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PURINETHOL is a brand name for Mercaptopurine, supplied as a tablet. The medicine, its uses, side effects and dosage are the same regardless of brand.
Used for: PURINETHOL® (mercaptopurine tablets) is indicated for: • The maintenance therapy of the acute lymphatic (lymphocytic, lymphoblastic) leukemia as part of a combination regimen. Combination therapy with multiple agents has produced results superior to that achieved with mercaptopurine alone. The effectiveness of…
Verbatim from this product's HC label. Tap a section to expand.
1 Dosing considerations Once complete hematologic remission is obtained with induction and consolidation therapies, maintenance therapy with PURINETHOL in combination with other agents can be considered. This is indicated in children with acute lymphatic leukemia.
The use of mercaptopurine in maintenance schedules for adults with acute lymphatic leukemia has not been established to be effective. If remission is achieved, maintenance doses will vary from patient to patient. It is to be emphasized that in children 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. 5 mg/kg orally once daily as part of combination chemotherapy maintenance regimen. The response to this agent depends upon the particular sub classification of the acute lymphatic leukemia and the age of the patient (pediatric or adult).
Dosage modification in patients with TPMT and NUDT15 -deficiency TPMT deficiency Consider testing for TPMT and NUDT15 deficiency in patients who experience severe myelosuppression or repeated episodes of myelosuppression. PURINETHOL® (mercaptopurine) Page 7 of 34 Patients with inherited little or no thiopurine S-methyltransferase (TPMT) activity are at increased risk for severe PURINETHOL toxicity from conventional doses of mercaptopurine and generally require dose reduction (See 7 WARNINGS AND PRECUATIONS; Patients with NUDT15 variant).
The optimal starting dose for homozygous deficient patients has not been established. ) Most patients with heterozygous TPMT deficiency tolerated recommended PURINETHOL doses, but some require dose reduction. Genotypic and phenotypic testing of TPMT status are available.
(See 10 CLINICAL PHARMACOLOGY) NUDT15 deficiency Patients with inherited mutations in the NUDT15 gene are at an increased risk for severe mercaptopurine toxicity. These patients generally require dose reduction, particularly those being NUDT15 variant homozygotes (see 7 WARNINGS AND PRECAUTIONS, Hematologic).
Genotypic testing of NUDT15 variants may be considered before initiating 6-mercaptopurine therapy. In any case, close monitoring of blood counts is necessary. The prescribing physician is advised to establish whether dose reduction is required based on patient response to treatment as well as their genetic profile.
Use the lowest recommended starting dosage for PURINETHOL in patients with renal impairment (CLcr less than 50 mL/min). Adjust the dosage to maintain absolute neutrophil count (ANC) at a desirable level and for adverse reactions. Dosage Modification with Concomitant Use of Allopurinol Reduce the dose of PURINETHOL to one-third to one-quarter of the current dosage when coadministered with allopurinol (See 8 ADVERSE REACTION, Renal).
Dose Modification for Geriatrics No specific studies have been carried out in the elderly. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
4 Geriatrics). 4 Administration Do not administer to patients who are unable to swallow tablets. 5 Missed Dose If a dose is missed, the patient should be instructed to take their next dose as scheduled. Doses should not be doubled. 5 OVERDOSAGE Signs and symptoms of overdosage may be immediate such as anorexia, nausea, vomiting and diarrhea; or delayed such as myelosuppression, liver dysfunction, and gastroenteritis.
There is no known pharmacologic antagonist of mercaptopurine. The drug should be discontinued immediately if unintended toxicity occurs during treatment. If a patient is seen immediately following an accidental overdosage of the drug, induced emesis may be useful.
Active measures (such as the use of activated charcoal or gastric lavage) may not be effective in the event of overdose unless the procedure can be undertaken within 60 minutes of ingestion. Dialysis cannot be expected to clear mercaptopurine.
