Mercaptopurine

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using mercaptopurine and call your doctor right away if you have any of these symptoms of lymphoma:

• fever, night sweats, weight loss, tiredness;
• feeling full after eating only a small amount;
• pain in your upper stomach that may spread to your shoulder;
• easy bruising or bleeding, pale skin, feeling light-headed or short of breath, rapid heart rate; or
• nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Also call your doctor at once if you have:

• signs of infection (fever, swollen gums, painful mouth sores, pain when swallowing, skin sores, cold or flu symptoms, cough, trouble breathing);
• unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;
• severe nausea, vomiting, or diarrhea;
• pain or burning with urination; or
• bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds.

Common side effects may include:

• nausea, vomiting, loss of appetite;
• diarrhea; or
• skin rash.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

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.

Mercaptopurine is part of the drug class:

• Purine analogues

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.

Before taking mercaptopurine, tell your doctor about all of your medical conditions. Especially tell your doctor 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
• have liver problems
• have kidney problems
• have blood problems
• have any type of infection
• are scheduled to receive a vaccine
• are scheduled to receive surgery
• have a genetic deficiency with a specific enzyme called the TPMT enzyme
• are pregnant or breastfeeding

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

Your doctor or pharmacist can provide more information about mercaptopurine.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

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You should not use mercaptopurine if you have ever used mercaptopurine or thioguanine (Tabloid) and they were not effective in treating your condition.

Some people using mercaptopurine have developed a rare fast-growing type of lymphoma (cancer). This condition affects the liver, spleen, and bone marrow, and it can be fatal.

Call your doctor at once if you have symptoms of lymphoma, such as: fever, night sweats, weight loss, tiredness, feeling full after eating only a small amount, pain in your upper stomach, easy bruising or bleeding, dark urine, or jaundice (yellowing of the skin or eyes).

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Shake the oral suspension (liquid) well just before you measure a dose. Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

Mercaptopurine can lower blood cells that help your body fight infections and help your blood to clot. Your blood will need to be tested often. Your kidney and liver function may also need to be checked. Your cancer treatments may be delayed based on the results of these tests.

Store at room temperature away from moisture and heat.

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.

This medicine can pass into body fluids (urine, feces, vomit). Caregivers should wear rubber gloves while cleaning up a patient's body fluids, handling contaminated trash or laundry or changing diapers. Wash hands before and after removing gloves. Wash soiled clothing and linens separately from other laundry.

Do not receive a "live" vaccine while using mercaptopurine, and avoid coming into contact with anyone who has recently received a live vaccine. There is a chance that the virus could be passed on to you. Live vaccines include measles, mumps, rubella (MMR), polio, rotavirus, typhoid, yellow fever, varicella (chickenpox), zoster (shingles), and nasal flu (influenza) vaccine.

It is very important that your doctor check your progress at regular visits to make sure that mercaptopurine is working properly. Blood tests may be needed to check for unwanted effects. Genetic testing may also be performed to check your levels of thiopurine S-methyltransferase (an enzyme needed to metabolize mercaptopurine).

Using mercaptopurine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during therapy. If you think you have become pregnant while using mercaptopurine, tell your doctor right away.

Mercaptopurine can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

• If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
• Check with your doctor immediately if you notice any unusual bleeding or bruising, black, tarry stools, blood in the urine or stools, or pinpoint red spots on your skin.
• Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
• Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
• Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
• Avoid contact sports or other situations where bruising or injury could occur.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.

While you are being treated with mercaptopurine, and after you stop treatment with it, do not have any immunizations (vaccines) without your doctor's approval. Mercaptopurine may lower your body's resistance and the vaccine may not work as well or you might get the infection the vaccine is meant to prevent. In addition, you should not be around other persons living in your household who receive live virus vaccines because there is a chance they could pass the virus on to you. Some examples of live vaccines include measles, mumps, influenza (nasal flu vaccine), poliovirus (oral form), rotavirus, and rubella. Do not get close to them and do not stay in the same room with them for very long. If you have questions about this, talk to your doctor.

mercaptopurine may increase your risk of getting certain types of cancer, including skin cancer and cervical cancer. Some teenagers and young adults with Crohn's disease or ulcerative colitis developed a rare type of cancer called hepatosplenic T-cell lymphoma (HSTCL). Check with your doctor right away if you have unusual bleeding, bruising, or weakness, swollen lymph nodes in the neck, underarms, or groin, or unexplained weight loss.

mercaptopurine may cause a life-threatening condition called macrophage activation syndrome (MAS). This usually occurs in patients with an autoimmune disease (eg, inflammatory bowel disease) or virus infection (eg, Epstein-Barr, cytomegalovirus), and must be treated immediately. Tell your doctor right away if you have a fever, cough that does not go away, redness in one part of your body, or warm feeling or swelling of your skin.

mercaptopurine may make your skin more sensitive to sunlight. Wear sunscreen. Do not use sunlamps or tanning beds.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

• Black, tarry stools
• clay colored stools
• cough or hoarseness
• dark urine
• decreased appetite
• fever or chills
• headache
• loss of appetite
• lower back or side pain
• nausea, vomiting
• painful or difficult urination
• pinpoint red spots on the skin
• rash, itchy skin
• stomach pain or tenderness
• swelling of the feet or lower legs
• unusual bleeding or bruising
• unusual tiredness or weakness
• yellow eyes or skin

• Bleeding gums
• chest pain
• joint pain
• pale skin
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• swollen glands
• trouble with breathing upon exertion

• Constipation
• diarrhea
• heartburn
• indigestion
• joint pain, stiffness, or swelling
• stomach cramping or burning
• vomiting of blood or material that looks like coffee grounds

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Darkening of the skin
• headache

• Hair loss or thinning of the hair
• low sperm count

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

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

Mercaptopurine tablets are indicated for maintenance therapy of acute lymphatic (lymphocytic, lymophoblastic) leukemia as part of a combination regimen. The response to this agent depends upon the particular subclassification of acute lymphatic leukemia and the age of the patient (pediatric or adult).

