What drug interaction typically increases the QT duration?

The proposed cellular mechanism of drug-induced prolonged QT interval involves inhibition of the rapid component of the delayed rectifier potassium current (IKr). Blocking IKr leads to prolongation of the ventricular action potential duration, leading to an excess sodium influx or a decreased potassium efflux.

Which of the following medications are most likely to cause prolonged QT interval and potentially induced Torsades de Pointes?

(A) Self limiting torsades de pointes (TdP). (B) TdP leading to ventricular fibrillation. Many of the drugs that were initially known to prolong the QT interval were antiarrhythmics, and quinidine was the most commonly implicated agent.

Does Cipro prolonged QT interval?

Purpose: Ciprofloxacin may prolong the QT interval and increase the risk of Torsade de Pointes (TdP). Intravenous administration of ciprofloxacin in patients with additional risks may elevate the risk of QTc interval prolongation.

What meds can cause torsades?

Other drugs that prolong the QT interval and have been implicated in cases of torsade include phenothiazines, tricyclic antidepressants, lithium carbonate, ziprasidone, cisapride, highly active antiretroviral drugs, high-dose methadone, anthracycline chemotherapeutic agents (eg, doxorubicin, daunomycin), some …

Does phenytoin cause QT prolongation?

Two previous studies of phenytoin toxicity (with levels as high as 76 µg/mL) did not report any wide complex tachycardias or prolongation of the QRS or QT intervals.

Which medication can cause a prolonged QT interval leading to torsades de pointe a lethal arrhythmia?

Perhaps the most common cardiac side effect of opioids is the prolongation of the QT interval, which can lead to torsades de pointes (TdP), which is a kind of ventricular tachyarrhythmia with the potential of causing sudden death [11-13].

Can doxycycline cause QT prolongation?

Of the macrolides, azithromycin,17, 18 clarithromycin,19, 20 erythromycin21, 22 and roxithromycin23 have all been shown to prolong the QT interval. Doxycycline, a tetracycline antibiotic, should be considered to replace azithromycin or roxithromycin for treatment of atypical pneumonia.

Does metoprolol increase QTc?

Conclusions/interpretation: This study is the first to address the QTc interval and QTc dispersion in Type 1 diabetic patients treated with metoprolol. Beta blocker treatment caused a decrease in QTc interval but no change in QTc dispersion.

Can doxycycline prolong QTc?