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Warning: Risks Of Hepatotoxicity And Embryo-Fetal Toxicity
Because of the risks of hepatotoxicity and birth defects, bosentan is available only through a restricted program called the Bosentan REMS Program. The Bosentan REMS Program is a component of the Bosentan Risk Evaluation and Mitigation Strategy (REMS). Under the Bosentan REMS, prescribers, patients, and pharmacies must enroll in the program. [see Warnings and Precautions (5.3)].
HepatotoxicityIn clinical studies, bosentan caused at least 3-fold upper limit of normal (ULN) elevation of liver aminotransferases (ALT and AST) in about 11% of patients, accompanied by elevated bilirubin in a small number of cases. Because these changes are a marker for potential serious hepatotoxicity, serum aminotransferase levels must be measured prior to initiation of treatment and then monthly [see Dosage and Administration (2.4), Warnings and Precautions (5.1)]. In the postmarketing period, in the setting of close monitoring, rare cases of unexplained hepatic cirrhosis were reported after prolonged (> 12 months) therapy with bosentan in patients with multiple comorbidities and drug therapies. There have also been reports of liver failure. The contribution of bosentan in these cases could not be excluded.In at least one case, the initial presentation (after > 20 months of treatment) included pronounced elevations in aminotransferases and bilirubin levels accompanied by non-specific symptoms, all of which resolved slowly over time after discontinuation of bosentan. This case reinforces the importance of strict adherence to the monthly monitoring schedule for the duration of treatment and the treatment algorithm, which includes stopping bosentan with a rise of aminotransferases accompanied by signs or symptoms of liver dysfunction [see Dosage and Administration (2.4)].Elevations in aminotransferases require close attention [see Dosage and Administration (2.4)]. Bosentan should generally be avoided in patients with elevated aminotransferases (> 3 × ULN) at baseline because monitoring for hepatotoxicity may be more difficult. 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, treatment with bosentan should be stopped. There is no experience with the reintroduction of bosentan in these circumstances.
Embryo-Fetal ToxicityBosentan is likely to cause major birth defects if used by pregnant females based on animal data [see Warnings and Precautions (5.2), Use in Specific Populations (8.1)]. Therefore, pregnancy must be excluded before the start of treatment with bosentan. Throughout treatment and for one month after stopping bosentan, females of reproductive potential must use two reliable methods of contraception unless the patient has an intrauterine device (IUD) or tubal sterilization, in which case no other contraception is needed. Hormonal contraceptives, including oral, injectable, transdermal, and implantable contraceptives should not be used as the sole means of contraception because these may not be effective in patients receiving bosentan [see Drug Interactions (7.2)]. Obtain monthly pregnancy tests.
Coadministration of Bosentan in Patients on RitonavirIn patients who have been receiving ritonavir for at least 10 days, start bosentan at 62.5 mg once daily or every other day based upon individual tolerability [see Cytochrome P450 Drug Interactions (7.1)].
Coadministration of Ritonavir in Patients on BosentanDiscontinue use of bosentan at least 36 hours prior to initiation of ritonavir. After at least 10 days following the initiation of ritonavir, resume bosentan at 62.5 mg once daily or every other day based upon individual tolerability [see Cytochrome P450 Drug Interactions (7.1)].
Decreased Sperm CountsAn open-label, single arm, multicenter, safety study evaluated the effect on testicular function of bosentan 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 bosentan. 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. Bosentan 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 bosentan have an adverse effect on spermatogenesis.
Decreases in Hemoglobin and HematocritTreatment with bosentan 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 bosentan-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 bosentan treatment and hemoglobin levels stabilized by 4–12 weeks of bosentan treatment. In placebo-controlled studies of all uses of bosentan, marked decreases in hemoglobin (> 15% decrease from baseline resulting in values < 11 g/dL) were observed in 6% of bosentan-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 bosentan-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 bosentan treatment.During the course of treatment the hemoglobin concentration remained within normal limits in 68% of bosentan-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.
Risk SummaryBased on data from animal reproduction studies, bosentan 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)]. There are limited data on bosentan use in pregnant women. In animal reproduction studies, oral administration of bosentan to pregnant rats at 2-times the maximum recommended human dose (MRHD) on a mg/m2 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.
Animal DataBosentan was teratogenic in rats given oral doses two times the MRHD (on a mg/m2 basis). In an embryo-fetal toxicity study in rats, bosentan showed dose-dependent teratogenic effects, including malformations of the head, mouth, face and large blood vessels. Bosentan increased stillbirths and pup mortality at oral doses 2 and 10 times the MRHD (on a mg/m2 basis). Although birth defects were not observed in rabbits given oral doses of up to the equivalent of 10.5 g/day in a 70 kg person, plasma concentrations of bosentan in rabbits were lower than those reached in the rat. The similarity of malformations induced by bosentan and those observed in endothelin-1 knockout mice and in animals treated with other endothelin receptor antagonists indicates that embryo-fetal toxicity is a class effect of these drugs.
