TRACLEER ® is the proprietary name for bosentan, an endothelin receptor antagonist that belongs to a class of highly substituted pyrimidine derivatives, with no chiral centers. It is designated chemically as 4-tert-butyl-N-[6-(2-hydroxy-ethoxy)-5-(2-methoxy-phenoxy)-[2,2´]-bipyrimidin-4-yl]- benzenesulfonamide monohydrate and has the following structural formula: Bosentan has a molecular weight of 569.64 and a molecular formula of C 27 H 29 N 5 O 6 S∙H 2 O. Bosentan is a white to yellowish powder. It is poorly soluble in water (1.0 mg/100 mL) and in aqueous solutions at low pH (0.1 mg/100 mL at pH 1.1 and 4.0; 0.2 mg/100 mL at pH 5.0). Solubility increases at higher pH values (43 mg/100 mL at pH 7.5). In the solid state, bosentan is very stable, is not hygroscopic and is not light sensitive. TRACLEER is available as 62.5 mg and 125 mg film-coated tablets for oral administration, and contains the following excipients: corn starch, ethylcellulose, glyceryl behenate, hydroxypropylmethylcellulose, iron oxide red, iron oxide yellow, magnesium stearate, povidone, pregelatinized starch, sodium starch glycolate, talc, titanium dioxide, and triacetin. Each TRACLEER 62.5 mg tablet contains 64.54 mg of bosentan monohydrate, equivalent to 62.5 mg of anhydrous bosentan. Each TRACLEER 125 mg tablet contains 129.08 mg of bosentan monohydrate, equivalent to 125 mg of anhydrous bosentan. TRACLEER is also available as a 32 mg tablet for oral suspension and contains the following excipients: acesulfame potassium, aspartame (E951), calcium hydrogen phosphate anhydrous, cellulose microcrystalline, croscarmellose sodium, magnesium stearate, silica colloidal anhydrous, tartaric acid, and tutti frutti flavor. Each dispersible tablet contains 1.87 mg of phenylalanine. Each dispersible tablet contains 33.045 mg of bosentan monohydrate, equivalent to 32 mg anhydrous bosentan. Chemical Structure

TRACLEER is indicated for the treatment of pulmonary arterial hypertension (PAH) (WHO Group 1): in adults to improve exercise ability and to decrease clinical worsening. Studies establishing effectiveness included predominantly patients with WHO Functional Class II-IV symptoms and etiologies of idiopathic or heritable PAH (60%), PAH associated with connective tissue diseases (21%), and PAH associated with congenital heart disease with left-to-right shunts (18%) . in pediatric patients aged 3 years and older with idiopathic or congenital PAH to improve pulmonary vascular resistance (PVR), which is expected to result in an improvement in exercise ability. TRACLEER is an endothelin receptor antagonist indicated for the treatment of pulmonary arterial hypertension (PAH) (WHO Group 1): in adults to improve exercise ability and to decrease clinical worsening. Studies establishing effectiveness included predominantly patients with WHO Functional Class II-IV symptoms and etiologies of idiopathic or heritable PAH (60%), PAH associated with connective tissue diseases (21%), and PAH associated with congenital heart disease with left-to-right shunts (18%). in pediatric patients aged 3 years and older with idiopathic or congenital PAH to improve pulmonary vascular resistance (PVR), which is expected to result in an improvement in exercise ability.

62.5 mg tablets : round, biconvex, orange-white tablets, debossed with identification marking "62,5" 125 mg tablets : oval, biconvex, orange-white tablets, debossed with identification marking "125" 32 mg tablets for oral suspension : round, pale yellow to off-white tablets, bisected on one side and debossed with identification marking “32” on the other side. Film-coated tablet: 62.5 mg and 125 mg. Tablet for oral suspension: 32 mg.

