HRIG Dosing for an 80-kg Adult
For an 80-kg adult, the total dose of human rabies immune globulin (HRIG) is 1,600 IU (approximately 10.6 mL). 1, 2, 3
Dose Calculation
- The standard dose of HRIG is 20 IU/kg body weight for all patients regardless of age 1, 2, 4, 3
- For an 80-kg adult: 20 IU/kg × 80 kg = 1,600 IU total dose 1, 3
- This translates to approximately 10.6 mL (using the standard concentration of 150 IU/mL) 1, 3
- Multiple vials will be required—typically five 2-mL vials (300 IU each) plus a partial sixth vial to deliver the complete 1,600 IU dose 3
Critical Administration Guidelines
- Infiltrate the full calculated dose around and into all wounds if anatomically feasible; any remaining volume should be injected intramuscularly at a site distant from the vaccine injection 1, 2, 4, 3
- Never administer HRIG in the same syringe or at the same anatomical site as the rabies vaccine, as this interferes with active antibody production 1, 2, 4, 3
- Do not exceed 20 IU/kg—higher doses partially suppress the active antibody response to the vaccine and may compromise protection 1, 2, 4, 3
Timing Considerations
- HRIG should be administered on day 0, ideally simultaneously with the first rabies vaccine dose 1, 2, 4, 3
- If not given initially, HRIG can still be administered up to and including day 7 after the first vaccine dose 2, 4
- After day 7, do not give HRIG—vaccine-induced antibodies are presumed to have developed by then, and additional passive antibody may suppress the active immune response 2, 4
Common Pitfall to Avoid
- A 2020 multi-hospital study found that while 98% of patients received correct HRIG dosing and 100% received it within the proper timeframe, only 56% of eligible patients actually received wound infiltration as recommended—this is a critical error that may reduce prophylaxis effectiveness 5