No Clinically Significant Drug Interaction Between Ivermectin and Verzenio
Based on FDA labeling and pharmacological evidence, ivermectin does not interfere with Verzenio (abemaciclib) through any clinically relevant mechanism, and these medications can be used together without dose adjustment.
Pharmacological Rationale
Verzenio's Drug Interaction Profile
The FDA label for Verzenio clearly defines its drug interaction concerns 1:
- CYP3A metabolism: Abemaciclib is primarily metabolized by CYP3A4 enzymes
- Clinically significant interactions occur with:
- Strong CYP3A inhibitors (e.g., ketoconazole - avoid completely; other strong inhibitors require dose reduction to 100 mg twice daily)
- Moderate CYP3A inhibitors (monitor and consider dose reduction)
- Strong/moderate CYP3A inducers (avoid use)
Ivermectin's Interaction Profile
Ivermectin does not significantly affect CYP3A4 activity. Research demonstrates that ivermectin interacts with efflux transporters (ABCG2 and ABCB1) 2, but these are not the pathways relevant to abemaciclib metabolism or elimination. The pharmacokinetic profile of ivermectin in humans shows it is a substrate of these transporters, not a significant inhibitor of CYP enzymes 3.
Key Mechanistic Considerations
Different metabolic pathways:
- Abemaciclib requires CYP3A4 for metabolism
- Ivermectin does not inhibit or induce CYP3A4 to any clinically meaningful degree
- Ivermectin's transporter interactions (ABCG2/ABCB1) do not affect abemaciclib disposition
Renal effects are independent:
- Abemaciclib causes reversible creatinine elevation by inhibiting renal tubular transporters (OCT2, MATE1, MATE2-K) without true kidney injury 4, 5, 6
- This effect is unrelated to ivermectin administration
- Both drugs can be monitored independently for their respective renal effects
Clinical Management
No dose adjustments needed for either medication when used concomitantly.
Monitor as you would for each drug individually:
- For Verzenio: diarrhea (83.5% incidence), neutropenia (45.8%), fatigue (40.6%), and creatinine elevation 7, 1
- For ivermectin: standard monitoring per indication (typically parasitic infections)
Common Pitfalls to Avoid
- Do not confuse transporter interactions with CYP interactions: Ivermectin's ABCG2 interaction 2 is irrelevant to abemaciclib's CYP3A4-dependent metabolism
- Do not attribute creatinine changes to drug interaction: If creatinine rises, this is expected from abemaciclib alone (occurs in 99% of patients) 4, 5 and represents transporter inhibition, not true renal dysfunction
- Do not unnecessarily hold either medication: There is no pharmacological basis for concern about concurrent use
Context for Verzenio Use
Verzenio is indicated for HR+/HER2- early breast cancer at high risk of recurrence, given for 2 years with endocrine therapy 7, 8. The drug's significant interactions are limited to CYP3A modulators, and ivermectin does not fall into this category.