Usage
This combination is used for active immunization against infection caused by all known subtypes of the Hepatitis B virus. Since Hepatitis D requires Hepatitis B infection to occur, vaccination against Hepatitis B is also preventative for Hepatitis D. Though sources mention thiomersal, one source states that current formulations may be thiomersal-free.
Pharmacological classification: Vaccine
Mechanism of Action: The hepatitis B vaccine introduces a purified, non-infectious surface antigen of the hepatitis B virus (HBsAg). This stimulates the body’s immune system to produce antibodies against HBsAg, providing immunity against future infection with the actual virus. Aluminium hydroxide acts as an adjuvant, enhancing the immune response to the vaccine. Thiomersal, where present, is used as a preservative to prevent bacterial or fungal contamination.
Alternate Names
Hepatitis B vaccine (rDNA) BP
Hepa-B
GeneVac-B
How It Works
Pharmacodynamics: The vaccine mimics a natural hepatitis B infection, triggering the body’s humoral immune response without causing the disease. This leads to the production of specific antibodies against the hepatitis B surface antigen, conferring immunity.
Pharmacokinetics: The vaccine is administered intramuscularly. The HBsAg is adsorbed onto aluminium hydroxide, creating a depot at the injection site that releases the antigen gradually. This sustained release prolongs antigen exposure, maximizing immune stimulation. The antigen itself is processed by antigen-presenting cells and presented to lymphocytes, triggering the adaptive immune response. The pharmacokinetics of thiomersal, a mercury-containing compound, are not relevant to the vaccine’s efficacy, but are important to consider regarding safety concerns in some populations. It can be metabolized to ethylmercury and excreted in the urine. Aluminium hydroxide is not readily absorbed and does not typically have systemic effects.
Mode of Action: The hepatitis B vaccine utilizes the humoral arm of the adaptive immune system. The HBsAg activates B cells, leading to the production of antigen-specific antibodies. These antibodies circulate and bind to HBsAg, neutralizing the actual hepatitis B virus upon subsequent exposure, preventing infection.
Receptor Binding, Enzyme Inhibition, or Neurotransmitter Modulation: The hepatitis B vaccine does not have any direct effect on receptors, enzymes, or neurotransmitters. Its action is entirely through the stimulation of the adaptive immune response.
Elimination Pathways: Aluminium hydroxide is minimally absorbed from the injection site. It is gradually eliminated through the reticuloendothelial system. As the body’s adaptive immune response is stimulated, it would create memory B cells that would trigger antibody creation if presented with the actual Hepatitis B virus.
Dosage
Standard Dosage
Adults:
- 20 mcg (1.0 mL) intramuscularly at 0, 1, and 6 months, or 0, 1, and 2 months (for rapid protection).
Children (Neonates, Infants, Children, and Adolescents up to 19 Years of Age):
- 10 mcg (0.5 mL) intramuscularly at 6, 10, and 14 weeks for infants or 0, 1, and 6 months.
Special Cases:
- Elderly Patients: Same as adult dosing. Immunogenicity may be reduced in this population.
- Patients with Renal Impairment: No dosage adjustment is typically necessary.
- Patients with Hepatic Dysfunction: No dosage adjustment is generally required. However, close monitoring of antibody response is recommended.
- Patients with Comorbid Conditions: Dosage adjustments may be needed based on the specific comorbidity.
Clinical Use Cases
The Hepatitis B vaccine is for prophylactic use, not for the treatment of acute conditions like those listed below. It is not typically given in settings like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations.
Dosage Adjustments
No specific dosage adjustments are typically needed for renal/hepatic dysfunction, metabolic disorders, or genetic polymorphisms.
Side Effects
Common Side Effects:
- Pain, swelling, and redness at the injection site
- Mild fever
- Headache
- Fatigue
Rare but Serious Side Effects:
- Allergic reactions (e.g., anaphylaxis)
- Guillain-Barré Syndrome (GBS) (extremely rare)
Long-Term Effects:
No long-term adverse effects associated with the hepatitis B vaccine have been identified.
Adverse Drug Reactions (ADR):
Anaphylaxis is a rare but serious ADR requiring immediate medical intervention.
Contraindications
- Severe allergic reaction to a previous dose of hepatitis B vaccine or any component of the vaccine (including yeast, thiomersal if present)
Drug Interactions
- Immunosuppressants may reduce the immune response to the vaccine.
- Concomitant administration with other vaccines is generally safe, although separate injection sites should be used.
Pregnancy and Breastfeeding
The hepatitis B vaccine is considered safe during pregnancy and breastfeeding. It is not known to pose a risk to the fetus or the nursing infant. However, the potential benefits of vaccination should outweigh the potential risks in each individual case.
Drug Profile Summary
- Mechanism of Action: Stimulates the immune system to produce antibodies against hepatitis B surface antigen.
- Side Effects: Injection site reactions, fever, headache, fatigue. Rarely, allergic reactions or GBS.
- Contraindications: Hypersensitivity to vaccine components.
- Drug Interactions: Immunosuppressants.
- Pregnancy & Breastfeeding: Generally safe.
- Dosage: Adults: 20 mcg at 0, 1, and 6 months (or 0, 1, and 2 months for rapid protection). Children: 10 mcg at 6, 10, and 14 weeks for infants or 0, 1, and 6 months.
- Monitoring Parameters: Antibody titers post-vaccination may be checked in certain populations to assess response.
Popular Combinations
The hepatitis B vaccine is often given in combination with other childhood vaccines, such as DTaP, IPV, Hib, and MMR.
Precautions
- Standard precautions for administering intramuscular injections should be followed.
- Patients should be observed for signs of allergic reactions after vaccination.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for the hepatitis B vaccine?
A: Adults: 20 mcg (1.0 mL) at 0, 1, and 6 months or 0, 1, and 2 months for rapid protection. Children: 10 mcg (0.5 mL) at 6, 10, and 14 weeks for infants or 0, 1, and 6 months.
Q2: Can pregnant or breastfeeding women receive the hepatitis B vaccine?
A: Yes, the vaccine is generally considered safe for both pregnant and breastfeeding women.
Q3: What are the common side effects of the hepatitis B vaccine?
A: Common side effects include pain, swelling, or redness at the injection site, mild fever, headache, and fatigue.
Q4: Are there any serious side effects associated with the hepatitis B vaccine?
A: Serious side effects are rare but can include allergic reactions (anaphylaxis) and, extremely rarely, Guillain-Barré syndrome.
Q5: What should I do if a patient experiences an allergic reaction after receiving the vaccine?
A: Immediate medical attention is required. Epinephrine should be administered according to standard protocols for anaphylaxis.
Q6: Can the hepatitis B vaccine be administered with other vaccines?
A: Yes, it can generally be given concurrently with other vaccines, but separate injection sites should be used.
Q7: How effective is the hepatitis B vaccine?
A: The hepatitis B vaccine is highly effective, providing protection against hepatitis B infection in over 90% of vaccinated individuals.
A: No, it only protects against hepatitis B. It does not protect against hepatitis A, C, or other hepatitis viruses.
Q9: Who should receive the hepatitis B vaccine?
A: Immunization is recommended for all infants and individuals at increased risk of exposure to hepatitis B, such as healthcare workers, people with multiple sexual partners, intravenous drug users, and household contacts of people infected with hepatitis B.
Q10: Does the Hepatitis B vaccine contain thiomersal?
A: Some formulations may contain thiomersal as a preservative, while others are thiomersal-free. It is best to consult the manufacturer’s information for the specific vaccine being administered.
