19. IMMUNOLOGICAL PRODUCTS

IMMUNOLOGICAL PRODUCTS: A TEACHER’S COMPREHENSIVE GUIDE

Welcome, future pharmacists and healthcare professionals!

The WHO defined immunisation as “the process by which an individual is made immune or resistant to an infectious disease, typically by the administration of a vaccine.” Vaccines stimulate the immune system of the body to provide protection against the infection or disease for which vaccine has been administered. Immunological products are a group of pharmaceutical preparations of different compositions but a common pharmacological purpose.

Immunity is an individual’s ability to respond to foreign substances and microbes. Each immunological product serves to modify the immune system of the receiver, either to provide immunity against an infectious disease, or to view the current immune status (in vivo diagnostics) to check any previous exposure to the sensitising agent.

As a pharmacy educator with years of experience teaching immunology and pharmaceutical microbiology, I have observed that students often find immunological products challenging due to their complex preparation methods. Let me tell you: Immunological products are the cornerstone of preventive medicine—they have saved millions of lives through vaccination.

In this comprehensive guide, I will walk you through the fundamentals of immunological products—vaccines, toxoids, and sera. I will cover their classification, preparation methods, storage conditions, and applications. By the end of this article, you will have a thorough understanding of these essential biological products. Let us begin!

Dpharmguru’s exam insights:

Immunological products are frequently tested in pharmacy exams. Remember: Vaccines provide active immunity. Sera provide passive immunity. BCG vaccine is for tuberculosis. DTP vaccine contains Diphtheria, Tetanus, and Pertussis. Toxoids are inactivated toxins. Antisera provide immediate protection. Storage temperature for most vaccines is 2–8°C. These are classic exam questions!

5.5. IMMUNOLOGICAL PRODUCTS

Immunological products currently available include vaccines, in vivo diagnostics, immune sera, human immunoglobulins, monoclonal antibodies, and antibody-targeted therapeutics and diagnostics.

Classification of Immunological Products

• For Active Immunisation:
  • Bacterial Vaccines: BCG, Cholera, Pertussis, Typhoid
  • Viral and Rickettsial Vaccines: Smallpox, Yellow Fever, Measles, Poliomyelitis, Rabies, Typhus
  • Preparations Containing Toxoids: Diphtheria toxoid, Tetanus toxoid
• For Passive Immunisation:
  • Antitoxins: Diphtheria antitoxin, Tetanus antitoxin, Gas-gangrene antitoxin
  • Antiviral Serum: Rabies antiserum
  • Antibacterial Serum
  • Immune Blood Derivatives: Human normal immunoglobulin, Dried human normal immunoglobulin

Storage of Immunological Products

• Should be stored in a refrigerator but not allowed to freeze
• Temperature: 2–8°C
• Vaccines and immunoglobulins should be kept protected from light

Vaccines

A vaccine is a live attenuated (weakened) or killed microorganism or parts or products of them containing antigens which induce a specific immune response consisting of protective antibodies and T cell immunity.

Ideal properties of a vaccine: Effective, well-tolerated, easy and inexpensive to produce, easy to administer, and convenient to store.

Classification of Vaccines

• Inactivated-Killed Vaccines: Pathogen killed or inactivated using heat or chemicals; require booster doses
  • Bacterial: Typhoid, Cholera, Plague, Whooping cough
  • Viral: Rabies, Influenza, Hepatitis, Polio (IPV)
• Live Attenuated Vaccines: Non-virulent microorganism retaining antigenicity; provide lifelong immunity; not for immunocompromised patients
  • Bacterial: BCG
  • Viral: MMR, Polio (Sabin)
• Toxoids: Inactivated toxins retaining antigenicity; prepared by formalin treatment; e.g., Tetanus toxoid, Diphtheria toxoid

5.6. BACTERIAL VACCINES

5.6.1.1. Bacillus Calmette-Guerin (BCG) Vaccine

BCG vaccine provides immunisation against tuberculosis. It is prepared using live attenuated bovine tuberculosis bacillus strain of Mycobacterium bovis.

Preparation: Pure culture of attenuated Mycobacterium tuberculosis grown for 2 weeks on suitable media; suspended in liquid medium; dispensed in freeze-dried or liquid form.

Administration: Intradermal route at the point of insertion of deltoid muscle. Tuberculin skin test should be done before administration (except in neonates).

Storage: Freeze-dried; store in dark at 2–8°C; more stable at −20°C; protect from light.

5.6.1.2. Cholera Vaccine

Homogeneous suspension of strains of Vibrio cholerae (Inaba and Ogawa).