Risk SummaryThere are no data on the presence of bosentan in human milk, the effects on the breastfed infant, or the effect on milk production. Because of the potential for serious adverse reactions, such as fluid retention and hepatotoxicity, in breastfed infants from bosentan, advise women not to breastfeed during treatment with bosentan.
Pregnancy TestingVerify the pregnancy status of females of reproductive potential prior to initiating bosentan, monthly during treatment and one month after stopping treatment with bosentan. 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.
ContraceptionDrug 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 bosentan and should not be used as a patient's only contraceptive method [see Drug Interactions (7.2)]. Females of reproductive potential using bosentan must use two acceptable methods of contraception during treatment and for 1 month after treatment with bosentan. 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 [see Boxed Warning].
MalesDecreased sperm counts have been observed in patients receiving bosentan. Based on these findings and findings in animals, bosentan may impair fertility in males of reproductive potential. It is not known whether effects on fertility would be reversible [see Warnings and Precautions (5.6), Adverse Reactions (6.1), Nonclinical Toxicology (13.1)].
Juvenile Animal Toxicity DataIn 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.
GeneralAfter oral administration, maximum plasma concentrations of bosentan are attained within 3–5 hours and the terminal elimination half-life (t1/2) is about 5 hours in healthy adult subjects. The exposure to bosentan after intravenous and oral administration is about 2-fold greater in adult patients with PAH than 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.
AbsorptionThe 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.
MetabolismBosentan has three metabolites, one of which is pharmacologically active and may contribute 10%–20% of the effect of bosentan. Bosentan is an inducer of CYP2C9 and CYP3A and possibly also of CYP2C19. Upon multiple oral dosing, plasma concentrations in healthy adults decrease gradually to 50-65% of those seen after single dose administration, probably the effect of auto-induction of the metabolizing liver enzymes. Steady-state is reached within 3-5 days.
ExcretionBosentan is eliminated by biliary excretion following metabolism in the liver. Less than 3% of an administered oral dose is recovered in urine. Total clearance after a single intravenous dose is about 4 L/h in patients with PAH.
Specific PopulationsIt is not known whether bosentan's pharmacokinetics is influenced by gender, race, or age.
Hepatic ImpairmentIn vitro and in vivo evidence showing extensive hepatic metabolism of bosentan suggests that liver impairment could significantly increase exposure of bosentan. In a study comparing 8 patients with mild liver impairment (Child-Pugh Class A) to 8 controls, the single- and multiple-dose pharmacokinetics of bosentan was not altered in patients with mild hepatic impairment.In another small (N=8) pharmacokinetic study, the steady-state AUC of bosentan was on average 4.7 times higher and the active metabolite Ro 48-5033 was 12.4 times higher in 5 patients with moderately impaired liver function (Child-Pugh Class B) and PAH associated with portal hypertension than in 3 patients with normal liver function and PAH of other etiologies.The pharmacokinetics of bosentan have not been evaluated in patients with severe liver impairment (Child-Pugh Class C) [see Dosage and Administration (2.2), Warnings and Precautions (5.1), Use in Specific Populations (8.6)].
Renal ImpairmentIn patients with severe renal impairment (creatinine clearance 15–30 mL/min), plasma concentrations of bosentan were essentially unchanged and plasma concentrations of the three metabolites were increased about 2-fold compared to people with normal renal function. These differences do not appear to be clinically important.
KetoconazoleCo-administration of bosentan 125 mg twice daily and ketoconazole, a potent CYP3A inhibitor, increased the plasma concentrations of bosentan by approximately 100% in normal volunteers. No dose adjustment of bosentan is necessary, but increased effects of bosentan should be considered.
WarfarinCo-administration of bosentan 500 mg twice daily for 6 days in normal volunteers decreased the plasma concentrations of both S-warfarin (a CYP2C9 substrate) and R-warfarin (a CYP3A substrate) by 29 and 38%, respectively. Clinical experience with concomitant administration of bosentan and warfarin in patients with PAH did not show clinically relevant changes in INR or warfarin dose (baseline vs. end of the clinical studies), and the need to change the warfarin dose during the trials due to changes in INR or due to adverse events was similar among bosentan- and placebo-treated patients.
Digoxin, Nimodipine, and LosartanBosentan has no significant pharmacokinetic interactions with digoxin and nimodipine, and losartan has no significant effect on plasma levels of bosentan.
