-soda process; it may also be made directly by reacting ammonia with hydrochloric acid.
NH₃ + HCl → NH₄Cl Assay: by the Kjeldahl method 🔊: the sample is treated with NaOH, the liberated NH₃ is distilled and absorbed in standard acid, and the excess acid is back-titrated.
Mechanism of acidification: in the liver, ammonium ion is converted to urea, with net release of H⁺.
2 NH₄⁺ + CO₂ → CO(NH₂)₂ + 2 H⁺ + H₂O Uses: expectorant (stimulates respiratory-tract secretion), systemic acidifier (correction of metabolic alkalosis), urinary acidifier (enhances renal excretion of basic drugs and activates methenamine therapy), and mild diuretic.
Dose: 0.3 – 1 g; as an expectorant 250 mg – 1 g.

Dilute Hydrochloric Acid IP:
Preparation: dilute 226 mL of concentrated HCl (approximately 11.7 N) to 1000 mL with water; this gives approximately 10 % w/w HCl (about 3 N).
Assay: titration with 1 N sodium carbonate (a primary standard) using methyl orange indicator.
Uses: gastric acidifier in achlorhydria (usually combined with pepsin), given diluted (one teaspoonful in water) with meals; also used as a laboratory reagent.
Caution: it corrodes tooth enamel, so it must be sipped through a straw.

⚡ AT-A-GLANCE SUMMARY

NH₄Cl: assayed by the Kjeldahl method; used as expectorant and as systemic or urinary acidifier.
NH₄Cl mechanism: hepatic conversion of NH₄⁺ to urea releases H⁺.
Dilute HCl: approximately 10 % w/w; assayed with Na₂CO₃ + methyl orange; used in achlorhydria (with pepsin); sip through a straw.

UNIT IV

Miscellaneous Compounds (8 h)

Describe haematinics 🔊. Discuss the preparation, assay and uses of ferrous sulphate and ferrous gluconate.

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10MLong Essay

Detailed Answer:

✍️ OPENING LINE Haematinics are preparations used to treat IDA, the most common anaemia worldwide, particularly in menstruating women, pregnant women and children. They replace iron and promote erythropoiesis 🔊. Oral ferrous salts, particularly ferrous sulphate, remain the first-line agents.

A Brief Note on Iron Metabolism:
Dietary Fe³⁺ is reduced to Fe²⁺ in the duodenum by gastric acid and the brush-border enzyme DcytB; the ferrous ion is absorbed through DMT-1. Inside the enterocyte it is oxidised back to Fe³⁺, bound to transferrin and carried to the bone marrow for haem synthesis or stored in liver and spleen as ferritin 🔊 and haemosiderin. The daily requirement is about 10 mg in men, 15 mg in women and 30 mg in pregnancy.

Ferrous Sulphate (FeSO₄·7H₂O, "Green Vitriol"):
Preparation: scrap iron is reacted with dilute sulphuric acid; the solution is filtered, evaporated and crystallised as the heptahydrate.
Fe + H₂SO₄ → FeSO₄ + H₂↑ Properties: pale bluish-green crystals that are efflorescent, being oxidised in moist air to yellow-brown ferric sulphate; soluble in water and insoluble in ethanol. It contains approximately 20 % elemental iron.
Assay: by cerimetry — Fe²⁺ is oxidised to Fe³⁺ with ceric ammonium sulphate using ferroin as indicator (colour change red to pale blue at end-point).
2 Fe²⁺ + 2 Ce⁴⁺ → 2 Fe³⁺ + 2 Ce³⁺ Each millilitre of 0.1 N cerium(IV) sulphate is equivalent to 27.80 mg of FeSO₄·7H₂O.
Uses: treatment of iron-deficiency anaemia; the usual oral dose is 200 mg three times a day, giving about 60 mg of elemental iron per dose.
Side effects: gastrointestinal irritation (nausea, black stools and constipation). Overdose causes acute iron poisoning, treated with the chelating agent deferoxamine 🔊.

Ferrous Gluconate:
Preparation: ferrous carbonate is treated with gluconic acid.
FeCO₃ + 2 C₆H₁₂O₇ → Fe(C₆H₁₁O₇)₂ + CO₂↑ + H₂O Properties: yellow-green powder containing approximately 12 % elemental iron; better tolerated than ferrous sulphate.
Uses: iron-deficiency anaemia; the usual oral dose is 300 – 600 mg three times a day, providing about 35 – 70 mg of elemental iron.
Advantages: less gastrointestinal irritation and better palatability than ferrous sulphate.

