Drug Interaction Report

Quinidine and Nisoldipine: Interaction Details

A pharmacist-reviewed analysis of the Quinidine and Nisoldipine interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Quinidine

Cardioquin® Cin-Quin® Duraquin® Quinact® Quinaglute® Quinalan® Quinatime® Quinidex®
+

Nisoldipine

Sular Sular®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Moderate
Can be significant — usually manageable with monitoring.
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.

Of 91 documented Quinidine interactions, 8 are rated moderate — including this one.
Onset
delayed
Evidence
probable
Severity
Moderate

What happens

Quinidine toxicity (ventricular arrhythmias, hypotension, exacerbation of heart failure) or decreased efficacy of nisoldipine

Interaction Deep Dive

Concurrent use of nisoldipine and quinidine may result in decreased bioavailability (AUC) of nisoldipine5.

Why it happens (mechanism)

Unknown

Literature reports

1 report — tap to read

a) In one study, the bioavailability (AUC) of nisoldipine decreased by 26% during concomitant therapy with quinidine (648 mg twice daily); however, the peak concentration did not change. Concurrent use of immediate release nisoldipine and quinidine increased plasma levels of quinidine by approximately 20%. No ECG changes accompanied this interaction and the clinical significance is unknown 1. Neither diltiazem nor felodipine appear to alter quinidine pharmacokinetics 23. In another study, nisoldipine had no effect on quinidine serum levels 4.

Common questions

Can I take Quinidine and Nisoldipine together?

Quinidine toxicity (ventricular arrhythmias, hypotension, exacerbation of heart failure) or decreased efficacy of nisoldipine Always confirm with your pharmacist or prescriber before making any change.

How serious is the Quinidine and Nisoldipine interaction?

It is rated moderate. Can be significant — usually manageable with monitoring.

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 "probable". Good supporting evidence, though not definitively proven.

Questions for your pharmacist

  • Does my dose of Quinidine or Nisoldipine 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 (5)

  1. Product Information: Sular(TM), nisoldipine. Zeneca Pharmaceuticals, Wilmington, DE, 1996. DailyMed
  2. Matera MG, De Santis D, Vacca C, et al: Quinidine-diltiazem: pharmacokinetic interaction in humans. Curr Ther Res 1986; 40:653-656.
  3. Bailey DG, Freeman DJ, Melendez LJ, et al: Quinidine interaction with nifedipine and felodipine: pharmacokinetic and pharmacodynamic evaluation. Clin Pharmacol Ther 1993; 53:354-359. PubMed
  4. Friedel HA & Sorkin EM: Nisoldipine: a preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in the treatment of angina pectoris, hypertension and related cardiovascular disorders. Drugs 1988; 36:682-731.
  5. Product Information: Sular(TM), nisoldipine. Zeneca Pharmaceuticals, Wilmington, DE, 1996. DailyMed
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Quinidine

Keep reading about Quinidine

All Quinidine interactions (91) Quinidine drug information
Also serious with: Colchicine Ketoconazole Topical Lefamulin Dofetilide
Nisoldipine

Keep reading about Nisoldipine

All Nisoldipine interactions (86) Nisoldipine drug information
Also serious with: Ketoconazole Ensitrelvir Levoketoconazole Itraconazole
Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Quinidine + Activated Charcoal American Hellebore Arsenic Beer Cesium Cinchona Ephedra Grapefruit + 199 more
Nisoldipine + Activated Charcoal American Hellebore American Mistletoe Coleus Grapefruit St. John's Wort Tyramine Acacia Rigidula + 224 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.