Hemodialysis is thought to be of marginal use due to the rapid intracellular incorporation of mercaptopurine into active metabolites with long persistence. 6 DOSAGE FORMS, STRENGTHS, COMPOSITION AND PACKAGING Table - Dosage Forms, Strengths, Composition and Packaging Route of Administration Dosage Form / Strength / Composition Non-medicinal Ingredients Oral Tablet / 50 mg Corn starch, lactose, magnesium stearate, potato starch and stearic acid.
1 Dosing considerations Once complete hematologic remission is obtained with induction and consolidation therapies, maintenance therapy with PURINETHOL in combination with other agents can be considered. This is indicated in children with acute lymphatic leukemia.
The use of mercaptopurine in maintenance schedules for adults with acute lymphatic leukemia has not been established to be effective. If remission is achieved, maintenance doses will vary from patient to patient. It is to be emphasized that in children 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. 5 mg/kg orally once daily as part of combination chemotherapy maintenance regimen. The response to this agent depends upon the particular sub classification of the acute lymphatic leukemia and the age of the patient (pediatric or adult).
Dosage modification in patients with TPMT and NUDT15 -deficiency TPMT deficiency Consider testing for TPMT and NUDT15 deficiency in patients who experience severe myelosuppression or repeated episodes of myelosuppression. PURINETHOL® (mercaptopurine) Page 7 of 34 Patients with inherited little or no thiopurine S-methyltransferase (TPMT) activity are at increased risk for severe PURINETHOL toxicity from conventional doses of mercaptopurine and generally require dose reduction (See 7 WARNINGS AND PRECUATIONS; Patients with NUDT15 variant).
The optimal starting dose for homozygous deficient patients has not been established. ) Most patients with heterozygous TPMT deficiency tolerated recommended PURINETHOL doses, but some require dose reduction. Genotypic and phenotypic testing of TPMT status are available.
(See 10 CLINICAL PHARMACOLOGY) NUDT15 deficiency Patients with inherited mutations in the NUDT15 gene are at an increased risk for severe mercaptopurine toxicity. These patients generally require dose reduction, particularly those being NUDT15 variant homozygotes (see 7 WARNINGS AND PRECAUTIONS, Hematologic).
• Patients who are hypersensitive to this drug or to any ingredient in the formulation. For a complete listing, see 6 DOSAGE FORMS, STRENGTHS, COMPOSITION AND PACKAGING section of the product monograph. • PURINETHOL® (mercaptopurine) should only be used when a diagnosis of acute leukemia has been adequately established and the responsible physician is knowledgeable in assessing response to chemotherapy.
Mercaptopurine is contraindicated in patients whose disease has demonstrated prior resistance to this drug. In animals and man there is usually complete cross-resistance between mercaptopurine and thioguanine. • Immunization using a live organism vaccine has the potential to cause infection in immunocompromised hosts.
Therefore, immunizations with live organism vaccines is contraindicated in patients treated with PURINETHOL (See 7 Warnings and Precautions; Immune). PURINETHOL® (mercaptopurine) Page 6 of 34
Not medical advice. Always read the patient information leaflet and follow your prescriber or pharmacist.
Other brands of Mercaptopurine in Canada.
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Dosage modification in Hepatic Impairment patients Use the lowest recommended starting dosage for PURINETHOL in patients with hepatic impairment. Adjust the dosage to maintain absolute neutrophil count (ANC) at a desirable level and for adverse reactions (See 7 WARNINGS AND PRECAUTIONS, Hepatic).
Dosage modification in Renal Impairment patients Consideration should be given to starting with smaller dosages in patients with impaired renal function, since these patients may have a slower elimination of the drug and a greater cumulative effect See 8 ADVERSE REACTIONS.
Use the lowest recommended starting dosage for PURINETHOL in patients with renal impairment (CLcr less than 50 mL/min). Adjust the dosage to maintain absolute neutrophil count (ANC) at a desirable level and for adverse reactions. Dosage Modification with Concomitant Use of Allopurinol Reduce the dose of PURINETHOL to one-third to one-quarter of the current dosage when coadministered with allopurinol (See 8 ADVERSE REACTION, Renal).
