What the FDA labels say about taking them together
Abemaciclib and ritonavir
Ritonavir's FDA label of July 23, 2026 names abemaciclib in its drug interactions section; the abemaciclib label PlainMeds reads does not name ritonavir. The ritonavir label: “Apalutamide is contraindicated due to potential for loss of virologic response and possible resistance to NORVIR or to the class of protease inhibitors. …”
Check it at the source: the abemaciclib FDA label on DailyMed (effective July 13, 2026, Eli Lilly and Company); the ritonavir FDA label on DailyMed (effective July 23, 2026, AbbVie Inc.).
What does the abemaciclib label say about ritonavir?
Abemaciclib's label (effective July 13, 2026) does not name ritonavir in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Verzenio), Eli Lilly and Company, effective July 13, 2026 (SPL set be4bc0de-0fdc-4d46-8d25-be43c79e6a06), via openFDA; the full label on DailyMed
What does the ritonavir label say about abemaciclib?
Ritonavir label, drug interactionsConcomitant Drug Class/Drug Name: Anticancer Agents: abemaciclib, apalutamide, dasatinib, encorafenib, ibrutinib, ivosidenib, neratinib, nilotinib, venetoclax, vinblastine, vincristine; Effect on Concentration of Ritonavir or Concomitant Drug: ↑ anticancer agents ↓ ritonavir #; Clinical Comment: Apalutamide is contraindicated due to potential for loss of virologic response and possible resistance to NORVIR or to the class of protease inhibitors [see Contraindications () ]. Avoid co-administration of encorafenib or ivosidenib with NORVIR due to potential risk of serious adverse events such as QT interval prolongation. …
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
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
| Abemaciclib | Ritonavir | |
|---|---|---|
| Labeled for | Breast cancer | HIV |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $0.607 per tablet 100 mg tablet |
| 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