SildenafilIn normal volunteers, co-administration of multiple doses of 125 mg twice daily bosentan and 80 mg three times daily sildenafil resulted in a reduction of sildenafil plasma concentrations by 63% and increased bosentan plasma concentrations by 50%. The changes in plasma concentrations were not considered clinically relevant and dose adjustments are not necessary. This recommendation holds true when sildenafil is used for the treatment of PAH or erectile dysfunction.
TadalafilBosentan (125 mg twice daily) reduced tadalafil (40 mg once per day) systemic exposure (AUC) by 42% and Cmax by 27% following multiple dose co-administration. Tadalafil did not affect the exposure (AUC and Cmax) of bosentan or its metabolites.Figure 3. CYP Induction-mediated effect of bosentan on other drugsFigure 4. Effects of other drugs on bosentan
Distributed by:Patriot Pharmaceuticals, LLCHorsham, PA 19044Manufactured for: CoTherix, Inc.South San Francisco, CA 94080ACT20181025
- Restricted accessAdvise the patient that bosentan is only available through a restricted access program called the Bosentan REMS Program.As a component of the Bosentan REMS, prescribers must review the contents of the bosentan Medication Guide with the patient before initiating bosentan.Instruct patients that the risks associated with bosentan include:HepatotoxicityDiscuss with the patient the requirement to measure serum aminotransferases monthly.Embryo-fetal toxicityEducate and counsel female patients of reproductive potential about the need to use reliable methods of contraception during treatment with bosentan and for one month after treatment discontinuation. Females of reproductive potential must have monthly pregnancy tests and must use two different forms of contraception while taking bosentan and for one month after discontinuing bosentan [see Use in Specific Populations (8.1)].Females who have intrauterine devices (IUD) or tubal sterilization can use these contraceptive methods alone. Patients should be instructed to immediately contact their physician if they suspect they may be pregnant. Patients should seek additional contraceptive advice from a gynecologist or similar expert as needed.Educate and counsel females of reproductive potential on the use of emergency contraception in the event of unprotected sex or contraceptive failure.Advise pre-pubertal females to report any changes in their reproductive status immediately to her prescriber.Advise patients to contact their gynecologist or healthcare provider if they want to change the form of birth control which is used to ensure that another acceptable form of birth control is selected.Advise the patient that bosentan is available only from pharmacies that are enrolled in the Bosentan REMS Program.Patients must sign the Bosentan Patient Enrollment and Consent Form to confirm that they understand the risks of bosentan.LactationAdvise women not to breastfeed during treatment with bosentan [see Use in Specific Populations (8.2)].InfertilityAdvise males of reproductive potential that bosentan may impair fertility [see Warnings and Precautions (5.6), Adverse Reactions (6.1), Use in Specific Populations (8.3) and Nonclinical Toxicology (13.1)].
Other Risks Associated with BosentanInstruct patients that the risks associated with bosentan also include the following:Decreases in hemoglobin and hematocrit – advise patients of the importance of hemoglobin testingDecreases in sperm countFluid retention
1. Indications And Usage
Bosentan is indicated for the treatment of pulmonary arterial hypertension (PAH) (WHO Group 1) 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%) [see Clinical Studies (14.1)].
2.1 Required Monitoring
Healthcare professionals who prescribe bosentan must enroll in the Bosentan REMS Program and must comply with the required monitoring to minimize the risks associated with bosentan [see Warnings and Precautions (5.3)].Obtain a pregnancy test in females of reproductive potential prior to bosentan treatment, monthly during treatment and one month after stopping bosentan. Initiate treatment with bosentan in females of reproductive potential only after a negative pregnancy test [see Boxed Warning, Contraindications (4.1), Warnings and Precautions (5.3), Use in Specific Populations (8.1, 8.3)].Measure liver aminotransferase levels prior to initiation of treatment and then monthly [see Warnings and Precautions (5.1)].
2.2 Recommended Dosage
Administer bosentan 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 RecommendationsInitial 4 weeksMaintenance (after 4 weeks)Patients >12 years of age and >40 kg 62.5 mg twice daily125 mg twice dailyPatients >12 years of age and <40 kg62.5 mg twice daily62.5 mg twice daily
Bosentan film-coated tablets should be administered orally twice daily.
2.4 Dosage Adjustments For Patients Developing Aminotransferase Elevations
If aminotransferase levels increase, adjust monitoring and treatment plan according to Table 2.Discontinue bosentan 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 bosentan in these circumstances.Table 2: Dosage Adjustment and Monitoring in Patients Developing Aminotransferase Elevations > 3 × ULNALT/AST levelsTreatment and monitoring recommendations> 3 and ≤ 5 × ULNConfirm by another aminotransferase test; if confirmed,- in adults and pediatric patients >12 years, 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.> 5 and ≤ 8 × ULNConfirm 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, consider reintroduction of treatment at 62.5 mg twice daily, with reassessment of aminotransferase levels within 3 days.> 8 × ULNStop treatment permanently. There is no experience with reintroduction of bosentan in these circumstances.