Patients older than 12 years of age: initiate at 62.5 mg orally twice daily; for patients weighing greater than 40 kg, increase to 125 mg orally twice daily after 4 weeks. Patients 12 years of age and younger: dosage is based on weight, see Table 1. Reduce the dose and closely monitor patients developing aminotransferase elevations more than 3×Upper Limit of Normal (ULN)

Required Monitoring Healthcare professionals who prescribe TRACLEER must enroll in the Bosentan REMS and must comply with the required monitoring to minimize the risks associated with TRACLEER . Measure liver aminotransferase levels prior to initiation of treatment and then monthly . Exclude pregnancy before initiating treatment with TRACLEER in females of reproductive potential

Recommended Dosage Administer TRACLEER orally following the dosing recommendations in Table 1. Doses above 125 mg twice daily did not appear to confer additional benefit sufficient to offset the increased risk of hepatotoxicity. Table 1: Dosing Recommendations Initial 4 weeks Maintenance (after 4 weeks) Patients >12 years of age and >40 kg 62.5 mg twice daily 125 mg twice daily Patients >12 years of age and <40 kg 62.5 mg twice daily 62.5 mg twice daily Patients ≤12 years of age ≥4–8 kg 16 mg twice daily 16 mg twice daily >8–16 kg 32 mg twice daily 32 mg twice daily >16–24 kg 48 mg twice daily 48 mg twice daily >24–40 kg 64 mg twice daily 64 mg twice daily 2.3 Administration TRACLEER film-coated tablets and tablets for oral suspension (dispersible tablets) should be administered orally twice daily. Disperse tablets for oral suspension, or dispersible tablet half, in a minimal amount of water immediately before administration. Store divided dispersible tablet pieces at 20 ºC to 25 ºC (68 ºF to 77 ºF) in the opened blister for up to 7 days

Dosage Adjustments for Aminotransferase Elevations If aminotransferase levels increase, adjust monitoring and treatment plan according to Table 2. Discontinue TRACLEER if liver aminotransferase elevations are accompanied by clinical symptoms of hepatotoxicity (such as nausea, vomiting, fever, abdominal pain, jaundice, or unusual lethargy or fatigue) or bilirubin ≥2 × Upper Limit of Normal (ULN). There is no experience with the reintroduction of TRACLEER in these circumstances. Table 2: Dosage Adjustment and Monitoring in Patients Developing Aminotransferase Elevations >3×ULN ALT/AST levels Treatment and monitoring recommendations >3 and ≤5 × ULN Confirm by another aminotransferase test; if confirmed, in adults and pediatric patients >12 years and >40 kg , reduce the daily dose to 62.5 mg twice daily or interrupt treatment, and monitor aminotransferase levels at least every 2 weeks. If the aminotransferase levels return to pretreatment values, treatment may continue or be reintroduced at 62.5 mg twice daily, with reassessment of aminotransferase levels within 3 days. in all other pediatric patients , interrupt treatment with no prior dose reduction. If the aminotransferase levels return to pretreatment values, reintroduce at the dose used prior to treatment interruption, with reassessment of aminotransferase levels within 3 days. >5 and ≤8 × ULN Confirm by another aminotransferase test; if confirmed, stop treatment and monitor aminotransferase levels at least every 2 weeks. Once the aminotransferase levels return to pretreatment values, in adults and pediatric patients >12 years and >40 kg , consider reintroduction of treatment at 62.5 mg twice daily, with reassessment of aminotransferase levels within 3 days. in all other pediatric patients , consider reintroduction at the dose used prior to treatment interruption, with reassessment of aminotransferase levels within 3 days. >8 × ULN Stop treatment permanently. There is no experience with reintroduction of TRACLEER in these circumstances

Use with Ritonavir Co-administration of TRACLEER in Patients on Ritonavir In patients who have been receiving ritonavir for at least 10 days, start TRACLEER at the recommended initial dose once daily or every other day based upon individual tolerability . Co-administration of Ritonavir in Patients on TRACLEER Discontinue use of TRACLEER at least 36 hours prior to initiation of ritonavir. After at least 10 days following the initiation of ritonavir, resume TRACLEER at the recommended initial dose once daily or every other day based upon individual tolerability

Use in Patients with Pre-existing Hepatic Impairment Avoid initiation of TRACLEER in patients with aminotransferases >3 × ULN. No dose adjustment is required in patients with mildly impaired liver function .

