Imuran: Another Miracle Drug    

Imuran¨ (also known as azathioprine) is one of the antirejection drugs most people take after a transplant.

While each transplant center has its own protocols for preventing rejection, many use Imuran along with prednisone and cyclosporine. Using three drugs that work in slightly different ways improves control and causes fewer side effects.

Imuran has been in use for more than 25 years. It works by interfering with the growth of T-lymphocytes. These specialized white blood cells are one of the main instigators of the rejection process. While suppressing these cells to help prevent rejection, Imuran also can suppress all blood cells, including white cells, red cells, and platelets.

White blood cells are the part of the immune system that surveys the body for foreign invaders, such as bacteria, viruses, and, of course, transplanted organs. When these foreign materials are found, the immune system swings into action, alerting cells to fight and kill the invaders. Immunosuppressants slow down the white blood cells and interfere with the rejection process. The body then allows the new organ to remain - but sometimes viruses and bacteria remain or enter the body also, resulting in infection. That's why you and your transplant team must always be on the lookout for infection. Sometimes cancer cells also can grow. In fact, most immunosuppressive drugs, including Imuran, can make you more susceptible to infection and malignancy.

Imuran is used to help prevent rejection, not to treat it. It comes in one size, a 50-mg. tablet, which may be easily broken in half. The dose of Imuran can range from 25 mg. every other day to 200 to 300 mg. each day. Doses are adjusted according to the white blood cell count measured from a blood sample. Imuran is usually taken once or twice each day. Some people find it helpful to take their dose just before bedtime to avoid stomach discomfort.

Your transplant team may reduce or even temporarily discontinue Imuran when certain types of infections are being treated. This allows the bodyÕs natural disease fighters to attack the infection.

Side Effects

Understanding the potential side effects of Imuran is an important part of your care after transplant. The side effects with Imuran are the same for adults and children, and most are dose-related and respond well to a lowered dose. Your transplant team will monitor you closely for complications, but you need to be aware of potential complications so you can alert your team early and be treated promptly.

The most common side effect of Imuran is bone-marrow suppression. To identify this, your transplant team will obtain periodic complete blood counts (CBCs) that measure white cells, platelets, hemoglobin, and the percentage of red cells in the blood (hematocrit).

After a transplant, even seemingly insignificant signs of illness should be reported to your transplant team immediately. Early detection is the key to effective treatment. Avoiding people who are ill and washing your hands often and carefully can help prevent infections.

In addition, you should check regularly for any signs of malignancyÑfor example through self breast exams and self testicular exams and by checking your skin for any changes. Always use a sunscreen with a sun protective factor (SPF) of 15 or higher and avoid prolonged exposure to direct sunlight. Imuran and other immunosuppressive drugs can make skin more sensitive to the sun and therefore to skin cancer.

Hepatotoxicity (damage to liver cells) occasionally occurs with Imuran therapy. To check for this, your transplant team will have routine lab tests done to monitor your liver function. The lab tests include AST-SGOT, ALT-SGPT, bilirubin, and alkaline phosphatase. Jaundice (yellowing of the skin) may be a sign of liver problems and should be reported to your transplant team right away.

Other less common complications affecting the gastrointestinal tract include pancreatitis (inflammation of the pancreas) and hepatitis (inflammation of the liver). Nausea, vomiting, and diarrhea occur rarely. Imuran can cause sores in the mouth, so good mouth care is essential.

Alopecia (hair loss) may also occur, although it is usually temporary and mild. Excess hair growth, also called hirsutism, often occurs with cyclosporine and prednisone therapy and usually more than makes up for any hair loss.

Drug Interactions

When several different immunosuppressant drugs are used with other medications, the way they interact is a concern. Although a number of medications may interact with Imuran in some manner, one in particular should be mentioned. Allopurinol (Zyloprim¨) is a medication often prescribed for treatment of gout. When used with Imuran, it can dramatically affect the degree of bone-marrow suppression. Therefore, the amount of Imuran you take may need to be reduced, sometimes by as much as two-thirds. Be sure you always discuss any changes in your medications with your transplant team.