2.6 Use In Patients With Pre-Existing Hepatic Impairment
Avoid initiation of bosentan in patients with aminotransferases >3 × ULN. No dose adjustment is required in patients with mildly impaired liver function [see Warnings and Precautions (5.3), Use in Specific Populations (8.6), Clinical Pharmacology (12.3)].
3. Dosage Forms And Strengths
62.5 mg tablets: round, biconvex, orange-white tablets, embossed with identification marking "62,5"125 mg tablets: oval, biconvex, orange-white tablets, embossed with identification marking "125"
Use of bosentan is contraindicated in females who are or may become pregnant. To prevent pregnancy, females of reproductive potential must use two reliable forms of contraception during treatment and for one month after stopping bosentan [see Boxed Warning, Warnings and Precautions (5.2), Drug Interactions (7.2), Use in Specific Populations (8.1)].
4.2 Use With Cyclosporine A
Coadministration of cyclosporine A and bosentan resulted in markedly increased plasma concentrations of bosentan. Therefore, concomitant use of bosentan and cyclosporine A is contraindicated [see Cytochrome P450 Drug Interactions (7.1)].
4.3 Use With Glyburide
An increased risk of liver enzyme elevations was observed in patients receiving glyburide concomitantly with bosentan. Therefore coadministration of glyburide and bosentan is contraindicated [see Cytochrome P450 Drug Interactions (7.1)].
Bosentan is contraindicated in patients who are hypersensitive to bosentan or any component of the product. Observed reactions include Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), anaphylaxis, rash and angioedema [see Adverse Reactions (6.2), Description (11)].
ALT or AST > 3 × ULN were observed in 11% of bosentan-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 bosentan. 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 bosentan 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 bosentan.Liver aminotransferase levels must be measured prior to initiation of treatment and then monthly and therapy adjusted accordingly [see Dosage and Administration (2.1, 2.4)]. Discontinue bosentan 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 bosentan in patients with elevated aminotransferases (> 3 × ULN) prior to drug initiation because monitoring hepatotoxicity in these patients may be more difficult [see Boxed Warning, Dosage and Administration (2.6), Use in Specific Populations (8.6)].In WHO Functional Class II patients, consider whether the benefits of bosentan are sufficient to offset the risk of hepatotoxicity, which may preclude future use as their disease progresses.
5.2 Embryo-Fetal Toxicity
Based on data from animal reproduction studies, bosentan may cause fetal harm when administered to a pregnant female and is contraindicated in females who are pregnant. Advise females of reproductive potential of the potential risk to a fetus. Obtain a pregnancy test prior to bosentan treatment, monthly during treatment and for one month after stopping treatment. Advise females of reproductive potential to use two reliable forms of contraception during treatment with bosentan and for at least one month after the last dose [see Dosage and Administration (2), Use in Specific Populations (8.1, 8.3)].Bosentan is only available for females through a restricted program under REMS [see Warnings and Precautions (5.3)].
5.3 Prescribing And Distribution Program For Bosentan
- Because of the risks of hepatotoxicity and birth defects, bosentan is available only through a restricted program called the Bosentan REMS Program. As a component of the Bosentan REMS, prescribers, patients, and pharmacies must enroll in the program [see Boxed Warning and Contraindications (4.1)].Required components of the Bosentan REMS are:Healthcare professionals who prescribe bosentan must review the prescriber educational materials, enroll in the Bosentan REMS Program and comply with its requirements.Healthcare professionals must (1) review serum aminotransferases (ALT/AST) and bilirubin, and agree to order and monitor these tests monthly; and (2) for females of reproductive potential, confirm that the patient is not pregnant, and agree to order and monitor pregnancy tests monthly. To receive bosentan, all patients must understand the risks and benefits, complete a patient enrollment form. Pharmacies that dispense bosentan must enroll in the program and agree to comply with the Bosentan REMS Program requirements.Further information about bosentan and the Bosentan REMS Program is available at www.BosentanREMSProgram.com or 1-866-359-2612.
5.4 Fluid Retention
Peripheral edema is a known clinical consequence of PAH and worsening PAH and is also a known effect of bosentan and other endothelin receptor antagonists. In PAH clinical trials with bosentan, 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 bosentan. 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 bosentan or underlying heart failure, and the possible need for treatment or discontinuation of bosentan [see Adverse Reactions (6.1) and Clinical Studies (14.2)].
