What the FDA labels say about taking them together
Ritonavir and thiotepa
Thiotepa's FDA label of January 30, 2026 names ritonavir in its drug interactions section; the ritonavir label PlainMeds reads does not name thiotepa. The thiotepa label: “Avoid co-administration of strong CYP3A4 inhibitors and strong CYP3A4 inducers with TEPADINA due to the potential effects on efficacy and toxicity.”
Check it at the source: the ritonavir FDA label on DailyMed (effective July 23, 2026, AbbVie Inc.); the thiotepa FDA label on DailyMed (effective January 30, 2026, Amneal Pharmaceuticals LLC).
What does the ritonavir label say about thiotepa?
Ritonavir's label (effective July 23, 2026) does not name thiotepa in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Norvir), AbbVie Inc., effective July 23, 2026 (SPL set 2849298e-de6e-47bb-8194-56e075b33fc3), via openFDA; the full label on DailyMed
What does the thiotepa label say about ritonavir?
Thiotepa label, drug interactionsAvoid co-administration of strong CYP3A4 inhibitors (e.g., itraconazole, clarithromycin, ritonavir) and strong CYP3A4 inducers (e.g., rifampin, phenytoin) with TEPADINA due to the potential effects on efficacy and toxicity [see Clinical Pharmacology ( 12.3 ) ].
Source: FDA drug label (TEPADINA), NDA208264 (Adienne Sa), as published by Amneal Pharmaceuticals LLC, effective January 30, 2026 (SPL set 559e353c-2dc0-16ba-e054-00144ff8d46c), 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
| Ritonavir | Thiotepa | |
|---|---|---|
| Labeled for | HIV | Organ transplant rejection |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.607 per tablet 100 mg tablet | n/a |
| Shortage now | A presentation being discontinued | No current entry |
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