Get your patient on Tracleer (Bosentan)

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 [see Drug Interactions (7.1) ] .

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 [see Drug Interactions (7.1) ] .

Risk Summary

Based on data from animal reproduction studies, TRACLEER may cause fetal harm, including birth defects and fetal death, when administered to a pregnant female and is contraindicated during pregnancy [see Contraindications (4.1) ] . Available data from postmarketing reports and published literature over decades of use with endothelin receptor antagonists (ERA) in the same class as TRACLEER have not identified an increased risk of major birth defects; however, these data are limited. Methodological limitations of these postmarketing reports and published literature include lack of a control group; limited information regarding dose, duration, and timing of drug exposure; and missing data. These limitations preclude establishing a reliable estimate of the risk of adverse fetal and neonatal outcomes with maternal ERA use. In animal reproduction studies, oral administration of bosentan to pregnant rats at 2-times the maximum recommended human dose (MRHD) on a mg/m ² basis caused teratogenic effects in rats, including malformations of the head, mouth, face, and large blood vessels [see Animal Data ] . Advise pregnant women of the potential risk to a fetus.

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 miscarriage in clinically recognized pregnancies is 2–4% and 15–20%, respectively.

Data

Risk Summary

Data from a case report describe the presence of bosentan in human milk. There is insufficient information about the effects of bosentan on the breastfed infant and no information on the effects of bosentan on milk production. Because of the potential for serious adverse reactions, such as fluid retention and hepatotoxicity, in breastfed infants from TRACLEER, advise women not to breastfeed during treatment with TRACLEER.

Pregnancy Testing

Verify that females of reproductive potential are not pregnant prior to initiating TRACLEER. The patient should contact her physician immediately for pregnancy testing if onset of menses is delayed or pregnancy is suspected. If the pregnancy test is positive, the physician and patient must discuss the risks to her, the pregnancy, and the fetus [see Dosage and Administration (2.1) , Contraindications (4.1) , Warnings and Precautions (5.3) ] .

Contraception

Drug interaction studies show that bosentan reduces serum levels of the estrogen and progestin in oral contraceptives. Based on these findings, hormonal contraceptives (including oral, injectable, transdermal, and implantable contraceptives) may be less effective for preventing pregnancy in patients using TRACLEER and should not be used as a patient's only contraceptive method [see Drug Interactions (7.2) ] . Females of reproductive potential using TRACLEER should use effective methods of contraception prior to initiation of treatment, during treatment, and for 1 month after treatment with TRACLEER [see Warnings and Precautions (5.3) ] . Patients may choose one highly effective form of contraception (intrauterine devices (IUD) or tubal sterilization) or a combination of methods (hormone method with a barrier method or two barrier methods). If a partner's vasectomy is the chosen method of contraception, a hormone or barrier method must be used along with this method. Counsel patients on pregnancy planning and prevention, including emergency contraception, or designate counseling by another healthcare provider trained in contraceptive counseling.

Infertility

Juvenile Animal Toxicity Data

In a juvenile rat toxicity study, rats were treated from Day 4 postpartum to adulthood (Day 69 postpartum). Decreased body weights, absolute weights of testes and epididymides, and reduced number of sperm in epididymides were observed after weaning. No effect on testis histology or sperm morphology and function was seen. The NOAEL was 4 times (at Day 4 postpartum) and 2 times (Day 69 postpartum) the human therapeutic exposure, respectively.

No effects on general development, sensory, cognitive function and reproductive performance were detected at the highest dose tested in juvenile rats, 7 times the therapeutic exposure in children with PAH.