Preservation of Ferrous Salts:
Ferrous salts are readily oxidised in solution to the poorly absorbed ferric form. A reducing agent such as glucose or ascorbic acid is added to the formulation to maintain the iron in the ferrous state during storage.

⚡ AT-A-GLANCE SUMMARY

Haematinics: ferrous sulphate, ferrous gluconate, ferrous fumarate; parenteral — iron sucrose and iron dextran.
FeSO₄·7H₂O: "green vitriol"; about 20 % elemental iron; assayed by cerimetry using ferroin indicator.
Ferrous gluconate: about 12 % elemental iron; better gastrointestinal tolerance.
Daily requirement: 10 mg (male), 15 mg (female), 30 mg (pregnancy).
Side effects: gastrointestinal (black stools and constipation); acute overdose treated with deferoxamine.
Protection: glucose or ascorbic acid added to prevent oxidation of Fe²⁺ to Fe³⁺.

Discuss the role of antidotes 🔊 — sodium thiosulphate, activated charcoal and sodium nitrite.

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10MLong Essay

Detailed Answer:

✍️ OPENING LINE Antidotes are life-saving agents that neutralise the toxic effects of poisons by chemical reaction, by physical adsorption or by physiological antagonism. Three important inorganic antidotes are sodium thiosulphate (cyanide), activated charcoal (universal adsorbent) and sodium nitrite (cyanide).

Classification of Antidotes:
(1) Physical antidotes such as activated charcoal, tannic acid and egg white, which act by adsorption or precipitation.
(2) Chemical antidotes, which react chemically with the poison; examples are sodium thiosulphate (binds cyanide as thiocyanate) and deferoxamine (chelates iron).
(3) Physiological (functional) antidotes, which antagonise the biochemical action of the poison; examples are atropine for organophosphate poisoning and naloxone for opioid poisoning.

1. Sodium Thiosulphate (Na₂S₂O₃·5H₂O):
Preparation: sodium sulphite is boiled with sulphur in water, the solution is filtered and crystallised.
Na₂SO₃ + S → Na₂S₂O₃ Assay: by iodometry — the sample is titrated with standard iodine solution using starch as end-point indicator.
2 Na₂S₂O₃ + I₂ → Na₂S₄O₆ + 2 NaI Antidote mechanism in cyanide poisoning: sodium thiosulphate supplies sulphur, which the hepatic enzyme rhodanese 🔊 transfers to cyanide to form non-toxic thiocyanate, which is excreted in urine.
CN⁻ + S₂O₃²⁻ → SCN⁻ + SO₃²⁻ Dose: 12.5 g intravenously, given slowly together with sodium nitrite 300 mg IV.
Other uses: antidote in iodine, iodide and arsenic poisoning; topical treatment of tinea versicolor.

2. Activated Charcoal:
Preparation: obtained by carbonisation of wood or coconut shell followed by activation with steam at approximately 900 °C, which produces an enormous internal surface area of about 1000 m² per gram.
Mechanism: non-selective adsorption of ingested organic toxins, alkaloids, drugs and pesticides in the gastrointestinal tract, which prevents their systemic absorption.
Dose: 50 – 100 g of an aqueous suspension in adults or 1 g/kg in children, ideally 10 times the weight of the poison ingested.
Not effective against heavy metals (iron, lithium), alcohols, cyanide, mineral acids and alkalis, and petroleum products.
Other uses: flatulence and as a colloidal adsorbent in various formulations.

3. Sodium Nitrite (NaNO₂):
Preparation: sodium nitrate is reduced with hot lead to give sodium nitrite.
NaNO₃ + Pb → NaNO₂ + PbO Mechanism as cyanide antidote: sodium nitrite oxidises the Fe²⁺ of haemoglobin to Fe³⁺ to give methaemoglobin 🔊. Methaemoglobin has a high affinity for cyanide and forms cyanmethaemoglobin, which removes the cyanide from the essential enzyme cytochrome oxidase.
Dose: 300 mg intravenously, followed by 12.5 g of sodium thiosulphate intravenously.
Other uses: reagent in diazotisation titration and historically as a vasodilator.
Caution: excessive doses can produce dangerous methaemoglobinaemia.

