Lapatinib
Pronouncation: (la-PA-ti-nib)Class: Tyrosine kinase inhibitor
Trade Names:
Tykerb
- Tablets 250 mg
Pharmacology
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Inhibits epidermal growth factor receptor and human epidermal receptor 2–driven tumor cell growth in vitro and in animal models.
Pharmacokinetics
Absorption
Oral absorption is incomplete and variable. C max occurs approximately 4 h after administration, and steady state is reached in 6 to 7 days. Following a dose of 1,250 mg daily, the C max was 2.43 mcg/mL. The AUC is 2-fold higher with divided daily doses compared with single-dose administration. When taken with a low-fat or high-fat meal, AUC is increased 3- and 4-fold, respectively.
Distribution
Binding to albumin and alpha-1 acid glycoprotein is greater than 99%.
Metabolism
Primarily metabolized by CYP3A4 and CYP3A5, with minor metabolism by CYP2C19 and CYP2C8.
Elimination
The t ½ is 24 h with repeated dosing. Elimination is primarily via CYP3A4/5 metabolism, with negligible renal excretion. Fecal elimination accounts for approximately 27%.
Indications and Usage
In combination with capecitabine for the treatment of advanced or metastatic breast cancer in patients whose tumors overexpress human epidermal receptor type 2 and who have received prior therapy, including an anthracycline, a taxane, and trastuzumab.
Contraindications
Standard considerations.
Dosage and Administration
AdultsPO 1,250 mg once daily on days 1 to 21 continuously with capecitabine 2,000 mg/m 2 /day on days 1 to 14 in a repeating 21-day cycle. Discontinuation or interruption of dosing may be considered if the patient develops at least grade 2 National Cancer Institute Common Terminology Criteria toxicity. Restart treatment at 1,250 mg/day when toxicity improves to grade 1 or less. If toxicity recurs, restart at 1,000 mg/day.
Coadministration With a Strong CYP3A4 InducerAdults
PO Consider gradually increasing dose from 1,250 to 4,500 mg/day based on tolerability. When the inducer is discontinued, reduce the dose to the indicated dose.
Coadministration With a Strong CYP3A4 InhibitorAdults
PO Consider dose reduction to 500 mg/day. When the inhibitor is discontinued, allow 1 wk before adjusting dose upward to the indicated dose.
Cardiac EventsAdults
PO Discontinue in patients with a decreased left ventricular ejection fraction (LVEF) that is grade 2 or greater and in patients with an LVEF that drops below the lower limit of normal. Restart at a reduced dose of 1,000 mg/day after a minimum of 2 wk if LVEF recovers to normal and the patient is asymptomatic.
Hepatic Function ImpairmentAdults
PO In severe hepatic function impairment, consider dose reduction to 750 mg/day.
General Advice
- Take lapatinib once daily at least 1 h before or after a meal.
Storage/Stability
Store at 59° to 86°F.
Drug Interactions
Antiarrhythmic agents or drugs that prolong the QTc intervalBecause lapatinib may prolong the QTc interval, use with caution in patients receiving medications that produce QT prolongation.
CYP2C8 (eg, paclitaxel) and CYP3A4 (eg, cyclosporine) substratesBecause lapatinib inhibits CYP2C8 and CYP3A4, use with caution with drugs that are substrates for these isozymes, especially when medication has a narrow therapeutic window.
CYP3A4 inducers (eg, carbamazepine, dexamethasone, phenobarbital, phenytoin, rifabutin, rifampin, rifapentine, St. John's wort)Lapatinib plasma concentrations may be reduced, decreasing efficacy. A lapatinib dose increase may be needed.
CYP3A4 inhibitors (eg, atazanavir, clarithromycin, indinavir, itraconazole, ketoconazole, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, voriconazole)Lapatinib plasma concentrations may be elevated, increasing the risk of toxicity. Lapatinib dose reduction may be needed.
P-glycoprotein inhibitors (eg, quinidine)Lapatinib plasma concentrations may be elevated, increasing the risk of toxicity. Use with caution.
P-glycoprotein substrates (eg, amiodarone, digoxin)Because lapatinib inhibits P-glycoprotein, increased concentrations of drugs that are substrates for P-glycoprotein may occur. Use with caution.
Laboratory Test Interactions
None well documented.
Adverse Reactions
The following adverse reactions were reported with combined use of lapatinib and capecitabine.
Cardiovascular
Decreased left ventricular ejection fraction.
CNS
Insomnia (10%).
Dermatologic
Palmar-plantar erythrodysesthesia (53%); rash (28%); dry skin (10%).
GI
Diarrhea (65%); nausea (44%); vomiting (26%); stomatitis (14%); dyspepsia (11%).
Hematologic-Lymphatic
Abnormal hemoglobin (56%); neutrophils (22%); platelets (18%).
Hepatic
Abnormal AST (49%); total bilirubin (45%); ALT (37%).
Musculoskeletal
Pain in extremities (12%); back pain (11%).
Respiratory
Dyspnea (12%).
Miscellaneous
Mucosal inflammation (15%).
Precautions
Pregnancy
Category D .
Lactation
Undetermined.
Children
Safety and efficacy not established.
Hepatic Function
Lapatinib dose reduction may be needed in patients with severe hepatic function impairment.
CV
Left ventricular ejection fraction may be reduced.
Overdosage
Symptoms
Toxicity may be increased; grade 3 diarrhea and vomiting have been reported.
Patient Information
- Advise patient to read the patient information leaflet before using product the first time and with each refill.
- Instruct patient to take exactly as prescribed and not to change the dose or discontinue therapy unless advised by health care provider.
- Instruct patient to take lapatinib once daily and, if a dose is missed, not to double the dose the next day.
- Instruct patient to inform health care provider if shortness of breath, palpitations, fatigue, or severe diarrhea occurs.
- Instruct patient to take lapatinib at least 1 h before or after a meal.
- Advise patients who have heart or liver problems to inform health care provider of the medical condition.
- Advise patient not to eat or drink grapefruit products while taking this product.
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