Decreased Sperm Counts

An open-label, single-arm, multicenter, safety study evaluated the effect on testicular function of TRACLEER 62.5 mg twice daily for 4 weeks, followed by 125 mg twice daily for 5 months. Twenty-five male patients with WHO functional class III and IV PAH and normal baseline sperm count were enrolled. Twenty-three completed the study and 2 discontinued due to adverse events not related to testicular function. There was a decline in sperm count of at least 50% in 25% of the patients after 3 or 6 months of treatment with TRACLEER. Sperm count remained within the normal range in all 22 patients with data after 6 months and no changes in sperm morphology, sperm motility, or hormone levels were observed. One patient developed marked oligospermia at 3 months and the sperm count remained low with 2 follow-up measurements over the subsequent 6 weeks. TRACLEER was discontinued and after 2 months the sperm count had returned to baseline levels. Based on these findings and preclinical data from endothelin receptor antagonists, it cannot be excluded that endothelin receptor antagonists such as TRACLEER have an adverse effect on spermatogenesis.

Decreases in Hemoglobin and Hematocrit

Treatment with TRACLEER can cause a dose-related decrease in hemoglobin and hematocrit. 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.

The overall mean decrease in hemoglobin concentration for adult TRACLEER-treated patients was 0.9 g/dL (change to end of treatment). Most of this decrease of hemoglobin concentration was detected during the first few weeks of TRACLEER treatment and hemoglobin levels stabilized by 4–12 weeks of TRACLEER treatment. In placebo-controlled studies of all uses of TRACLEER, marked decreases in hemoglobin (>15% decrease from baseline resulting in values <11 g/dL) were observed in 6% of TRACLEER-treated patients and 3% of placebo-treated patients. In patients with PAH treated with doses of 125 and 250 mg twice daily, marked decreases in hemoglobin occurred in 3% compared to 1% in placebo-treated patients.

A decrease in hemoglobin concentration by at least 1 g/dL was observed in 57% of TRACLEER-treated patients as compared to 29% of placebo-treated patients. In 80% of those patients whose hemoglobin decreased by at least 1 g/dL, the decrease occurred during the first 6 weeks of TRACLEER treatment.

During the course of treatment, the hemoglobin concentration remained within normal limits in 68% of TRACLEER-treated patients compared to 76% of placebo patients. The explanation for the change in hemoglobin is not known, but it does not appear to be hemorrhage or hemolysis.

In a pooled analysis of pediatric patients (N=100) with PAH treated with TRACLEER, a decrease in hemoglobin levels to <10 g/dL from baseline was reported in 11% of patients. There was no decrease to <8 g/dL.

General

After oral administration, maximum plasma concentrations of bosentan are attained within 3–5 hours and the terminal elimination half-life is about 5 hours in healthy adult subjects. The exposure to bosentan after intravenous and oral administration is about twice as high in adult patients with PAH as it is in healthy adult subjects.

In a relative bioavailability study in healthy adults, the peak plasma concentration and area under the plasma concentration-time curve for bosentan are on an average 14% and 11%, respectively, lower following administration of the oral dispersible tablet compared to the film-coated tablet.

Absorption

The absolute bioavailability of bosentan in normal volunteers is about 50% and is unaffected by food.

Bosentan is highly bound (>98%) to plasma proteins, mainly albumin. Bosentan does not penetrate into erythrocytes. The volume of distribution is about 18 L.

Elimination

Specific Populations

Drug Interactions

Carcinogenesis and Mutagenesis

Two years of dietary administration of bosentan to mice produced an increased incidence of hepatocellular adenomas and carcinomas in males at doses as low as 450 mg/kg/day (about 8 times the maximum recommended human dose [MRHD] of 125 mg twice daily, on a mg/m ² basis). In the same study, doses greater than 2000 mg/kg/day (about 32 times the MRHD) were associated with an increased incidence of colon adenomas in both males and females. In rats, dietary administration of bosentan for two years was associated with an increased incidence of brain astrocytomas in males at doses as low as 500 mg/kg/day (about 16 times the MRHD). In a comprehensive battery of in vitro tests (the microbial mutagenesis assay, the unscheduled DNA synthesis assay, the V-79 mammalian cell mutagenesis assay, and human lymphocyte assay) and an in vivo mouse micronucleus assay, there was no evidence for any mutagenic or clastogenic activity of bosentan.

