Thymoglobulin

Indications

Anti-Thymocyte Globulin is used in transplant medicine to prevent and treat rejection of a transplanted organ, such as a kidney, and as part of conditioning before some stem cell transplants to prevent graft-versus-host disease. It is also used to treat severe aplastic anaemia, a condition in which the bone marrow stops making enough blood cells.

How It Works

Anti-Thymocyte Globulin is made of antibodies produced in animals (usually rabbits or horses) against human T cells, a type of white blood cell that drives rejection. The antibodies attach to T cells and remove them from the blood or reduce their activity. This lowers the immune attack on the new organ, and in aplastic anaemia it reduces the immune damage to the bone marrow.

Dosage and Administration

It is given by a doctor or nurse in hospital as a slow infusion into a large vein, usually over several hours, for a number of days. The dose depends on body weight, the reason for treatment and blood counts, and is as prescribed by the specialist. Medicines such as steroids, an antihistamine and Paracetamol are usually given before each infusion to reduce reactions.

Interactions

• Other immunosuppressants (such as Ciclosporin, Tacrolimus, Mycophenolate or steroids) add to the risk of infection and low blood counts; doses are adjusted by the specialist.
• Live vaccines should not be given during and after treatment.

Contraindications

• Allergy to Anti-Thymocyte Globulin or to rabbit or horse proteins (depending on the product).
• Active serious infection that is not controlled.

Side Effects

Infusion reactions are common, including fever, chills, shaking, rash, itching, headache, low or high blood pressure and fast heartbeat; these are caused by the release of chemicals from immune cells. Low white cell and platelet counts are common. Infections, including viral infections such as cytomegalovirus, are more likely. Serum sickness (fever, rash, joint pain) may appear 1 to 2 weeks later. Over the long term, a weakened immune system slightly raises the risk of some cancers, such as lymphoma.

Tell the nurse at once or get urgent medical help if you have difficulty breathing, chest pain, swelling of the face or throat, severe dizziness, a high fever, unusual bleeding or bruising, or signs of infection after leaving hospital.

Pregnancy and Lactation

There is little information on use in pregnancy; it is used only if the benefit clearly outweighs the risk. Effective contraception is advised during treatment. Breastfeeding is not recommended during treatment; follow the specialist's advice.

Precautions and Warnings

• Given only in a hospital with staff experienced in immunosuppressive treatment.
• Blood counts are checked daily; the dose may be reduced if counts fall too low.
• Infections must be reported early; preventive antiviral or antibiotic medicines may be given.
• Previous treatment with an animal-derived globulin increases the risk of allergy.

Overdose

Overdose may cause severe falls in white cells and platelets and serious infection. It is managed in hospital with supportive care; there is no specific antidote.

Therapeutic Class

Immunosuppressant; polyclonal anti-T-cell antibody.

Storage

Store in a refrigerator at 2 to 8°C, do not freeze, and protect from light. It is stored and prepared by hospital staff as directed on the pack.