Mercaptopurine

The recommended dose of mercaptopurine varies according to the specific disease being treated, the response to therapy, the other medications used, the stage of the disease, and the person's body size or weight. A typical starting dose for adults and children is 2.5 mg per kg of body weight per day, or 50 mg to 75 mg per metre squared of body surface area per day. The appropriate dose of mercaptopurine is usually taken by mouth as a single dose on a daily basis.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Mercaptopurine can irritate the eyes and skin if they come into contact with the medication. Wash your hands with soap and water immediately after taking a dose of this medication to prevent particles of the tablet from spreading to other areas of the skin.

Your doctor or pharmacist may suggest that you take Mercaptopurine at a specific time of the day. Some studies suggest that the time of day Mercaptopurine is taken affects the success of the treatment.

It is important to take Mercaptopurine exactly as prescribed by your doctor. If you vomit shortly after taking the medicine, contact your doctor for instruction on whether to take more medication or not. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Your doctor may want you to drink extra fluids while taking Mercaptopurine in order to help you pass more fluid and protect your kidneys.

Store Mercaptopurine at room temperature, and protect it from excessive heat, direct light, and moisture. Keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

In addition to its desired action, this medication may cause some adverse effects, notably: it may cause mouth irritation and sores; it may decrease your appetite; it may cause diarrhea; it may affect your liver and may lead to jaundice in rare cases; it may lower your white blood cell count, which can lead to unusual tiredness, fever, chills, sore throat or infections - if you experience any of these symptoms, contact your doctor right away; it may make your skin more sensitive to UV rays (e.g., sunlight, tanning lamps) - avoid exposure to UV rays as much as possible and protect yourself when out in the sun. Each person may react differently to a treatment. If you think this medication may be causing adverse effects (including those described here, or others), talk to your health care professional. He or she can help you to determine whether or not the medication is the source of the problem.

Each pale yellow, scored, biconvex tablet, with product identification "54 420" on one side, contains 50 mg mercaptopurine. Nonmedicinal ingredients: corn starch, hypromellose, lactose monohydrate, lactose, sodium starch glycolate, magnesium stearate, potato starch, and stearic acid.

Do not take mercaptopurine if you:

• are allergic to mercaptopurine or any ingredients of Mercaptopurine
• have been resistant to the effects of mercaptopurine or Thioguanine in the past

There may be an interaction between mercaptopurine and any of the following:

• Allopurinol
• amphotericin B
• Azathioprine
• Clozapine
• Denosumab
• immunosuppressants (e.g., Prednisone, Dexamethasone, Tacrolimus, Cyclosporine)
• echinacea
• Febuxostat
• Leflunomide
• Mesalamine
• Natalizumab
• Pimecrolimus

• Olsalazine
• other cancer medications (e.g., Cyclophosphamide, Doxorubicin, Etoposide)
• sulfamethoxazole
• Sulfasalazine
• Trastuzumab
• Trimethoprim
• vaccines (e.g., yellow fever, BCG, Cholera, typhoid, varicella, meningococcal, diphtheria)
• Warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Mercaptopurine. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Mercaptopurine.

HEALTH CANADA ADVISORY

March 27, 2014

Health Canada has issued new restrictions concerning the use of Purinethol (mercaptopurine). To read the full Health Canada Advisory, visit Health Canada's web site at www.hc-sc.gc.ca.

Anemia: Mercaptopurine may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.

Birth control: Effective birth control should be practiced if either partner is using Mercaptopurine as Mercaptopurine may harm the baby if used during pregnancy. If you become pregnant while taking Mercaptopurine, contact your doctor immediately.

Bleeding: Mercaptopurine can reduce the number of platelet cells in the blood. Platelets help the blood to clot, and a shortage could make you bleed more easily. Tell your doctor of any signs that your blood is not clotting as quickly. Such symptoms may include black and tarry stools, blood in the urine, easy bruising, or cuts that won't stop bleeding.

Infection and vaccines: As well as killing cancer cells, Mercaptopurine can reduce the number of cells that fight infection in the body (white blood cells). Avoid contact with people with contagious infections and tell your doctor if you begin to notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness. Also tell your doctor if you have been vaccinated, or are planning to be vaccinated with a live vaccine.

Kidney function: Kidney Disease or reduced kidney function may cause Mercaptopurine to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how Mercaptopurine may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Mercaptopurine, and whether any special monitoring is needed.

Liver function: Mercaptopurine can reduce liver function and can cause liver failure. If you have liver problems, discuss with your doctor how Mercaptopurine may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Mercaptopurine, and whether any special monitoring is needed. Your doctor will test your liver function regularly with blood tests while you are taking Mercaptopurine.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Second cancers: Mercaptopurine can cause damage to other normal genes and cells. Rarely there have been reports of certain types of leukemia and lymphoma developing in people who have been treated with mercaptopurine. Discuss any concerns you may have with your doctor.

Tumour lysis syndrome: Mercaptopurine, like many other cancer medications, causes many cancer cells to be suddenly killed when treatment is first started. This can overwhelm the body with waste products from the cells. As a result, the body may not be able to keep up with getting rid of all the waste. When this happens, you may experience nausea, shortness of breath, notice cloudy urine or joint pain. This is called tumour lysis syndrome. Your doctor may prescribe some medications to help your body get rid of the waste products. Make sure you understand how to use these medications and report any of these signs or symptoms to your doctor immediately.

Pregnancy: There is a possibility of birth defect if either the man or woman is using mercaptopurine at the time of conception, or if it is taken during pregnancy. Effective birth control should be practiced while using Mercaptopurine. Mercaptopurine should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while you or your partner are taking Mercaptopurine, contact your doctor immediately.

Breast-feeding: Mercaptopurine passes into breast milk. Because of the risks associated with mercaptopurine, a decision should be made to cease breast-feeding or discontinue the medication, taking into account the importance of the medication to the mother. Women who are taking Mercaptopurine should not breast-feed.

Seniors: Seniors may be more likely to experience side effects from Mercaptopurine. Discuss any concerns you have with your doctor.

To fully benefit from the effect of this medication, and to limit any adverse reactions, make sure that the health care facility overseeing your treatment has provided you with all the information needed to properly administer this drug. This medication is typically used only once a day. However, your pharmacist may have suggested a different schedule that is more appropriate for you. Take it regularly and continuously to maintain its beneficial effects. Important: Follow the instructions on the label. Do not use more of this product, or more often, than prescribed. If you forget a dose, take it as soon as you remember -- unless it is almost time for your next dose. In that case, skip the missed dose. Do not double the next dose to catch up. This medication should not be taken with food. It is best taken on an empty stomach, one hour before or 2 hours after a meal. It is recommended to drink plenty of water while using this medication. To ensure effectiveness, avoid taking milk with this medication.