Impairment of Fertility/Testicular Function

The development of testicular tubular atrophy and impaired fertility has been linked with the chronic administration of certain endothelin receptor antagonists in rodents.

Treatment with bosentan at oral doses of up to 1500 mg/kg/day (50 times the MRHD on a mg/m ² basis) or intravenous doses up to 40 mg/kg/day had no effects on sperm count, sperm motility, mating performance or fertility in male and female rats. An increased incidence of testicular tubular atrophy was observed in rats given bosentan orally at doses as low as 125 mg/kg/ day (about 4 times the MRHD and the lowest doses tested) for two years but not at doses as high as 1500 mg/kg/day (about 50 times the MRHD) for 6 months. Effects on sperm count and motility were evaluated only in the much shorter duration fertility studies in which males had been exposed to the drug for 4–6 weeks. An increased incidence of tubular atrophy was not observed in mice treated for 2 years at doses up to 4500 mg/kg/day (about 75 times the MRHD) or in dogs treated up to 12 months at doses up to 500 mg/kg/day (about 50 times the MRHD).

WHO Functional Class III-IV

Two randomized, double-blind, multi-center, placebo-controlled trials were conducted in 32 and 213 patients. The larger study (BREATHE-1) compared 2 doses (125 mg twice daily and 250 mg twice daily) of TRACLEER with placebo. The smaller study (Study 351) compared 125 mg twice daily with placebo. Patients had severe (WHO functional Class III–IV) PAH: idiopathic or heritable PAH (72%) or PAH associated with scleroderma or other connective tissue diseases (21%), or to autoimmune diseases (7%). There were no patients with PAH associated with other conditions such as HIV disease or recurrent pulmonary emboli.

In both studies, TRACLEER or placebo was added to patients' current therapy, which could have included a combination of digoxin, anticoagulants, diuretics, and vasodilators (e.g., calcium channel blockers, ACE inhibitors), but not epoprostenol. TRACLEER was given at a dose of 62.5 mg twice daily for 4 weeks and then at 125 mg twice daily or 250 mg twice daily for either 12 (BREATHE-1) or 8 (Study 351) additional weeks. The primary study endpoint was 6-minute walk distance. In addition, symptoms and functional status were assessed. Hemodynamic measurements were made at 12 weeks in Study 351.

The mean age was about 49 years. About 80% of patients were female, and about 80% were Caucasian. Patients had been diagnosed with pulmonary hypertension for a mean of 2.4 years.

Submaximal Exercise Ability

Results of the 6-minute walk distance at 3 months (Study 351) or 4 months (BREATHE-1) are shown in Table 4.

In both trials, treatment with TRACLEER resulted in a significant increase in exercise ability. The improvement in walk distance was apparent after 1 month of treatment (with 62.5 mg twice daily) and fully developed by about 2 months of treatment (Figure 5). It was maintained for up to 7 months of double-blind treatment. Walking distance was somewhat greater with 250 mg twice daily, but the potential for increased hepatotoxicity causes this dose not to be recommended [see Dosage and Administration (2.2) ] . There were no apparent differences in treatment effects on walk distance among subgroups analyzed by demographic factors, baseline disease severity, or disease etiology, but the studies had little power to detect such differences.

Figure 5. Mean Change in 6-min Walk Distance (BREATHE-1)

Change from baseline in 6-minute walking distance from start of therapy to week 16 in the placebo and combined TRACLEER (125 mg twice daily and 250 mg twice daily) groups. Values are expressed as mean ± standard error of the mean.

Hemodynamic Changes

Invasive hemodynamic parameters were assessed in Study 351. Treatment with TRACLEER led to a significant increase in cardiac index (CI) associated with a significant reduction in pulmonary artery pressure (PAP), pulmonary vascular resistance (PVR), and mean right atrial pressure (RAP) (Table 5).

The relationship between hemodynamic effects and improvements in 6-minute walk distance is unknown.