5.5 Pulmonary Veno-Occlusive Disease
If signs of pulmonary edema occur, consider the possibility of associated pulmonary veno-occlusive disease and consider whether bosentan should be discontinued.
5.6 Decreased Sperm Counts
Decreased sperm counts have been observed in patients receiving bosentan. Preclinical data also suggest that bosentan, similar to other endothelin receptor antagonists, may have an adverse effect on spermatogenesis [see Adverse Reactions (6.1), Nonclinical Toxicology (13.1)].
5.7 Decreases In Hemoglobin And Hematocrit
Treatment with bosentan 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 [see Adverse Reactions 6.1].
6. Adverse Reactions
- The following important adverse reactions are described elsewhere in the labeling:Hepatotoxicity [see Boxed Warning, Warnings and Precautions (5.1)]Embryo-fetal Toxicity [see Boxed Warning, Warnings and Precautions (5.2)]Fluid retention [see Warnings and Precautions (5.4)]
6.1 Clinical Studies Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.Safety data on bosentan were obtained from 13 clinical studies (9 placebo-controlled and 4 open-label) in 870 adult patients with PAH and other diseases. Doses up to 8 times the currently recommended clinical dose (125 mg twice daily) were administered for a variety of durations. The exposure to bosentan in these trials ranged from 1 day to 4.1 years (n=94 for 1 year; n=61 for 1.5 years and n=39 for more than 2 years). Exposure of PAH patients (n=328) to bosentan ranged from 1 day to 1.7 years (n=174 more than 6 months and n=28 more than 12 months).Treatment discontinuations due to adverse events other than those related to pulmonary hypertension during the clinical trials in patients with PAH were more frequent on bosentan (6%; 15/258 patients) than on placebo (3%; 5/172 patients). In this database the only cause of discontinuations > 1% and occurring more often on bosentan was abnormal liver function.The adverse drug events that occurred in ≥3% of the bosentan-treated patients and were more common on bosentan in placebo-controlled trials in PAH at doses of 125 or 250 mg twice daily are shown in Table 3:Table 3. Adverse eventsNote: only AEs with onset from start of treatment to 1 calendar day after end of treatment are included. All reported events (at least 3%) are included except those too general to be informative, and those not reasonably associated with the use of the drug because they were associated with the condition being treated or are very common in the treated population. occurring in ≥3% of patients treated with bosentan 125-250 mg twice daily and more common on bosentan in placebo-controlled studies in pulmonary arterial hypertensionAdverse EventBosentann = 258Placebon = 172No.%No.% Respiratory Tract InfectionRespiratory Tract Infection combines the terms "Nasopharyngitis", "Upper Respiratory Tract Infection" and "Respiratory Tract Infection".Combined data from Study 351, BREATHE-1 and EARLY5622%3017% Headache3915%2514% Edema2811%169% Chest Pain135%85% Syncope125%74% Flushing104%53% Hypotension104%32% Sinusitis94%42% Arthralgia94%32% Serum Aminotransferases, abnormal94%32% Palpitations94%32% Anemia83%-
6.2 Postmarketing Experience
- There have been several postmarketing reports of angioedema associated with the use of bosentan. The onset of the reported cases occurred within a range of 8 hours to 21 days after starting therapy. Some patients were treated with an antihistamine and their signs of angioedema resolved without discontinuing bosentan.The following additional adverse reactions have been reported during the postapproval use of bosentan. Because these adverse reactions are reported from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to bosentan exposure: Unexplained hepatic cirrhosis [see Boxed Warning] Liver failure [see Boxed Warning] Hypersensitivity, DRESS, and anaphylaxis [see Contraindications (4.4)] Thrombocytopenia Rash Jaundice Anemia requiring transfusion Neutropenia and leukopenia Nasal congestion
7.1 Cytochrome P450 Drug Interactions
Bosentan is metabolized by CYP2C9 and CYP3A. Inhibition of these enzymes may increase the plasma concentration of bosentan [see Pharmacokinetics (12.3)]. 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 bosentan will likely lead to large increases in plasma concentrations of bosentan. Coadministration of such combinations of a CYP2C9 inhibitor plus a strong or moderate CYP3A inhibitor with bosentan 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 bosentan is coadministered. Bosentan had no relevant inhibitory effect on any CYP isozyme in vitro (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A). Consequently, bosentan is not expected to increase the plasma concentrations of drugs metabolized by these enzymes.Figure 1. CYP3A induction-mediated effect of bosentan on other drugsFigure 2. Effect of other drugs on bosentan
7.2 Hormonal Contraceptives
Hormonal contraceptives, including oral, injectable, transdermal, and implantable forms, may not be reliable when bosentan is coadministered. Females should practice additional methods of contraception and not rely on hormonal contraception alone when taking bosentan [see Use in Specific Populations (8.3)].An interaction study demonstrated that coadministration 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.
