6. INORGANIC PHARMACEUTICALS

INORGANIC PHARMACEUTICALS: HAEMATINICS, GI AGENTS, ANTACIDS, TOPICAL AGENTS & MEDICINAL GASES: A TEACHER’S COMPREHENSIVE GUIDE

Welcome, future pharmaceutical scientists and healthcare professionals!

Inorganic pharmaceuticals play a vital role in modern medicine—from treating anaemia with iron supplements to relieving acidity with antacids, and from disinfecting wounds with antiseptics to saving lives with medicinal gases. As a pharmaceutical chemistry educator with years of experience teaching inorganic pharmaceutical chemistry, I have observed that students often struggle to remember the classifications, properties, and uses of these important compounds. Let me tell you: Inorganic pharmaceuticals are the foundation of many essential medicines.

In this comprehensive guide, I will walk you through the major classes of inorganic pharmaceuticals—haematinics, gastrointestinal agents, antacids, acidifying agents, protectives and adsorbents, cathartics, topical agents, dental products, and medicinal gases. I will explain their classifications, physical and chemical properties, uses, and storage requirements. By the end of this article, you will have a thorough understanding of these essential pharmaceutical compounds. Let us begin our journey!

Dpharmguru’s exam insights:

Inorganic pharmaceuticals are frequently tested in pharmacy exams. Remember: Haematinics treat anaemia, GI agents treat digestive disorders, antacids neutralize stomach acid, and topical agents prevent infections. Pay special attention to the classifications, properties, and uses of each compound—these are almost always asked in exams! Also, remember the ideal requirements of a good antacid—this is a classic exam question.

1. HAEMATINICS

Haematinics are medicines which increase the haemoglobin level in blood. They are mainly used to treat anaemia caused by iron deficiency. These medicines support the formation of blood and help the body maintain normal red blood cell production.

Classification of Haematinics

• Iron Preparations:
  • Oral Forms: Ferrous sulphate, Ferrous fumarate, Carbonyl iron, Ferrous ascorbate, Ferric ammonium citrate
  • Parenteral Forms (Injection): Iron dextran, Ferric carboxymaltose
• Maturation Factors:
  • Vitamin B12: Cyanocobalamin, Methylcobalamin
  • Folic Acid: Folinic acid (Leucovorin)
• Hematopoietic Growth Factor: Erythropoietin (EPO): Epoetin alpha, Epoetin beta

A. Ferrous Sulphate (Green Vitriol)

Ferrous sulphate contains not less than 98% ferrous ion (Fe²⁺) and not more than 103.3% FeSO₄·7H₂O.

Physical Properties:

• Pale bluish-green crystals or granules
• Odourless
• Salty and astringent (bitter) taste
• Soluble in water (43.5 g in 100 g at 15°C)
• Acidic (around pH 3.7)
• Oxidizes on exposure to air and forms brown patches due to efflorescence

Chemical Properties:

• On heating at 300°C it becomes white due to dehydration. Further heating produces SO₂, SO₃ and ferric oxide.
• It gets oxidised easily to ferric sulphate and hence acts as a strong reducing agent. It reduces KMnO₄, K₂Cr₂O₇, etc.
• With sodium carbonate, it evolves CO₂ gas.
• As a reducing agent, it decolourises KMnO₄ and reduces potassium dichromate to green colour compounds.

Uses:

• Most widely used oral haematinic for iron-deficiency anaemia
• Used as a mordant in dyeing and a constituent of blue-black ink
• Used in agriculture as an insecticide

Storage: Keep out of reach of children (common cause of fatal poisoning). Use child-resistant containers.

Market Brands: B-Protected, Pedia Iron, Fer-In-Sol, FeroSul, FerrouSul, Slow Fe

B. Ferrous Fumarate

Physical Properties:

• Reddish-brown powder
• Odourless
• Hardly soluble in water and slightly soluble in alcohol
• Basic salt

Uses:

• Used to treat pernicious anaemia
• Used in iron-deficiency anaemia
• Preferred when patients cannot tolerate other forms of iron

Market Brands: Hemocyte, PureFe Plus, Slow-Fe

C. Ferric Ammonium Citrate

It is a complex salt which contains 20.5–22.5% of iron.

