Mercaptopurine methotrexate, interaction

Andersen JB, Szumlanski C, Weinshilboum RM et al. Pharmacokinetics, dose adjustments, and 6-mercaptopurine/methotrexate drug interactions in two patients with thiopurine methyltransferase deficiency. Acta Paediatr 1998 87 108-111. 

Clinically important, potentially hazardous interactions with altretamine, amikacin, aminoglycosides, antineoplastics, bleomycin, busulfan, carboplatin, carmustine, chlorambucil, cisplatin, corticosteroids, cyclophosphamide, cytarabine, dacarbazine, dactinomycin, daunorubicin, docetaxel, doxorubicin, estramustine, etoposide, fludarabine, fluorouracil, gemcitabine, gentamicin, hydroxyurea, idarubicin, ifosfamide, indomethacin, kanamycin, levamisole, lomustine, mechlorethamine, melphalan, mercaptopurine, methotrexate, mitomycin, mitotane, mitoxantrone, neomycin, pentostatin, plicamycin, procarbazine, streptomycin, streptozocin, thioguanine, thiotepa, tobramycin, tretinoin, uracil, vinblastine, vincristine, vinorelbine... 

Clinically important, potentially hazardous interactions with aminophylline, carbamazepine, cyclosporine, mercaptopurine, methotrexate, phenobarbital, prednisone, vincristine, warfarin... 

In 14 children receiving maintenance therapy for leukaemia oral low-dose methotrexate 20 mg/m increased the AUC and peak plasma levels of mercaptopurine 75 mg/m by 31% and 26%, respectively. In another study, 10 children with acute lymphoblastic leukaemia in remission were treated with mercaptopurine 25 mg/m daily and intravenous infusions of high-dose methotrexate 2 or 5 g/m once every other week for consolidation therapy. It was found that methotrexate 2 or 5 g/m increased the AUC of mercaptopurine by 69% and 93%, respectively, and raised the maximum serum levels of mercaptopurine by 108% and 121%, respectively. The reasons for this pharmacokinetic interaction are not understood, although it is thought that methotrexate is a xanthine oxidase... 

Drug-drug interactious Methotrexate The pharmacokinetic interaction between methotrexate and mercaptopurine has been studied in 20 children with acute lymphoblastic leukemia [154 ]. High-dose methotrexate (5 g/m over 24 hours) produced a rapid reduction in erythrocyte concentrations of thioguanine within 24 hours, and... 

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