Mercaptopurine

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Generic Name: Mercaptopurine Brand Name(s): Generics only. No brands available.

Uses

What is Mercaptopurine used for?

Mercaptopurine is used with other drugs to treat a certain type of cancer (acute lymphocytic leukemia). It is a chemotherapy drug that works by slowing or stopping the growth of cancer cells.

Talk to the doctor about the risks and benefits of mercaptopurine, especially when used in children and young adults.

How should I take Mercaptopurine?

Take this medication by mouth with or without food as directed by your doctor, usually once daily. Drink plenty of fluids while taking this medication unless otherwise directed by your doctor. Doing so may help decrease the risk of certain side effects (kidney problems).

If you are using the suspension, shake the bottle well for at least 30 seconds before each dose. Carefully measure the dose using the provided special measuring device. Do not use a household spoon because you may not get the correct dose. Avoid getting any of the suspension on your skin or in your eyes. If contact occurs, wash the affected skin area or rinse your eyes with water. Consult your pharmacist for details.

The dosage is based on your medical condition, weight, and response to treatment. Do not increase your dose or use this drug more often or for longer than prescribed. Your condition will not improve any faster, and your risk of serious side effects will increase.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day.

Since this drug can be absorbed through the skin and lungs and may harm an unborn baby, women who are pregnant or who may become pregnant should not handle this medication or breathe the dust from the tablets.

How do I store Mercaptopurine?

Mercaptopurine is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Mercaptopurine in the bathroom or the freezer. There may be different brands of Mercaptopurine that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Mercaptopurine down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Mercaptopurine?

Before taking mercaptopurine, tell your doctor or pharmacist if you are allergic to it; or to azathioprine; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease, liver disease, cancer, a certain enzyme disorder (TPMT deficiency).

Mercaptopurine can make you more likely to get infections or may worsen any current infections. Avoid contact with people who have infections that may spread to others (such as chickenpox, measles, flu). Consult your doctor if you have been exposed to an infection or for more details.

Do not have immunizations/vaccinations without the consent of your doctor. Avoid contact with people who have recently received live vaccines (such as flu vaccine inhaled through the nose).

To lower the chance of getting cut, bruised, or injured, use caution with sharp objects like razors and nail cutters, and avoid activities such as contact sports.

This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Since this drug can be absorbed through the skin and lungs and may harm an unborn baby, women who are pregnant or who may become pregnant should not handle this medication or breathe the dust from the tablets.

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using mercaptopurine. Mercaptopurine may harm an unborn baby, especially during the first 3 months of pregnancy. Ask about reliable forms of birth control while using this medication. If you become pregnant, talk to your doctor right away about the risks and benefits of this medication.

It is unknown if this drug passes into breast milk. Consult your doctor before breast-feeding.

Is it safe during pregnancy or breast-feeding?

There are no adequate studies in women for determining risk when using this Mercaptopurine during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking Mercaptopurine. Mercaptopurine is pregnancy risk category D according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk,
  • B=No risk in some studies,
  • C=There may be some risk,
  • D=Positive evidence of risk,
  • X=Contraindicated,
  • N=Unknown

Side effects

What side effects can occur from Mercaptopurine?

Nausea, vomiting, diarrhea, and loss of appetite may occur. Temporary hair loss may also occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

People using this medication may have serious side effects. However, your doctor has prescribed this drug because he or she has judged that the benefit to you is greater than the risk of side effects. Careful monitoring by your doctor may decrease your risk.

Tell your doctor right away if you have any serious side effects, including: joint pain/swelling, black stools, vomit that looks like coffee grounds, signs of kidney problems (such as change in the amount of urine, pain in the lower back/side).

Get medical help right away if you have any very serious side effects, including: symptoms of liver disease (such as nausea/vomiting that doesn’t stop, stomach/abdominal pain, yellowing eyes/skin, dark urine).

