From the Guidelines
The concurrent use of Levaquin (levofloxacin) and sotalol carries a significant risk of interaction, with a notable chance of causing additive QT interval prolongation, particularly in patients with underlying risk factors. The exact percentage chance of interaction is not explicitly stated in the provided evidence, but it is clear that both medications independently prolong the QT interval, and when combined, they increase the risk of developing dangerous cardiac arrhythmias, particularly Torsades de Pointes 1.
Key Points to Consider
- Levaquin inhibits certain potassium channels in cardiac cells, while sotalol, as a Class III antiarrhythmic, deliberately blocks potassium channels as its primary mechanism of action, creating a "double hit" effect on cardiac repolarization.
- Risk factors that further increase danger include electrolyte abnormalities (especially hypokalemia or hypomagnesemia), female gender, advanced age, structural heart disease, and renal impairment (as both drugs are renally cleared) 1.
- The guidelines recommend careful monitoring for QT prolongation and abnormal TU waves, and suggest stopping or reducing sotalol if the QT interval exceeds 500 ms 1.
Recommendations
- Consider alternative antibiotics without QT prolongation effects when possible, such as ceftriaxone or amoxicillin/clavulanate.
- If the combination cannot be avoided, correct any electrolyte abnormalities, monitor QTc intervals regularly, and maintain the lowest effective doses of both medications.
- Close cardiac monitoring with baseline and follow-up ECGs is essential when using these medications together.
From the Research
Interaction between Levofloxacin and Sotalol
- The interaction between Levofloxacin (Levaquin) and Sotalol can increase the risk of QT interval abnormalities, which may lead to torsades de pointes (TdP) 2, 3.
- Fluoroquinolones, including Levofloxacin, can prolong the QT interval by blocking voltage-gated potassium channels, especially the rapid component of the delayed rectifier potassium current I(Kr) 2.
- Sotalol, a class III antiarrhythmic medication, can also prolong the QT interval and increase the risk of TdP 3, 4.
Percentage Chance of QT Interval Abnormalities
- The overall risk of TdP is small with the use of fluoroquinolones, including Levofloxacin 2.
- According to one study, the incidence of QTc prolongation (≥500 milliseconds or ≥15% from baseline) was 57.5% in patients receiving nonstandard dosing of sotalol, which may be relevant to patients taking Levofloxacin concurrently 4.
- However, the exact percentage chance of QT interval abnormalities with the combination of Levofloxacin and Sotalol is not specified in the available studies.
Cause of QT Interval Abnormalities
- The cause of QT interval abnormalities with Levofloxacin and Sotalol is related to the blockade of potassium channels, particularly the I(Kr) channel, which can lead to a prolongation of the QT interval 2, 3.
- Other factors, such as high doses of Sotalol, female gender, age, reduced left ventricular ejection fraction, hypertrophic cardiomyopathy, and loop diuretic co-administration, can also contribute to the increase in QTc interval 3.