What is the time frame for administering rabies immunoglobulins (Rabies Immune Globulin) after a dog bite?

Timing of Rabies Immunoglobulins Administration After Dog Bite

Rabies immunoglobulins (RIG) should be administered as soon as possible after exposure, ideally within 24 hours of the dog bite, but can still be beneficial when administered at any time before the onset of rabies symptoms, even months after exposure.

Key Principles of Post-Exposure Prophylaxis

Timing of Administration

• Immediate administration is optimal - The ACIP recommends that post-exposure prophylaxis (PEP), including RIG, should begin as soon as possible after exposure 1
• While administration within 24 hours is ideal, RIG can still be administered days, weeks, or even months after exposure if indicated 1
• There is no absolute cutoff time - PEP should be administered regardless of the length of delay, provided that the exposed person does not yet show clinical signs of rabies 1

Components of Proper PEP

1. Immediate wound cleansing - Thorough washing with soap and water for at least 15 minutes 2
2. RIG administration - 20 IU/kg body weight, infiltrated into and around all wounds 3
3. Vaccination series - Current recommendation is a 4-dose regimen on days 0,3,7, and 14 1

Administration Guidelines for RIG

Proper Administration Technique

• RIG should be infiltrated deep into and around all wounds 3, 2
• Only 56% of eligible patients receive proper wound infiltration with RIG, highlighting a common error in administration 4
• Any remaining RIG that cannot be infiltrated into wounds should be administered intramuscularly at a site distant from vaccine administration 3

Dosing

• The recommended dose is 20 IU/kg body weight 3, 4
• Studies have shown that doses of 10 IU/kg may be insufficient, while 40 IU/kg may interfere with optimal antibody production from the vaccine 5

Special Considerations

Previously Vaccinated vs. Unvaccinated Individuals

• Previously unvaccinated individuals require both RIG and the full vaccination series 3
• Previously vaccinated individuals (with documented adequate vaccination) only need the 2-dose vaccine series without RIG 3

Immunocompromised Patients

• Immunocompromised patients should receive a 5-dose vaccination regimen with RIG 3
• These patients should have antibody titers checked after vaccination 3

Common Pitfalls to Avoid

1. Delayed initiation - While PEP should be started as soon as possible, it should never be withheld regardless of time elapsed since exposure 1
2. Improper RIG infiltration - Failure to properly infiltrate wounds with RIG is a common error 4
3. Incorrect dosing - Ensure accurate weight-based dosing at 20 IU/kg 4
4. Inadequate wound cleansing - Thorough washing with soap and water is critical 2
5. Administering RIG to previously vaccinated individuals - Not necessary and wastes a valuable resource 3

Conclusion

While immediate administration of RIG is ideal, the critical point is that there is no maximum time limit for starting PEP after exposure as long as the person remains asymptomatic. The effectiveness of PEP, including RIG, remains high even when initiated days or weeks after exposure, given the typically long incubation period of rabies (1-3 months, though it can range from days to years) 1.