Human Rabies Immunoglobulin (HRIG) is a sterile, concentrated solution of immunoglobulins (IgG) prepared from pooled human plasma of donors hyperimmunized with rabies vaccine. It provides immediate, passive immunity against the rabies virus by neutralizing the virus at the site of exposure before it can enter the nervous system. It is a critical component of rabies post-exposure prophylaxis (PEP) for Category III exposures as per WHO and National Centre for Disease Control (NCDC) guidelines.
Adult: 20 IU per kg body weight. For a 750 IU vial, it is typically used for individuals weighing up to 37.5 kg. The entire content of the vial(s) calculated for the dose must be used.
Note: 1. Calculate total dose (20 IU/kg). 2. Clean wounds thoroughly with soap and water, povidone-iodine. 3. Infiltrate as much of the calculated dose as possible **around and into** the depth of all wounds. 4. If the total volume exceeds wound infiltration capacity, administer the **remaining volume** by **IM injection** at a site **distant from** the rabies vaccine injection site (e.g., vaccine in left deltoid, HRIG IM in right gluteus or anterolateral thigh). 5. NEVER administer in the same syringe or site as the vaccine. 6. Use a separate syringe for each wound site if multiple. 7. Administration must occur **on Day 0**, concurrently with the first dose of rabies vaccine, but **as soon as possible** after exposure, ideally within 24 hours. It can be given up to 7 days after the first vaccine dose if not initially available.
HRIG provides immediate, pre-formed, virus-neutralizing antibodies against the rabies virus. These antibodies bind to the glycoprotein antigens on the surface of the rabies virus, preventing its attachment and entry into susceptible host cells, particularly at the site of the bite/injury. This neutralization provides critical passive immunity during the latent period before the patient's own active immune response (triggered by the rabies vaccine) can produce sufficient antibodies.
Pregnancy: US FDA Category C. No well-controlled studies. However, for post-exposure rabies prophylaxis, it is considered ESSENTIAL and should NOT be withheld. The risk of clinical rabies far outweighs theoretical risks to the fetus.
Driving: Unlikely to affect ability. However, dizziness or malaise from the injection or the stress of the exposure may impair skills.
| Live Virus Vaccines (e.g., MMR, Varicella, Yellow Fever) | HRIG may interfere with the immune response to live virus vaccines. Administration of such vaccines should be deferred for at least 3 months (up to 6 months for measles) after HRIG administration. | Major |
| Other Immunoglobulin Preparations | May increase the risk of systemic adverse reactions and antibody overload. Space administrations appropriately. | Moderate |