Clindamycin Vaginal and Selpercatinib: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Clindamycin Vaginal
Selpercatinib
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased substrate exposure and an increased risk for adverse effects
Interaction Deep Dive
Avoid coadministration of selpercatinib (weak CYP3A inhibitor) with a CYP3A substrate where minimal concentration changes may lead to adverse reactions. In a pharmacokinetic trial, concomitant use with midazolam (a sensitive CYP3A substrate) increased midazolam AUC (0 to inf) by 54% and Cmax by 39%. If concomitant use of selpercatinib with a such a CYP3A substrate is necessary, consider dose reduction of the substrate, as appropriate1.
Why it happens (mechanism)
Inhibition of CYP3A-mediated metabolism by selpercatinib
Literature reports
1 report — tap to read
a) In a pharmacokinetic study, coadministration of selpercatinib with midazolam (a sensitive CYP3A substrate) increased midazolam AUC (0 to inf) by 54% and Cmax by 39% 1.
Common questions
Can I take Clindamycin Vaginal and Selpercatinib together?
Increased substrate exposure and an increased risk for adverse effects Always confirm with your pharmacist or prescriber before making any change.
How serious is the Clindamycin Vaginal and Selpercatinib interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Clindamycin Vaginal or Selpercatinib need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: RETEVMO(R) oral capsules, tablets, selpercatinib oral capsules, tablets. Lilly USA LLC (per FDA), Indianapolis, IN, 2024. DailyMed
Keep reading about Clindamycin Vaginal
Keep reading about Selpercatinib
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