8.4 Pediatric Use
Safety and efficacy in pediatric patients have not been established.
8.5 Geriatric Use
Clinical studies of bosentan did not include sufficient numbers of subjects aged 65 and older to determine whether they respond differently from younger subjects.
8.6 Hepatic Impairment
Because there is in vitro and in vivo evidence that the main route of excretion of bosentan is biliary, liver impairment could be expected to increase exposure (Cmax and AUC) of bosentan. The pharmacokinetics of bosentan has not been evaluated in patients with severe liver impairment (Child-Pugh Class C). In patients with moderate hepatic impairment (Child-Pugh Class B), the systemic exposures to bosentan and its active metabolite increased significantly. bosentan should generally be avoided in patients with moderate or severe liver impairment. Pharmacokinetics of bosentan was not altered in patients with mild impairment of hepatic function (Child-Pugh Class A) [see Dosage and Administration (2.6), Warnings and Precautions (5.1), Pharmacokinetics (12.3)].
8.7 Renal Impairment
The effect of renal impairment on the pharmacokinetics of bosentan is small and does not require dosing adjustment [see Pharmacokinetics (12.3)].
Bosentan has been given as a single dose of up to 2400 mg in normal volunteers, or up to 2000 mg/day for 2 months in patients, without any major clinical consequences. The most common side effect was headache of mild to moderate intensity. In the cyclosporine A interaction study, in which doses of 500 and 1000 mg twice daily of bosentan were given concomitantly with cyclosporine A, trough plasma concentrations of bosentan increased 30-fold, resulting in severe headache, nausea, and vomiting, but no serious adverse events. Mild decreases in blood pressure and increases in heart rate were observed.In the postmarketing period, there was one reported overdose of 10,000 mg of bosentan taken by an adolescent male patient. He had symptoms of nausea, vomiting, hypotension, dizziness, sweating, and blurred vision. He recovered within 24 hours with blood pressure support.Bosentan is unlikely to be effectively removed by dialysis due to the high molecular weight and extensive plasma protein binding.
Bosentan is 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 C27H29N5O6S∙H2O. 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.Bosentan is available as 62.5 mg and 125 mg film-coated tablets for oral administration, and contains the following excipients: corn starch, pregelatinized starch, sodium starch glycolate, povidone, glyceryl behenate, magnesium stearate, hydroxypropylmethylcellulose, triacetin, talc, titanium dioxide, iron oxide yellow, iron oxide red, and ethylcellulose. Each bosentan 62.5 mg tablet contains 64.54 mg of bosentan monohydrate, equivalent to 62.5 mg of anhydrous bosentan. Each bosentan 125 mg tablet contains 129.08 mg of bosentan monohydrate, equivalent to 125 mg of anhydrous bosentan.
12.1 Mechanism Of Action
Bosentan is a specific and competitive antagonist at endothelin receptor types ETA and ETB. Bosentan has a slightly higher affinity for ETA receptors than for ETB receptors. The clinical impact of dual endothelin blockage is unknown.Endothelin-1 (ET-1) is a neurohormone, the effects of which are mediated by binding to ETA and ETB receptors in the endothelium and vascular smooth muscle. ET-1 concentrations are elevated in plasma and lung tissue of patients with pulmonary arterial hypertension, suggesting a pathogenic role for ET-1 in this disease.
14.2 Lack Of Benefit In Congestive Heart Failure
Bosentan is not effective in the treatment of congestive heart failure with left ventricular dysfunction. In a pair of studies, 1613 subjects with NYHA Class III-IV heart failure, left ventricular ejection fraction <35%, on diuretics, ACE inhibitor, and other therapies, were randomized to placebo or bosentan (62.5 mg twice daily titrated as tolerated to 125 mg twice daily) and followed for up to 70 weeks. Use of bosentan was associated with no benefit on patient global assessment (the primary end point) or mortality. However, hospitalizations for heart failure were more common during the first 4 to 8 weeks after bosentan was initiated. In a placebo-controlled trial of patients with severe chronic heart failure, there was an increased incidence of hospitalization for CHF associated with weight gain and increased leg edema during the first 4-8 weeks of treatment with bosentan. Patients required intervention with a diuretic, fluid management, or hospitalization for decompensating heart failure.
16. How Supplied/Storage And Handling
62.5 mg film-coated, round, biconvex, orange-white tablets, embossed with identification marking "62,5", packaged in a white high-density polyethylene bottle and a white polypropylene child-resistant cap.NDC 10148-625-60: Bottle containing 60 tablets.125 mg film-coated, oval, biconvex, orange-white tablets, embossed with identification marking "125", packaged in a white high-density polyethylene bottle and a white polypropylene child-resistant cap.NDC 10148-125-60: Bottle containing 60 tablets.
