Human Hepatitis B Immunoglobulin

Human hepatitis B immunoglobulin (HBIG) is a purified human plasma-derived immunoglobulin containing high concentrations of antibodies directed against hepatitis B surface antigen (anti-HBs). It belongs to the pharmacotherapeutic group of immune sera and immunoglobulins and provides passive immunization by supplying ready-made antibodies rather than stimulating the body to develop its own long-term immune response. These antibodies can bind hepatitis B virus and help prevent infection when administered as prophylaxis after an appropriate exposure. Depending on the specific product and indication, human hepatitis B immunoglobulin is administered by intramuscular, intravenous, or subcutaneous injection. It is clinically important because passive antibody protection becomes available immediately, whereas protection from hepatitis B vaccination develops over time. HBIG therefore has an established role in post-exposure prophylaxis, particularly after exposure to hepatitis B surface antigen-positive blood or body fluids, perinatal exposure, and certain sexual or household exposures. It may also be used in selected liver-transplant recipients to prevent hepatitis B reinfection. HBIG provides temporary protection and is not equivalent to hepatitis B vaccination; when indicated for post-exposure prophylaxis, it is commonly administered together with hepatitis B vaccine.

Human hepatitis B immunoglobulin preparations were developed from plasma collected from donors with high levels of antibodies against hepatitis B surface antigen. Regulatory products have subsequently been developed for different prophylactic settings. In the United States, the FDA lists Hepatitis B Immune Globulin (Human), HyperHEP B, under STN 101146, with indications covering post-exposure prophylaxis following exposure to HBsAg-positive blood or materials, perinatal exposure, sexual exposure, and specified household exposure in infants. In the European Union, human hepatitis B immunoglobulin products have included ImmunoGam and Zutectra. The European Commission granted marketing authorisation for Zutectra on 30 November 2009 for prevention of HBV reinfection in appropriately selected adults after liver transplantation for hepatitis B-induced liver failure. Zutectra's product information specifies use in HBsAg- and HBV-DNA-negative adults after transplantation, with appropriate antiviral therapy considered as part of prophylaxis.

Human hepatitis B immunoglobulin is used primarily for prevention of hepatitis B infection after significant exposure. Approved uses for post-exposure products include exposure to HBsAg-positive blood through needlestick or other parenteral exposure, direct mucous-membrane exposure, certain occupational accidents, perinatal exposure in infants born to HBsAg-positive mothers, sexual exposure to an HBsAg-positive person, and specified household exposure involving young infants. For an unvaccinated person exposed to an HBsAg-positive source, HBIG is generally administered together with hepatitis B vaccine at separate anatomical sites. HBIG may also be considered for selected people who have not developed an adequate response to vaccination. Certain products have a separate indication for prevention of HBV reinfection in appropriately selected liver-transplant recipients who do not have active HBV infection. Human hepatitis B immunoglobulin is a prophylactic treatment and is not used to cure established chronic hepatitis B infection.

Administration and dosing depend on the specific human hepatitis B immunoglobulin product, route, exposure, patient characteristics, and clinical indication. For post-exposure prophylaxis, the CDC recommends 0.06 mL/kg of HBIG when indicated. After exposure to an HBsAg-positive source, HBIG should be administered as soon as possible, preferably within 24 hours, and hepatitis B vaccine should be given at a separate anatomical site when both are indicated. Neonates born to HBsAg-positive mothers require prompt prophylaxis according to established neonatal hepatitis B protocols. Treatment may consist of a single post-exposure dose, while selected vaccine nonresponders or particular exposure situations may require additional dosing. For the liver-transplant indication, the dosing schedule is product-specific; for example, some transplant-related products are administered subcutaneously at regular intervals according to serum anti-HBs concentrations, following initial stabilization with intravenous hepatitis B immunoglobulin. Monitoring and duration therefore depend on the indication and product used.

Common adverse effects of human hepatitis B immunoglobulin are generally mild and may include pain, tenderness, redness, swelling, bruising or other reactions at the injection site. Depending on the product and route of administration, patients may also experience headache, fatigue, fever, chills, nausea, vomiting, rash or other temporary systemic symptoms. Some transplant-related products commonly cause injection-site reactions such as pain, urticaria, hematoma and erythema. Individual responses vary, and most localized reactions are temporary. Patients should inform their healthcare professional about previous reactions to human immunoglobulin products before administration.

Serious adverse reactions to human hepatitis B immunoglobulin are uncommon but may include severe hypersensitivity or anaphylactic reactions. Immunoglobulin preparations can also rarely be associated with complications such as thrombotic events, hemolysis, renal impairment or other systemic reactions, depending on the product and patient risk factors. Products intended for intramuscular or subcutaneous use must not be administered into a blood vessel. Human plasma-derived products undergo donor screening and manufacturing processes designed to reduce the risk of transmission of infectious agents, although such risk cannot be regarded as absolutely zero. Patients with previous serious reactions to human immunoglobulins require careful assessment before treatment. Clinically significant hypersensitivity reactions require prompt treatment and discontinuation or interruption according to the relevant product information.

Before administration, clinicians should assess the nature and timing of exposure, HBsAg status of the source when available, hepatitis B vaccination history, previous anti-HBs results, and any history of serious reactions to immunoglobulins. HBIG should not be considered a replacement for hepatitis B vaccination when vaccination is indicated. When HBIG and hepatitis B vaccine are administered together, they should be injected at separate anatomical sites. Immunoglobulins can interfere with immune responses to certain live attenuated vaccines, so vaccination timing should be considered according to the specific product and vaccine. Conventional metabolic drug interactions are generally uncommon because human hepatitis B immunoglobulin is an antibody preparation rather than a small-molecule drug. Additional caution may be appropriate in patients with known immunoglobulin hypersensitivity, certain IgA-related reactions, thrombotic risk, renal impairment or other clinically relevant conditions.

Confirm the exposure circumstances, source HBsAg status, vaccination history and previous immune response before selecting post-exposure prophylaxis. When HBIG is indicated, administration should occur as soon as possible, preferably within 24 hours for many discrete exposures. If HBIG and hepatitis B vaccine are both required, administer them at separate anatomical sites and document completion of the vaccine schedule. For infants born to HBsAg-positive mothers, coordinate HBIG and hepatitis B vaccination promptly according to neonatal protocols. Verify the exact product because concentration, route, dose and approved indications differ between human hepatitis B immunoglobulin preparations. For liver-transplant recipients, prophylaxis should be coordinated with the transplant and hepatology teams, with appropriate antiviral therapy and monitoring of HBV markers and anti-HBs concentrations according to the selected product and clinical protocol.