Lumacaftor and ivacaftor

5.8 Drug Interactions Substrates of CYP3A Lumacaftor is a strong inducer of CYP3A. Administration of ORKAMBI may decrease systemic exposure of medicinal products that are substrates of CYP3A, which may decrease therapeutic effect. Co-administration with sensitive CYP3A substrates or CYP3A substrates with a narrow therapeutic index is not recommended. ORKAMBI may substantially decrease hormonal contraceptive exposure, reducing their effectiveness and increasing the incidence of menstruation-associated adverse reactions, e.g., amenorrhea, dysmenorrhea, menorrhagia, menstrual irregular (27% in women using hormonal contraceptives compared with 3% in women not using hormonal contraceptives).

Hormonal contraceptives, including oral, injectable, transdermal, and implantable, should not be relied upon as an effective method of contraception when co-administered with ORKAMBI [see Adverse Reactions (6.1) , Drug Interactions (7.3 , 7.11) , and Clinical Pharmacology (12.3) ] . Strong CYP3A Inducers Ivacaftor is a substrate of CYP3A4 and CYP3A5 isoenzymes. Use of ORKAMBI with strong CYP3A inducers, such as rifampin, significantly reduces ivacaftor exposure, which may reduce the therapeutic effectiveness of ORKAMBI. Therefore, co-administration with strong CYP3A inducers (e.g., rifampin, St.

John's wort [ Hypericum perforatum ]) is not recommended [see Drug Interactions (7.2) and Clinical Pharmacology (12.3) ] . 7 DRUG INTERACTIONS See Full Prescribing Information for a complete list. ( 2.3 , 7 , 12.3 ) Potential for Other Drugs to Affect Lumacaftor/Ivacaftor

7.1 Inhibitors of CYP3A Co-administration of lumacaftor/ivacaftor with itraconazole, a strong CYP3A inhibitor, did not impact the exposure of lumacaftor, but increased ivacaftor exposure by 4.3-fold. Due to the induction effect of lumacaftor on CYP3A, at steady-state, the net exposure of ivacaftor is not expected to exceed that when given in the absence of lumacaftor at a dose of 150 mg every 12 hours (the approved dose of ivacaftor monotherapy). Therefore, no dosage adjustment is necessary when CYP3A inhibitors are initiated in patients currently taking ORKAMBI.

However, when initiating ORKAMBI in patients taking strong CYP3A inhibitors, reduce the ORKAMBI dosage as recommended for the first week of treatment to allow for the steady-state induction effect of lumacaftor. Following this period, continue with the recommended daily dose [see Dosage and Administration (2.3) ] . Examples of strong CYP3A inhibitors include: ketoconazole, itraconazole, posaconazole, and voriconazole. telithromycin, clarithromycin. No dosage adjustment is recommended when used with moderate or weak CYP3A inhibitors.

7.2 Inducers of CYP3A Co-administration of lumacaftor/ivacaftor with rifampin, a strong CYP3A inducer, had minimal effect on the exposure of lumacaftor, but decreased ivacaftor exposure (AUC) by 57%. This may reduce the effectiveness of ORKAMBI. Therefore, co-administration with strong CYP3A inducers, such as rifampin, rifabutin, phenobarbital, carbamazepine, phenytoin, and St. John's wort ( Hypericum perforatum ), is not recommended [see Warnings and Precautions (5.8) and Clinical Pharmacology (12.3) ] . No dosage adjustment is recommended when used with moderate or weak CYP3A inducers. Potential for Lumacaftor/Ivacaftor to Affect Other Drugs

7.3 CYP3A Substrates Lumacaftor is a strong inducer of CYP3A. Co-administration of lumacaftor with ivacaftor, a sensitive CYP3A substrate, decreased ivacaftor exposure by approximately 80%. Administration of ORKAMBI may decrease systemic exposure of medicinal products which are substrates of CYP3A, thereby decreasing the therapeutic effect of the medicinal product. Co-administration of ORKAMBI is not recommended with sensitive CYP3A substrates or CYP3A substrates with a narrow therapeutic index [see Warnings and Precautions (5.8) and Clinical Pharmacology (12.3) ] such as: Benzodiazepines : midazolam, triazolam (consider an alternative to these benzodiazepines).

Immunosuppressants : cyclosporine, everolimus, sirolimus, and tacrolimus (avoid the use of ORKAMBI).

7.4 CYP2B6 and CYP2C Substrates In vitro studies suggest that lumacaftor has the potential to induce CYP2B6, CYP2C8, CYP2C9, and CYP2C19; inhibition of CYP2C8 and CYP2C9 has also been observed in vitro . Additionally, in vitro studies suggest that ivacaftor may inhibit CYP2C9. Therefore, concomitant use of ORKAMBI with CYP2B6, CYP2C8, CYP2C9, and CYP2C19 substrates may alter the exposure of these substrates.

7.5 Digoxin and Other P-gp Substrates Based on in vitro results which showed P-gp inhibition and pregnane-X-receptor (PXR) activation, lumacaftor has the potential to both inhibit and induce P-gp. Additionally, a clinical study with ivacaftor monotherapy showed that ivacaftor is a weak inhibitor of P-gp. Therefore, concomitant use of ORKAMBI with P-gp substrates may alter the exposure of these substrates. Monitor the serum concentration of digoxin and titrate the digoxin dose to obtain the desired clinical effect.

