Usage
Human Hepatitis B Immunoglobulin (HBIG) is a sterile solution of antibodies specific to the hepatitis B virus surface antigen (HBsAg). It is used for post-exposure prophylaxis to prevent hepatitis B infection after exposure to the virus and also for pre-exposure prophylaxis in specific populations. It is also used to prevent recurrence of Hepatitis B in liver transplant patients. It falls under the pharmacological classification of immunoglobulin, specifically an immune serum.
HBIG works by providing passive immunity. The antibodies in HBIG bind to HBsAg, neutralizing the virus and preventing it from infecting liver cells. This passive immunity is temporary, providing immediate but short-term protection.
Alternate Names
HBIG is also known as Hepatitis B Immune Globulin (Human). Brand names include:
- HyperHEP B® S/D
- HepaGam B®
- Nabi-HB®
- Hepatitis B Immunoglobulin-VF
- ImmunoGam
How It Works
Pharmacodynamics: HBIG provides passive immunity by delivering pre-formed antibodies against HBsAg. These antibodies neutralize the hepatitis B virus, preventing infection of hepatocytes.
Pharmacokinetics:
- Absorption: When administered intramuscularly (IM), HBIG is absorbed into the systemic circulation. Intravenous (IV) administration achieves immediate systemic levels.
- Distribution: HBIG distributes throughout the extracellular fluid compartment.
- Metabolism: As a protein, HBIG is broken down into amino acids, mainly by the reticuloendothelial system.
- Elimination: The elimination half-life of HBIG is variable, ranging from several weeks to months. It is not cleared via CYP enzymes.
Mode of Action: HBIG binds directly to HBsAg, the major surface antigen of HBV. This binding neutralizes the virus, thereby preventing attachment and entry into liver cells. This prevents the establishment of infection. There is no receptor binding, enzyme inhibition, or neurotransmitter modulation involved.
Dosage
Standard Dosage
Adults:
- Post-exposure Prophylaxis: 0.06 mL/kg (or 5 mL for adults), IM, as soon as possible after exposure (ideally within 24 hours, and up to 7 days). In some cases a second dose is recommended one month later.
- Pre-exposure Prophylaxis (e.g. immunocompromised individuals at risk): 500 IU every 2 months.
Children:
- Post-exposure Prophylaxis: 0.06 mL/kg IM, following the same timing guidelines as adults. Specific pediatric dosages can range from 200 IU to 300 IU based on age.
- Pre-exposure Prophylaxis: 8 IU/kg, with a maximum of 500 IU every 2 months.
- Neonates born to HBsAg-positive mothers: 100 IU IM, preferably within 12 hours of birth, but no later than 48 hours.
Special Cases:
- Elderly Patients: No specific dosage adjustments are generally required. However, monitor for potential underlying conditions.
- Patients with Renal Impairment: No specific dosage adjustments are typically necessary.
- Patients with Hepatic Dysfunction: No specific dosage adjustments are typically necessary.
- Patients with Comorbid Conditions: Evaluate on a case-by-case basis.
Clinical Use Cases
HBIG is not typically administered in clinical settings such as intubation, surgical procedures, mechanical ventilation, or emergency situations for the primary purpose of those clinical settings. The use is limited to post-exposure prophylaxis.
Dosage Adjustments
Adjustments may be necessary for large volumes (>2 mL in children, >5 mL in adults) by dividing doses and administering at different sites.
Side Effects
Common Side Effects
- Pain, redness, swelling at the injection site
- Mild fever
- Headache
- Nausea, vomiting
- Dizziness
Rare but Serious Side Effects
- Anaphylaxis (rare but serious; requires immediate discontinuation)
- Hypotension
Long-Term Effects
No specific long-term adverse effects have been identified.
Contraindications
- Hypersensitivity to human immunoglobulin
- IgA deficiency with anti-IgA antibodies
Drug Interactions
- Live attenuated vaccines (measles, mumps, rubella, varicella): Administer at least 3 months after HBIG.
- May interfere with serological tests.
Pregnancy and Breastfeeding
HBIG can be used during pregnancy and breastfeeding if clearly needed, but consult current clinical guidelines. No specific precautions are required during breastfeeding after the infant has received the recommended HBIG and HBV vaccine doses.
Drug Profile Summary
- Mechanism of Action: Provides passive immunity via anti-HBs antibodies.
- Side Effects: Injection site reactions, fever, headache, nausea. Rarely, anaphylaxis.
- Contraindications: Hypersensitivity to human immunoglobulin, IgA deficiency with anti-IgA antibodies.
- Drug Interactions: Live attenuated vaccines, some serological tests.
- Pregnancy & Breastfeeding: Can be used if clinically indicated.
- Dosage: See detailed section above.
- Monitoring Parameters: Anti-HBs antibody titers.
Popular Combinations
HBIG is commonly used in conjunction with the hepatitis B vaccine for post-exposure prophylaxis to provide both immediate (passive) and long-term (active) protection.
Precautions
- Administer IM. Avoid intravenous administration due to the risk of severe reactions.
- Monitor for signs of hypersensitivity or anaphylaxis.
- In patients with bleeding disorders, subcutaneous administration can be considered if intravenous HBIG is unavailable.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Human Hepatitis B Immunoglobulin?
A: Dosing depends on the indication and patient’s age. For post-exposure prophylaxis, it is 0.06 mL/kg IM for adults and children. For neonates born to HBsAg-positive mothers, it is 100 IU IM. For pre-exposure prophylaxis it is 500 IU for adults and 8 IU/kg for children.
Q2: How soon after exposure should HBIG be administered?
A: Ideally within 24 hours, though it may still offer benefit if given up to 7 days post-exposure.
Q3: Can HBIG be given intravenously?
A: No, HBIG should be administered intramuscularly. IV administration poses a risk of serious reactions. Only in the case of some products for prophylaxis of Hepatitis B recurrence in liver transplant patients.
Q4: What is the difference between HBIG and the hepatitis B vaccine?
A: HBIG provides immediate, short-term, passive immunity, while the hepatitis B vaccine induces active immunity which develops over time and is long-lasting.
Q5: Can HBIG be given to pregnant women?
A: Yes, if clinically indicated. Consult current clinical guidelines.
Q6: Are there any drug interactions with HBIG?
A: Yes, concomitant administration with live attenuated vaccines should be avoided. There may also be interference with serological testing.
Q7: What are the common side effects of HBIG?
A: Common side effects include pain, redness, and swelling at the injection site; mild fever; headache; nausea; and dizziness.
Q8: What are the contraindications to HBIG administration?
A: Contraindications include prior anaphylactic reaction to human immunoglobulin or an IgA deficiency with anti-IgA antibodies.
Q9: Is HBIG effective for long-term protection against hepatitis B?
A: No, HBIG provides only short-term protection. For long-term protection, the hepatitis B vaccine is necessary.
