1. Clinical Overview
A sterile suspension of adsorbed, purified diphtheria, tetanus, and pertussis toxoids for active immunization. It is a triple antigen vaccine that stimulates the immune system to produce protective antibodies against diphtheria, tetanus, and pertussis (whooping cough). It is a critical component of the Universal Immunization Programme (UIP) in India for primary immunization in infants and children.
| Onset | Duration | Bioavailability |
|---|---|---|
| Protective antibody levels typically develop 2-4 weeks after the completion of the primary series. | Protection from diphtheria and tetanus can last approximately 10 years, after which booster doses are recommended. Pertussis immunity wanes more rapidly, typically over 5-10 years. | Not applicable (N/A) for parenteral vaccines. Immunogenicity is the relevant measure. |
2. Mechanism of Action
Contains formaldehyde-inactivated toxins (toxoids) from Corynebacterium diphtheriae, Clostridium tetani, and Bordetella pertussis. Upon intramuscular administration, the adsorbed toxoids are taken up by antigen-presenting cells, processed, and presented to helper T-cells. This stimulates B-lymphocytes to proliferate and differentiate into memory B-cells and antibody-producing plasma cells. The produced neutralizing antibodies (IgG) provide protection against the respective diseases.
3. Indications & Uses
- Primary immunization of infants and children (typically starting at 6 weeks of age) against diphtheria, tetanus, and pertussis (whooping cough).
- As part of the National Immunization Schedule (NIS) of India: Three primary doses at 6, 10, and 14 weeks, followed by a first booster at 16-24 months (as DPT).
4. Dosage & Administration
Adult Dosage: NOT RECOMMENDED for adults. For adults and children ≥7 years, Tdap (reduced diphtheria and pertussis antigen) is used.
Administration: Shake the vial/vial or pre-filled syringe well before use. Administer by deep intramuscular injection, preferably in the anterolateral aspect of the mid-thigh in infants or the deltoid muscle in older children. Do not administer intravenously, intradermally, or subcutaneously. Use a separate, sterile syringe and needle for each patient.
5. Side Effects
Common side effects may include:
- Pain, redness, swelling, or induration at the injection site (very common, up to 50%).
- Mild fever (<39°C / 102.2°F).
- Fussiness, irritability, drowsiness.
- Loss of appetite.
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Immunosuppressants (e.g., high-dose corticosteroids, chemotherapy, biologics) | Diminished or suboptimal immune response to the vaccine. | Major |
| Other Live Vaccines (e.g., Oral Polio, MMR, Varicella) | No significant interaction. Can be administered simultaneously at different sites. If not given together, a 4-week interval is recommended for live vaccines. | Moderate |
| Anticoagulants (e.g., Warfarin) | Increased risk of bleeding or hematoma at injection site. Use fine needle and apply firm pressure. | Moderate |
7. Patient Counselling
- DO complete the full schedule of 3 primary doses and the booster for optimal protection.
- DO inform the doctor about any severe reaction to a previous vaccine dose or any neurological conditions.
- DO keep a record of the vaccination (Mother & Child Protection card).
- DONT give the vaccine if the child has a high fever or severe acute illness.
- DONT massage the injection site vigorously after administration.
8. Toxicology & Storage
Overdose: Overdose is unlikely due to fixed-dose presentation in single-use vials/syringes. Theoretical risk includes severe local reaction (pain, swelling), high fever, and exaggerated systemic side effects.
Storage: Store between +2°C to +8°C in a refrigerator. DO NOT FREEZE. Freezing destroys the vaccine potency. Protect from light. Use immediately after opening the vial. Do not use if the vaccine is frozen, discolored, or contains particulate matter. Transport in a cold chain.