Preparation: Each strain grown individually on solid medium for 1–2 days; washed with normal saline; heated at 56°C for one hour or treated with phenol/formaldehyde.

Storage: 2–8°C; should not be frozen.

5.6.1.3. Pertussis Vaccine (Whooping Cough Vaccine)

Whooping cough is caused by Bordetella pertussis. Pertussis vaccine is a whole cell preparation obtained from killed Bordetella pertussis. It is the third constituent of the DTP-triple vaccine.

Preparation: B. pertussis isolated and cultured; suspended in NaCl injection with 0.01–0.02% thimerosal; stored for 3 months in refrigerator to reduce toxicity.

Storage: Concentrated preparation stored for 3 months in refrigerator.

5.6.1.4. Typhoid Vaccine

Mixture of suspension of killed Salmonella typhi and tetanus formol toxoid.

Preparation: Ty 2 strain of S. typhi used; grown on seed-lot system; harvested and inactivated.

Storage: Dried vaccine: below 25°C; Liquid vaccine: 2–10°C.

5.6.2. VIRAL VACCINES

5.6.2.1. Polio Vaccine

Polio is caused by poliovirus. Poliomyelitis Vaccine, Live (Oral) is an aqueous clear suspension of live, attenuated strains of poliomyelitis virus (types 1, 2, or 3).

Preparation: Based on seed-lot system; each virus type grown in cultures; tested for identity, bacterial sterility, and freedom from extraneous viruses; filtered through bacteria-retentive filter; neurovirulence test performed in monkeys.

Storage: Below −20°C until expiry; can be stored for six months at 5 ± 3°C.

5.6.2.2. Rabies Vaccine

Rabies vaccine is a fluid or freeze-dried preparation consisting of rabies virus (a neurotropic virus).

Preparation Methods:

• Method I (Seed-Lot System): Virus grown in cell cultures; tested for identity, bacterial sterility, and freedom from extraneous viruses; inactivated, purified, and concentrated; potency test at 37°C for 4 weeks
• Method II (Chick and Duck Embryos): Rabies virus strains grown in chick or duck embryos; inactivated by β-propiolactone
• Method III (Brains of Suckling Mice, Rats, Rabbits, Sheep): Animals infected intracerebrally; brains harvested and homogenised; inactivated using phenol, formalin, β-propiolactone, or UV-light

Storage: Freeze-dried rabies vaccine at 2–8°C; should not be frozen.

5.7. TOXOIDS

A toxoid is an inactivated toxin whose toxicity has been suppressed either by chemical or heat treatment but left capable of inducing the formation of antibodies. Examples: Tetanus toxoid, Diphtheria toxoid, Botulinum toxoid.

5.7.1. Tetanus Toxoid

Tetanus vaccine is a clear liquid (colourless or brownish-yellow) with characteristic odour of formaldehyde.

Preparation: Tetanus toxins produced by Clostridium tetani; treated with formaldehyde solution to form tetanus formol toxoid; adsorbed on aluminium phosphate or aluminium potassium sulphate (mineral adjuvant).

Storage: 2–8°C; should not be frozen.

5.7.2. General Preparation of Toxoids

• Formal Toxoid (FT): Selected strain of bacteria cultivated on liquid medium; incubated until satisfactory toxin produced; formaldehyde added; incubated at 37°C for 2–3 months
• Alum Precipitated Toxoid (APT): High quality formal toxoid treated with charcoal to remove colouring matter; alum added to form precipitate; toxoid adsorbed on precipitate; suspended in bactericide-containing saline
• Purified Toxoid Aluminium Phosphate (PTAT): Purer form; prepared using semi-synthetic medium; purified with magnesium hydroxide

5.8. SERA

Sera (singular – serum) are blood components which are neither a blood cell nor a clotting factor, but the blood plasma without fibrinogen. Antisera are blood serum containing antibodies and provide passive immunity to an individual against several diseases.

Examples of antisera: Botulinus antitoxin, Tetanus antitoxin, Diphtheria antitoxin, Anti-Snake Venom (ASV), Anti-Rabies immunoglobulin, Hepatitis B antiserum.

5.8.2. Diphtheria Antitoxin

Preparation: Formal toxoid prepared from toxins produced by Corynebacterium diphtheriae; mineral carrier (hydrated Al(OH)₃, AlPO₄, or Ca₃(PO₄)₂) added.

