Crohn's disease:Adult:Initially 1-1.5 mg/kg daily, may increase to 125 mg daily.Child:Initially 1-1.5 mg/kg daily increased to a max of 75 mg dailyAcute lymphocytic leukemia:Adult:Usual maintenance dose: Initially, 1.5-2.5 mg/kg daily as a single dose, usually used in combination with methotrexate. Dose may vary individually based on response and tolerance. Monitor blood counts at least once wkly. Withdraw treatment immedietely if there is a sharp drop in the white cell count or severe bone-marrow depression. May resume treatment slowly and carefully if white cell count remains constant for 2-3 days or rises. Reduce dose when used with allopurinol.Child:Usual maintenance dose: Initially, 1.5-2.5 mg/kg daily as a single dose, usually used in combination with methotrexate. Dose may vary individually based on response and tolerance. Monitor blood counts at least once wkly. Withdraw treatment immedietely if there is a sharp drop in the white cell count or severe bone-marrow depression. May resume treatment slowly and carefully if white cell count remains constant for 2-3 days or rises. Reduce dose when used with allopurinol.
Mercaptopurine
Mercaptopurine is a purine antagonist which is converted intracellularly into its active nucleotides, including thioinosinic acid. The nucleotides inhibit several reactions which ultimately interferes with nucleic acid synthesis and prevents the formation of RNA and DNA.
Should be taken on an empty stomach. Best taken on an empty stomach 1 hr before or 2 hr after meals. Ensure adequate fluid intake.
Anticoagulant action of warfarin may be inhibited by Leukin. Enhanced toxicity with myelosuppressive drugs.
Pregnancy and lactation. Prior resistance to mercaptopurine or thioguanine; severe liver disease; severe bone marrow suppression.
Hyperuricaemia, bone marrow toxicity, hypoplasia, anorexia, diarrhoea, leukopenia, thrombocytopenia, intestinal ulceration, crystalluria with haematuria, immunosuppression, interstitial pneumonitis. Cutaneous hyperpigmentation, alopecia.
Pregnancy category D. There is positive evidence of human foetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).
Hepatic or renal dysfunction; monitor hepatic function periodically. Leukin is potentially carcinogenic. Thiopurine S-methyl transferase (TPMT) deficiency; porphyria.
Cytotoxic Chemotherapy
Store at 20-25° C
Renal Impairment:Dosage may need to be reduced.Hepatic Impairment:Crohn's disease: Dosage may need to be reduced.Acute lymphocytic leukemia: Dosage may need to be reducedDosage adjustment in patients with thiopurine-S-methyl transferase (TPMT) deficiency to prevent life-threatening myelotoxicity.For patients with homozygous TPMT deficiency: Substantial reduction is required.For patients with heterozygous TPMT deficiency: Some may require reduction but most will tolerate the usual dosages.
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