6-MP (Mercaptopurine)

Mercaptopurine is used alone or with other chemotherapy drugs to treat acute lymphocytic leukemia (ALL; also called acute lymphoblastic leukemia and acute lymphatic leukemia; a type of cancer that begins in the white blood cells). Mercaptopurine is in a class of medications called purine antagonists. It works by stopping the growth of cancer cells.

Mercaptopurine comes as a tablet and a suspension (liquid) to take by mouth. It is usually taken once a day. Take mercaptopurine at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take mercaptopurine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

If you are taking the suspension, shake the bottle very well for 30 seconds before each use to mix the medication evenly. It is important to use an oral syringe (measuring device) to accurately measure and take your dose of mercaptopurine. If you do not find an oral syringe with your medication, ask your pharmacist to give you one. After you use the oral syringe to take your medication, remove the plunger from the rest of the measuring device, wash both parts with warm soapy water, and rinse under running tap water. Allow the parts to air dry before putting back together for the next use.

Continue to take mercaptopurine even if you feel well. Do not stop taking mercaptopurine without talking to your doctor

Mercaptopurine is also sometimes used to treat certain other types of cancer, Crohn's disease (a condition in which the body attacks the lining of the digestive tract causing pain, diarrhea, weight loss, and fever), and ulcerative colitis (condition in which sores develop in the intestines causing pain and diarrhea). Talk to your doctor about the possible risks of using this medication for your condition.

Before taking mercaptopurine,

• tell your doctor and pharmacist if you are allergic to mercaptopurine, any other medications, or any of the ingredients in mercaptopurine tablets or suspension. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: allopurinol (Lopurin, Zyloprim); aminosalicylates such as mesalamine (Apriso, Asacol, Canasa, Lialda, Delzicol, Pentasa, others), olsalazine (Dipentum), and sulfasalazine (Azulfidine); anticoagulants ('blood thinners') such as warfarin (Coumadin, Jantoven); doxorubicin (Doxil); and trimethoprim and sulfamethoxazole (Bactrim, Septra). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you have already taken mercaptopurine or thioguanine to treat your cancer. Your doctor may tell you not to take mercaptopurine if either of these medications did not work well against your cancer in the past.
• tell your doctor if you have any type of infection and if you have or have ever had liver or kidney disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. You should use birth control to avoid pregnancy during your treatment with mercaptopurine. If you become pregnant while taking mercaptopurine, call your doctor immediately. Mercaptopurine may harm the fetus.
• if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking mercaptopurine.
• do not have any vaccinations without talking to your doctor.
• you should know that the risk that you will develop serious side effects of mercaptopurine may be higher if you have a genetic (inherited) risk factor. Your doctor may order tests before or during your treatment to see if you have this risk factor.