This medication may decrease bone marrow function, an effect that may lead to a low number of blood cells such as red cells, white cells, and platelets. This effect can cause anemia, decrease your body’s ability to fight an infection, or cause easy bruising/bleeding. Tell your doctor right away if you develop any of the following symptoms: unusual tiredness, pale skin, signs of infection (such as sore throat that doesn’t go away, fever, chills), easy bruising/bleeding.

Mercaptopurine may rarely increase your risk of developing certain types of cancer (such as lymphoma, skin, cervical). This risk is higher in children/young adults being treated for certain bowel diseases (such as Crohn’s disease, ulcerative colitis). Keep all medical and laboratory appointments. Tell your doctor right away if you develop any of the following symptoms: swollen abdomen, swollen lymph nodes, night sweats, unexplained weight loss, unusual skin changes (such as new skin lesion or bump, or change in size or color of a mole), unusual vaginal bleeding/discharge.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), dizziness, trouble breathing.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Interactions

What drugs may interact with Mercaptopurine?

Some products that may interact with this drug are: febuxostat, other drugs that weaken the immune system/increase the risk of infection (such as rituximab, tofacitinib).

This medication may interfere with certain lab tests (such as uric acid levels), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

Mercaptopurine is very similar to azathioprine. Do not use medications containing azathioprine while using mercaptopurine.

Mercaptopurine may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with Mercaptopurine?

Mercaptopurine may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Mercaptopurine?

Mercaptopurine may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

Dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this Mercaptopurine.

What is the dose of Mercaptopurine for an adult?

Usual Adult Dose for Intestinal Arterial Insufficiency

Initial Dosage:

Oral: 2.5 mg/kg of body weight per day (100 to 200 mg in the average adult). This dose may be continued daily for several weeks or more in some patients. If, after 4 weeks at this dosage, there is no clinical improvement and no definite evidence of leukocyte or platelet depression, the dosage may be increased up to 5 mg/kg daily. A dosage of 2.5 mg/kg per day may result in a rapid fall in leukocyte count within 1 to 2 weeks in some adults with acute lymphatic leukemia and high total leukocyte counts.

The total daily dosage may be given at one time. It is calculated to the nearest multiple of 25 mg.

Maintenance Therapy: Once a complete hematologic remission is obtained, maintenance therapy is considered essential. A usual daily maintenance dose of mercaptopurine is 1.5 to 2.5 mg/kg per day as a single dose. Mercaptopurine should rarely be relied upon as a single agent for the maintenance of remissions induced in acute leukemia.

Usual Adult Dose for Acute Lymphoblastic Leukemia

Initial Dosage:

Oral: 2.5 mg/kg of body weight per day (100 to 200 mg in the average adult). This dose may be continued daily for several weeks or more in some patients. If, after 4 weeks at this dosage, there is no clinical improvement and no definite evidence of leukocyte or platelet depression, the dosage may be increased up to 5 mg/kg daily. A dosage of 2.5 mg/kg per day may result in a rapid fall in leukocyte count within 1 to 2 weeks in some adults with acute lymphatic leukemia and high total leukocyte counts.

The total daily dosage may be given at one time. It is calculated to the nearest multiple of 25 mg.

Maintenance Therapy: Once a complete hematologic remission is obtained, maintenance therapy is considered essential. A usual daily maintenance dose of mercaptopurine is 1.5 to 2.5 mg/kg per day as a single dose. Mercaptopurine should rarely be relied upon as a single agent for the maintenance of remissions induced in acute leukemia.

Usual Adult Dose for Crohn’s Disease – Acute

Oral: 1.0 to 1.5 mg/kg of body weight per day

Usual Adult Dose for Crohn’s Disease – Maintenance

Oral: 1.0 to 1.5 mg/kg of body weight per day

Usual Adult Dose for Ulcerative Colitis – Maintenance

Oral: 1.0 to 1.5 mg/kg of body weight per day

Usual Adult Dose for Inflammatory Bowel Disease

Oral: 1.0 to 1.5 mg/kg of body weight per day

Renal Dose Adjustments

It is probably advisable to start with smaller dosages in patients with impaired renal function, since the latter might result in slower elimination of the drug and metabolites and a greater cumulative effect.

