Anti-D(rh) immunoglobulin

Anti-D(rh) immunoglobulin is a human antibody used to prevent an immune response in patients without rhesus factor (RhD negative) who have been exposed to rhesus factor (RhD positive) blood during pregnancy or blood transfusions. It is administered by intramuscular or intravenous injection and is used to prevent an immunological condition known as Rh incompatibility (or Rh incompatibility, especially in newborns). If left untreated, this incompatibility leads to the destruction of the child's red blood cells. This condition is also known as hemolyticus neonatorum. Anti-D immunoglobulins are administered either as an IV solution or directly as a prefilled syringe.

History
Rhesus factor was discovered and named by Karl Landsteiner and Alexander Wiener in 1937. Shortly thereafter, it was discovered that people without rhesus could develop immunity to rhesus blood cells. In the 1950s, blood exchange transfusions achieved initial success in the treatment of haemolyticus neonatorum. In 1968, prophylactic therapy with immunoglobulins (anti-D prophylaxis) was first approved and is still commonly used today.

Pharmacology and Mechanism of Action

Rh incompatibility is an immune reaction between the blood of the mother and the blood of the fetus. A prerequisite is that the mother's blood is RhD negative and the fetus's blood is RhD positive. During the first pregnancy, the RhD-negative mother's exposure to RhD-positive fetal RBCs is extremely low because they cannot cross the placental barrier. However, during delivery, the placenta separates from the uterine wall, allowing umbilical cord blood to enter the maternal circulation, resulting in an immune response by the mother to clear the RhD-positive blood cells from her circulation. Some time after this initial immune response, the mother's immune system forms what are called memory B cells, which can produce antibodies (IgG type) against RhD. In a subsequent second pregnancy with an RhD-positive child, these IgG antibodies can cross the placental barrier and enter the fetal circulation. This causes the fetal erythrocytes to dissolve, significantly reducing the oxygen supply to the tissues. This complication may result in fetal death. Anti-D(rh) immunoglobulin is used to prevent this process. This involves injecting the mother with immunoglobulins during pregnancy and immediately after the birth of the first RhD positive child to prevent initial immunization against rhesus factor.

Pharmacokinetics

After intravenous or intramuscular injection, antibodies are detectable in the patient for at least 9 weeks. Human immunoglobulin and its fragments can be detected in stool and urine.

Contraindications

Use of anti-D(rh) immunoglobulins is not indicated in the following patient populations:

• Women who are RhD positive
• Women who have previously received immunization with anti-D immunoglobulins
• Women who are RhD-negative and in whom the fetus is known to also be RhD-negative

Side effects

Possible side effects after anti-D prophylaxis may include:

• Difficulty breathing (dyspnea)
• fever and chills
• aching joints
• skin rash, itching, redness, hives
• palpitations and tachycardia
• back pain
• dizziness
• nausea
• vomiting
• malaise
• Headache