Mercaptopurine is 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 subclassification of acute lymphatic leukemia and the age of the patient (pediatric or adult).
Mercaptopurine is not effective for prophylaxis or treatment of central nervous system leukemia.
Mercaptopurine is not effective in acute myelogenous leukemia, chronic lymphatic leukemia, the lymphomas(including Hodgkins Disease), or solid tumors.
DOSAGE AND ADMINISTRATION
Once a complete hematologic remission is obtained, maintenance therapy is considered essential.Maintenance doses will vary from patient to patient. The usual daily maintenance dose of mercaptopurine is
1.5 to 2.5 mg/kg/day as a single dose. It is to be emphasized that in pediatric patients with acute lymphaticleukemia in remission, superior results have been obtained when mercaptopurine has been combined withother agents (most frequently with methotrexate) for remission maintenance. Mercaptopurine should rarelybe relied upon as a single agent for the maintenance of remissions induced in acute leukemia.
Procedures for proper handling and disposal of anticancer drugs should be considered. Several guidelines onthis subject have been published. 1-8 There is no general agreement that all of the procedures recommendedin the guidelines are necessary or appropriate.
Dosage With Concomitant Allopurinol
When allopurinol and mercaptopurine are administered concomitantly, the dose of mercaptopurine must bereduced to one-third to one-quarter of the usual dose to avoid severe toxicity.
Dosage In Patients With TPMT And/Or NUDT15 Deficiency
Homozygous Deficiency In Either TPMT Or NUDT15
Patients with homozygous deficiency of either enzyme typically require 10% or less of the standard PURIXAN dosage. Reduce initial dosage in patients who are known to have homozygous TPMT or NUDT15 deficiency.
Heterozygous Deficiency In TPMT And/Or NUDT15
Reduce the PURIXAN dosage based on tolerability. Most patients with heterozygous TPMT or NUDT15deficiency tolerate recommended mercaptopurine doses, but some require dose reduction based ontoxicities. Patients who are heterozygous for both TPMT and NUDT15 may require more substantial dosage reductions.
Dosage In Renal And Hepatic Impairment
It is probably advisable to start with lower dosages in patients with impaired renal function, due to slowerelimination of the drug and metabolites and a greater cumulative effect. Consideration should be given to reducing the dosage in patients with impaired hepatic function.
Pale yellow to buff, scored tablets containing 50 mg mercaptopurine, imprinted with “9|3”; bottles of 25 (NDC 69076-913-02) and bottles of 250 (NDC 69076-913-25).
Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature]. Store in a dry place. Dispense in tight container as defined in the USP.
1. ONS Clinical Practice Committee. Cancer Chemotherapy Guidelines and Recommendations for Practice.Pittsburgh, PA: Oncology Nursing Society;1999:32-41.
2. Recommendations for the safe handling of parenteral antineoplastic drugs. Washington, DC: Division ofSafety; Clinical Center Pharmacy Department and Cancer Nursing Services, National Institutes of Health;1992. US Dept of Health and Human Services. Public Health Service publication NIH 92-2621.
3. AMA Council on Scientific Affairs. Guidelines for handling parenteral antineoplastics. JAMA. 1985;253:1590-1591.
4. National Study Commission on Cytotoxic Exposure. Recommendations for handling cytotoxic agents. 1987.Available from Louis P. Jeffrey, Chairman, National Study Commission on Cytotoxic Exposure. MassachusettsCollege of Pharmacy and Allied Health Sciences, 179 Longwood Avenue, Boston, MA 02115.
5. Clinical Oncological Society of Australia. Guidelines and recommendations for safe handling ofantineoplastic agents. Med J Australia. 1983;1:426-428.
6. Jones RB, Frank R, Mass T. Safe handling of chemotherapeutic agents: a report from the Mount Sinai Medical Center. CA-A Cancer J for Clinicians. 1983;33:258-263.
7. American Society of Hospital Pharmacists. ASHP technical assistance bulletin on handling cytotoxic andhazardous drugs. Am J Hosp Pharm. 1990;47:1033-1049.
8. Controlling Occupational Exposure to Hazardous Drugs. (OSHA Work-Practice Guidelines.) Am J Health-Syst Pharm. 1996;53:1669-1685.
Manufactured for: Quinn Pharmaceuticals, LLC Coral Springs, FL. Revised: May 2018