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Breast Cancer Drugs and Their Interactions Drug Name
Lab Effects/Interference
Drug Interactions
Warfarin: increased INR, monitor and adjust dose prnPhenytoin: monitor phenytoin serum level closely and adjust prnLeucovorin: synergy and increased toxicity; monitor closely Cisplatin: combination may cause increased Myelosuppresive drugs: combination may cause increased bone marrow depressionTaxol: carboplatin administered following taxol maximizes efficacyAvoid aluminum needles in drug handling Succinylcholine: may prolong neuromuscular blockageBarbiturates and other CYP450 inducers: increase cyclophosphamide activation and toxicity Inhibitors of CYP3A4: can decrease drug elimination and increasetoxicity; caution should be observed Barbiturates and other CYP450 inducers: may Increased uric acid secondary Cyclophosphamide: combination may increase to tumor lysis risk of hemorrhage and cardiotoxicityMitomycin: combination may increase risk of cardiotoxicityDigoxin: combination decreases digoxin serum concentrationsMercaptopurine: combination may increase risk of hepatotoxcity however, recommed same cautions as those calcium-channel blockers may increase risk of CHF; close cardiac function monitoring requiredPotential radiosensitization: given after radiation therapy; radiation recall inflammatory reaction may occur at site of prior radiationCrimetidine: combination increases drug AUC by 50%. Do not use concurrently; hold cimetidine during treatment.
CYP450 inducers: may increase drug clearance (20% incidence)Elevated LFT (AST, ALT, alkaline phosphatase, GGT) rarely CYP450 inhibitors and inducers: may alter Folic acid: can antagonize drug effect; high testosterone, WBC, and total serum protein; increased calciumInjection: increased bun and creatinineDepot injection: increased LDH, alkaline phosphatase, AST, uric acid, cholesterol, LDL, triglycerides, glucose, WBC count, phosphate; decreased potassium and platelets Protein-bound drugs (aspirin, sulfonamides, sulfonylureas, phenytoin, tetracycline, NSAIDs (including indomethacin and ketoprofen): may increase methotrexate serum concentration. Do not administer concurrently with high doses of methotrexate; caution should be observed at moderate or low dosesCotrimoxazole and pyrimethamine: increase methotrexate serum levels; do not use concurrently Myelosuppressive agents: combination can Cisplatin: taxol should be given prior to cisplatin to avoid decreased clearance and increased myelosuppressionKetoconazole and CYP3A4 inhibitors: may inhibit paclitaxel clearance; use together with cautionCarboplatin: may increase cytotoxicity when administered after doxorubicin and liposomal formation: may increase incidence of neutropenia and stomatitis when adminstered after paclitaxel; combination may increase cardiotoxicityBeta blockers, calcium-channel blockers, and digoxin: additive bradycardia may occur; assess/monitor patient closely Anticoagulants: increase PT; monitor PT closely Thisazide diruetics: combination may increase risk of hypercalcemiaAnticoagulants: increased PT; monitor PT closely and reduce anticoagulant dose Testosterone and cyclosporine: may inhibit metabolismCYP450 inhibitors and inducers alter tamoxifen metabolismThiazide fiuretics: combination may increase risk of hypercalcemiaAnticoagulants: increased PT; monitor PT closely and reduce anticoagulant dose Mitomycin: combination may increase acute pulmonary reactionsCYP450 inhibitors: may alter metabolism; caution recommended when given concurrently Aminoglycoside antibiotics and loop diuretics: ALT: alanine aminotransferase; AST: aspartate aminotransferase; AUC: area under the curve; BUN blood urea nitrogen; CBC: complete blood count; CHF: congestive heart failure; DNA: deoxyribonucleic acid; GGT: gamma glutamyl transferase; INR: International Normalized Ratio; LDH: lactic dehydrogenase hormone; LDL: low-density lipoprotein; LFT: liver function tests; NSAIDs: nonsteroidalanti-inflammatory drugs; prn: pro re nata ("as needed"); PSA: prostate specific antigen; PT: prothrombin time; RFT: respiratory functiontests; SIADH: syndrome of inappropriate antidiuretic hormone; TFT: thyroid function tests; WBC: white blood cell Printed with permission from the author.
Shockney, L. D. (2008). The johns hopkins breast cancer handbook for healthcare professionals.
In L. Shockney & T. Tsangaris (Eds.), Breast cancer drugs and their interactions (pp128-135). Massachusetts: Jones and Bartlett Publishers.

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