Properties:

• Bright brownish-red scales
• Soluble in water, insoluble in alcohol
• Deliquescent (absorbs moisture)
• Slightly astringent taste

Uses:

• Used as a haematinic
• Effective iron supplement, less constipating and less irritant than other iron salts

Market Brands: Deriton, Geritol Liquid

D. Ferrous Ascorbate

Ferrous ascorbate is an iron supplement used in the treatment of low iron levels. Ascorbic acid increases the absorption of iron from the stomach.

Uses:

• Iron deficiency anaemia
• Anaemia due to chronic kidney disease

Market Brands: Ascofer Cap, Iron Ascorbate Caps, Solufer Syrup

E. Carbonyl Iron

Carbonyl iron is elemental iron prepared in very fine particles. It gets absorbed slowly and safely.

Uses:

• Dietary iron supplement
• Treatment of iron-deficiency anaemia

Market Brands: Feosol, IcarC, Icar Pediatric, Irco

Dpharmguru’s exam insights:

Haematinics are frequently tested. Remember: Ferrous sulphate is the most widely used oral haematinic. Ferrous fumarate is preferred when patients cannot tolerate other forms. Ferric ammonium citrate is less constipating. Carbonyl iron is absorbed slowly and safely. A common exam question is: “Which iron preparation is preferred for patients who cannot tolerate other forms?” (Answer: Ferrous fumarate).

2. GASTROINTESTINAL AGENTS

Gastrointestinal (GI) agents are medicines used to treat disorders of the stomach and intestines. When normal digestion is disturbed, many problems can occur, such as acidity, constipation, diarrhoea, and reduced secretion of gastric acid.

Common GI Disorders

• Achlorhydria / Hypochlorhydria: Very low or no hydrochloric acid secretion in the stomach
• Hyperacidity: Excess gastric acid secretion leading to irritation, inflammation, pain, and ulcer formation
• Diarrhoea: Rapid movement of intestinal contents due to toxins, gases, infection, or poor absorption
• Constipation: Very slow movement of the intestine causing difficulty in passing stools

Classification of GI Agents

3. ANTACIDS

Antacids are substances used to neutralise the excess amount of acid in our stomach. They may cause many severe problems like pain, ulceration, and also inactivate pepsin (proteolytic enzyme).

The stomach pH can range from pH 1 when empty to pH 7 when food is present. The low pH is due to the presence of endogenous hydrochloric acid, which is always present under physiological conditions.

Ideal Requirements of a Good Antacid

• Should not be absorbed systemically (to avoid alkalosis)
• Should not cause constipation
• Should act rapidly and last longer
• Should maintain stomach pH between 4–6
• Should not release excess gas (CO₂) when reacting with acid
• Should suppress pepsin activity
• Should not interfere with digestion and absorption of food
• Should be cheap and palatable

Classification of Antacids

• Systemic (Absorbable Antacids): Example: Sodium bicarbonate. These are rapidly absorbed and may cause systemic alkalosis.
• Non-Systemic (Non-absorbable Antacids): Examples: Aluminium hydroxide, Magnesium hydroxide, Calcium carbonate, Magaldrate. These are not absorbed and act locally without systemic effects.

Comparison of Antacids

4. ACIDIFYING AGENTS

Acidifying agents are drugs that increase the acidity (lower the pH) in the body or specific organs such as the stomach or urinary tract. They are used in conditions where lack of acid leads to digestive or metabolic problems.

Classification of Acidifying Agents

• Gastric Acidifiers: Used in achlorhydria or hypochlorhydria to restore stomach acidity temporarily
• Urinary Acidifiers: Used to acidify urine for treatment of urinary tract disorders and to prevent bacterial growth in urine
• Systemic Acidifiers: Used to control systemic alkalosis by neutralizing excess base in the blood
• Acids (Pharmaceutical Aids): Used in formulations, laboratory tests, and as pH modifiers

Dilute Hydrochloric Acid (Dil. HCl)

Used to treat achlorhydria (absence of gastric acid) and hypochlorhydria (low gastric acid). It helps in digestion by providing the acidic environment needed for pepsin activity.

