Rabies Immunoglobulin Dose Calculation

Rabies Immunoglobulin Dose Calculator

Calculated Rabies Immunoglobulin Dose:

Total IU Required:

Volume Required:

Note: The standard dose is 20 IU/kg. This calculator provides an estimated dose based on the provided concentration. Always consult product-specific guidelines and a healthcare professional for exact dosing and administration.

Understanding Rabies Immunoglobulin (RIG) Dosage

Rabies is a severe viral disease that is almost always fatal once clinical symptoms appear. Post-exposure prophylaxis (PEP) is crucial for preventing the disease after potential exposure. A key component of PEP, especially for severe exposures, is the administration of Rabies Immunoglobulin (RIG).

What is Rabies Immunoglobulin?

Rabies Immunoglobulin provides immediate, passive immunity to an individual exposed to the rabies virus. It contains antibodies that neutralize the virus at the site of the wound before the body can mount its own active immune response from the rabies vaccine. RIG is typically administered once, at the beginning of the PEP regimen, along with the first dose of rabies vaccine.

When is RIG Indicated?

RIG is recommended for all category III exposures (e.g., transdermal bites or scratches, licks on broken skin, contamination of mucous membranes with saliva from a suspected rabid animal) and for category II exposures in immunocompromised individuals, according to World Health Organization (WHO) guidelines. It is crucial for exposures where the skin barrier has been broken.

How is the Dose Determined?

The standard dose for Rabies Immunoglobulin is 20 International Units (IU) per kilogram (kg) of body weight. This dose applies to both Human Rabies Immunoglobulin (HRIG) and Equine Rabies Immunoglobulin (ERIG), though the specific product concentration (IU/mL) will vary.

• Total IU Needed: The patient's weight in kilograms is multiplied by 20 IU/kg to determine the total International Units required.
• Volume Needed: To convert the total IU into a practical volume (mL) for administration, the total IU is divided by the concentration of the specific RIG product available (e.g., 150 IU/mL for some HRIG products).

Administration of RIG

The calculated dose of RIG should be infiltrated as much as anatomically possible into and around the wound(s). This ensures that the antibodies are delivered directly to the site where the virus may have entered the body. If the volume of RIG is too large to be fully infiltrated into the wound(s), the remainder should be administered intramuscularly (IM) at a site distant from where the rabies vaccine will be given (e.g., gluteal region if vaccine is given in the deltoid).

It is important not to exceed the recommended dose of 20 IU/kg, as higher doses can interfere with the body's active immune response to the rabies vaccine.

Example Calculation:

Let's consider a patient weighing 75 kg, and the available HRIG product has a concentration of 150 IU/mL.

1. Calculate Total IU Needed:
   75 kg × 20 IU/kg = 1500 IU
2. Calculate Volume Needed:
   1500 IU ÷ 150 IU/mL = 10 mL

In this example, the patient would require 1500 IU of RIG, which translates to 10 mL of the 150 IU/mL product.

Important Considerations:

• Always refer to the specific product insert for the RIG being used, as concentrations can vary.
• RIG should be administered by a trained healthcare professional.
• This calculator is a tool for estimation and does not replace professional medical judgment or official guidelines.
• RIG is only one part of rabies post-exposure prophylaxis; rabies vaccine administration is also critical.

Proper and timely administration of RIG, along with the rabies vaccine, is critical in preventing rabies after exposure. Always consult with local public health authorities and medical professionals for the most current and appropriate guidance.