Storage And Handling
Store at 20ºC – 25ºC (68ºF – 77ºF). Excursions are permitted between 15°C and 30°C (59°F and 86°F). [See USP Controlled Room Temperature].
17. Patient Counseling Information
See FDA-approved patient labeling (Medication Guide)
- Medication GuideBosentan (bo-SEN-tan)TabletsThis Medication Guide has been approved by the U.S. Food and Drug Administration.Revised: October 2018 Read the Medication Guide that comes with bosentan before you start taking it and each time you get a refill. There may be new information. This Medication Guide does not take the place of talking with your healthcare provider about your medical condition or your treatment.What is the most important information I should know about bosentan?Bosentan is only available through the Bosentan REMS Program. Before you begin taking bosentan, you must read and agree to all of the instructions in the Bosentan REMS Program.Bosentan can cause serious side effects including:Liver damage.Liver damage may not cause symptoms at first. Only a blood test can show if you have early liver damage. You must have your blood tested to check your liver function before you start bosentan and each month after that. Your healthcare provider will order these tests. Regular blood tests are important because they will help your healthcare provider adjust or stop your treatment before there is permanent damage.Tell your healthcare provider if you have had liver problems, including liver problems while taking other medicines. Call your healthcare provider right away if you have any of these symptoms of liver problems while taking bosentan: nauseavomitingfeverunusual tirednessstomach area (abdominal) painyellowing of the skin or the whites of your eyes (jaundice)Serious birth defects.Bosentan can cause serious birth defects if taken during pregnancy. You must not be pregnant when you start taking bosentan or during bosentan treatment. Serious birth defects from bosentan can happen early in pregnancy. Females who are able to get pregnant must have a negative pregnancy test before starting treatment with bosentan, each month during treatment with bosentan, and 1 month after stopping treatment with bosentan.Talk to your healthcare provider about your menstrual cycle. Your healthcare provider will decide when to do a pregnancy test and will order a pregnancy test for you depending on your menstrual cycle. Females who are able to get pregnant are females who: have entered puberty, even if they have not started their menstrual period, andhave a uterus, andhave not gone through menopause. Menopause means that you have not had a menstrual period for at least 12 months for natural reasons, or that you have had your ovaries removed.Females who are not able to get pregnant are females who:have not yet entered puberty, ordo not have a uterus, orhave gone through menopause. Menopause means that you have not had a menstrual period for at least 12 months for natural reasons, or that you have had your ovaries removed orare infertile for other medical reasons and this infertility is permanent and cannot be reversed.Females who are able to get pregnant must use two acceptable forms of birth control during treatment with bosentan, and for one month after stopping bosentan because the medicine may still be in the body.If you have had a tubal sterilization or have an IUD (intrauterine device), these methods can be used alone and no other form of birth control is needed.Talk with your healthcare provider or gynecologist (a doctor who specializes in female reproduction) to find out about options for acceptable birth control that you may use to prevent pregnancy during treatment with bosentan.If you decide that you want to change the form of birth control that you use, talk with your healthcare provider or gynecologist to be sure that you choose another acceptable form of birth control.See the chart below for Acceptable Birth Control Options during treatment with bosentan.Do not have unprotected sex. Talk to your healthcare provider or pharmacist right away if you have unprotected sex or if you think your birth control has failed. Your healthcare provider may talk with you about using emergency birth control.Tell your healthcare provider right away if you miss a menstrual period or think you may be pregnant.If you are the parent or caregiver of a female child who started taking bosentan before reaching puberty, you should check your child regularly to see if she is developing signs of puberty. Tell your healthcare provider right away if you notice that she is developing breast buds or any pubic hair. Your healthcare provider should decide if your child has reached puberty. Your child may reach puberty before having her first menstrual period.See "What are the possible side effects of bosentan?" for more information about side effects. What is bosentan?Bosentan is a prescription medicine used to treat people with certain types of pulmonary arterial hypertension (PAH), which is high blood pressure in the vessels of the lungs.Bosentan can improve your ability to exercise and can slow the worsening of your physical condition and symptoms. Bosentan lowers high blood pressure in your lungs and lets your heart pump blood more efficiently.Bosentan is only:Prescribed by healthcare providers who are enrolled in the Bosentan REMS Program.Available to people who understand and agree to enroll in the Bosentan REMS Program.Who should not take bosentan?Do not take bosentan if you:are pregnant, plan to become pregnant, or become pregnant during bosentan treatment. Bosentan can cause serious birth defects. All females should read the birth defects