Cyanide Antidote Kit (Lilly Kit):
The classical kit has three components: (1) amyl nitrite, given by inhalation as a first aid measure; (2) sodium nitrite 300 mg intravenously, to form methaemoglobin; and (3) sodium thiosulphate 12.5 g intravenously, to convert the cyanide to thiocyanate for excretion. The modern alternative is hydroxocobalamin (Cyanokit), which binds cyanide to form cyanocobalamin (vitamin B₁₂).

⚡ AT-A-GLANCE SUMMARY

Antidotes: physical (activated charcoal), chemical (Na₂S₂O₃), physiological (atropine, naloxone).
Na₂S₂O₃: CN⁻ + S₂O₃²⁻ → SCN⁻ (non-toxic) via rhodanese.
Activated charcoal: surface area ≈ 1000 m²/g; adsorbs organic toxins; dose 50 – 100 g; not effective against heavy metals, alcohols or cyanide.
NaNO₂: forms methaemoglobin, which binds CN⁻; 300 mg IV followed by Na₂S₂O₃ 12.5 g IV.
Modern cyanide antidote: hydroxocobalamin (Cyanokit).

Write short notes on emetics, expectorants 🔊 and astringents 🔊.

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5MShort Note

Detailed Answer:

✍️ OPENING LINE Emetics, expectorants and astringents are three minor but traditional classes of inorganic pharmaceuticals that address vomiting, cough and superficial tissue haemostasis respectively.

Emetics:
Emetics are agents that induce vomiting and were used historically to expel an ingested poison.
Copper sulphate (CuSO₄·5H₂O, "blue vitriol") was given at a dose of about 250 mg in water; it acts by local gastric irritation but has limited use now because of its own toxicity.
Sodium-potassium tartrate (tartar emetic, antimony potassium tartrate) was formerly used as both emetic and expectorant but is now obsolete.
Modern practice: routine use of emetics (such as ipecacuanha syrup or apomorphine) is no longer recommended; gastric lavage together with activated charcoal is preferred.

Expectorants:
Potassium iodide (KI) stimulates bronchial glands and liquefies thick sputum; the usual adult dose is 0.3 – 1 g three times a day.
Ammonium chloride (NH₄Cl) is a mild irritant to the gastric mucosa and produces reflex stimulation of bronchial secretion.
Both agents are used in productive cough and chronic bronchitis.

Astringents:
Zinc sulphate (ZnSO₄·7H₂O, "white vitriol") is used as 0.25 % eye drops (the zinc-boric acid collyrium) and as a mouthwash; it acts as an emetic at higher doses.
Potash alum (K₂SO₄·Al₂(SO₄)₃·24H₂O) is a classical styptic 🔊, applied to shaving cuts, and is also used as a mouthwash, douche and water-purifier (it flocculates suspended matter).
Both agents precipitate surface proteins, thereby reducing bleeding and secretion.

⚡ AT-A-GLANCE SUMMARY

Emetics: CuSO₄ (blue vitriol), tartar emetic — now rarely used.
Expectorants: KI, NH₄Cl — liquefy mucus and stimulate bronchial secretion.
Astringents: ZnSO₄ (white vitriol) and potash alum — precipitate surface proteins; styptic.

UNIT V

Radiopharmaceuticals (7 h)

Define radioactivity 🔊. Compare the properties of α, β and γ radiations. Discuss half-life and the measurement of radioactivity.

★★★★

10MLong Essay

Detailed Answer:

✍️ OPENING LINE Radioactivity is the spontaneous disintegration of unstable atomic nuclei with the emission of energetic particles (α and β) or electromagnetic radiation (γ). It was first described by Henri Becquerel 🔊 in 1896 and now underpins diagnostic imaging, therapy and research in modern pharmacy.

Properties of α, β and γ Radiations:
The three classical emissions differ markedly in nature, penetration and ionising power, as summarised in the table below.