Variants:

• ADV for Adults and Adolescents: Not less than 2 units per dose (2.0 Lf per dose)
• Diphtheria Toxoid (DT): Corynebacterium diphtheriae treated with formaldehyde; sterile solution; no phenolic preservative
• Diphtheria Toxoid Adsorbed (DTA): Plain diphtheria toxoid in precipitated form or adsorbed phosphate

Storage: 2–8°C; should not be frozen; protect from light.

Properties of Diphtheria Toxin and Toxoid

Properties	Diphtheria Toxin	Diphtheria Toxoid
Toxicity	Highly toxic	No specific toxicity
Reactions	Causes inflamed area around injection site	Causes local reactions, especially in elderly subjects
Stability	Not quite stable	Quite stable at room temperature (2–8°C) for at least 2 years
Antibody Formation	Stimulates antibody formation when injected	Stimulates antibody formation when injected
Combination with Antitoxin	Positive	Positive

Dpharmguru’s exam insights:

Toxoids are frequently tested. Remember: Toxoids are inactivated toxins that retain antigenicity. Tetanus toxoid is prepared from Clostridium tetani. Diphtheria toxoid is prepared from Corynebacterium diphtheriae. Formal toxoid is treated with formaldehyde. APT and PTAT are purified forms. These are classic exam questions!

COMPARISON: ACTIVE VS PASSIVE IMMUNISATION

Feature	Active Immunisation	Passive Immunisation
Type of Immunity	Active	Passive
Products Used	Vaccines, Toxoids	Antisera, Immunoglobulins
Onset of Action	Slow (days to weeks)	Immediate
Duration of Protection	Long-lasting (years to lifetime)	Short-term (weeks to months)
Memory Response	Yes	No
Examples	BCG, Polio, Tetanus toxoid	ATS, Anti-Snake Venom

FREQUENTLY ASKED QUESTIONS (FAQs)

1. What is the difference between a vaccine and a toxoid?

A vaccine contains live attenuated or killed microorganisms that induce immunity. A toxoid is an inactivated toxin (from bacteria) that has lost its toxicity but retains antigenicity, e.g., tetanus toxoid.

2. What is the BCG vaccine used for?

BCG (Bacillus Calmette-Guerin) vaccine provides immunisation against tuberculosis. It is prepared using live attenuated Mycobacterium bovis.

3. What is the recommended storage temperature for immunological products?

Most immunological products should be stored at 2–8°C in a refrigerator. They should not be frozen and should be protected from light.

4. What is the difference between active and passive immunisation?

Active immunisation uses vaccines or toxoids to stimulate the body’s immune system to produce antibodies (long-lasting). Passive immunisation uses antisera or immunoglobulins containing pre-formed antibodies (immediate but short-term).

5. What is the DTP vaccine?

The DTP vaccine is a combination vaccine containing Diphtheria toxoid, Tetanus toxoid, and Pertussis (whole cell) vaccine. It provides protection against all three diseases.

6. What is an antiserum?

An antiserum is blood serum containing antibodies that provide passive immunity. Examples include Anti-Tetanus Serum (ATS), Anti-Snake Venom (ASV), and Rabies antiserum.

SUMMARY

Immunological products are essential biological products for preventing and treating infectious diseases. This guide covered:

• Vaccines: Live attenuated (BCG, MMR) and Inactivated-killed (Typhoid, Cholera, Rabies)
• Toxoids: Inactivated toxins (Tetanus, Diphtheria)
• Sera: Antisera containing antibodies for passive immunity (ATS, ASV)
• Storage: 2–8°C, protect from light, do not freeze
• BCG Vaccine: For tuberculosis; intradermal administration
• Polio Vaccine: Oral live attenuated vaccine (Sabin)
• DTP Vaccine: Combination of Diphtheria, Tetanus, and Pertussis

As I always tell my students: “Immunological products are the triumph of modern medicine—they have eradicated smallpox, nearly eliminated polio, and saved countless lives through vaccination.”

REFERENCES AND FURTHER READING

• Pharmacy Council of India (PCI). (2022). Pharmaceutics Syllabus. New Delhi: PCI.
• Indian Pharmacopoeia Commission (IPC). (2018). Indian Pharmacopoeia (8th ed.). Ghaziabad: IPC.
• World Health Organization (WHO). (2022). Immunization, Vaccines and Biologicals. Retrieved from https://www.who.int.
• Aulton, M. E., & Taylor, K. M. G. (2018). Aulton’s Pharmaceutics: The Design and Manufacture of Medicines (5th ed.). Elsevier.
• Kuby, J. (2019). Immunology (8th ed.). W.H. Freeman.
• Park, K. (2021). Park’s Textbook of Preventive and Social Medicine (26th ed.). Banarsidas Bhanot.

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.

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