section of "What is the most important information I should know about bosentan?"take any of these medicines:cyclosporine A used to treat psoriasis and rheumatoid arthritis, and to prevent rejection of heart, liver, and kidney transplantsglyburide used to treat diabetesare allergic to bosentan or any of the ingredients in bosentan. See the end of this Medication Guide for a complete list of the ingredients in bosentan. If you have a rash, hives or your lips swell after taking bosentan, it may be a sign of allergy. You should stop taking your bosentan and talk to your healthcare provider.What should I tell my healthcare provider before taking bosentan?Bosentan may not be right for you. Tell your healthcare provider about all your medical conditions, including if you:have liver problems.are breast-feeding or plan to breast feed. It is not known if bosentan passes into your milk. You and your healthcare provider should decide if you will take bosentan or breastfeed. You should not do both.Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Bosentan and other medicines may affect how each other works and cause side effects. Especially tell your healthcare provider if you take:hormone-based birth control, such as pills, shots, patches, and implants. These birth control methods may not work as well when taken with bosentan.simvastatin or other "-statin" medicines used to lower cholesterolrifampin used for tuberculosisketoconazole, fluconazole, itraconazole, or voriconazole used for fungal infectionswarfarin sodium used to prevent blood clotsritonavir used to treat HIVThere may be more than one brand name medicine. Ask your healthcare provider if you are not sure if your medicine is one that is listed above.Know the medicines you take. Keep a list of them and show it to your healthcare provider or pharmacist when you get a new medicine.How should I take bosentan?Your healthcare provider will give you detailed information about the Bosentan REMS Program.Bosentan is only available through certified pharmacies. You will only receive a 30-day supply of bosentan at one time.Take bosentan exactly as prescribed.Your healthcare provider will tell you how much bosentan to take and when to take it.In most cases, you will take 1 tablet in the morning and 1 in the evening.You can take bosentan orally with or without food.If you take more than the prescribed dose of bosentan, call your healthcare provider right away.If you miss a dose of bosentan, take your tablet as soon as you remember. Do not take 2 doses at the same time. If it is almost time for your next dose, skip the missed dose. Just take the next dose at your regular time.Do not stop taking bosentan unless your healthcare provider tells you to. Suddenly stopping your treatment may cause your symptoms to get worse. If you need to stop taking bosentan, speak with your healthcare provider about the right way to stop.What are the possible side effects of bosentan?Bosentan can cause serious side effects, including:See "What is the most important information I should know about bosentan?"Fluid retention and swelling of your ankles and legs. Bosentan can cause your body to hold too much water, and you may get swelling of your ankles and legs. Tell your healthcare provider if you have swelling of your ankles and legs that happens either with or without weight gain, or if you have more trouble with your breathing than normal. Your healthcare provider will look for the cause of this.Lower Sperm Count. Some men who take bosentan may have lower sperm counts. This may affect your ability to father a child. Tell your healthcare provider if fertility is a concern for you.Low red blood cell levels (anemia). Your healthcare provider will do blood tests to check your red blood cells during treatment with bosentan.The most common side effects of bosentan include:respiratory tract infectionheadachefaintingflushinglow blood pressureinflamed nose passages (sinusitis)joint painirregular heart beatsTell your doctor if you have any side effect that bothers you or that does not go away. These are not all the possible side effects of bosentan. For more information, ask your doctor or pharmacist.Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.How should I store bosentan?Store bosentan at room temperature between 68°F to 77°F (20°C to 25°C).Keep bosentan and all medicines out of the reach of children.General information about bosentanMedicines are sometimes prescribed for purposes other than those listed in a Medication Guide. Do not use bosentan for a condition for which it was not prescribed. Do not give bosentan to other people, even if they have the same symptoms that you have. It may harm them.This Medication Guide summarizes the most important information about bosentan. If you would like more information, talk with your healthcare provider. You can ask your pharmacist or healthcare provider for information about bosentan that is written for health professionals. For more information, go to www.BosentanREMSProgram.com or call 1-866-359-2612.What are the ingredients in bosentan?Active ingredient: bosentanInactive ingredients in 62.5 mg and 125 mg film-coated tablets: corn starch, pregelatinized starch, sodium starch glycolate, povidone, glyceryl behenate, and magnesium stearate, hydroxypropylmethylcellulose, triacetin, talc, titanium dioxide, iron oxide yellow, iron oxide red, ethylcellulose.Distributed by:Patriot Pharmaceuticals, LLCHorsham, PA 19044Manufactured for:CoTherix, Inc.5000 Shoreline Court, Ste 200South San Francisco, CA 94080© 2018 Patriot Pharmaceuticals, LLCACT20181025
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