Mercaptopurine

What is Mercaptopurine?

• Mercaptopurine (Purinethol; Purixan) is a nucleoside metabolic inhibitor used for treatment of adult and pediatric patients with acute lymphoblastic leukemia (ALL).

Mercaptopurine

Mercaptopurine molecule ball from xtal

Mercaptopurine 3D spacefill

What are the uses of this medicine?

Mercaptopurine is approved to be used with other drugs to treat:

• Acute lymphoblastic leukemia (ALL):
• It is used as maintenance therapy in adults and children.

How does this medicine work?

• Mercaptopurine (mer kap" toe pure' een) is a purine analogue that acts as an antimetabolite by antagonism of purine metabolism which results in a general inhibition of DNA, RNA and subsequent protein synthesis.
• Mercaptopurine also has antiinflammatory and immunosuppressive activity, inhibiting the maturation of T cells and blocking delayed hypersensitivity reactions.

Who Should Not Use this medicine ?

• This medicine have no usage limitations.

What drug interactions can this medicine cause?

Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following:

• allopurinol (Lopurin, Zyloprim)
• aminosalicylates such as mesalamine (Apriso, Asacol, Canasa, Lialda, Delzicol, Pentasa, others), olsalazine (Dipentum), and sulfasalazine (Azulfidine)
• anticoagulants ('blood thinners') such as warfarin (Coumadin, Jantoven)
• doxorubicin (Doxil)
• trimethoprim and sulfamethoxazole (Bactrim, Septra)

Is this medicine FDA approved?

• Mercaptopurine was introduced into use in the 1950s for the therapy of leukemia and lymphoma and was formally approved for use in the United States in 1953.
• It is still used in therapy of acute lymphocytic leukemia and off-label for autoimmune conditions such as Crohn’s disease.

How should this medicine be used?

Recommended dosage:

• The recommended starting dose of mercaptopurine tablets is 1.5 mg/kg to 2.5 mg/kg orally once daily as part of a combination chemotherapy maintenance regimen.
• Adjust dose to maintain desirable absolute neutrophil count and for excessive myelosuppression.

Renal Impairment:

• Use the lowest recommended starting dose or increase the dosing interval.

Hepatic Impairment:

• Use the lowest recommended starting dose.

Administration:

• Mercaptopurine comes as a tablet and a suspension (liquid) to take by mouth.
• It is usually taken once a day.
• Take mercaptopurine at around the same time every day.
• If you are taking the suspension, shake the bottle very well for 30 seconds before each use to mix the medication evenly.
• It is important to use an oral syringe (measuring device) to accurately measure and take your dose of mercaptopurine.

What are the dosage forms and brand names of this medicine?

This medicine is available in fallowing doasage form:

• As Tablets: 50 mg
• Oral suspension: 2000 mg/100 mL (20 mg/mL).

This medicine is available in fallowing brand namesː

• Purinethol; Purixan

What side effects can this medication cause?

The most common side effects of this medicine include: myelosuppression, including anemia, leukopenia and thrombocytopenia

Other side effects may include:

• anorexia
• nausea
• vomiting
• diarrhea
• malaise
• rash

What special precautions should I follow?

• The most consistent, dose-related adverse reaction is myelosuppression, manifested by anemia, leukopenia, thrombocytopenia, or any combination of these. Monitor complete blood count (CBC) and adjust the dose of mercaptopurine tablets for excessive myelosuppression. Consider testing in patients with severe myelosuppression or repeated episodes of myelosuppression for thiopurine S-methyltransferase (TPMT) or nucleotide diphosphatase (NUDT15) deficiency. Patients with homozygous or homozygous TPMT or NUDT15 deficiency may require a dose reduction.
• Mercaptopurine is hepatotoxic. Monitor transaminases, alkaline phosphatase and bilirubin. Withhold mercaptopurine tablets at onset of hepatotoxicity.
• Mercaptopurine is immunosuppressive and may impair the immune response to infectious agents or vaccines. Response to all vaccines may be diminished and there is a risk of infection with live virus vaccines. Consult immunization guidelines for immunocompromised patients.
• Aggressive and fatal cases of hepatosplenic T-cell lymphoma have occurred.
• Macrophage activation syndrome (MAS) (hemophagocytic lymphohistiocytosis) is a known, life-threatening disorder that may develop in patients with autoimmune conditions, in particular with inflammatory bowel disease (IBD), and there could potentially be an increased susceptibility for developing the condition with the use of mercaptopurine. Monitor for and treat promptly; discontinue mercaptopurine tablets.
• Mercaptopurine can cause fetal harm. Advise patients of reproductive potential of the potential risk to a fetus and to use effective contraception.
• Mercaptopurine therapy is associated with a high rate of serum aminotransferase elevations which can be accompanied by jaundice. In addition, mercaptopurine has been linked to instances of clinically apparent acute liver injury and long term therapy to nodular regenerative hyperplasia.

What to do in case of emergency/overdose?

Symptoms of overdosage may include:

• anorexia
• nausea
• vomiting
• diarrhea
• myelosuppression
• liver dysfunction
• gastroenteritis

Management of overdosage:

• Withhold mercaptopurine tablets immediately for severe or life-threatening adverse reactions occur during treatment.
• If a patient is seen immediately following an accidental overdosage, it may be useful to induce emesis.
• Dialysis cannot be expected to clear mercaptopurine.
• Hemodialysis is thought to be of marginal use.

Can this medicine be used in pregnancy?

• Mercaptopurine tablets can cause fetal harm when administered to a pregnant woman.
• Pregnant women who receive mercaptopurine have an increased incidence of miscarriage and stillbirth.
• Advise pregnant women of the potential risk to a fetus.

Can this medicine be used in children?

• Safety and effectiveness of mercaptopurine tablets have been established in pediatric patients.

What are the active and inactive ingredients in this medicine?

Active ingredient:

• MERCAPTOPURINE

Inactive ingredients:

• STARCH, CORN
• LACTOSE MONOHYDRATE
• MAGNESIUM STEARATE
• SODIUM LAURYL SULFATE

Who manufactures and distributes this medicine?

Manufactured for:

• Mylan Pharmaceuticals Inc.
• Morgantown, WV U.S.A.

Manufactured by:

• Auro PR Inc.
• RD 156 Caguas West Industrial Park, Lot 24
• Caguas, PR U.S.A.

What should I know about storage and disposal of this medication?

• Store at 20° to 25°C (68° to 77°F).
• Protect from moisture.
• Dispense in a tight, light-resistant container as defined in the USP using a child-resistant closure.
• Mercaptopurine tablets are a cytotoxic drug.
• Follow special handling and disposal procedures.

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• Dailymed label info on Mercaptopurine
• FDA Mercaptopurine

Mercaptopurine Resources
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