Purinethol

Purinethol is a prescription medication used to treat a type of cancer called acute lymphatic/lymphoblastic leukemia, or ALL. Purinethol belongs to a group of drugs called purine antagonists, which work by stopping the growth of cancer cells.

This medication comes in tablet form and is taken once a day, with or without food.

Common side effects of Purinethol include changes in blood counts, nausea, vomiting, hair loss, and rash.

Mercaptopurine is a prescription medication used to treat a type of cancer called acute lymphatic/lymphoblastic leukemia, or ALL.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Take mercaptopurine exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The mercaptopurine dose your doctor recommends will be based on the following:

• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• whether or not you have a genetic deficiency of the TPMT enzyme
• your liver function
• your kidney function
• your age

The recommended dose range for mercaptopurine is 1.5 to 2.5 mg/kg/day once daily.

Serious side effects have been reported with mercaptopurine including the following:

• lowered blood counts. This is medically known as bone marrow suppression. Bone marrow suppression can lead to thrombocytopenia, anemia, and leukopenia.
  • thrombocytopenia. This is a condition in which your blood has a lower than normal number of blood cell fragments called platelets. Tell your healthcare provider right away if you have the following signs and symptoms of thrombocytopenia:
    • mild to serious bleeding
    • purple, brown, and red bruises (purpura)
    • small red or purple dots on your skin (petechiae)
    • prolonged bleeding, even from minor cuts
    • bleeding or oozing from the mouth or nose, especially nosebleeds or bleeding from brushing your teeth
    • abnormal vaginal bleeding (especially heavy menstrual flow)
    • blood in the urine or stool or bleeding from the rectum. Blood in the stool can appear as red blood or as a dark, tarry color. Taking iron supplements also can cause dark, tarry stools.
    • headaches and other neurological symptoms. These problems are very rare, but you should discuss them with your doctor.
  • anemia. This is a condition in which your blood has a lower than normal number of red blood cells. Tell your healthcare provider right away if you have the following signs and symptoms of anemia:
    • shortness of breath
    • dizziness
    • headache
    • coldness in the hands and feet
    • pale skin
    • chest pain
  • leukopenia. This is a condition when there are a low number of white blood cells in your body. These cells help fight infections. You may become more susceptible to infections if you are taking mercaptopurine. Tell your healthcare provider if you are feeling “under the weather” or are running a fever. Also, let your healthcare provider know if you are scheduled to receive a vaccination, as your response to vaccines may be diminished and live vaccinations can make you sick.
• a decline in liver function. Tell your healthcare provider if you have any signs or symptoms of liver damage, which include the following:
  • yellowing of the skin or eyes
  • nausea
  • vomiting
  • fatigue
  • itching
• intestinal ulceration. Tell your healthcare provider if you have any signs or symptoms such as nausea, vomiting, bleeding from any site, or symptoms suggestive of anemia.

Do not take mercaptopurine if you:

• are allergic to mercaptopurine or to any of its ingredients
• have already taken this drug and it has shown to be ineffective
• have already taken thioguanine (Tabloid, 6-TG, 6-Thioguanine) and it has shown to be ineffective

Serious side effects have been reported with mercaptopurine. See the “Mercaptopurine Precautions” section.

Common side effects of mercaptopurine include changes in blood counts (anemia, neutropenia, thrombocytopenia), nausea, vomiting, hair loss, and rash.

This is not a complete list of mercaptopurine side effects. Ask your doctor or pharmacist for more information.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

• allopurinol (Zyloprim, Aloprim, Lopurin)
• thioguanine (Tabloid, 6-TG, 6-Thioguanine)
• aminosalicylates such as mesalamine (Apriso, Asacol, Pentasa), olsalazine (Dipentum), and sulfasalazine (Azulfidine)
• blood thinners such as warfarin (Coumadin, Jantoven)
• doxorubicin (Doxil)
• trimethoprim/sulfamethoxazole (Bactrim, Septra)

This is not a complete list of mercaptopurine drug interactions. Ask your doctor or pharmacist for more information.

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Mercaptopurine falls into category D. It has been shown that use of mercaptopurine in pregnant women caused some babies to be born with problems. However, in some serious situations, the benefit of using this medication may be greater than the risk of harm to the baby.

Avoiding pregnancy while taking mercaptopurine is recommended in women of childbearing potential.

Tell your doctor if you are breastfeeding or plan to breastfeed.

It is not known if mercaptopurine crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, a choice should be made whether to stop nursing or stop the use of this medication. Your doctor and you will decide if the benefits outweigh the risk of using mercaptopurine.

Since mercaptopurine can affect how you fight infections, you may become more susceptible to infections and even to negative reactions of live vaccines. Tell your healthcare provider if you are feeling “under the weather” or are running a fever.

Also, let your healthcare provider know if you are scheduled to receive a vaccination, as your response to vaccines may be diminished and live vaccinations can make you sick.

Since mercaptopurine can cause a low platelet count (thrombocytopenia), tell your doctor right away if you have any unusual bleeding, such as nosebleeds, or bruising under your skin.