Ketoconazole Topical and Lopinavir: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ketoconazole Topical
Lopinavir
No brand names on record
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 serum concentrations of ketoconazole and/or lopinavir/ritonavir; increased risk for QT interval prolongation
Interaction Deep Dive
Using ketoconazole with a CYP3A4 substrate known to prolong the QT interval, such as lopinavir/ritonavir may be contraindicated. Concomitant use may result in elevated plasma concentrations of lopinavir/ritonavir, increasing the risk for QT prolongation and life-threatening ventricular tachyarrhythmia, including torsades de pointes. In addition, ketoconazole is also a CYP3A4 substrate and lopinavir/ritonavir is also a potent CYP3A4 inhibitor; therefore concomitant use may result in elevated plasma concentrations of ketoconazole1. If concomitant use is required, doses of ketoconazole greater than 200 mg daily are not recommended 2. Monitor patients for signs and symptoms on increased of prolonged pharmacologic effects of ketoconazole 1.
Why it happens (mechanism)
Inhibition of CYP3A-mediated ketoconazole metabolism by lopinavir/ritonavir; inhibition of CYP3A-mediated lopinavir/ritonavir metabolism by ketoconazole
Literature reports
1 report — tap to read
a) A study of 12 subjects who received a single dose of ketoconazole 200 mg after a 16 day regimen of lopinavir 400 mg/ritonavir 100 mg twice daily demonstrated that the coadministration of these medications may result in increased plasma concentrations of ketoconazole. The Cmax ratio of ketoconazole plus lopinavir/ritonavir to ketoconazole alone (90% CI) was 1.13 (range 0.91 to 1.40), the AUC ratio was 3.04 (range 2.44 to 3.79). Ketoconazole, on the other hand, did not have a significant effect on the plasma concentrations of lopinavir. The resulting ratios of lopinavir plus ketoconazole to lopinavir alone (90% CI) were: Cmax 0.89 (range 0.80 to 0.99), AUC 0.87 (range 0.75 to 1.00) and Cmin 0.75 (range 0.55 to 1.00) 3.
Common questions
Can I take Ketoconazole Topical and Lopinavir together?
Increased serum concentrations of ketoconazole and/or lopinavir/ritonavir; increased risk for QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ketoconazole Topical and Lopinavir interaction?
It is rated contraindicated. These should generally not be used together.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
Questions for your pharmacist
- Does my dose of Ketoconazole Topical or Lopinavir 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 (3)
- Product Information: NIZORAL(R) oral tablets, ketoconazole oral tablets. Janssen Pharmaceuticals, Inc (per FDA), Titusville, NJ, 2014. DailyMed
- Product Information: KALETRA(R) oral tablets, oral solution, lopinavir ritonavir oral tablets, oral solution. Abbott Laboratories (per FDA), North Chicago, IL, 2013. DailyMed
- Product Information: KALETRA(R) oral capsule, oral solution, lopinavir/ritonavir oral capsule, oral solution. Abbott Laboratories, North Chicago, IL, 2005. DailyMed
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