Property	α (alpha)	β (beta)	γ (gamma)
Nature	Helium nucleus (2 p + 2 n)	Electron (β⁻) or positron (β⁺)	Electromagnetic photon
Charge	+2	−1 (β⁻) or +1 (β⁺)	0
Mass	≈ 4 amu	0.00055 amu	0
Speed	≈ 10 % of c	up to ≈ 99 % of c	c (speed of light)
Penetration	≈ 5 cm in air; stopped by paper	A few metres in air; stopped by Al foil	Metres of concrete; requires lead shielding
Ionising power	Strong	Moderate	Weak
Deflection in field	Small (+ve)	Large (−ve)	None
Example source	²³⁸U, ²²⁶Ra	³²P, ¹⁴C, ³H	⁶⁰Co, ¹³¹I, ⁹⁹ᵐTc

Half-Life (t_½):
The half-life of a radionuclide is the time required for its activity to decrease to half of the initial value. It is related to the initial activity and the decay constant (λ) by:
N = N₀ (½)^t/t½; λ = 0.693 / t_½ Typical pharmaceutical examples are ¹³¹I (t_½ = 8.02 days), ⁹⁹ᵐTc (t_½ = 6 hours), ¹⁴C (t_½ = 5730 years) and ²³⁸U (t_½ = 4.5 × 10⁹ years).

Measurement of Radioactivity:
Units:
The becquerel (Bq) is the SI unit, equal to one disintegration per second. The older curie (Ci) equals 3.7 × 10¹⁰ Bq (the activity of 1 g of radium). The rad (100 erg/g) and gray (Gy, 1 J/kg = 100 rad) measure absorbed dose. The roentgen (R) measures exposure in air, and the sievert (Sv) measures biologically effective dose.

Detection instruments:
(1) The Geiger–Müller counter 🔊 — a gas-filled ionisation detector for β and γ radiation.
(2) The scintillation counter — a NaI(Tl) crystal produces light flashes that are amplified by a photomultiplier tube; widely used for γ imaging.
(3) The ionisation chamber — a gas-filled detector used for quantitative measurement.
(4) The cloud or bubble chamber — visualises particle tracks.
(5) The film badge or thermoluminescent dosimeter (TLD) — used for personal exposure monitoring.

⚡ AT-A-GLANCE SUMMARY

α: helium nucleus; +2; stopped by paper; highly ionising; examples ²³⁸U, ²²⁶Ra.
β: electron; −1; stopped by aluminium foil; examples ³²P, ¹⁴C.
γ: electromagnetic photon; no charge; requires lead or concrete; examples ⁶⁰Co, ¹³¹I, ⁹⁹ᵐTc.
t_½ is constant for each nuclide: ¹³¹I = 8 d; ⁹⁹ᵐTc = 6 h.
Units: Bq (SI, 1 dps), Ci (3.7 × 10¹⁰ Bq), Gy (dose), Sv (biologically effective dose).
Detection: Geiger–Müller, scintillation, ionisation chamber, cloud chamber, film badge/TLD.

Write a note on radiopharmaceuticals 🔊 with particular reference to sodium iodide (¹³¹I) — storage, precautions and applications.

★★★★

5MShort Essay

Detailed Answer:

✍️ OPENING LINE Radiopharmaceuticals are pharmaceutical preparations labelled with radioactive isotopes that are administered for diagnostic imaging or targeted therapy. Because the thyroid gland avidly concentrates iodine, sodium iodide labelled with ¹³¹I is one of the most useful radiopharmaceuticals in clinical medicine.

Properties of Sodium Iodide (¹³¹I):
Iodine-131 has a half-life of 8.02 days and emits both β particles (606 keV, 90 %) and γ photons (364 keV, 81 %). It is available as an oral capsule, an oral solution or an intravenous injection and is produced either by neutron irradiation of ¹³⁰Te or as a fission product of uranium.

Applications:
Diagnostic use (low dose): thyroid function testing by measurement of RAIU, and thyroid scintigraphy to characterise nodules and goitre.
Therapeutic use (high dose): treatment of hyperthyroidism, especially Graves' disease and toxic multinodular goitre (the β particles destroy thyroid follicular cells), and ablation of residual thyroid tissue or metastases after thyroidectomy for thyroid cancer.
Typical doses: diagnostic 5 µCi; therapeutic 5 – 15 mCi for hyperthyroidism and 30 – 200 mCi for thyroid cancer.

Storage Conditions:
Sodium iodide ¹³¹I is stored in lead-shielded containers behind concrete walls in a licensed "hot lab" (in India, under AERB / DAE approval). Each container is labelled with the trefoil radiation symbol, the name, activity and calibration date. The preparation must be used within approximately 30 days because of the 8-day half-life.

