Adults: Take at least 1 hr ac or 1 hr pc. HER2-Positive Metastatic Breast Cancer: Usual: 1250mg
2 qd on Days 1-21 continuously with capecitabine 2000mg/m /day (2 doses 12 hrs apart) on Days 1-14 in a repeating 21-day cycle. Take capecitabine with food or within 30 min after food. Continue treatment until disease progression or unacceptable toxicity occurs. Hormone Receptor-Positive, HER2-Positive Metastatic Breast Cancer: Usual: 1500mg qd continuously with letrozole 2.5mg qd.
Refer to PI for dose modification guidelines.
Decreased left ventricular ejection fraction (LVEF) reported; confirm normal LVEF prior to therapy and monitor during treatment. Caution with conditions that may impair left ventricular function. Monitor LFTs before treatment, every 4-6 weeks during therapy, and as clinically indicated; d/c if severe liver function changes occur, and do not retreat. Consider reducing dose with severe preexisting hepatic impairment. Diarrhea, including severe cases and deaths, reported; early identification and intervention is critical. Prompt treatment of diarrhea with antidiarrheals (eg, loperamide) after the 1st unformed stool is recommended. Replace electrolytes/fluids, use antibiotics such as fluoroquinolones (especially if diarrhea persists beyond 24 hrs, there is fever, or Grade 3 or 4 neutropenia), and interrupt or d/c therapy if severe diarrhea occurs. Associated with interstitial lung disease and pneumonitis; d/c if pulmonary symptoms indicative of interstitial lung disease/pneumonitis (Grade 3) occur. QT prolongation observed; caution in patients who have or may develop prolongation of QTc (eg, hypokalemia, hypomagnesemia, congenital long QT syndrome, taking antiarrhythmics or other drugs that prolong the QT interval, and cumulative high-dose anthracycline therapy). Correct hypokalemia and hypomagnesemia before administration. May cause fetal harm.
Caution with substrates of CYP3A4, CYP2C8, and P-glycoprotein (P-gp); consider dose reduction of the substrate drug. Avoid with strong CYP3A4 inhibitors (eg, ketoconazole, itraconazole, clarithromycin, atazanavir, indinavir, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, voriconazole) and inducers (eg, dexamethasone, phenytoin, carbamazepine, rifampin, rifabutin, rifapentin, phenobarbital, St. John's wort); if unavoidable, consider dose modification of lapatinib. Avoid with grapefruit. Increased levels with P-gp inhibitors; use with caution. May increase exposure of paclitaxel and midazolam. May increase levels of digoxin; if digoxin level is >1.2ng/mL, reduce digoxin dose by 1/2.
Category D, not for use in nursing.
Kinase inhibitor; inhibits both epidermal growth factor receptors (EGFR [ErbB1]) and HER2 (ErbB2), resulting in tumor cell growth inhibition.
Absorption: Incomplete and variable. C=2.43mcg/mL, T=4 hrs, AUC=36.2mcg•hr/mL.
+ drug hypersensitivity, and possible drug interactions. Obtain baseline ECG, LFTs, serum K , and
2+ Mg levels.
Monitor for hepatotoxicity, diarrhea, bowel changes, pulmonary symptoms indicative of interstitial lung disease or pneumonitis, hypokalemia, hypomagnesemia, decreased LVEF, and QT prolongation. Consider ECG and electrolyte monitoring. Monitor LFTs every 4-6 weeks during therapy and as clinically indicated.
Instruct to notify physician if SOB, palpitations, or fatigue occur. Advise that diarrhea is a common side effect and instruct on how it should be managed/prevented; instruct to contact physician immediately if any change in bowel patterns or severe diarrhea occurs. Counsel to report use of any prescription/nonprescription drugs or herbal products. Instruct not to take with grapefruit products. Advise women not to become pregnant while on therapy. Advise against doubling dose the next day for a missed dose.
Administration: Oral route. Do not divide the daily dose. Storage: 25°C (77°F); excursions permitted to 15-30°C (59-86°F).
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