5. PROTECTIVES AND ADSORBENTS

Protectives and adsorbents are used to treat mild diarrhoea. They coat intestinal mucosa and adsorb toxins, bacteria, and unwanted chemicals from the digestive tract.

Key Features:

• Have strong adsorptive capacity to trap toxins and microorganisms
• Act by reducing peristalsis and providing a protective coating over mucosa
• Helpful in mild diarrhoea, dysentery, and poisoning cases

Examples: Bismuth subcarbonate, Kaolin

6. CATHARTICS

Cathartics or purgatives are drugs that increase bowel evacuation. Mild cathartics (safe for short-term) are called laxatives.

Types of Laxatives

Examples:

• Sodium Potassium Tartrate (Rochelle Salt): Used as a saline cathartic
• Magnesium Sulphate (Epsom Salt): Used as a saline cathartic; draws water into the intestine

7. TOPICAL AGENTS

Topical agents are substances applied directly to skin or mucous membranes to kill, prevent growth, or reduce the number of microorganisms (bacteria, fungi, viruses, protozoa). They are widely used in hospitals, dental clinics, wound care, household hygiene, and cosmetic formulations.

Classification of Topical Agents

A. Silver Nitrate (AgNO₃)

Also known as lunar caustic, it contains 99.5%–100.5% of AgNO₃.

Physical Properties:

• Colourless or white crystals
• Turns grey/black on exposure to light (due to reaction with organic matter)
• Odourless, bitter metallic taste
• Soluble in water and hot alcohol

Uses:

• Antiseptic and astringent
• Used in ophthalmia prophylaxis in newborns
• Used to remove warts and skin growths
• Used in wound healing

Storage: Store in amber-coloured bottles in a cool, dark place.

B. Chlorhexidine Gluconate

A widely used antiseptic since 1950.

Uses:

• Dental disinfectant and plaque control
• Used in surgical hand scrubs
• Used in dairy industry sanitation
• Used in wound cleansing solutions

C. Hydrogen Peroxide (H₂O₂)

Contains not less than 6% w/w of H₂O₂.

Physical Properties:

• Colourless, odourless liquid
• Slightly acidic taste
• Density = 1.463 g/cm³
• Melting point: –0.43°C; Boiling point: 150.2°C

Uses:

• Antiseptic and deodorant
• Used to clean wounds, root canals, dental sockets
• Used in 1.5% solution as mouthwash
• Used as ear drops to remove wax
• Strong bleaching and oxidizing agent

D. Boric Acid (H₃BO₃)

Contains 99.5%–100.5% of H₃BO₃.

Physical Properties:

• Colourless, odourless powder
• Soapy feel, pearly scales
• Soluble in hot water, alcohol, glycerine

Uses:

• Eye and mouth wash (2.5–4.5%)
• Used in diaper rash ointments
• Dusting powder
• Antiseptic, astringent, fungistatic

E. Bleaching Powder (Chlorinated Lime / Calcium Hypochlorite)

Bleaching powder is chemically known as calcium oxychloride. It contains not less than 30% available chlorine.

Formula: CaOCl₂·H₂O

Physical Properties:

• Dull white powder, characteristic chlorine-like odour
• Absorbs moisture from the air and slowly decomposes
• Partially soluble in water and alcohol

Uses:

• Power disinfectant and bleaching agent
• Used to disinfect drinking water supplies
• Used to clean infected floors, drainage, beds, and dressing rooms in hospitals

F. Potassium Permanganate (KMnO₄)

Also known as Condy’s crystals, it is the inorganic, water-soluble chemical compound consisting of equal moles of potassium (K⁺) and permanganate (MnO₄⁻) ions.

