Anti rabies serum dose
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anti rabies serum dose administration rabies post-exposure prophylaxis
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rabies immunoglobulin RIG dose wound infiltration passive immunization
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Anti-Rabies Serum (Rabies Immune Globulin) Dose
Anti-rabies serum refers to Rabies Immune Globulin (RIG), used for passive immunization as part of post-exposure prophylaxis (PEP).
Types of RIG
| Type | Abbreviation | Source |
|---|---|---|
| Human Rabies Immune Globulin | HRIG | Human plasma |
| Equine Rabies Immune Globulin | ERIG | Horse serum |
Dose
| Product | Dose |
|---|---|
| HRIG | 20 IU/kg body weight |
| ERIG | 40 IU/kg body weight |
Administration
- As much of the dose as possible should be infiltrated directly into and around the wound site(s)
- Any remaining RIG (after wound infiltration) is administered IM at a distant site (e.g., anterolateral thigh — different from vaccine site)
- For multiple or large wounds, the preparation may be diluted in normal saline to achieve sufficient volume for adequate infiltration of all sites
- For mucous membrane exposure, the entire dose is given IM
Timing
- Must be given simultaneously with the first dose of rabies vaccine (Day 0)
- Can be given up to Day 7 after the first vaccine dose if not immediately available
- NOT given after Day 7 — endogenous antibodies are being produced by then, and passive immunization may be counterproductive
- NOT given to previously vaccinated individuals (complete pre- or post-exposure series)
Key Points
- RIG provides immediate passive protection while the vaccine induces active immunity
- It is never repeated — given only once
- WHO recent recommendations: under certain circumstances, the remainder of the dose does not need to be given IM after complete local wound infiltration
- RIG and vaccine should be injected at separate anatomical sites
(Harrison's Principles of Internal Medicine, 21st Edition, p. 6085)
In millilitre
The dose in mL depends on the concentration of the preparation and the patient's weight.
Formula
Volume (mL) = Dose (IU/kg) × Body weight (kg) ÷ Concentration (IU/mL)
Standard Concentrations
| Product | Dose | Typical Concentration |
|---|---|---|
| HRIG (e.g., Imogam, Berirab) | 20 IU/kg | 150 IU/mL |
| ERIG (e.g., Abhayrab equine) | 40 IU/kg | 300 IU/mL |
Worked Example — 60 kg adult
| Product | Calculation | Volume |
|---|---|---|
| HRIG | 20 × 60 ÷ 150 | 8 mL |
| ERIG | 40 × 60 ÷ 300 | 8 mL |
(Both products are formulated so the resulting volume comes out similar)
Quick Reference by Weight (HRIG @ 150 IU/mL)
| Weight (kg) | Dose (IU) | Volume (mL) |
|---|---|---|
| 10 | 200 | 1.3 mL |
| 20 | 400 | 2.7 mL |
| 30 | 600 | 4.0 mL |
| 40 | 800 | 5.3 mL |
| 50 | 1000 | 6.7 mL |
| 60 | 1200 | 8.0 mL |
| 70 | 1400 | 9.3 mL |
| 80 | 1600 | 10.7 mL |
Always check the concentration printed on the vial before calculating, as it may vary by brand.
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