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Purinethol

Generic Name: mercaptopurine (Oral route)

mer-kap-toe-PURE-een

Commonly used brand name(s)

In the U.S.

  • Purinethol
  • Purixan

Available Dosage Forms:

  • Suspension
  • Tablet

Therapeutic Class: Antineoplastic Agent

Pharmacologic Class: Antimetabolite

Uses For Purinethol

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 lymphatic leukemia.

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

Slideshow: 2014 Update: First Time Brand-to-Generic Switches

Before you begin treatment with mercaptopurine, you and your doctor should talk about the benefits this medicine will do as well as the risks of using it.

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

Before Using Purinethol

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:

Allergies

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.

Pediatric

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.

Geriatric

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.

Pregnancy

Pregnancy Category Explanation
All Trimesters D Studies in pregnant women have demonstrated a risk to the fetus. However, the benefits of therapy in a life threatening situation or a serious disease, may outweigh the potential risk.

Breast Feeding

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.

Interactions with Medicines

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
  • Rotavirus 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 Type 4, Live
  • Adenovirus Vaccine Type 7, Live
  • Allopurinol
  • Azathioprine
  • Bacillus of Calmette and Guerin Vaccine, Live
  • Doxorubicin
  • Doxorubicin Hydrochloride Liposome
  • Influenza Virus Vaccine, Live
  • Measles Virus Vaccine, Live
  • Mesalamine
  • Mumps Virus Vaccine, Live
  • Olsalazine
  • Rubella Virus Vaccine, Live
  • Smallpox Vaccine
  • Sulfamethoxazole
  • Sulfasalazine
  • Trimethoprim
  • Typhoid Vaccine
  • Varicella Virus Vaccine
  • Warfarin
  • Yellow Fever Vaccine

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
  • Methotrexate

Interactions with Food/Tobacco/Alcohol

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.

Other Medical Problems

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.
  • 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.

Proper Use of mercaptopurine

This section provides information on the proper use of a number of products that contain mercaptopurine. It may not be specific to Purinethol. Please read with care.

Use this medicine exactly as directed by your doctor. Do not use more or less of it, and do not use it more often than your doctor ordered. Using too much may increase the chance of side effects, while using too little may not improve your condition.

Mercaptopurine is often given together with certain other medicines. If you are using a combination of medicines, make sure that you take each one at the right time and do not mix them. Ask your doctor to help you plan a way to remember to take your medicines at the right times.

Shake the bottle for at least 30 seconds to make sure that the oral suspension is well mixed. Measure the dose with a marked measuring oral syringe and adaptor. Rinse the dosing syringe with warm soapy water 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.

Dosing

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. The starting dose is usually 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.

Missed Dose

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.

Storage

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 suspension within 6 weeks.

Precautions While Using Purinethol

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. If you think you have become pregnant while using this medicine, tell your doctor right away.

Do not use this medicine if you are also taking azathioprine (Imuran®). Using these medicines together could cause serious unwanted effects. Also, do not use this medicine if you have been treated with mercaptopurine or thioguanine (Tabloid®) in the past and did not work well.

This medicine may increase your risk of getting certain types of 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). Talk with your doctor if you have unusual bleeding, bruising, or weakness, swollen lymph nodes in the neck, underarms, or groin, or unexplained weight loss.

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 there is a chance you might get the infection the vaccine is meant to prevent. In addition, other persons living in your household should not take oral polio vaccine since there is a chance they could pass the polio virus on to you. Also, avoid persons who have taken oral polio vaccine. Do not get close to them and do not stay in the same room with them for very long. If you cannot take these precautions, you should consider wearing a protective face mask that covers the nose and mouth.

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.

Do not stop taking this medicine without checking first with your doctor.

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

Tell the doctor in charge that you are taking this medicine before you have any medical tests. The results of tests for the amount of sugar or uric acid in the blood measured by a machine called a sequential multiple analyzer (SMA) may be affected by this medicine.

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.

Purinethol Side Effects

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:

More common
  • Abdominal or stomach pain or tenderness
  • black, tarry stools
  • blood in the urine or stools
  • clay colored stools
  • cough or hoarseness
  • dark urine
  • decreased appetite
  • fever or chills
  • headache
  • itching
  • loss of appetite
  • lower back or side pain
  • nausea and vomiting
  • painful or difficult urination
  • pinpoint red spots on the skin
  • skin rash
  • swelling of the feet or lower legs
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • yellow eyes or skin
Less common
  • Bleeding gums
  • chest pain
  • joint pain
  • pale skin
  • shortness of breath
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • troubled breathing with exertion
Incidence not known
  • Abdominal or stomach cramping or burning
  • constipation
  • diarrhea
  • heartburn
  • indigestion
  • joint pain, stiffness, or swelling
  • lower back or side pain
  • 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:

Less common
  • Darkening of the skin
  • headache
  • weakness
Incidence not known
  • 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.

See also: Side effects (in more detail)

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