Mercaptopurine

Pronunciation: mer-KAP-toe-PURE-een
Generic Name: Mercaptopurine
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


• you are taking azathioprine

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

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, or gout


• if you have an infection (including chickenpox), 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


• if you are taking a disease-modifying antirheumatic drug (DMARD) (eg, adalimumab, methotrexate)

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

• Alkylating agents (eg, chlorambucil, cyclophosphamide, melphalan) or tumor necrosis factor (TNF) blockers (eg, certolizumab, etanercept) because the risk of developing certain types of cancer may be increased


• Azathioprine because severe toxic effects, including severe bone marrow suppression or death, may occur


• Allopurinol, aminosalicylates (eg, mesalazine, olsalazine, sulfasalazine), angiotensin-converting enzyme (ACE) inhibitors (eg, enalapril), doxorubicin, or trimethoprim/sulfamethoxazole because they may increase the risk of Mercaptopurine's side effects


• Anticoagulants (eg, warfarin) or hydantoins (eg, phenytoin) because their 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 has 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. Contact your doctor right away if you develop dark urine, pale stools, stomach pain, or yellowing of the eyes or skin.


• Mercaptopurine may cause severe stomach or bowel problems. Contact your doctor right away if you develop nausea or vomiting.


• 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.


• PREGNANCY and BREAST-FEEDING: Mercaptopurine has been shown to cause harm to the fetus. 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. No COMMON side effects have been reported with Mercaptopurine. 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); dark urine; darkening of the skin; fever, chills, or sore throat; increased or painful urination; loss of appetite; nausea; pale stools; severe or persistent diarrhea; sores or white patches in the mouth; stomach pain, swelling, or tenderness; unusual bleeding or bruising; unusual growths or lumps; unusual tiredness or weakness; vomiting; yellowing of the skin or eyes.

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.

See also: Mercaptopurine side effects (in more detail)

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. Symptoms may include dark urine; loss of appetite; severe or persistent diarrhea, nausea, or vomiting; stomach pain; unusual bruising or bleeding; yellowing of the eyes or skin.

Proper storage of Mercaptopurine:

Store Mercaptopurine at room temperature, between 68 and 77 degrees F (20 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 is a summary only. It does not contain all information about Mercaptopurine. If you have questions about the medicine you are taking or would like more information, check with your doctor, pharmacist, or other health care provider.

Issue Date: February 1, 2012

Database Edition 12.1.1.002

Copyright © 2012 Wolters Kluwer Health, Inc.

More Mercaptopurine resources

• Mercaptopurine Side Effects (in more detail)
• Mercaptopurine Use in Pregnancy & Breastfeeding
• Drug Images
• Mercaptopurine Drug Interactions
• Mercaptopurine Support Group
• 4 Reviews for Mercaptopurine - Add your own review/rating

• Mercaptopurine Prescribing Information (FDA)


• Mercaptopurine Monograph (AHFS DI)


• Mercaptopurine Professional Patient Advice (Wolters Kluwer)


• mercaptopurine Concise Consumer Information (Cerner Multum)


• mercaptopurine Advanced Consumer (Micromedex) - Includes Dosage Information


• Purinethol Prescribing Information (FDA)

Compare Mercaptopurine with other medications

• Acute Lymphoblastic Leukemia
• Autoimmune Hepatitis
• Crohn's Disease, Acute
• Crohn's Disease, Maintenance
• Inflammatory Bowel Disease
• Intestinal Arterial Insufficiency
• Ulcerative Colitis, Maintenance