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Effect of Grapefruit on QT Interval in Healthy Volunteers and Patients With Congenital Long QT Syndrome

NCT02680080 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 25

Last updated 2019-05-24

No results posted yet for this study

Summary

The list of medications that prolong the QT interval and can provoke torsade de pointes keeps expanding. This list includes not only antiarrhythmic drugs, but also medications with no cardiac indications. All these medications prolong the QT interval because they block a specific potassium channel on the myocardial cell membrane: the channel for the rapid component of the delayed rectifier potassium current or "IKr". The risk for developing torsade de pointes for patients taking any of the medications with IKr blockade capabilities varies from \>4% for antiarrhythmic drugs to \<0.01% for non-cardiac medications. The risk depends on the strength of IKr blockade, but also on specific patient characteristics. The majority of patients who develop torsade de pointes from non-cardiac medications have identifiable risk factors. In this regard, patients with a congenital long QT syndrome are prone to develop torsade de pointes when treated with QT-prolonging medications. This is because, due to their genetically defective ion channels, patients with Long QT Syndrome (LQTS) have impaired ventricular repolarization and reduced "repolarization reserve." Therefore, it is common medical practice to strongly advise patients with congenital LQTS to avoid all medications that have IKr channel blocker capabilities. it was reported that some flavonoids contained in pink-grapefruit juice block the IKr channel. These investigators also reported that drinking 1 liter of pink-grapefruit juice causes QT prolongation in healthy volunteers. The magnitude of the QT prolongation provoked by grapefruit juice was small However, drugs causing minor QT prolongation in healthy volunteers may provoke major QT prolongation in rare or sick individuals who are then at risk for developing torsade de pointes. Consequently, one could argue that, until proven otherwise, pink-grapefruit should be added to the list of "drugs" that are forbidden for patients with LQTS

Conditions

  • Long QT Syndrome

Interventions

DRUG

Moxifloxacin

a single 400 mg tablet of Moxifloxacin

DIETARY_SUPPLEMENT

Grapefruit group

one liter of fresh pink-grapefruit juice

Sponsors & Collaborators

  • Tel Aviv Medical Center

    collaborator OTHER

  • Tel-Aviv Sourasky Medical Center

    lead OTHER_GOV

Principal Investigators

  • Ehud Chorin, MD · Tel Aviv MC

Study Design

Allocation
NON_RANDOMIZED
Purpose
DIAGNOSTIC
Masking
NONE
Model
CROSSOVER

Eligibility

Min Age
18 Years
Max Age
99 Years
Sex
ALL
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2016-12-01
Primary Completion
2018-06-12
Completion
2019-05-22

Countries

  • Israel

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT02680080 on ClinicalTrials.gov