Liver Dose Adjustments

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

Dose Adjustments

The dosage which will be tolerated and be effective varies from patient to patient, and therefore careful titration is necessary to obtain the optimum therapeutic effect without incurring excessive, unintended toxicity.

The dosage of mercaptopurine should be reduced to one third to one quarter of the usual dose if allopurinol is given concurrently.

Because the drug may have a delayed action, it should be discontinued at the first sign of an abnormally large or rapid fall in the leukocyte or platelet count. If subsequently the leukocyte count or platelet count remains constant for 2 or 3 days, or rises, treatment may be resumed.

Precautions

The most frequent, serious, toxic effect of mercaptopurine is myelosuppression resulting in leukopenia, thrombocytopenia, and anemia.

If it is not the intent to deliberately induce bone marrow hypoplasia, it is important to discontinue the drug temporarily at the first evidence of an abnormally large fall in white blood cell count, platelet count, or hemoglobin concentration.

Other Comments

Mercaptopurine is a potent drug. It should not be used unless a diagnosis of acute lymphatic leukemia has been adequately established.

What is the dose of Mercaptopurine for a child?

Usual Pediatric Dose for Intestinal Arterial Insufficiency

Initial Dosage:

Oral: 2.5 mg/kg of body weight per day (50 mg in an average 5-year-old child). Pediatric patients with acute leukemia have tolerated this dose without difficulty in most cases; it may be continued daily for several weeks or more in some patients. If, after 4 weeks at this dosage, there is no clinical improvement and no definite evidence of leukocyte or platelet depression, the dosage may be increased up to 5 mg/kg daily. A dosage of 2.5 mg/kg per day may result in a rapid fall in leukocyte count within 1 to 2 weeks in some adults with acute lymphatic leukemia and high total leukocyte counts.

The total daily dosage may be given at one time. It is calculated to the nearest multiple of 25 mg.

Maintenance Therapy: Once a complete hematologic remission is obtained, maintenance therapy is considered essential. A usual daily maintenance dose of mercaptopurine is 1.5 to 2.5 mg/kg per day as a single dose. It is to be emphasized that in pediatric patients with acute lymphatic leukemia in remission, superior results have been obtained when mercaptopurine has been combined with other agents (most frequently with methotrexate) for remission maintenance. Mercaptopurine should rarely be relied upon as a single agent for the maintenance of remissions induced in acute leukemia.

Usual Pediatric Dose for Acute Lymphoblastic Leukemia

Initial Dosage:

Oral: 2.5 mg/kg of body weight per day (50 mg in an average 5-year-old child). Pediatric patients with acute leukemia have tolerated this dose without difficulty in most cases; it may be continued daily for several weeks or more in some patients. If, after 4 weeks at this dosage, there is no clinical improvement and no definite evidence of leukocyte or platelet depression, the dosage may be increased up to 5 mg/kg daily. A dosage of 2.5 mg/kg per day may result in a rapid fall in leukocyte count within 1 to 2 weeks in some adults with acute lymphatic leukemia and high total leukocyte counts.

The total daily dosage may be given at one time. It is calculated to the nearest multiple of 25 mg.

Maintenance Therapy: Once a complete hematologic remission is obtained, maintenance therapy is considered essential. A usual daily maintenance dose of mercaptopurine is 1.5 to 2.5 mg/kg per day as a single dose. It is to be emphasized that in pediatric patients with acute lymphatic leukemia in remission, superior results have been obtained when mercaptopurine has been combined with other agents (most frequently with methotrexate) for remission maintenance. Mercaptopurine should rarely be relied upon as a single agent for the maintenance of remissions induced in acute leukemia.

How is Mercaptopurine available?

Mercaptopurine is available in the following dosage forms and strengths:

  • Oral tablet,
  • Oral suspension

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Mercaptopurine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Review Date: March 23, 2018 | Last Modified: March 23, 2018

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