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Basic Drug Info
Drug Name:Mercaptopurine
Manufacturer:Mylan Pharmaceuticals Inc.
Other Info:Mylan Pharmaceuticals Inc.Morgantown, WV 26505REVISED DECEMBER 2004MCPT:R2



Clinical Trials:


Indications and Usage

Mercaptopurine tablets are indicated for maintenance therapy of acute lymphatic (lymphocytic, lymphoblastic) leukemia as part of a combination regimen.

The response to this agent depends upon the particular sub-classification of acute lymphatic leukemia and the age of the patient (pediatric or adult).Mercaptopurine tablets are not effective for prophylaxis or treatment of central nervous system leukemia.Mercaptopurine tablets are not effective in acute myelogenous leukemia, chronic lymphatic leukemia, the lymphomas (including Hodgkins Disease), or solid tumors.
Acute lymphocytic leukemia -- acute leukemia in which lymphoblasts and their progenitor cells predominate; the most common childhood cancer and accounts for 20 percent of adult acute leukemia; common ALL antigen (CALLA) expressed in most cases.

Precursor Cell Lymphoblastic Leukemia Lymphoma -- A neoplasm characterized by abnormalities of the lymphoid cell precursors leading to excessive lymphoblasts in the marrow and other organs. It is the most common cancer in children and accounts for the vast majority of all childhood leukemias.

Central Nervous System Leukemia --

Leukemia, Myelocytic, Acute -- acute leukemia arising from myeloid tissue in which the granular, polymorphonuclear leukocytes and their precursors predominate.

Chronic Lymphocytic Leukemia -- chronic leukemia characterized by morphologically mature but immunologically less mature lymphocytes; manifested by an abnormal accumulation of these cells in blood, bone marrow, and lymphatic tissue.

Lymphoma -- A general term for various neoplastic diseases of the lymphoid tissue.

Hodgkins Disease -- A malignant disease characterized by progressive enlargement of the lymph nodes, spleen, and general lymphoid tissue. In the classical variant, giant usually multinucleate Hodgkin's and REED-STERNBERG CELLS are present; in the nodular lymphocyte predominant variant, lymphocytic and histiocytic cells are seen.

solid tumor -- Cancer of body tissues other than blood, bone marrow, or the lymphatic system.

Contraindications

Mercaptopurine should not be used in patients whose disease has demonstrated prior resistance to this drug.

In animals and humans, there is usually complete cross-resistance between mercaptopurine and thioguanine.Mercaptopurine should not be used in patients who have a hypersensitivity to mercaptopurine or any component of the formulation.
Disease -- A definite pathologic process with a characteristic set of signs and symptoms. It may affect the whole body or any of its parts, and its etiology, pathology, and prognosis may be known or unknown.

Hypersensitivity -- Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.

Warnings

The most consistent, dose-related toxicity is bone marrow suppression.

This may be manifest by anemia, leukopenia, thrombocytopenia, or any combination of these.

Any of these findings may also reflect progression of the underlying disease.

In many patients with severe depression of the formed elements of the blood due to mercaptopurine, the bone marrow appears hypoplastic on aspiration or biopsy, whereas in other cases it may appear normocellular.

The qualitative changes in the erythroid elements toward the megaloblastic series, characteristically seen with the folic acid antagonists and some other antimetabolites, are not seen with this drug.

Life-threatening infections and bleeding have been observed as a consequence of mercaptopurine-induced granulocytopenia and thrombocytopenia.

Since mercaptopurine may have a delayed effect, it is important to withdraw the medication temporarily at the first sign of an unexpected abnormally large fall in any of the formed elements of the blood, if not attributable to another drug or disease process.Individuals who are homozygous for an inherited defect in the TPMT (thiopurine-S-methyltransferase) gene are unusually sensitive to the myelosuppressive effects of mercaptopurine and prone to developing rapid bone marrow suppression following the initiation of treatment.

Laboratory tests are available, both genotypic and phenotypic, to determine the TPMT status.

Substantial dose reductions are generally required for homozygous-TPMT deficiency patients (two non-functional alleles) to avoid the development of life threatening bone marrow suppression.

Although heterozygous patients with intermediate TPMT activity may have increased mercaptopurine toxicity, this is variable, and the majority of patients tolerate normal doses of mercaptopurine.

If a patient has clinical or laboratory evidence of severe toxicity, particularly myelosuppression, TPMT testing should be considered.

In patients who exhibit excessive myelosuppression due to 6-mercaptopurine, it may be possible to adjust the mercaptopurine dose and administer the usual dosage of other myelo-suppressive chemotherapy as required for treatment (see DOSAGE AND ADMINISTRATION).Bone marrow toxicity may be more profound in patients treated with concomitant allopurinol (see PRECAUTIONS: Drug Interactions and DOSAGE AND ADMINISTRATION).

This problem could be exacerbated by coadministration with drugs that inhibit TPMT, such as olsalazine, mesalazine, or sulphasalazine.
Branded Drugs
The following US Branded drugs contain Mercaptopurine


PURINETHOL -- TEVA PHARMACEUTICALS USA INC


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