What is the recommended dose of rabies immunoglobulin (RIG) for post-exposure prophylaxis?

Rabies Immunoglobulin Dosing for Post-Exposure Prophylaxis

The recommended dose of rabies immunoglobulin (RIG) for post-exposure prophylaxis is 20 IU/kg body weight, applicable to all age groups including children. 1, 2

Administration Guidelines

Dosing Protocol

• The 20 IU/kg (0.133 mL/kg) body weight formula is standard for both human rabies immunoglobulin (HRIG) and equine rabies immunoglobulin (ERIG) 1
• RIG should be administered only once at the beginning of post-exposure prophylaxis to provide immediate passive immunity 1
• If not administered at the start of vaccination (day 0), RIG can still be given up to and including day 7 of the post-exposure prophylaxis series 1
• Beyond day 7, RIG is not indicated as an antibody response to the vaccine is presumed to have occurred 1

Administration Technique

• If anatomically feasible, the full dose of RIG should be thoroughly infiltrated in the area around and into the wounds 1
• Any remaining volume should be injected intramuscularly at a site distant from vaccine administration 1, 2
• This infiltration recommendation is based on reports of rare failures of post-exposure prophylaxis when less than the full amount of RIG was infiltrated at exposure sites 1
• Studies show that only 56% of eligible patients receive proper wound infiltration despite guidelines recommending this practice 3

Important Precautions

• RIG should never be administered in the same syringe or in the same anatomical site as the first vaccine dose 1, 2
• The gluteal area should not be used as an injection site due to risk of injury to the sciatic nerve 2
• Because RIG can partially suppress active production of antibody, the dose administered should not exceed the recommended dose 1
• This suppressive effect is more pronounced with human RIG than with equine RIG 4

Vaccination Schedule

• For previously unvaccinated persons, the current recommendation is a 4-dose vaccine schedule (days 0,3,7, and 14) along with RIG 1
• Previously, a 5-dose schedule was recommended (days 0,3,7,14, and 28) 1, 5
• For immunocompromised patients, the 5-dose schedule is still recommended 1
• Persons who have previously received complete rabies vaccination require only vaccine (2 doses on days 0 and 3) and no RIG 1

Clinical Considerations

• The combination of RIG and vaccine is recommended for both bite and non-bite exposures reported by previously unvaccinated persons 1
• If post-exposure prophylaxis has been initiated and appropriate laboratory testing confirms the animal was not rabid, prophylaxis can be discontinued 1
• Proper wound cleansing with soap and water and a virucidal agent such as povidone-iodine solution is an essential component of rabies prevention 1

The proper administration of RIG at the recommended dose of 20 IU/kg is a critical component of post-exposure prophylaxis for rabies, which remains nearly 100% fatal once clinical symptoms develop. Ensuring proper dosing and administration technique, particularly wound infiltration, is essential for preventing this devastating disease.