Dose Modification for Geriatrics No specific studies have been carried out in the elderly. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
4 Geriatrics). 4 Administration Do not administer to patients who are unable to swallow tablets. 5 Missed Dose If a dose is missed, the patient should be instructed to take their next dose as scheduled. Doses should not be doubled.
Description PURINETHOL® Tablets 50 mg are pale yellow to buff, scored tablets imprinted with "PURINETHOL" and "O4A". PURINETHOL® tablets are available in bottles of 25 and 60 tablets. For management of a suspected drug overdose, contact your regional poison control centre.
PURINETHOL® (mercaptopurine) Page 9 of 34 7 WARNINGS AND PRECAUTIONS General The safe and effective use of PURINETHOL® (mercaptopurine) demands a thorough knowledge of the natural history of the condition being treated. After selection of an initial dosage schedule, therapy will frequently need to be modified depending upon the patient's response and manifestations of toxicity.
The most frequent, serious, toxic effect of mercaptopurine is myelosuppression resulting in leukopenia, thrombocytopenia and anemia. Whether or not these manifestations demand modification or cessation of treatment and/or dosage depends both upon the response of the underlying disease and a careful consideration of supportive facilities (granulocyte and platelet transfusions) which may be available.
Life-threatening infections and bleeding have been observed as a consequence of mercaptopurine-induced granulocytopenia and thrombocytopenia. Severe hematologic toxicity may require supportive therapy with platelet transfusions for bleeding, and antibiotics and granulocyte transfusions if sepsis is documented.
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, as leukocyte and platelet counts continue to fall after treatment is stopped.
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 towards the megaloblastic series, characteristically seen with the folic acid antagonists and some other antimetabolites, are not seen with this drug.
It is recommended that evaluation of the hemoglobin or hematocrit, total white blood cell count and differential count, and quantitative platelet count be obtained weekly while the patient is on mercaptopurine therapy. The decision to increase, decrease, continue or discontinue a given dosage of mercaptopurine must be based not only on the absolute hematologic values, but also upon the rapidity with which changes are occurring.
In many instances, complete blood counts will need to be done more frequently than once weekly (often daily) in order to evaluate the effect of the therapy. The dosage of mercaptopurine may need to be reduced when this agent is combined with other drugs whose primary toxicity is myelosuppression.
PURINETHOL® (mercaptopurine) Page 10 of 34 Carcinogenesis and Mutagenesis PURINETHOL® in common with other anti-metabolites causes chromosomal aberrations in mice, rats and man and induces dominant-lethal mutations in male mice. Carcinogenic potential exists in man, as post-marketing surveys have documented the occurrence of acute non- lymphocytic leukaemia, acute myelogenous leukaemia and chronic myeloid leukaemia in patients treated with mercaptopurine.
These data include patients who received mercaptopurine for non-neoplastic disorders. In addition, post-marketing cases of the rare, very aggressive and usually fatal hepatosplenic T- cell lymphoma (HSTCL) have […]
Genotypic testing of NUDT15 variants may be considered before initiating 6-mercaptopurine therapy. In any case, close monitoring of blood counts is necessary. The prescribing physician is advised to establish whether dose reduction is required based on patient response to treatment as well as their genetic profile.
Dosage modification in Hepatic Impairment patients Use the lowest recommended starting dosage for PURINETHOL in patients with hepatic impairment. Adjust the dosage to maintain absolute neutrophil count (ANC) at a desirable level and for adverse reactions (See 7 WARNINGS AND PRECAUTIONS, Hepatic).
Dosage modification in Renal Impairment patients Consideration should be given to starting with smaller dosages in patients with impaired renal function, since these patients may have a slower elimination of the drug and a greater cumulative effect See