What is Mercaptopurine?

Mercaptopurine (6-MP) belongs to the group of medicines known as antimetabolites. It is used in combination with other medicines as maintenance treatment of acute lymphoblastic leukemia.

Mercaptopurine interferes with the growth of cancer cells, which are eventually destroyed. Since the growth of normal cells may also be affected by this medicine, other unwanted effects will also occur. Some of these may be serious and must be reported to your doctor.

This medicine is available only with your doctor's prescription.

Medicines used to treat cancer are very strong and can have many side effects. Before using this medicine, make sure you understand all the risks and benefits. It is important for you to work closely with your doctor during your treatment.

Use this medicine exactly as directed by your doctor. Do not use more of it, do not use it more often, and do not use it for a longer time than your doctor ordered.

Mercaptopurine is often given together with certain other medicines. If you are using a combination of medicines, it is important that you take each medicine at the right time. Follow your doctor's instructions on when to take these medicines.

Shake the oral liquid for at least 30 seconds to make sure that it is well mixed. Measure the dose with a marked measuring oral syringe and adaptor. Wash the dosing syringe with warm soapy water, rinse, and dry well after each use.

While you are using mercaptopurine, your doctor may want you to drink extra fluids so that you will pass more urine. This will help prevent kidney problems and keep your kidneys working well.

If you vomit shortly after taking a dose of mercaptopurine, check with your doctor. You will be told whether to take the dose again or to wait until the next scheduled dose.

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage forms (suspension or tablets):
  • For maintenance treatment of acute lymphatic leukemia:
    • Adults—Dose is based on body weight and must be determined by your doctor. At first, 1.5 to 2.5 milligrams (mg) per kilogram (kg) of body weight per day, taken as a single dose. Your doctor may adjust your dose as needed.
    • Children—Use and dose must be determined by your doctor.

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Once opened, use the oral liquid within 8 weeks.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Appropriate studies have not been performed on the relationship of age to the effects of mercaptopurine in the pediatric population. Safety and efficacy have not been established. The oral liquid may cause hypoglycemia (low blood sugar) in children younger than 6 years of age or with a low body mass index.

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of mercaptopurine in the elderly. However, elderly patients are more likely to have age-related kidney or liver problems, which may require caution and an adjustment in the dose for patients receiving mercaptopurine.

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

• Febuxostat
• Measles Virus Vaccine, Live
• Mumps Virus Vaccine, Live
• Rotavirus Vaccine, Live
• Rubella Virus Vaccine, Live
• Varicella Virus Vaccine, Live
• Zoster Vaccine, Live

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Adenovirus Vaccine
• Alacepril
• Alfalfa
• Allopurinol
• Azathioprine
• Bacillus of Calmette and Guerin Vaccine, Live
• Benazepril
• Black Cohosh
• Captopril
• Cholera Vaccine, Live
• Cilazapril
• Doxorubicin
• Doxorubicin Hydrochloride Liposome
• Enalaprilat
• Enalapril Maleate
• Fosinopril
• Influenza Virus Vaccine, Live
• Lisinopril
• Mesalamine
• Moexipril
• Mycophenolic Acid
• Olsalazine
• Oxypurinol
• Pentopril
• Perindopril
• Poliovirus Vaccine, Live
• Quinapril
• Ramipril
• Ribavirin
• Smallpox Vaccine
• Spirapril
• Sulfamethoxazole
• Sulfasalazine
• Trandolapril
• Trimethoprim
• Typhoid Vaccine
• Warfarin
• Yellow Fever Vaccine
• Zofenopril

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Acenocoumarol
• Cyclosporine
• Methotrexate
• Phenprocoumon

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Anemia or
• Blood or bone marrow problems or
• Bowel problems (eg, nausea, vomiting, diarrhea) or
• Gout or
• Leukopenia (low white blood cells) or
• Liver disease or
• Thrombocytopenia (low platelets in the blood)—Use with caution. May make these conditions worse.

• Autoimmune disease (eg, inflammatory bowel disease) or
• Virus infection (eg, Epstein-Barr, cytomegalovirus)—Use with caution. May cause side effects to become worse.

• Infection—May decrease your body's ability to fight infection.

• Kidney disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.

It is very important that your doctor check your progress at regular visits to make sure that this medicine 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 this medicine 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 this medicine, 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.

This medicine 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.

This medicine 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.

This medicine 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.