Indinavir and Isradipine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Indinavir
No brand names on recordIsradipine
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 plasma concentrations of calcium channel blockers
Interaction Deep Dive
Calcium channel blockers are metabolized by CYP3A4, which is inhibited by indinavir. Increased plasma calcium channel blocker concentrations may result with coadministration of indinavir. This may result in prolonged therapeutic and adverse effects of the calcium channel blocker2. In a patient receiving indinavir treatment, calcium channel blockers should be initiated at low doses and titrated based on response and development of toxicity 3. Monitor patients for signs and symptoms of hypotension and/or edema 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of calcium channel blockers by indinavir
Literature reports
1 report — tap to read
a) The coadministration of indinavir and ritonavir with amlodipine or diltiazem significantly increased exposure to amlodipine and to a lesser extent, diltiazem. In this study, healthy HIV-seronegative subjects participated in an open-label, randomized, 2-arm pharmacokinetic drug interaction study to evaluate the effects of ritonavir and indinavir on diltiazem and amlodipine. Subjects received either amlodipine (5 mg once daily; n=18) or diltiazem (120 mg once daily; n=13) alone for 7 days, followed by indinavir/ritonavir (800/100 mg twice daily) alone through day 19, followed by initiation of the calcium channel blocker in combination with indinavir/ritonavir through day 26. The amlodipine AUC was increased by 89.8% (p less than 0.0001), while the diltiazem AUC increased by 26.5% but was not statistically significant (p=0.06). The AUCs of the active desacetyldiltiazem metabolites doubled, however, this was considered not to be clinically significant, due to the lower activity of the metabolites in comparison with diltiazem. There were no significant changes in heart rate, blood pressure or ECG parameters detected during the study. No change in the AUC or Cmax of either indinavir or ritonavir was seen when coadministered with amlodipine or diltiazem 3.
Common questions
Can I take Indinavir and Isradipine together?
Increased plasma concentrations of calcium channel blockers Always confirm with your pharmacist or prescriber before making any change.
How serious is the Indinavir and Isradipine interaction?
It is rated moderate. Can be significant — usually manageable with 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Indinavir or Isradipine 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 anything you'd monitor while I'm on both?
References (3)
- Product Information: NORVASC(R) oral tablets, amlodipine besylate oral tablets. Pfizer Labs (per FDA), New York, NY, 2011. DailyMed
- Product Information: CRIXIVAN(R) capsules, indinavir oral capsules. Merck & CO, Inc, Whitehouse Station, NJ, 2005. DailyMed
- Glesby MJ, Aberg JA, Kendall MA, et al: Pharmacokinetic interactions between indinavir plus ritonavir and calcium channel blockers. Clin Pharmacol Ther 2005; 78(2):143-153. PubMed
Keep reading about Indinavir
Keep reading about Isradipine
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