What the FDA labels say about taking them together
Bosentan and diltiazem
Bosentan's FDA label of November 17, 2025 names diltiazem in its drug interactions section; the diltiazem labels PlainMeds reads (4) do not name bosentan. The bosentan label: “Concomitant administration of both a CYP2C9 inhibitor and a strong CYP3A inhibitor or a moderate CYP3A inhibitor with TRACLEER will likely lead to large increases in plasma concentrations of bosentan.”
Check it at the source: the bosentan FDA label on DailyMed (effective November 17, 2025, Actelion Pharmaceuticals US, Inc.); the diltiazem FDA label on DailyMed (effective August 7, 2026, Bausch Health US, LLC).
What does the bosentan label say about diltiazem?
Bosentan label, drug interactionsConcomitant 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.
Source: FDA drug label (Tracleer), Actelion Pharmaceuticals US, Inc., effective November 17, 2025 (SPL set 749e42fb-2fe0-45dd-9268-b43bb3f4081c), via openFDA; the full label on DailyMed
What does the diltiazem label say about bosentan?
Diltiazem's label (effective August 7, 2026) and its 3 other brand-application labels do not name bosentan in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (TIAZAC EXTENDED RELEASE), Bausch Health US, LLC, effective August 7, 2026 (SPL set c567fe7e-887e-4291-a0d1-2dd3f25cbf25), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Bosentan | Diltiazem | |
|---|---|---|
| Labeled for | Pulmonary arterial hypertension | High blood pressure, Angina, Atrial fibrillation |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | n/a | $0.144 per capsule 24h ER(cd) 120 mg capsule |
| Shortage now | No current entry | A presentation being discontinued |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once