Purinethol - Tablet Mercaptopurine - 50mg 1 Tablet(s) / Tablet Glaxo SmithKline Pharmaceuticals Ltd Introduction: Purinethol is used in the treatment of blood cancer. It shows its working by decreasing the number of red blood cells, which is produced by the body. Purinethol can be taken with or without food or you can have it one hour before or 2 hours after the meal. Your doctor will decide what dose is necessary and how often you need to take it. This will depend on what you are being treated for and may change from time to time. You should take it exactly as your doctor has advised. Taking it in the wrong way or taking... Uses of Purinethol: Blood cancer Side effects of Purinethol: NauseaVomitingRashDecreased white blood cell count (neutrophils)Intestinal ulcerAnemia (low number of red blood cells)Increased bilirubin in the bloodLow blood plateletsIncreased transaminase level in bloodDiarrheaLoss of appetite How to use Purinethol: Take this medicine in the dose and duration as advised by your doctor. Swallow it as a whole. Do not chew, crush or break it. Purinethol may be taken with or without food, but it is better to take it at a fixed time. How Purinethol works: Purinethol interferes with the growth of DNA and RNA of the cancer cells by substituting their building blocks. It prevents the cancer cells from growing and multiplying. Indication: Acute lymphatic leukaemia, Crohn's disease Administration: 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. Adult Dose: Acute Lymphatic Leukemia Induction: 2.5 mg/kg PO qDay; usually 100-200 mg PO qDay in average adult (other agents preferred) May increase by 5 mg/kg/day after 4 weeks Maintenance: 1.5-2.5 mg/kg PO qDay Reduce dose by 75% if concomitant allopurinol administration Crohn's disease Adult: Initially 1-1.5 mg/kg daily, may increase to 125 mg daily. Hepatic impairment: Dosage may need to be reduced. Child Dose: Acute Lymphatic Leukemia Starting dose: 1.25-2.5 mg/kg (50-75 mg/m²) PO qDay Maintenance: 1.5-2.5 mg/kg PO qDay in combination with methotrexate Renal Dose: Renal Impairment: Dosage may need to be reduced. Contraindication: Pregnancy and lactation. Prior resistance to mercaptopurine or thioguanine; severe liver disease; severe bone marrow suppression. Mode of Action: 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. Precaution: Hepatic or renal dysfunction; monitor hepatic function periodically. Mercaptopurine is potentially carcinogenic. Thiopurine S-methyl transferase (TPMT) deficiency; porphyria. Lactation: not known if excreted in breast milk, do not nurse Side Effect: >10% Elevated LFT's (15%) 1-10% Nausea (10%),Vomiting (10%),Stomatitis (3-10%),Thrombocytopenia (3-10%),Rash (1-3%),Diarrhea (1-3%),Dizziness (1-3%),Alopecia (1-3%),Leukopenia (1-3%) Frequency Not Defined Fatigue,Anorexia,Headache,Chills and fever,Chest pain,Mucositis,Upper respiratory infection,Cough,Ulceration of intestine,Ulcerative stomatitis,Myelosuppressionm,Decreased hematocrit,Hepatotoxicity,Decreased resistance to infections,Hyperuricemia,Nephrotoxicity,Increased risk of pancreatitis in pts with IBD,Hyperpigmentation of skin,Arthralgias,Eye discomfort,Tinnitus Potentially Fatal: Myelosuppression; hepatotoxicity, cholestatic jaundice. Interaction: Anticoagulant action of warfarin may be inhibited by mercaptopurine. Enhanced toxicity with myelosuppressive drugs. Potentially Fatal: Effects enhanced by allopurinol (reduce dose of mercaptopurine). Other hepatotoxic drugs (e.g. doxorubicin) potentiate toxicity.