Mercaptopurine

Pronunciation

Generic Name: mercaptopurine (mer-KAP-toe-PURE-een)
Brand Name: Purinethol

Mercaptopurine is used for:

Treating acute lymphatic leukemia along with other medicines. It may also be used for other conditions as determined by your doctor.

Mercaptopurine is an antimetabolite. It works by blocking the growth of certain cancer cells.

Do NOT use mercaptopurine if:

  • you are allergic to any ingredient in mercaptopurine
  • you have previously taken mercaptopurine or thioguanine and your cancer did not respond to it

Contact your doctor or health care provider right away if any of these apply to you.

Slideshow: 2014 Update - First Time Brand-to-Generic Switches

Before using mercaptopurine:

Some medical conditions may interact with mercaptopurine. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

  • if you are pregnant, planning to become pregnant, or are breast-feeding
  • if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
  • if you have allergies to medicines, foods, or other substances
  • if you have liver or kidney problems
  • if you have an infection (including chickenpox) or a history of frequent or prolonged infections, or you have recently had a vaccination
  • if you have a history of bone marrow problems, anemia, low white blood cell or platelet levels, or unusual bruising or bleeding
  • if you have a history of bowel inflammation (eg, Crohn disease, ulcerative colitis)
  • if you have certain enzyme deficiencies (thiopurine methyltransferase [TPMT] or xanthine oxidase) or you have recently had a blood transfusion

Some MEDICINES MAY INTERACT with mercaptopurine. Tell your health care provider if you are taking any other medicines, especially any of the following:

  • Medicine that may harm the liver (eg, acetaminophen, methotrexate, ketoconazole, isoniazid, certain medicines for HIV infection) because the risk of liver problems may be increased. Ask your doctor if you are unsure if any of your medicines might harm the liver
  • Allopurinol, aminosalicylates (eg, mesalamine, olsalazine, sulfasalazine), or medicines that may weaken the immune system because they may increase the risk of mercaptopurine's side effects. Talk with your doctor if you are not sure if any of your medicines may weaken the immune system
  • Warfarin because its effectiveness may be decreased by mercaptopurine

This may not be a complete list of all interactions that may occur. Ask your health care provider if mercaptopurine may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

How to use mercaptopurine:

Use mercaptopurine as directed by your doctor. Check the label on the medicine for exact dosing instructions.

  • Take mercaptopurine by mouth with or without food.
  • Drinking extra fluids while you are taking mercaptopurine is recommended. Check with your doctor for instructions.
  • Ask your doctor if you should follow any special guidelines for handling mercaptopurine.
  • If you miss a dose of mercaptopurine, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Ask your health care provider any questions you may have about how to use mercaptopurine.

Important safety information:

  • Mercaptopurine may lower the ability of your body to fight infection. Avoid contact with people who have colds or infections. Tell your doctor if you notice signs of infection like fever, sore throat, rash, or chills.
  • Mercaptopurine may reduce the number of clot-forming cells (platelets) in your blood. Avoid activities that may cause bruising or injury. Tell your doctor if you have unusual bruising or bleeding. Tell your doctor if you have dark, tarry, or bloody stools.
  • Tell your doctor or dentist that you take mercaptopurine before you receive any medical or dental care, emergency care, or surgery.
  • Talk with your doctor before you receive any vaccine while you are taking mercaptopurine.
  • Mercaptopurine may increase your risk of developing a tumor or other cancer. Contact your doctor right away if you notice any unusual growths or lumps. Discuss any questions or concerns with your doctor.
  • A rare type of cancer called hepatosplenic T-cell lymphoma (HSTCL) has been reported in patients using mercaptopurine. These cases have been fatal. Most of these cases occurred in teenagers or young adults. Most of these patients were using mercaptopurine to treat certain types of bowel inflammation (eg, Crohn disease, ulcerative colitis). The safety and effectiveness of using mercaptopurine to treat bowel inflammation have not been confirmed. Tell your doctor if you have or have ever had any type of cancer. Tell your doctor right away if you develop stomach pain or tenderness, fever, night sweats, or unexplained weight loss.
  • Mercaptopurine may cause severe liver problems. Rarely, this may be fatal. Taking more than the recommended dose may increase this risk. Contact your doctor right away if you develop yellowing of the skin or eyes, dark urine, pale stools, nausea, stomach pain, loss of appetite, or unusual tiredness.
  • If you have diarrhea, loss of appetite, nausea, or vomiting, talk with your doctor. There may be ways to lower these side effects.
  • An enzyme called TPMT helps to break mercaptopurine down in the body. Infrequently, some patients may have decreased TPMT enzyme activity. This may increase the risk of developing serious side effects (eg, severe bone marrow problems). Patients with decreased TPMT enzyme activity may need a lower dose of mercaptopurine. Discuss any questions or concerns with your doctor.
  • Lab tests, including complete blood cell counts, liver function, and TPMT enzyme activity, may be performed while you use mercaptopurine. These tests may be used to monitor your condition or to check for side effects. Be sure to keep all doctor and lab appointments.
  • If you may become pregnant, use an effective form of birth control while you take mercaptopurine. If you have questions about effective birth control, talk with your doctor.
  • PREGNANCY and BREAST-FEEDING: Mercaptopurine may cause harm to the fetus. The risk of losing the fetus may be increased if taking mercaptopurine in the first trimester but could happen at any time during pregnancy. Do not become pregnant while you are using it. If you think you may be pregnant, contact your doctor. You will need to discuss the benefits and risks of taking mercaptopurine while you are pregnant. It is not known if mercaptopurine is found in breast milk. Do not breast-feed while taking mercaptopurine.

Possible side effects of mercaptopurine:

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Diarrhea; loss of appetite; nausea; tiredness; vomiting.

Seek medical attention right away if any of these SEVERE side effects occur:

Severe allergic reactions (rash; itching; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); darkening of the skin; severe or persistent diarrhea, loss of appetite, nausea, or vomiting; shortness of breath; sores or white patches in the mouth; symptoms of bleeding (eg, throwing up blood or throw up that looks like coffee grounds; coughing up blood; blood in the urine; black, red, or tarry stools; bleeding from the gums; vaginal bleeding that is not normal; bruises without a reason or that get bigger; or any bleeding that is very bad or that you cannot stop); symptoms of infection (eg, fever, chills, cough, or sore throat; warm, red, or painful skin; increased or painful urination); unusual growths or lumps; unusual tiredness or weakness.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

If OVERDOSE is suspected:

Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately.

Proper storage of mercaptopurine:

Store mercaptopurine at room temperature, between 59 and 77 degrees F (15 and 25 degrees C). Store away from heat, moisture, and light. Do not store in the bathroom. Keep mercaptopurine out of the reach of children and away from pets.

General information:

  • If you have any questions about mercaptopurine, please talk with your doctor, pharmacist, or other health care provider.
  • Mercaptopurine is to be used only by the patient for whom it is prescribed. Do not share it with other people.
  • If your symptoms do not improve or if they become worse, check with your doctor.
  • Check with your pharmacist about how to dispose of unused medicine.

This information should not be used to decide whether or not to take mercaptopurine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about mercaptopurine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to mercaptopurine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using mercaptopurine.

Issue Date: November 5, 2014
Database Edition 14.4.1.002
Copyright © 2014 Wolters Kluwer Health, Inc.

Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using this medicine.

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