Rabies immune globulin, human

1. The introduction to Rabies immune globulin of human

Rabies immune globulin (RIG) is a medication used in the prevention of rabies infection. It is derived from human blood plasma containing high levels of specific antibodies against rabies virus. RIG provides immediate passive immunity by providing ready-made antibodies to neutralize the rabies virus before the immune system can produce its own.

When a person is exposed to the rabies virus, typically through a bite from an infected animal, immediate medical attention is required. Along with a series of rabies vaccinations, RIG is administered to provide immediate protection against the virus. It is usually given directly into the wound or nearby area of the bite followed by the remaining dose being injected into a muscle, such as the buttock or upper arm.

The introduction of RIG helps to enhance the body's immune response against the rabies virus, preventing or delaying the onset of rabies symptoms. It provides a temporary boost to the immune system while the rabies vaccine stimulates the body to produce its own long-term immunity.

2. The composition and structure of Rabies immune globulin (RIG)

Rabies immune globulin (RIG) is derived from human blood plasma and contains high levels of specific antibodies against the rabies virus. These antibodies are obtained from individuals who have been immunized against rabies or have recovered from a previous rabies infection. The manufacturing process for RIG involves collecting plasma from carefully screened donors who have high levels of rabies antibodies in their blood. The plasma is then processed to extract the antibodies, which are purified and concentrated to increase their potency. This ensures that RIG contains a sufficient quantity of antibodies to effectively neutralize the rabies virus.

The final composition of RIG typically consists of a sterile, clear to slightly opalescent liquid. It contains immunoglobulin G (IgG) antibodies directed against rabies virus antigens, specifically the glycoprotein present on the surface of the virus. These antibodies provide passive immunity and help prevent the rabies virus from spreading and causing infection. The structure of RIG closely resembles that of naturally occurring human antibodies. It consists of two heavy chains and two light chains, which are linked together by disulfide bonds. These chains form a Y-shaped structure with variable regions that can bind specifically to the rabies virus antigens.

The specific concentration and formulation of RIG can vary between manufacturers, but it generally contains at least 150 international units (IU) of rabies antibodies per milliliter (mL) of solution. This standardized concentration ensures a consistent level of protection across different batches of RIG. It is worth noting that RIG is a biological product and must be handled and stored carefully to maintain its efficacy. It should be stored at the recommended temperature and protected from light to avoid degradation of the antibodies.

3. Medical application of Rabies immune globulin (RIG)

Rabies immune globulin (RIG) is utilized as a vital component in the post-exposure prophylaxis (PEP) treatment for individuals who have been exposed to the rabies virus. Its medical application involves the following:

1. Prevention of Rabies Infection: RIG is administered to individuals who have been bitten or scratched by an animal suspected to be infected with the rabies virus. It plays a crucial role in providing immediate passive immunity, supplying the necessary antibodies to neutralize the virus and prevent its replication.
2. Complementing Rabies Vaccine: Along with RIG, individuals also receive a series of rabies vaccine doses as part of PEP. While the vaccine stimulates the person's immune system to produce their own antibodies against rabies, the RIG provides immediate protection until the vaccine-induced immunity develops.
3. Administered at the Bite Site: RIG is typically administered in and around the wound site to maximize its effectiveness. In cases where the bite or scratch wound is extensive, some RIG may also be injected intramuscularly at a different site.
4. Essential for High-Risk Exposures: RIG is particularly crucial when exposure to the rabies virus is considered high-risk. This includes bites or scratches from animals with confirmed or suspected rabies, contact with bats in certain circumstances, or exposure in geographical areas where rabies is endemic.
5. Dosage Based on Body Weight: The dose of RIG required depends on the individual's body weight and is typically calculated using a recommended dose range (e.g., 20 IU/kg). The specific dosage is determined by a healthcare professional, ensuring adequate coverage against the virus.

Overall, the primary medical application of RIG is to provide immediate passive immunity and prevent the establishment and spread of the rabies virus in individuals who have been exposed. Along with the concurrent administration of the rabies vaccine, RIG significantly enhances the chances of preventing the onset of rabies infection.