Eltrombopag

7 DRUG INTERACTIONS

7.1 Polyvalent Cations (Chelation) Eltrombopag chelates polyvalent cations (such as iron, calcium, aluminum, magnesium, selenium, and zinc) in foods, mineral supplements, and antacids. Take ALVAIZ at least 2 hours before or 4 hours after any medications or products containing polyvalent cations, such as antacids, dairy products, and mineral supplements to avoid significant reduction in absorption of ALVAIZ due to chelation [see Dosage and Administration ( 2.4 ), Clinical Pharmacology ( 12.3 )] .

7.2 Transporters Use caution when concomitantly administering ALVAIZ and drugs that are substrates of OATP1B1 (e.g., atorvastatin, bosentan, ezetimibe, fluvastatin, glyburide, olmesartan, pitavastatin, pravastatin, rosuvastatin, repaglinide, rifampin, simvastatin acid, SN-38 [active metabolite of irinotecan], valsartan) or breast cancer resistance protein (BCRP) (e.g., imatinib, irinotecan, lapatinib, methotrexate, mitoxantrone, rosuvastatin, sulfasalazine, topotecan). Monitor patients closely for signs and symptoms of excessive exposure to the drugs that are substrates of OATP1B1 or BCRP and consider reduction of the dose of these drugs, if appropriate.

In clinical trials with eltrombopag, a dose reduction of rosuvastatin by 50% was recommended.

7.3 Protease Inhibitors HIV Protease Inhibitors: No dose adjustment is recommended when ALVAIZ is coadministered with lopinavir/ritonavir (LPV/RTV). Drug interactions with other HIV protease inhibitors have not been evaluated. Hepatitis C Virus Protease Inhibitors: No dose adjustments are recommended when ALVAIZ is coadministered with boceprevir or telaprevir. Drug interactions with other hepatitis C virus (HCV) protease inhibitors have not been evaluated.

7.4 Peginterferon Alfa-2a/b Therapy No dose adjustments are recommended when ALVAIZ is coadministered with peginterferon alfa-2a (PEGASYS ® ) or -2b (PEGINTRON ® ).

7.5 Interference with Clinical Laboratory Tests Eltrombopag (ALVAIZ) is highly colored and can cause patient sample discoloration, which is reported to interfere with some clinical laboratory tests, including, but not limited to bilirubin and creatinine. Bilirubin Testing : Eltrombopag can cause both positive and negative interference with bilirubin assays. If the laboratory results for bilirubin are inconsistent with clinical observations, further evaluation of liver function should be performed to clarify the clinical status of the patient.

Evaluating contemporaneous aminotransferase values (AST, ALT) may help determine the validity of normal total bilirubin levels in the presence of clinical jaundice. Creatinine Testing : Eltrombopag can cause positive interference with creatinine measurements, leading to falsely elevated creatinine levels. In the event of an unexpected serum creatinine test result, further evaluation of renal function should be performed. Blood urea should be evaluated if serum creatinine is unexpectedly high. Communicate to the lab conducting testing if the patient is taking ALVAIZ. Re-testing using other methods may also help in determining the validity of the test results.

8.1 Pregnancy Risk Summary Available data from a small number of published case reports and postmarketing experience with eltrombopag use in pregnant women are insufficient to assess any drug-associated risks for major birth defects, miscarriage, or adverse maternal or fetal outcomes. In animal reproduction and developmental toxicity studies, oral administration of eltrombopag to pregnant rats during organogenesis resulted in embryolethality and reduced fetal weights at maternally toxic doses.

These effects were observed at doses resulting in exposures that were six times the human clinical exposure based on area under the curve (AUC) in patients with persistent or chronic ITP at 75 mg/day, and three times the AUC in patients with chronic hepatitis C at 100 mg/day (see Data) . The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and of miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

Data Animal Data In an early embryonic development study, female rats received oral eltrombopag at doses of 10, 20, or 60 mg/kg/day (0.8, 2, and 6 times, respectively, the human clinical exposure based on AUC in patients with ITP at 75 mg/day and 0.3, 1, and 3 times, respectively, the human clinical exposure based on AUC in patients with chronic hepatitis C at 100 mg/day). Increased pre- and post-implantation loss and reduced fetal weight were observed at the highest dose which also caused maternal toxicity.

In an embryo-fetal development study eltrombopag was administered orally to pregnant rats during the period of organogenesis at doses of 10, 20, or 60 mg/kg/day (0.8, 2, and 6 times, respectively, the human clinical exposure based on AUC in patients with ITP at 75 mg/day and 0.3, 1, and 3 times, respectively, the human clinical exposure based on AUC in patients with chronic hepatitis C at 100 mg/day). Decreased fetal weights (6% to 7%) and a slight increase in the presence of cervical ribs were observed at the highest dose which also caused maternal toxicity. However, no evidence of major structural malformations was observed.

In an embryo-fetal development study eltrombopag was administered orally to pregnant rabbits during the period of organogenesis at doses of 30, 80, or 150 mg/kg/day (0.04, 0.3, and 0.5 times, respectively, the human clinical exposure based on AUC in patients with ITP at 75 mg/day…