Physical Properties:

• Dark purple crystals, metallic lustre
• Odourless
• Soluble in 15 parts of cold water, 3.5 parts hot water
• Astringent taste
• Solutions are deep purple in colour

Uses:

• Local antiseptic and disinfectant
• Used for mouthwashes, urethritis treatment, wet dressings in ulcers, abscesses, dermatitis, eczema
• Deodorant due to oxidation of foul-smelling substances
• Kills bacteria by protein oxidation

Storage: Store in tightly closed containers. Avoid contact with organic materials (risk of explosion).

8. DENTAL PRODUCTS

Dental products include inorganic compounds used to maintain oral hygiene, prevent dental diseases, clean prosthetic appliances, and relieve dental sensitivity.

Inorganic Compounds Used in Dentistry

• Cleaning agents
• Dentifrices (tooth-cleaning products)
• Anti-caries agents (fluorides)
• Desensitising agents
• Cements and fillers
• Oral antiseptics and astringents
• Polishing/Abrasive agents

Dentifrices

A dentifrice is a substance used with a toothbrush to clean teeth surfaces. They help remove plaque, stains, food particles, and prevent dental problems.

Anti-Caries Agents / Fluorides

Dental caries occurs when bacteria convert sugars to acids, leading to demineralization (loss of enamel). Fluorides prevent dental decay by:

• Increasing enamel resistance to acids
• Promoting enamel remineralization
• Reducing bacterial activity

Examples: Sodium fluoride, Sodium metaphosphate, Stannous fluoride, Zinc chloride.

Sodium Fluoride (NaF)

Physical Properties: White, odourless solid. Melting point: 993°C.

Uses:

• Prevents dental caries
• Strengthens enamel
• Works as insecticide (roaches, ants)
• Used for drinking water fluoridation

9. MEDICINAL GASES

Medicinal gases are pharmaceutical-grade gases used for therapy, diagnosis, anesthesia, and life support in hospitals. They are stored in compressed cylinders, labelled with specific colours for safety.

A. Oxygen (O₂)

Oxygen is a life-saving medicinal gas used to maintain normal oxygen levels in tissues. Medical oxygen contains not less than 99% v/v of O₂.

Physical Properties: Colourless, odourless, tasteless gas. Supports combustion.

Uses:

• Treats hypoxia (low oxygen level in blood)
• Used during anaesthesia
• Treatment of asthma, respiratory failure
• Used in carbon monoxide poisoning
• Diluent for anaesthetic gases

Storage: Stored in metal cylinders under pressure. Shoulder colour: White (international code); rest of cylinder black. Name “OXYGEN” clearly painted.

B. Carbon Dioxide (CO₂)

Medical CO₂ contains not less than 99% w/w of CO₂.

Physical Properties: Colourless, odourless gas. Slight acidic taste. Does NOT support combustion.

Uses:

• Respiratory stimulant when inhaled in low concentration
• 5–7% CO₂ with Oxygen used in carbon monoxide poisoning and to stimulate breathing reflex
• Used in cryotherapy, skin lesion removal
• Used in endoscopy and surgical insufflation

Storage: Stored in metallic cylinders under pressure. Shoulder colour: Grey. Name “CO₂” stencilled.

C. Nitrous Oxide (N₂O)

Also called laughing gas, contains not less than 99% v/v of N₂O.

Physical Properties: Colourless, slightly sweet-smelling gas. Non-flammable but supports burning.

Uses:

• As an inhalation anaesthetic
• Analgesic (pain relief) during childbirth (50:50 mixture with O₂), dental procedures, myocardial infarction
• In higher concentrations, produces euphoric “laughing” effect

Storage: Stored in compressed metallic cylinders. Shoulder colour: Blue. Name “N₂O” clearly printed.

COMPARISON: MEDICINAL GASES

Dpharmguru’s exam insights:

Medicinal gases are frequently tested. Remember: Oxygen is life-saving, CO₂ is a respiratory stimulant, and N₂O is an anaesthetic. Also, remember the cylinder colour codes—White for Oxygen, Grey for CO₂, and Blue for N₂O. These are classic exam questions!