Fluid retention: May require intervention. Pulmonary veno-occlusive disease (PVOD): If signs of pulmonary edema occur, consider the diagnosis of associated PVOD and consider discontinuing TRACLEER. Decreased sperm counts. Decreases in hemoglobin and hematocrit: Monitor hemoglobin levels after 1 and 3 months of treatment, then every 3 months thereafter

Hepatotoxicity ALT or AST >3 × ULN were observed in 11% of TRACLEER-treated patients (n=658) compared to 2% of placebo-treated patients (n=280). Three-fold increases were seen in 12% of 95 pulmonary arterial hypertension (PAH) patients on 125 mg twice daily and 14% of 70 PAH patients on 250 mg twice daily. Eight-fold increases were seen in 2% of PAH patients on 125 mg twice daily and 7% of PAH patients on 250 mg twice daily. Bilirubin increases to ≥3 × ULN were associated with aminotransferase increases in 2 of 658 (0.3%) of patients treated with TRACLEER. In a pooled analysis of four pediatric studies conducted in PAH (n=100), elevations in liver aminotransferases ≥3×ULN were observed in 2% of patients. The combination of hepatocellular injury (increases in aminotransferases of >3 × ULN) and increases in total bilirubin (≥2 × ULN) is a marker for potential serious hepatotoxicity. Elevations of AST or ALT associated with TRACLEER are dose-dependent, occur both early and late in treatment, usually progress slowly, are typically asymptomatic, and usually have been reversible after treatment interruption or cessation. Aminotransferase elevations also may reverse spontaneously while continuing treatment with TRACLEER. Liver aminotransferase levels must be measured prior to initiation of treatment and then monthly and therapy adjusted accordingly . Discontinue TRACLEER if liver aminotransferase elevations are accompanied by clinical symptoms of hepatotoxicity (such as nausea, vomiting, fever, abdominal pain, jaundice, or unusual lethargy or fatigue) or increases in bilirubin ≥2 × ULN. Avoid initiation of TRACLEER in patients with elevated aminotransferases (>3 × ULN) prior to drug initiation because monitoring hepatotoxicity in these patients may be more difficult . In WHO Functional Class II patients, consider whether the benefits of TRACLEER are sufficient to offset the risk of hepatotoxicity, which may preclude future use as their disease progresses. TRACLEER is only available through a restricted program under REMS

Bosentan REMS Because of the risks of hepatotoxicity , TRACLEER is available only through a restricted program called the Bosentan REMS. As a component of the Bosentan REMS, prescribers, patients, and pharmacies must enroll in the program . Required components of the Bosentan REMS are: Healthcare professionals who prescribe TRACLEER must review the prescriber educational materials, enroll in the Bosentan REMS and comply with its requirements. Healthcare professionals must review serum aminotransferases (ALT/AST) and bilirubin, and agree to order and monitor these tests monthly. To receive TRACLEER, all patients must understand the risks and benefits, and complete a patient enrollment form with their prescriber. Pharmacies that dispense TRACLEER must enroll in the program and agree to comply with the Bosentan REMS requirements. Further information about TRACLEER and the Bosentan REMS is available at www.BosentanREMSProgram.com or 1-866-359-2612

Embryo-Fetal Toxicity Based on data from animal reproduction studies, TRACLEER may cause fetal harm when administered to a pregnant female and is contraindicated in females who are pregnant. The available human data for endothelin receptor antagonists do not establish the presence or absence of major birth defects related to the use of TRACLEER. Advise females of reproductive potential about the potential risk to a fetus. Exclude pregnancy prior to TRACLEER treatment. Advise females of reproductive potential to use effective contraception prior to initiation of treatment with TRACLEER, during treatment, and for at least one month after the last dose. When pregnancy is detected, discontinue TRACLEER as soon as possible