7.6 Anti-allergics and Systemic Corticosteroids ORKAMBI may decrease the exposure of montelukast, which may reduce its efficacy. No dosage adjustment for montelukast is recommended. Employ appropriate clinical monitoring, as is reasonable, when co-administered with ORKAMBI. Concomitant use of ORKAMBI may reduce the exposure and effectiveness of prednisone and methylprednisolone. A higher dose of these systemic corticosteroids may be required to obtain the desired clinical effect.

7.7 Antibiotics Concomitant use of ORKAMBI may decrease the exposure of clarithromycin, erythromycin, and telithromycin, which may reduce the effectiveness of these antibiotics. Consider an alternative to these antibiotics, such as ciprofloxacin, azithromycin, and levofloxacin.

7.8 Antifungals Concomitant use of ORKAMBI may reduce the exposure and effectiveness of itraconazole, ketoconazole, posaconazole, and voriconazole. Concomitant use of ORKAMBI with these antifungals is not recommended. Monitor patients closely for breakthrough fungal infections if such drugs are necessary. Consider an alternative such as fluconazole.

7.9 Anti-inflammatories Concomitant use of ORKAMBI may reduce the exposure and effectiveness of ibuprofen. A higher dose of ibuprofen may be required to obtain the desired clinical effect.

7.10 Antidepressants Concomitant use of ORKAMBI may reduce the exposure and effectiveness of citalopram, escitalopram, and sertraline. A higher dose of these antidepressants may be required to obtain the desired clinical effect.

7.11 Hormonal Contraceptives ORKAMBI may decrease hormonal contraceptive exposure, reducing the effectiveness. Hormonal contraceptives, including oral, injectable, transdermal, and implantable, should not be relied upon as an effective method of contraception when co-administered with ORKAMBI. Concomitant use of ORKAMBI with hormonal contraceptives increased the menstrual abnormality events [see Adverse Reactions (6.1) ] . Avoid concomitant use unless the benefit outweighs the risks.

7.12 Oral Hypoglycemics Concomitant use of ORKAMBI may reduce the exposure and effectiveness of repaglinide and may alter the exposure of sulfonylurea. A dosage adjustment may be required to obtain the desired clinical effect. No dosage adjustment is recommended for metformin.

7.13 Proton Pump Inhibitors, H 2 Blockers, Antacids ORKAMBI may reduce the exposure and effectiveness of proton pump inhibitors such as omeprazole, esomeprazole, and lansoprazole, and may alter the exposure of ranitidine. A dose adjustment may be required to obtain the desired clinical effect. No dose adjustment is recommended for calcium carbonate antacid.

7.14 Warfarin ORKAMBI may alter the exposure of warfarin. Monitor the international normalized ratio (INR) when warfarin co-administration with ORKAMBI is required.

7.15 Concomitant Drugs That Do Not Need Dosage Adjustment No dosage adjustment of ORKAMBI or concomitant drug is recommended when ORKAMBI is given with the following: azithromycin, aztreonam, budesonide, ceftazidime, cetirizine, ciprofloxacin, colistimethate, colistin, dornase alfa, fluticasone, ipratropium, levofloxacin, pancreatin, pancrelipase, salbutamol, salmeterol, sulfamethoxazole, trimethoprim, tiotropium, and tobramycin. Based on the metabolism and route of elimination, ORKAMBI is not expected to impact the exposure of these drugs.

8.1 Pregnancy Risk Summary There are limited and incomplete human data from clinical trials and postmarketing reports on use of ORKAMBI or its individual components, lumacaftor or ivacaftor, in pregnant women to inform a drug-associated risk. In animal reproduction studies, oral administration of lumacaftor to pregnant rats and rabbits during organogenesis demonstrated no adverse effects on fetal development at doses that produced maternal exposures up to approximately 8 (rats) and 5 (rabbits) times the exposure at the maximum recommended human dose (MRHD).

Oral administration of ivacaftor to pregnant rats and rabbits during organogenesis demonstrated no adverse effects on fetal development at doses that produced maternal exposures up to approximately 7 (rats) and 45 (rabbits) times the exposure at the MRHD. No adverse developmental effects were observed after oral administration of either lumacaftor or ivacaftor to pregnant rats from organogenesis through lactation at doses that produced maternal exposures approximately 8 and 5 times the exposures at the MRHD, respectively (see Data ) . There are no animal reproduction studies with concomitant administration of lumacaftor and ivacaftor.

The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Animal Data Lumacaftor In an embryo-fetal development (EFD) study, pregnant rats were administered lumacaftor at oral doses of 500, 1000, or 2000 mg/kg/day during the period of organogenesis from gestation days 7-17. Lumacaftor did not affect fetal development or survival at exposures up to 8 times the MRHD (on an AUC basis at maternal oral doses up to 2000 mg/kg/day).

In an EFD study, pregnant rabbits were administered lumacaftor at oral doses of 50, 100, or 200 mg/kg/day during the period of organogenesis from gestation days 7-19. Lumacaftor did not affect fetal development or survival at exposures up to 5 times the MRHD (on an AUC basis at maternal oral doses up to 200 mg/kg/day). Maternal toxicity as evidenced by decreased body weight, decreased food consumption, and clinical signs was observed at 100 and 200 mg/kg/day without any adverse fetal effects.

In a pre- and post-natal development study in pregnant female rats administered lumacaftor at 250, 500, or 1000 mg/kg/day from gestation day 6 through lactation day 20, lumacaftor had no effects on delivery or growth and development of…