Bosentan (Tracleer)

How Medicare covers it

Part D (forms used at home). Part A during a covered inpatient stay. No Part B clinician-administered form in the CMS Part B spending file.

What it treats

Tracleer (bosentan) treats pulmonary arterial hypertension (PAH, WHO Group 1) — high blood pressure in the arteries of the lungs. In adults it is used to improve exercise ability and to decrease clinical worsening. In children 3 years of age and older with idiopathic (no known cause) or congenital PAH, it is used to improve pulmonary vascular resistance (the resistance in the lung blood vessels), which is expected to improve exercise ability.

What it is for, in depth

Tracleer is a long-term daily medicine for pulmonary arterial hypertension, a disease in which the arteries carrying blood from the heart to the lungs become narrowed, so blood pressure in the lungs rises and the heart must work harder. In adults it improves the ability to exercise and slows clinical worsening of the disease. It is also used in children 3 years of age and older with idiopathic or congenital PAH to lower resistance in the lung vessels. Because it can injure the liver and cause birth defects, it is dispensed only through the Bosentan REMS restricted program, with monthly liver blood tests and, for females who can become pregnant, monthly pregnancy tests. It comes as 62.5 mg and 125 mg tablets and a 32 mg dispersible tablet, all taken twice a day, with the dose set by age and body weight.

How it works

Bosentan is an endothelin receptor antagonist. It blocks endothelin-1 (ET-1), a natural substance that tightens (narrows) blood vessels, at both of its receptors, ET-A and ET-B, in the lining and smooth muscle of blood vessels. ET-1 levels are raised in the blood and lung tissue of people with PAH. By blocking ET-1, bosentan helps the lung arteries relax and widen, which lowers the pressure the heart has to pump against.

How it is taken

Tracleer is taken by mouth twice a day. For patients older than 12 years and weighing more than 40 kg, the starting dose is 62.5 mg twice daily for 4 weeks, then the dose is raised to 125 mg twice daily. Patients weighing less than 40 kg stay at 62.5 mg twice daily, and doses for children 12 years and younger are based on weight. Doses above 125 mg twice daily did not add benefit and raised the risk of liver injury. It comes as 62.5 mg and 125 mg film-coated tablets and as a 32 mg tablet for oral suspension (dispersed in a small amount of water) used mainly for children.

Common side effects

In placebo-controlled PAH trials at 125 to 250 mg twice daily, the most common side effects on Tracleer were respiratory tract infection (22%), headache (15%), edema (swelling, 11%), chest pain (5%), syncope (fainting, 5%), flushing (4%), hypotension (low blood pressure, 4%), sinusitis (4%), arthralgia (joint pain, 4%), abnormal serum aminotransferases (liver enzymes, 4%), palpitations (4%), and anemia (3%).

Serious warnings

Tracleer can seriously injure the liver: liver aminotransferases (ALT and AST) rose to more than 3 times the upper limit of normal in about 11% of patients, and rare cases of liver failure and unexplained cirrhosis after long treatment have been reported, so liver enzymes must be measured before starting and every month during treatment. It can cause major birth defects (see the boxed warning). Other serious effects include fluid retention that may need treatment, pulmonary veno-occlusive disease (if signs of pulmonary edema occur, the drug may need to be stopped), decreased sperm counts, and drops in hemoglobin and hematocrit, so hemoglobin should be checked after 1 and 3 months and then every 3 months.

Boxed warning

WARNING: RISKS OF HEPATOTOXICITY and EMBRYO-FETAL TOXICITY — Because of the risk of hepatotoxicity (liver injury), TRACLEER is available only through a restricted program called the Bosentan Risk Evaluation and Mitigation Strategy (REMS); prescribers, patients, and pharmacies must enroll in the program. Elevations of liver aminotransferases (ALT, AST) and liver failure have been reported, so liver enzymes are measured before treatment and then monthly, and TRACLEER is stopped if elevations come with signs of liver injury or with bilirubin at least 2 times the upper limit of normal. Based on animal data, TRACLEER may cause fetal harm and major birth defects if used during pregnancy; pregnancy must be excluded before starting, tested monthly, and prevented with reliable contraception during treatment.

Who should be careful

Tracleer is contraindicated in pregnancy, with cyclosporine A, with glyburide, and in patients allergic (hypersensitive) to bosentan or any component — reactions have included DRESS, anaphylaxis, rash, and angioedema. Females who can become pregnant need a negative pregnancy test before starting, monthly pregnancy tests, and reliable contraception. Tell your doctor if you have liver problems (the drug should generally be avoided if baseline liver enzymes are already more than 3 times normal), anemia, heart failure or fluid retention, or low sperm count concerns. Prescribers, patients, and pharmacies must enroll in the Bosentan REMS program.