FREQUENTLY ASKED QUESTIONS (FAQs)

1. What is the difference between an antiseptic and a disinfectant?

Antiseptics are applied to living tissues (skin, wounds) to prevent microbial growth. Disinfectants are applied to non-living objects (instruments, floors) to destroy pathogenic organisms.

2. Why is ferrous sulphate the most widely used oral haematinic?

Ferrous sulphate is the most widely used oral haematinic because it is cheap, effective, and well-absorbed. It provides the necessary iron for haemoglobin synthesis in iron-deficiency anaemia.

3. What is the ideal pH range for antacid action?

A good antacid should maintain stomach pH between 4 and 6. This range is sufficient to neutralize excess acid without causing alkalosis.

4. What is the difference between systemic and non-systemic antacids?

Systemic antacids (e.g., Sodium bicarbonate) are absorbed into the bloodstream and may cause alkalosis. Non-systemic antacids (e.g., Aluminium hydroxide) are not absorbed and act locally in the stomach.

5. Why is potassium permanganate stored away from organic materials?

Potassium permanganate is a strong oxidizing agent. It reacts violently with organic materials and may cause explosions. It must be stored in tightly closed containers away from organic substances.

6. What are the cylinder colour codes for medicinal gases?

Oxygen (O₂) = White shoulder, Carbon Dioxide (CO₂) = Grey shoulder, Nitrous Oxide (N₂O) = Blue shoulder. These codes ensure safe identification in hospitals.

SUMMARY

Inorganic pharmaceuticals play a vital role in healthcare. This guide covered the major classes:

• Haematinics (Ferrous sulphate, Ferrous fumarate, Ferric ammonium citrate, Ferrous ascorbate, Carbonyl iron) treat anaemia
• Gastrointestinal agents treat digestive disorders—antacids neutralize acid, acidifying agents restore acid, protectives adsorb toxins, and cathartics relieve constipation
• Topical agents (Silver nitrate, Chlorhexidine, Hydrogen peroxide, Boric acid, Bleaching powder, Potassium permanganate) prevent infections in wounds and skin
• Dental products maintain oral hygiene and prevent caries
• Medicinal gases (Oxygen, Carbon dioxide, Nitrous oxide) are essential for life support, anaesthesia, and therapy

As I always tell my students: “Understanding inorganic pharmaceuticals is essential for prescribing, dispensing, and manufacturing safe and effective medicines.”

REFERENCES AND FURTHER READING

• Pharmacy Council of India (PCI). (2022). Pharmaceutical Chemistry Syllabus. New Delhi: PCI.
• Chatwal, G. R. (2019). Pharmaceutical Chemistry: Inorganic (5th ed.). Himalaya Publishing House.
• Wilson, C. O., & Gisvold, O. (2020). Wilson and Gisvold’s Textbook of Organic Medicinal and Pharmaceutical Chemistry (12th ed.). Wolters Kluwer.
• Indian Pharmacopoeia Commission. (2022). Indian Pharmacopoeia (IP). Ghaziabad: IPC.
• World Health Organization (WHO). (2022). Model List of Essential Medicines. Retrieved from https://www.who.int.

Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult qualified healthcare professionals for medical concerns. Pharmaceutical regulations and guidelines may vary by region—always refer to your local regulatory authorities for specific requirements.

written by:
Dr. N. Sujith Kumar

Dr. N. Sujith Kumar is a pharmacy educator, Pharm.D graduate, and academic content creator from Jawaharlal Nehru Technological University Kakinada (JNTUK), where he completed his Doctor of Pharmacy (Pharm.D) degree between 2015 and 2021. He has more than 7 years of experience creating pharmacy educational content, writing study materials, and reviewing academic articles for pharmacy students. He has also contributed guest articles to pharmacy education platforms, including PharmD Guru. At D.PharmGuru, his work focuses on simplifying complex Diploma in Pharmacy (D.Pharmacy) subjects into easy-to-understand notes, practical explanations, and exam-oriented educational resources for students across India. His areas of focus include Human Anatomy and Physiology, Pharmaceutics, Pharmacology, Pharmaceutical Chemistry, Hospital and Clinical Pharmacy, and other core D.Pharmacy subjects.

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