Articles: qt-prolongation.
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Drugs can cause prolongation of the QT interval, alone or in combination, potentially leading to fatal arrhythmias such as torsades de pointes. When prescribing drugs that prolong the QT interval, the balance of benefit versus harm should always be considered. Readouts from automated ECG machines are unreliable. ⋯ Changes in heart rate influence the absolute QT interval. Heart rate correction formulae are inaccurate, particularly for fast and slow heart rates. The QT nomogram, a plot of QT interval versus heart rate, can be used as a risk assessment tool to detect an abnormal QT interval.
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Prolongation of the QT interval has been observed with ondansetron and other members of the 5-HT3 antagonist class. This is the first thorough QTc study of ondansetron conducted in accordance with ICH E14 guidelines, designed to investigate the effect of single intravenous (IV) doses of ondansetron on cardiac conduction compared to placebo and a positive control, moxifloxacin, in healthy subjects. ⋯ As a result, single IV doses of ondansetron greater than 16 mg should no longer be used. Adult cancer patients, under 75 years, may receive up to a maximum initial 15-minute IV dose of 16 mg, prior to chemotherapy, followed by 2 additional IV or IM doses of 8 mg for the management of chemotherapy-induced nausea and vomiting (CINV).
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Expert Opin Drug Saf · Oct 2014
Review5-Hydroxytryptamine3 receptor antagonists and cardiac side effects.
5-Hydroxytryptamine3-receptor antagonists (5-HT3-RA) are the most widely used antiemetics in oncology, and although tolerability is high, QTC prolongation has been observed in some patients. ⋯ Most of the studies analyze electrocardiogram (ECG) changes after 5-HT3-RA administrations in healthy, young adults, or in noncancer patients to treat postoperative nausea and vomiting (PONV). Only a few studies have addressed ECG changes in cancer patients treated for chemotherapy-induced nausea and vomiting (CINV). Investigations in cancer patients are essential, because these patients are older and have a higher incidence of comorbidity, than those usually included in clinical trials. Furthermore, polypharmacy is frequent and drug-drug interactions between chemotherapy and other QTc-prolonging drugs may influence the pharmacokinetics and pharmacodynamics of the 5-HT3-RAs. During the next 10 - 15 years a huge increase in the number of cancer patients is expected, primarily in the group of 65-plus-year old. Therefore it will be crucial to address the incidence of cardiac AEs in cancer patients with known heart disease receiving chemotherapy and a 5-HT3 RA for the prophylaxis of CINV.
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Existing formulas for rate-corrected QT (QTc) commonly fail to properly adjust the upper normal limits which are more critical than the mean QTc for evaluation of prolonged QT. Age- and sex-related differences in QTc are also often overlooked. Our goal was to establish criteria for prolonged QTc using formulas that minimize QTc bias at the upper normal limits. ⋯ Sex difference in QTc originates from shortened QT in adolescent males. Upper normal limits for QTc vary substantially by age and sex, and it is essential to use age- and sex-specific criteria for evaluation of QT prolongation.
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Br J Clin Pharmacol · May 2014
High dose droperidol and QT prolongation: analysis of continuous 12-lead recordings.
To investigate the QT interval after high dose droperidol using continuous 12-lead Holter recordings. ⋯ QT prolongation was observed with high dose droperidol. However, there was little evidence supporting droperidol being the cause and QT prolongation was more likely due to pre-existing conditions or other drugs.