Two medicines, side by side
Bosentan vs ambrisentan
Bosentan and ambrisentan are both labeled for pulmonary arterial hypertension. Drugs@FDA records approvals of bosentan since 2001 and of ambrisentan since 2007. How each works, in its label's words: Bosentan, “Bosentan is a specific and competitive antagonist at endothelin receptor types ET A and ET B .”; Ambrisentan, “Two receptor subtypes, ET A and ET B , mediate the effects of ET-1 in the vascular smooth muscle and endothelium.”
Check it at the source: the bosentan FDA label on DailyMed (effective November 17, 2025); the ambrisentan FDA label on DailyMed (effective September 3, 2026).
Highlights of the bosentan record
Bosentan (Tracleer) · label of November 17, 2025
RISKS OF HEPATOTOXICITY and EMBRYO-FETAL TOXICITY Because of the risk of hepatotoxicity, TRACLEER is available only through a restricted program called 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 (5.2) ]. WARNING: RISKS OF HEPATOTOXICITY and EMBRYO-FETAL TOXICITY See full prescribing information for complete boxed warning.
Used for
From the label: indicationsTRACLEER is indicated for the treatment of pulmonary arterial hypertension (PAH) (WHO Group 1): in adults to improve exercise ability and to decrease clinical worsening. […]
On the market
- Earliest approval on file
- November 20, 2001
- Generic labelers
- 5 labelers
- Pharmacy cost
- Not in the survey
Supply and safety
- Shortage
- No current entry
- Recalls
- 0
Highlights of the ambrisentan record
Ambrisentan (Letairis) · label of September 3, 2026
EMBRYO-FETAL TOXICITY Ambrisentan tablets are contraindicat ed for use during pregnancy because it may cause major birth defects if used by pregnant patients, based on studies in animals [see Contraindications (4.1), Warnings and Precautions (5.1), and Use in Specific Populations (8.1)]. Therefore, for females of reproductive potential, exclude pregnancy before the initiation of treatment must use acceptable methods of contraception during treatment with ambrisentan tablets.
Used for
From the label: indicationsAmbrisentan tablets are indicated for the treatment of pulmonary arterial hypertension (PAH) (WHO Group 1) in adult patients: To improve exercise ability and delay clinical worsening. Studies establishing effectiveness included predominantly patients with WHO Functional Class II–III symptoms and etiologies of idiopathic or heritable PAH (60%) or PAH associated with connective tissue diseases (34%). […]
On the market
- Earliest approval on file
- June 15, 2007
- Generic labelers
- 12 labelers
- Pharmacy cost
- $8.02 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 0
Source: FDA drug labels via openFDA (Bosentan label of November 17, 2025, Ambrisentan label of September 3, 2026); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do bosentan and ambrisentan differ on the record?
How each works, in its label's words: Bosentan, “Bosentan is a specific and competitive antagonist at endothelin receptor types ET A and ET B .”; Ambrisentan, “Two receptor subtypes, ET A and ET B , mediate the effects of ET-1 in the vascular smooth muscle and endothelium.”
Both are in FDA's class endothelin receptor antagonists.
Half-life, in each label's words: Bosentan, “12.3 Pharmacokinetics General After oral administration, maximum plasma concentrations of bosentan are attained within …”; Ambrisentan, “an trough concentration of ambrisentan at steady-state is about 15% of the mean peak concentration and the accumulation …”
Both labels carry a boxed warning; the records quote them.
Generics: bosentan since 2019; ambrisentan since 2019 (Drugs@FDA).
| Bosentan | Ambrisentan | |
|---|---|---|
| Labeled for | Pulmonary arterial hypertension | Pulmonary arterial hypertension |
| Pharmacologic class | Endothelin Receptor Antagonist | Endothelin Receptor Antagonist |
| How it works (label) | Bosentan is a specific and competitive antagonist at endothelin receptor types ET A and ET B . Bosentan has a slightly higher affinity for ET A receptors than for ET B receptors. The clinical impact of dual endothelin blockage is unknown. | Endothelin-1 (ET-1) is a potent autocrine and paracrine peptide. Two receptor subtypes, ET A and ET B , mediate the effects of ET-1 in the vascular smooth muscle and endothelium. |
| Half-life (label) | 12.3 Pharmacokinetics 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. | an trough concentration of ambrisentan at steady-state is about 15% of the mean peak concentration and the accumulation factor is about 1.2 after long-term daily dosing, indicating that the effective half-life of … |
| Earliest approval on file (Drugs@FDA) | November 20, 2001 | June 15, 2007 |
| First generic approved | April 26, 2019 | March 28, 2019 |
| Generic labelers (NDC) | 5 labelers | 12 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | n/a | $8.02 per tablet (Ambrisentan 10 mg tablet) |
| 12-month price change | n/a | -18% |
| Boxed warning | Yes | Yes |
| Shortage now | No current entry | No current entry |
| Recalls recorded | 0 | 0 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 50,111 | 124,133 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
What next?
- Alternatives to bosentan
- every medicine labeled for the same conditions