Piperacillin Methotrexate

The more basic interactions between piperacillin and methotrexate and its major metabolite 7-hydroxymetho-trexate have been stndied in rabbits (255). The interaction was mainly cansed by rednced renal clearance of both methotrexate and its metabolite. The anthors concluded that renal function in patients taking this combination should be monitored, with adequate fluid intake, especially in elderly patients, because dehydration may accelerate the occurrence of toxicity. 

Clinically important, potentially hazardous interactions with amoxicillin, ampicillin, antacids, bacampicillin, calcium carbonate, carbenicillin, cloxacillin, digoxin, methotrexate, methoxyflurane, mezlocillin, nafcillin, oxacillin, penicillins, piperacillin, ticarcillin, zinc... 

Clinically important, potentially hazardous interactions with acitretin, aluminum hydroxide, amoxicillin, ampicillin, antacids, bacampicillin, betamethasone, bismuth, bromelain, calcium, carbenicillin, cholestyramine, doxacillin, corticosteroids, dairy products, dicloxacillin, didanosine, digoxin, food, glidazide, iron, isotretinoin, methicillin, methotrexate, methoxyflurane, mezlocillin, nafcillin, oxacillin, penicillins, piperacillin, retinoids, rocuronium, strontium ranelate, sucralfate, ticarcillin, vitamin A, zinc... 

Noninterfering acetaminophen, acyclovir, allopurinol, amoxicillin, amphotericin B, am-picillin, aspirin, azlocillin, bendrofluazide, bumetanide, buprenorphine, carbenidllin, cefazolin, cefotaxime, cefoxitin, ceftazidime, cefuroxime, cephalexin, chlorambucil, chloramphenicol, chlordiazepoxide, chlorpheniramine, chlorpropamide, cyclophosphamide, cyclosporin, C5d arabine, daunorubicin, dextropropoxyphene, dihydrocodeine, domperidone, flucytosine, furosemide, gentamicin, griseofulvin, melphalan, methotrexate, metochlo-pramide, metronidazole, miconazole, nabilone, netilmicin, nicotinamide, nitrazepam, penicillin G, piperacillin, prednisolone, procarbeizine, prochlorperazine, riboflavin, rifampin, sulfamethoxazole, thioguanine, tobramycin, tolbutamide, trimethoprim... 

Reduced clearance and acute methotrexate toxicity has been attributed to the concurrent use of various penicillins (amoxicillin, benzylpenicillin, carbenicillin, dicloxacillin, flucloxacillin, mezlocillin, oxacillin, penicillin, phenoxymethylpenicillin, piperacillin, ticarcillin) in a small number of case reports. 

Intravenous bolus 15 to 60 mg/m, then 15 to 60 mg/m intravenous infusion over 36 hours Piperacillin (not stated) Chronic Myeloid Leukaemia (1) 67% reduction in methotrexate clearance prolonged folinic acid rescue necessary 3... 

Intravenous infusion 3 g/m over 6 hours Piperacillin (1 g every 6 hours intravenously) Non-Hodgkin s lymphoma (1) Reduced methotrexate clearance 6... 

Yamamoto K, Sawada Y, Matsushita U, Moriwaki K, Bessho F, Iga T. Delayed elimination of methotrexate associated with piperacillin administration. Ann Phamiacotber (1997) 31, 1261-2. 

Iven H, BraschH. Influence of the antibiotics piperacillin, doxycycline, and tobramycin on the pharmacokinetics of methotrexate in rabbits. Cancer ChemoAer Phamacol (i9Z6) 17, 218-22. 

---