7.1 Effect of Other Drugs on Doxorubicin Hydrochloride Injection/for Injection
Inhibitors of CYP3A4, CYP2D6, and P-gp
Concomitant use of doxorubicin hydrochloride with inhibitors of CYP3A4, CYP2D6, or P-glycoprotein (P-gp), increased concentrations of doxorubicin, which may increase the incidence and severity of adverse reactions of doxorubicin hydrochloride. Avoid concomitant use of Doxorubicin Hydrochloride Injection/for Injection with inhibitors of CYP3A4, CYP2D6, or P-gp.
Inducers of CYP3A4, CYP2D6, or P-gp
Concomitant use of doxorubicin hydrochloride with inducers of CYP3A4, CYP2D6, or P-gp may decrease the concentration of doxorubicin. Avoid concomitant use of Doxorubicin Hydrochloride Injection/for Injection with inducers of CYP3A4, CYP2D6, or P-gp.
Paclitaxel
Paclitaxel, when given prior to doxorubicin hydrochloride, increases the plasma-concentrations of doxorubicin and its metabolites. Administer Doxorubicin Hydrochloride Injection/for Injection prior to paclitaxel if used concomitantly.
7.2 Concomitant Use of Trastuzumab
Concomitant use of trastuzumab and doxorubicin hydrochloride results in an increased risk of cardiac dysfunction. Avoid concomitant administration of Doxorubicin Hydrochloride Injection/for Injection and trastuzumab [see Warnings and Precautions (5.1)].
Patients receiving doxorubicin after stopping treatment with trastuzumab may also be at an increased risk of developing cardiotoxicity. Trastuzumab may persist in the circulation for up to 7 months. Therefore, avoid anthracycline-based therapy for up to 7 months after stopping trastuzumab when possible. If anthracyclines are used before this time, carefully monitor cardiac function.
7.3 Concomitant Use of Dexrazoxane
Do not administer dexrazoxane as a cardioprotectant at the initiation of doxorubicin hydrochloride-containing chemotherapy regimens. In a randomized trial in women with metastatic breast cancer, initiation of dexrazoxane with doxorubicin hydrochloride-based chemotherapy resulted in a significantly lower tumor response rate (48% vs. 63%; p=0.007) and shorter time to progression compared to doxorubicin hydrochloride-based chemotherapy alone.
7.4 Concomitant Use of 6-Mercaptopurine
Doxorubicin hydrochloride may potentiate 6-mercaptopurine-induced hepatotoxicity. In 11 patients with refractory leukemia treated with 6-mercaptopurine (500 mg/m2 intravenously daily for 5 days per cycle every 2–3 weeks) and doxorubicin hydrochloride (50 mg/m2 intravenous once per cycle every 2–3 weeks) alone or with vincristine and prednisone, all developed hepatic dysfunction manifested by increased total serum bilirubin, alkaline phosphatase and aspartate aminotransferase.