Major interactions

Tracleer must not be used with cyclosporine A, which greatly raises bosentan levels, and must not be used with glyburide, because the combination raises the risk of liver enzyme elevations. Taking a CYP2C9 inhibitor (such as fluconazole or amiodarone) together with a strong or moderate CYP3A inhibitor (such as ketoconazole, itraconazole, erythromycin, or diltiazem) can greatly raise bosentan levels, and those combinations are not recommended. Bosentan lowers the blood levels of drugs broken down by CYP3A and CYP2C9, and it makes hormonal contraceptives (pills, injections, patches, and implants) less reliable, so an additional method of birth control is needed.

Cost and saving notes

If this drug is covered under your Medicare Part D plan and the cost is high, you can ask your plan for a tier exception to pay a lower cost share. If you have limited income, Extra Help (the Part D Low-Income Subsidy) can lower your Part D premiums and drug costs. In 2027, your total yearly out-of-pocket spending on covered Part D drugs is capped at $2,400, and you can spread those costs out in monthly payments through the Medicare Prescription Payment Plan.

Why it is in its tier

Bosentan (Tracleer) sits on Tier 5 in 92.1% of the plans that list it (3404 of 3696 listing plans). Tier 5 is the specialty tier — instead of a flat copay, patients usually pay a percentage of the drug's cost (coinsurance), which is why specialty drugs feel expensive even with coverage. The data-visible drivers: It is sold both as a brand product and in generic form, and the CMS dashboard puts its average Part D spending at about $32,160 per beneficiary for 2024 — among the highest-cost drugs in the program, which matches where plans place it. It is listed by 67.26% of Part D plans. The tier shown is the most common one; individual plans vary.

Sources

• TRACLEER (BOSENTAN) TABLET, FILM COATED TRACLEER (BOSENTAN) TABLET, FOR SUSPENSION [ACTELION PHARMACEUTICALS US, INC.] — DailyMed
• MedlinePlus — National Library of Medicine
• MedlinePlus — Bosentan

What official patient guides say

Bosentan (Tracleer) is a tablet you take by mouth twice a day, in the morning and in the evening, at about the same times every day, with or without food. Your doctor will probably start you on a low dose and raise it after 4 weeks. If you use the dispersible tablet, place it in a small amount of liquid right before you take it; if you take a half tablet, put the other half back in the opened blister and use it within 7 days. Bosentan controls the symptoms of pulmonary arterial hypertension but does not cure it, and it may take 1 to 2 months or longer to feel the full benefit, so keep taking it even if you feel well and do not stop suddenly. If you forget a dose, take it as soon as you remember, unless it is almost time for the next dose — then skip it, and never take a double dose. Keep the tablets in the container they came in, tightly closed, at room temperature, away from extra heat and moisture (not in the bathroom), and out of children's reach. Keep your monthly liver blood tests and other program appointments.

Source: MedlinePlus — Bosentan

Part D formulary coverage

Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.

What you pay

A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.

Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-07

Coverage by plan and tier

Of the 5,495 Medicare drug plans we track for 2027, 3,696 list Bosentan (Tracleer) — 67.3% of plans. Most of those plans put it on Tier 5: 3,404 plans, 92.1% of the plans that list it. Other plans place it on Tier 2 (120 plans), Tier 1 (88 plans) or Tier 4 (84 plans). For example: Aetna Medicare Dual Extra (HMO D-SNP) puts it on Tier 5; Aetna Medicare Dual Extra Care (PPO D-SNP) puts it on Tier 5; Aetna Medicare Value Plus (PPO) puts it on Tier 5. You can compare these plans side by side on our Medicare Advantage hub. A tier is not a price. What you pay also depends on whether you have met your plan';s deductible, whether the drug costs a flat copay or a share of the price, and whether you get Extra Help or Medicaid.

Read next

• Part D in 2027: The $700 Deductible, the $2,400 Cap, and the $35 Insulin Rule
• Extra Help in 2027: Lower Drug Copays and Who Qualifies
• Checking Medicare Savings Programs and Extra Help

Part D spending averages (2024)

Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30

Companies covering this drug

Part D and Medicare Advantage plan sponsors that list this drug on a formulary, 50 at a time.