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Effect of ciprofloxacin and levofloxacin on the QT interval: is this a significant "clinical" event?

Makaryus AN, Byrns K, Makaryus MN, Natarajan U, Singer C, Goldner B

Southern medical journal, 2006

38 participants

Abstract

BACKGROUND: The widespread use of the fluoroquinolones has raised the question of the cardiac safety of these medications. This widespread use of this class of antibiotics has displayed their safety profile, which is actually more favorable than many other drug classes. The cardiac toxicity issue at the center of this discussion is the prolongation of the QT interval leading to torsade de pointes. Ciprofloxacin and levofloxacin, two of the more commonly used fluoroquinolones, are considered less likely than other fluoroquinolones to prolong the QT interval. The authors set out to evaluate the effect on the QT interval of patients after administration of ciprofloxacin and levofloxacin.

METHODS: A prospective evaluation of 38 consecutive patients evaluated by the infectious disease service and receiving either ciprofloxacin or levofloxacin was undertaken. Twelve-lead electrocardiograms were obtained at baseline and at least 48 hours after the first dose of the antibiotic was administered. Both the longest QT interval and the mean QT interval were evaluated. To account for variations in heart rate, the corrected QT interval was calculated by using Bazett's formula (QTc = QT(square root of) R-R). Statistical analysis was undertaken to assess for the presence of a change after the administration of the antibiotic.

RESULTS: Thirty-eight patients (mean age, 65 +/- 19 years), 23 women and 15 men, were studied. There was a small but significant increase in the longest QTc intervals…

How strong is the evidence?

Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 38 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

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