Fluid Retention Peripheral edema is a known clinical consequence of PAH and worsening PAH and is also a known effect of TRACLEER and other endothelin receptor antagonists. In PAH clinical trials with TRACLEER, combined adverse events of fluid retention or edema were reported in 1.7% (placebo-corrected) of patients. In addition, there have been numerous postmarketing reports of fluid retention in patients with pulmonary hypertension occurring within weeks after starting TRACLEER. Patients required intervention with a diuretic, fluid management, or hospitalization for decompensating heart failure. If clinically significant fluid retention develops, with or without associated weight gain, further evaluation should be undertaken to determine the cause, such as TRACLEER or underlying heart failure, and the possible need for treatment or discontinuation of TRACLEER

Pulmonary Veno-Occlusive Disease If signs of pulmonary edema occur, consider the possibility of associated pulmonary veno-occlusive disease and consider whether TRACLEER should be discontinued

Decreased Sperm Counts Decreased sperm counts have been observed in patients receiving TRACLEER. Preclinical data also suggest that TRACLEER, similar to other endothelin receptor antagonists, may have an adverse effect on spermatogenesis

Decreases in Hemoglobin and Hematocrit Treatment with TRACLEER can cause a dose-related decrease in hemoglobin and hematocrit. There have been postmarketing reports of decreases in hemoglobin concentration and hematocrit that have resulted in anemia requiring transfusion. It is recommended that hemoglobin concentrations be checked after 1 and 3 months, and every 3 months thereafter. If a marked decrease in hemoglobin concentration occurs, further evaluation should be undertaken to determine the cause and need for specific treatment .

Cytochrome P450: Coadministration of TRACLEER with drugs metabolized by CYP2C9 and CYP3A can increase exposure to TRACLEER and/or the coadministered drug ( 4.2 , 4.3 , 7.1 ). Hormonal contraceptives: TRACLEER use decreases contraceptive exposure and reduces effectiveness

Cytochrome P450 Drug Interactions Bosentan is metabolized by CYP2C9 and CYP3A. Inhibition of these enzymes may increase the plasma concentration of bosentan . Concomitant administration of both a CYP2C9 inhibitor (such as fluconazole or amiodarone) and a strong CYP3A inhibitor (e.g., ketoconazole, itraconazole) or a moderate CYP3A inhibitor (e.g., amprenavir, erythromycin, fluconazole, diltiazem) with TRACLEER will likely lead to large increases in plasma concentrations of bosentan. Co-administration of such combinations of a CYP2C9 inhibitor plus a strong or moderate CYP3A inhibitor with TRACLEER is not recommended. Bosentan is an inducer of CYP3A and CYP2C9. Consequently plasma concentrations of drugs metabolized by these two isozymes will be decreased when TRACLEER is co-administered. Bosentan had no relevant inhibitory effect on any CYP isozyme in vitro (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A). Consequently, TRACLEER is not expected to increase the plasma concentrations of drugs metabolized by these enzymes. Figure 1. CYP3A induction-mediated effect of bosentan on other drugs Figure 2. Effect of other drugs on bosentan Figure 1 Figure 2 7.2 Hormonal Contraceptives Hormonal contraceptives, including oral, injectable, transdermal, and implantable forms, may not be reliable when TRACLEER is co-administered. Females should practice additional methods of contraception and not rely on hormonal contraception alone when taking TRACLEER . An interaction study demonstrated that co-administration of bosentan and a combination oral hormonal contraceptive produced average decreases of norethindrone and ethinyl estradiol levels of 14% and 31%, respectively. However, decreases in exposure were as much as 56% and 66%, respectively, in individual subjects.