Equine Rabies Immunoglobulin (ERIG) is a sterile, purified, and concentrated solution of immunoglobulins derived from the plasma of horses hyperimmunized with rabies virus vaccine. It provides immediate, passive immunity against the rabies virus following a Category III exposure (transdermal bites, licks on broken skin, contamination of mucous membrane with saliva) as per WHO and National Rabies Control Programme (NRCP) guidelines. It is a critical component of Post-Exposure Prophylaxis (PEP) and must be administered as soon as possible after exposure, infiltrated around and into the wound(s), with the remainder given intramuscularly at a site distant from the rabies vaccine administration.
Adult: 20 IU per kg body weight. For a 300IU vial, calculate total required dose (e.g., 15 kg patient requires 300IU). The entire calculated dose should be administered. As much as anatomically feasible is infiltrated into and around the wound(s). Any remaining volume is administered by deep intramuscular injection at a site distant from the rabies vaccine site (e.g., anterolateral thigh or deltoid).
Note: 1. Calculate dose (20 IU/kg). 2. Perform skin sensitivity test if recommended by manufacturer/guidelines. 3. Clean wound thoroughly with soap and water, povidone-iodine. 4. Infiltrate as much of the dose as possible into and around all wound(s). Use a fine needle. 5. If volume is large or for multiple wounds, divide dose to infiltrate all sites. 6. Any leftover immunoglobulin is given IM in the anterolateral thigh (preferred) or deltoid, opposite the limb where vaccine is given. 7. NEVER administer in the same syringe or at the same site as the rabies vaccine. 8. Administer at the same time as the first dose of rabies vaccine (Day 0), but always after wound cleansing.
ERIG contains high-titer neutralizing antibodies (IgG) against the rabies virus. Upon administration, these antibodies bind to the rabies virus glycoprotein antigens, neutralizing the virus and preventing its attachment and entry into susceptible host cells (primarily neurons). This provides immediate, short-term passive immunity, which is crucial during the initial period before the patient's own active immune response is generated by the concurrently administered rabies vaccine.
Pregnancy: Pregnancy is NOT a contraindication. Rabies is fatal, and PEP with ERIG plus vaccine is recommended for Category III exposures in pregnant women. Benefits far outweigh risks. Category C (US FDA).
Driving: Unlikely to affect ability. However, malaise or dizziness from potential serum sickness should be considered.
| Live Virus Vaccines (e.g., MMR, Varicella) | ERIG may interfere with the immune response to live virus vaccines. Administration of such vaccines should be deferred for at least 3 months after ERIG administration. | Moderate |
| Immunosuppressants (e.g., Corticosteroids, Chemotherapy) | May theoretically reduce the efficacy of the concurrent active rabies vaccination. However, rabies PEP is never withheld. Use standard PEP schedule. | Moderate |
| Other Immunoglobulins | May increase the risk of systemic adverse reactions. Not typically co-administered. | Low |
Same composition (Equine Rabies Immunoglobulin (300IU)), different brands: