Where should rabies Immunoglobulin (IG) be injected?

Rabies Immunoglobulin (RIG) Injection Sites

Rabies immunoglobulin (RIG) should be thoroughly infiltrated in and around the wound(s) if anatomically feasible, with any remaining volume injected intramuscularly at a site distant from vaccine administration. 1, 2

Proper Administration of Rabies Immunoglobulin

Dosage and Timing

• The recommended dose of human RIG is 20 IU/kg body weight for all age groups, including children 2
• RIG should be administered at the time of the first vaccine dose (day 0) 1
• If not given initially, RIG can be administered up to day 7 after the first vaccine dose 2
• Beyond day 7, RIG is not indicated as antibody response to the vaccine is presumed to have occurred 2

Injection Technique

1. Primary site: Wound infiltration

   • If anatomically feasible, the full dose of RIG should be thoroughly infiltrated in the area around and into the wounds 2
   • This 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 2
   • Studies show only 56% of eligible patients receive proper wound infiltration despite guidelines 3

2. Secondary site: Intramuscular injection

   • Any remaining volume that cannot be infiltrated into the wound should be injected intramuscularly at a site distant from vaccine administration 1
   • For adults, this is typically in a large muscle mass away from the deltoid (where vaccine is given)

Important Precautions

• RIG should never be administered in the same syringe or at the same anatomical site as the first vaccine dose 2
• However, subsequent doses of vaccine in the series can be administered in the same anatomic location where the RIG was given, if this is the preferred site 2
• The gluteal area should never be used for vaccine injections as this results in lower neutralizing antibody titers 2

Rationale for Wound Infiltration

Research demonstrates that:

• Local infiltration of RIG at wound sites is crucial for effective post-exposure prophylaxis 4
• Administering RIG to wounds only (without distant IM injection of remaining volume) uses less product while maintaining effectiveness 5
• RIG shows significant retention and local diffusion at the injection site for at least 24 hours 4

Common Pitfalls to Avoid

1. Incorrect administration site

   • Failure to infiltrate wounds with RIG has been associated with post-exposure prophylaxis failures 2
   • Studies show nearly half of patients don't receive proper wound infiltration despite clear guidelines 3

2. Improper dosing

   • Using more than the recommended dose (20 IU/kg) can suppress active antibody production 2
   • Using less than the recommended dose may lead to treatment failure 2

3. Delayed administration

   • While RIG can be given up to 7 days after the first vaccine dose, it should ideally be administered immediately with the first dose 1

4. Neglecting wound care

   • Thorough wound cleansing with soap and water for at least 15 minutes is essential before RIG administration 1
   • A virucidal agent such as povidone-iodine solution is recommended if available 1

By following these guidelines for RIG administration, with proper wound infiltration as the primary site and distant IM injection for any remaining volume, healthcare providers can optimize the effectiveness of rabies post-exposure prophylaxis.