In acquired aplastic anemia, immunosuppressive therapy with anti-thymocyte globulin (ATG) plus cyclosporine is the therapy of choice for older patients. It is also used for patients who do not have a matched stem cell donor.
How Thymogam Helps
Thymogam kills specific cells in immune system called T-lymphocytes — the cells that are attacking stem cells. This allows bone marrow to rebuild its supply of stem cells. The stem cells, in turn, make more blood cells.
How Thymogam is Given
Usually, Thymogam is given by IV for 8-12 hours a day, for 4 days at a dose of 30-40 mg/kg/day. The dose varies with patient's weight, disease condition.
How well does Thymogam works?
It may take a few months to notice the effects of these medicines. Most often, as blood cell counts rise, symptoms lessen. Blood cell counts in people who respond well to these medicines usually don't reach normal levels. However, the blood cell counts often are high enough to allow people to do their normal activities. Once Thymogam works, it stops the need for blood transfusion within 3 months.
People who have aplastic anemia may need long-term treatment with immunosuppressants.
Side Effects of Thymogam when receiving the treatment, patient may have:
- Skin rash
These side effects go away after treatment.
Less CommonSide Effects of Thymogam
Rarely, patients experience a severe allergic reaction to ATG. This is called anaphylaxis which causes a drop in blood pressure and trouble with breathing. It can even cause death.
Before patient receive Thymogam, patient should have a skin test to find out if patient is likely to develop anaphylaxis to this medicine. If patient have a mild allergic reaction to the skin test, patient can still take ATG, but patient will need to start with a small amount to get body used to it.
Another side effect of Thymogam is serum sickness. This happens when immune system reacts to foreign proteins in the medicine. It causes fever, rash, joint pain, and muscle aches.
Thymogam should not be administered to a patient who has previous history of severe systemic reaction to this preparation or any other equine globulin preparations.
Warnings and Precautions :
Only physicians experienced in immunosuppressive therapy should use Thymogam. Use Thymogam only in facilities equipped and staffed with adequate laboratory and supportive medical resources. Discontinue therapy if anaphylaxis or severe and unremitting thrombocytopenia or leucopenia occurs. As observed with products derived from or purified with human blood components, the possibility of transmission of some infectious disseases should be borne in mind. Monitor patients carefully for concurrent infection. Several studies have suggested and increase in the incidence of cytomegalovirus infection in patients receiving Thymogam. To identify those at greatest risk of systemic anaphylaxis, physician should strongly recommend skin testing before commencing treatment.
A conservative, conventional approach would first employ epicutaneous (prick) testing with undiluted Thymogam. If the subject does not show a wheal ten minutes after pricking, proceed to intradermal testing with 0.02mL of a 1:1000 dilution of Thymogam in Sodium chloride injection with a separate Sodium chloride injection control of similar volume. Observe the results every 10 minutes over the first hour after intradermal injection. A wheal of 3mm or greater in diameter at the site of Thymogam injection than that at the Sodium chloride injection control site (or a positive prick test) shows clinical sensitivity and an increased possibility of systemic allergic reactions. intradermal testing with 0.02mL of a 1:1000 dilution of Thymogam in Sodium chloride injection with a separate Sodium chloride injection control of similar volume. Observe the results every 10 minutes over the first hour after intradermal injection. A wheal of 3mm or greater in diameter at the site of Thymogam injection than that at the Sodium chloride injection control site (or a positive prick test) shows clinical sensitivity and an increased possibility of systemic allergic reactions.
The predictive value of this test has not been proved clinically. Allergic reactions such as anaphylaxis have occurred in patients whose skin test is negative. In the presence of a locally positive skin test to Thymogam, serious consideration to alternative forms of therapy should be given.A systemic reaction such as a generalized rash, tachycardia, dyspnea, hypotension, or anaphylaxis precludes any additional administration of Thymogam.
Use during pregnancy and lactation :
Thymogam has not been evaluated in either pregnant or lactating women. Animal reproduction studies have not been conducted with Thymogam. It is also not known whether Thymogam can cause foetal harm when administered to a pregnant woman or can affect reproduction capacity. Thymogam administration to pregnant women is not recommended and should be considered only under exceptional circumstances. It is not known whether Thymogam is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from Thymogam, caution should be exercised when Thymogam is administered to a nursing woman.
Adverse Effects :
- Renal Transplantation : The primary clinical experience with Thymogam has been in renal allograft patients receiving concurrent standard immunosuppressive treatment. In these patients, investigators have most frequently reported fever, chills, leucopenia, thrombocytopenia, arthralgia and dermatologic reactions such as rash, urticaria, wheal, flare and pruritis.
- Aplastic Anaemia : The incidence of adverse reaction has been found more in patients being treated for aplastic anaemia. Frequently reported adverse reactions among patients enrolled in aplastic anaemia studies were fever, chills, skin rashes, arthralgia and thrombocytopenia. In patients with aplastic anaemia and other haematologic abnormalities who have received Thymogam, abnormal tests of liver function (SGOT, SGPT, alkaline phosphatase) and renal function (serum creatinine) have been observed. In some trials, clinical and laboratory findings of serum sickness have been in majority of patients.
- Other Reactions : Other reactions reported are : headache, nausea, vomiting, diarrhoea, dyspnoea, hypotension, night sweats, stomatitis, chest pain, back pain, pain at the infusion site, clotted A/V fistula and peripheral thrombophlebitis. Reactions reported rarely are : periorbital oedema, agitation, dizziness, weakness or faintness, malaise, epigastric pain or hiccoughs, laryngospasm, paraesthesia, lymphadenopathy, infection, possible encephalitis, herpes simplex reactivation, wound dehiscence, hyperglycaemia, hypertension, oedema, pulmonary oedema, pleural effusions, tachycardia, seizure, anaphylaxis, iliac vein obstruction, renal artery thrombosis, proteinuria and toxic epidermal necrosis.