Precautions:
All handling is carried out in accordance with the ALARA principle, using a lead apron, disposable gloves, tongs and remote handling tools. Personnel wear film badges or thermoluminescent dosimeters. Patients receiving therapeutic doses greater than 30 mCi are isolated, and they avoid contact with pregnant women and small children for 5 – 7 days. ¹³¹I is contraindicated in pregnancy (because it crosses the placenta and destroys the fetal thyroid) and in lactation. Radioactive waste is segregated and disposed of according to regulatory norms, and contamination is checked with a whole-body counter.

⚡ AT-A-GLANCE SUMMARY

¹³¹I: β + γ emitter; t_½ = 8 days; given as oral sodium iodide.
Diagnostic: RAIU test and thyroid scan (dose around 5 µCi).
Therapeutic: Graves' disease and toxic MNG (5 – 15 mCi); thyroid cancer (30 – 200 mCi).
Storage: lead-shielded hot lab with AERB approval; 30-day expiry.
Precautions: ALARA, shielding, dosimeter, patient isolation; contraindicated in pregnancy and lactation.

SYLLABUS COMPLETION

Less Important — But Must Read for Full Syllabus Coverage

Preparation, assay and uses of boric acid and potash alum.

★★★

5MShort Note

Detailed Answer:

✍️ OPENING LINE Boric acid and potash alum are two traditional inorganic pharmaceuticals. Boric acid serves as a mild antiseptic, while potash alum is a classical astringent and water-purifying agent.

Boric Acid (H₃BO₃):
Preparation: borax is treated with dilute hydrochloric acid to give boric acid, which is then purified by recrystallisation.
Na₂B₄O₇·10H₂O + 2 HCl → 4 H₃BO₃ + 2 NaCl + 5 H₂O Properties: white crystalline powder; slightly soluble in cold water but more soluble in hot water; a weak acid with pK_a about 9.2.
Assay: boric acid is too weak to titrate directly with NaOH; addition of mannitol or glycerol converts it to the much stronger mannitoboric acid, which is then titrated with 0.1 N NaOH using phenolphthalein indicator.
Uses: 3 % solution as eye wash, mouthwash or ear drops; dusting powder for skin; preservative in cosmetics and in honey.

Potash Alum (K₂SO₄·Al₂(SO₄)₃·24H₂O):
Preparation: equimolar solutions of potassium sulphate and aluminium sulphate are mixed in warm water, and potash alum crystallises on cooling as large octahedral crystals.
K₂SO₄ + Al₂(SO₄)₃ + 24 H₂O → K₂SO₄·Al₂(SO₄)₃·24H₂O Properties: colourless octahedral crystals with an astringent taste; freely soluble in water and insoluble in ethanol.
Uses: astringent, styptic (for shaving cuts), mouthwash, vaginal douche, water-purification coagulant and baking-powder ingredient.

⚡ AT-A-GLANCE SUMMARY

Boric acid: weak acid; assayed with NaOH after addition of mannitol; used as 3 % eye wash and as dusting powder.
Potash alum: double salt of K and Al sulphates with 24 H₂O; astringent, styptic and water purifier.

📚 BP104T INORGANIC CHEMISTRY EXAM STRATEGY

Always write the balanced chemical equation for preparation + assay + reaction with HCl. Examiners count the equation as 2–3 marks.
Copy the Opening Line verbatim as your first paragraph; then list + explain.
Memorise standard formulae: FeSO₄·7H₂O (278 g/mol, 20 % Fe); Al(OH)₃ (78), Mg(OH)₂ (58), NaHCO₃ (84), borax (381).
Memorise limit tests + reagents: Cl⁻ (AgNO₃/HNO₃), SO₄²⁻ (BaCl₂/HCl), Fe (thioglycollic/NH₃), As (Gutzeit/HgCl₂), Pb (dithizone), HM (H₂S).
ORS (WHO 2002): NaCl 2.6 + KCl 1.5 + Na citrate 2.9 + glucose 13.5 / L water — numbers matter.
Antacid combinations: always mention Al(OH)₃ + Mg(OH)₂ complementary effect.
Cyanide antidote: mention the 3-step kit (amyl nitrite → Na nitrite → Na thiosulphate) OR hydroxocobalamin.
Radioactivity: tabulate α / β / γ and remember units (Bq, Ci, Gy, Sv) and t₁/₂ of ¹³¹I (8 d), ⁹⁹ᵐTc (6 h).

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