Symptoms and Functional Status

Symptoms of PAH were assessed by Borg dyspnea score, WHO functional class, and rate of "clinical worsening." Clinical worsening was assessed as the sum of death, hospitalizations for PAH, discontinuation of therapy because of PAH, and need for epoprostenol. There was a significant reduction in dyspnea during walk tests (Borg dyspnea score), and significant improvement in WHO functional class in TRACLEER-treated patients. There was a significant reduction in the rate of clinical worsening (Table 6 and Figure 6). Figure 6 shows the log-rank test reflecting clinical worsening over 28 weeks.

Figure 6. Time to Clinical Worsening (BREATHE-1)

Time from randomization to clinical worsening with Kaplan-Meier estimate of the proportions of failures in BREATHE-1. All patients (n=144 in the TRACLEER group and n=69 in the placebo group) participated in the first 16 weeks of the study. A subset of this population (n=35 in the TRACLEER group and 13 in the placebo group) continued double-blind therapy for up to 28 weeks.

WHO Functional Class II

In a randomized, double-blind, multicenter, placebo-controlled trial, 185 mildly symptomatic PAH patients with WHO Functional Class II (mean baseline 6-minute walk distance of 443 meters) received TRACLEER 62.5 mg twice daily for 4 weeks followed by 125 mg twice daily (n=93), or placebo (n=92) for 6 months. Enrolled patients were treatment-naïve (n=156) or on a stable dose of sildenafil (n=29). The coprimary endpoints were change from baseline to month 6 in PVR and 6-minute walk distance. Time to clinical worsening (assessed as the sum of death, hospitalization due to PAH complications, or symptomatic progression of PAH), Borg dyspnea index, change in WHO functional class and hemodynamics were assessed as secondary endpoints.

Compared with placebo, TRACLEER treatment was associated with a reduced incidence of worsening of at least one functional class (3% TRACLEER vs. 13% placebo, p=0.03), and improvement in hemodynamic variables (PVR, mPAP, TPR, cardiac index, and SVO ₂ ; p <0.05). The +19 m mean (+14 m median) increase in 6-minute walk distance with TRACLEER vs. placebo was not significant (p=0.08). There was a significant delay in time to clinical worsening (first seen primarily as symptomatic progression of PAH) with TRACLEER compared with placebo (hazard ratio 0.2, p=0.01). Findings were consistent in strata with or without treatment with sildenafil at baseline.

Long-term Treatment of PAH

Long-term follow-up of patients with Class III and IV PAH who were treated with TRACLEER in open-label extensions of trials (N=235) showed that 93% and 84% of patients were still alive at 1 and 2 years, respectively, after the start of treatment.

These uncontrolled observations do not allow comparison with a group not given TRACLEER and cannot be used to determine the long-term effect of TRACLEER on mortality.

Pediatric Studies

The efficacy of bosentan was evaluated in an open-label, uncontrolled study in 19 pediatric patients with PAH aged 3 to 15 years. Patients had primary pulmonary hypertension (n=10) or PAH related to congenital heart diseases (9 patients) and were WHO functional class II (n=15, 79%) or class III (n=4; 21%) at baseline. Patients were dosed with bosentan at approximately 2 mg/kg twice daily (body weight adjusted dose, corresponding to the recommended adult dose) [see Dosage and Administration (2.1) ] for 12 weeks. Half of the patients in each group were already being treated with intravenous epoprostenol and the dose of epoprostenol remained constant for the duration of the study.

Hemodynamics were measured in 17 patients (Table 7). The mean decrease in PVR was 389 dyn∙sec∙cm ^-5 , which was similar to the effect seen in adults. Hemodynamic improvements from baseline were similar with or without co-administration of epoprostenol.

Pulmonary Arterial Hypertension in Adults related to Congenital Heart Disease with Left-to-Right Shunts

A small study (N=54) and its open-label extension (N=37) of up to 40 weeks in adult patients with Eisenmenger physiology demonstrated effects of TRACLEER on exercise and safety that were similar to those seen in other trials in patients with PAH (WHO Group 1).