Mercaptopurine tablets are not effective prophylaxis or treatment of central nervous system leukemia.

Mercaptopurine tablets are not effective in acute myelogenous leukemia, chronic lymphatic leukemia, the lymphomas (including Hodgkins Disease), or solid tumors.

Signs and symptoms of overdosage may be immediate (anorexia, nausea, vomiting, and diarrhea); or delayed (myelosuppression, liver dysfunction, and gastroenteritis). Dialysis cannot be expected to clear Mercaptopurine. Hemodialysis is thought to be of marginal use due to the rapid intracellular incorporation of Mercaptopurine into active metabolites with long persistence. The oral LD50 of Mercaptopurine was determined to be 480 mg/kg in the mouse and 425 mg/kg in the rat.

There is no known pharmacologic antagonist of Mercaptopurine. The drug should be discontinued immediately if unintended toxicity occurs during treatment. If a patient is seen immediately following an accidental overdosage of the drug, it may be useful to induce emesis.

Distr. by: West-Ward

Pharmaceuticals Corp.

Eatontown, NJ 07724

10002106/07 Revised August 2016

• Purinethol [DSC]
• Purixan

The manufacturer's labeling recommends starting with reduced doses (starting at the low end of the dosing range) or increasing the dosing interval to every 36 to 48 hours to avoid accumulation in patients with renal impairment; however, no specific dosage adjustment is provided. The following adjustments have also been recommended (Aronoff 2007): Children:

CrCl ≤50 mL/minute/1.73 m2: Administer every 48 hours

Hemodialysis: Administer every 48 hours

Continuous ambulatory peritoneal dialysis (CAPD): Administer every 48 hours

Continuous renal replacement therapy (CRRT): Administer every 48 hours

Administer preferably on an empty stomach (Burton 1986; Kantarjian 2000); avoid concomitant milk products if possible (de Lemos 2007). Administer at the same time(s) each day.

Acute lymphoblastic leukemia (ALL) treatment in children (Schmiegelow 1997): Administration in the evening has demonstrated superior outcome; administration with food did not significantly affect outcome.

If adherence is limited by administering on an empty stomach in the evening or by avoiding concomitant milk products, simplification of administration (eg, take with food/dairy without regard to time of day) should be considered. In adherent patients (taking mercaptopurine regularly), no association was seen between risk of ALL relapse and mercaptopurine ingestion habits; there was also no association noted with red cell thioguanine nucleotide (TGN) levels and administration with food, dairy, or time of day (Landier 2017).

Suspension: Shake well for at least 30 seconds to ensure suspension is mixed thoroughly (suspension is viscous). Measure dose with an oral dosing syringe (a 1 mL and a 5 mL oral dosing syringe are supplied by the manufacturer) to assure proper dose is administered. Patients and caregivers should be trained on appropriate measuring and administration, handling, storage, disposal, cleanup of accidental spills, and proper cleaning of oral dosing syringe. Use within 8 weeks after opening.

Frequency not always defined.

Central nervous system: Malaise (5% to 20%), drug fever

Dermatologic: Skin rash (5% to 20%), hyperpigmentation (<5%), urticaria (<5%), alopecia

Endocrine & metabolic: Hyperuricemia (<5%)

Gastrointestinal: Anorexia (5% to 20%), diarrhea (5% to 20%), nausea (5% to 20%; minimal), vomiting (5% to 20%; minimal), oral lesion (<5%), pancreatitis (<5%), cholestasis, mucositis, sprue-like symptoms, stomach pain, ulcerative bowel lesion

Genitourinary: Oligospermia, renal toxicity, uricosuria

Hematologic & oncologic: Bone marrow depression (>20%; onset 7 to 10 days; nadir 14 days; recovery: 21 days), anemia, granulocytopenia, hemorrhage, hepatosplenic T-cell lymphomas, leukopenia, lymphocytopenia, metastases, neutropenia, thrombocytopenia

Hepatic: Hyperbilirubinemia (<5%), increased serum transaminases (<5%), ascites, hepatic encephalopathy, hepatic fibrosis, hepatic injury, hepatic necrosis, hepatomegaly, hepatotoxicity, intrahepatic cholestasis, jaundice, toxic hepatitis

Immunologic: Immunosuppression

Infection: Infection

Respiratory: Pulmonary fibrosis

<1%, postmarketing, and/or case reports: Hypoglycemia, portal hypertension, skin photosensitivity

Consideration should be given to reducing the dosage in patients with impaired hepatic function.